A host server is configured to switch communications associated with an account between first and second mobile devices. The server stores a mapping of the account to a first PIN which identifies the first mobile device, and communicates messages via a wireless network based on the stored mapping using the first PIN for data synchronization therebetween. The server then receives a request for device switching. In response, the server switches the mapping of the account to a second PIN which identifies a second mobile device, and communicates messages via the wireless network based on the switched stored mapping using the second PIN for data is synchronization therebetween. The mapping of the account to the first PIN may be maintained even after switching the stored mapping to the second PIN, for a subsequent request for switching back to the first mobile device for the account.

1. Field of the Technology
The present disclosure relates generally to mobile communication devices which operate in wireless communication networks, and more particularly to methods and apparatus for switching user account data and operations from one mobile communication device to another mobile communication device.
2. Description of the Related Art
A mobile communication device, such as a mobile station, may be adapted to communicate with other devices via wireless radio frequency (RF) signals through a wireless communication network. Such a mobile communication device may be further operative to maintain data synchronization with a host server over the wireless communication network for user data of an application program associated with a user account. The application program may be or include, for example, an electronic mail (e-mail) application program for the communication of e-mail messages. For the data-synchronized communications, the host server maintains storage of a mapping of a user account name or identifier of the user account with a personal identification number of the mobile communication device. When communications are required with the mobile communication device, the personal identification number of the mobile communication device is used to route the messages to/from the device through the system.
Today, it is not uncommon for an individual to possess or own two different mobile communication devices for different uses. For example, the end user may desire to use a business model in the office during the weekdays (e.g. a mobile device having a QWERTY keyboard for e-mail communications), but may alternatively desire to use a consumer model over the weekend (e.g. a mobile device having a Suretype keypad and camera) while staying in touch with the office via e-mail. Thus, it is desirable that an end user be able to utilize one of two different mobile devices for the data-synchronized communications associated with the user account.
If switching of communications associated with user account were possible, it would be desirable that this device switch take less time than when performing a full backup/restore operation via a desktop manager on a computer. Wired connections between any of the mobile devices and any computer or server would be undesirable, as it would be most preferable that the end user could simply carry the two mobile devices on his person and perform the switch at any time. Further, the end user should not need to obtain an "out-of-band" user name and password from the network administrator to activate on the new mobile device. It would also be preferable that the new mobile device be automatically provided with a valid set of encryption/decryption keys for the data-synchronized communications, and this key transfer should occur through secure means. Settings that are specific to a mobile device, such as display, profile, owner info, and theme settings, must be preserved. The SIM card may or may not need to be transferred, as the end user may wish to make voice and data connections on a company SIM card regardless of the device utilized or alternatively on a personal SIM card outside of business hours per company policy.

Methods and apparatus for use in switching user account data and operations between two different mobile communication devices


A paper feeding system which comprises a paper rest rotatable around a support shaft provided on a main body; a pressure spring for pushing the paper rest to rotate toward a paper feed roller located above the paper rest; a baffle plate for preventing paper from shifting forward, provided on the main body at a position juxtapositioned to the leading end of the paper rest, with a clearance to allow the paper rest to rotate about the support shaft; paper stop ribs projecting from the surface of the baffle plate and running in the direction of the rotation of the paper rest; and notches formed in the leading end with respect to the paper feeding direction of the paper rest, permitting the ribs to interlock in the notches when the paper rest is rotated.

The present invention relates to a paper feeding system, and more specifically to a paper feed system for a shredder which contains a baffle plate for preventing paper from shifting forward.
The conventional shredder contains a paper rest on which to place a stack of papers, paper feeding means for supplying paper from the paper rest separately one by one, a transport block for leading the paper to a shredding cutter, and a reservoir for temporarily storing the shredded paper.
However, none of the conventional shredders has been provided with a means that effectively prevents effectively paper from clogging the paper feeding means.


A pair of second cameras mounted on a robot are located in front of, and symmetrically with respect to the center of a wheel hub of a vehicle, according to approximate coordinates of the center of the wheel hub calculated from an image of the wheel hub taken by a first camera. Revised coordinates of the center of the wheel hub, a rotational displacement from a standard rotational position of the wheel hub, and a turning angle of the wheel hub toward the right or left with respect to a progressive direction of the vehicle are calculated from the images obtained by the second cameras. A wheel is then automatically mounted to the wheel hub by the robot, according to the results of calculation.

1. Field of the Invention
The present invention relates to a method of automatically mounting a wheel to a wheel hub of a vehicle being conveyed along an assembly line, by detecting the center of the wheel hub, angular positions of hub bolts and a turning angle of the hub face.
2. Description of the Related Art
An automatic assembly system for mounting parts to a vehicle being conveyed on an assembly line by industrial robots has been progressing in the motor manufacturing industry. There, a method of acquiring information about images of wheel hubs, taken by cameras each having a charge-coupled device (CCD) has been employed in a wheel mounting robot for automatically mounting wheels to their corresponding wheel hubs. According to the method, the positions of hub bolts are detected by computation from the read image information.
However, in this type of detecting method, as it is difficult to locate the CCD cameras in the vicinity of the wheel hubs, the image of each wheel hub cannot be closed-up to the maximum on the screen. Therefore, the positions of the hub bolts cannot be detected with satisfactory accuracy.
On the other hand, a technical idea that a computational process is effected on read image to thereby improve the accuracy in the detection of respective positions of hub bolts, has been disclosed in Japanese Patent Application Laid-Open Publication No. 1-145288 entitled "A Method of Mounting Wheels To Vehicle", for example.
According to the above disclosure, information about images of respective wheel hubs is taken by cameras and information on a plurality of points recognized as hub bolts are detected or extracted from the images taken by the cameras. Then, recognized points identical in number to the hub bolts to be mounted are selected from the detected points. Further, a polygon formed by connecting the selected recognized points to each other by straight lines is compared with an array pattern of a predetermined polygon used as the standard. Thereafter, a combination of recognized points whose errors are held to the minimum is specified as the positions of the hub bolts.
In the conventional vehicle-wheel mounting method, however, often, when a hub face is not parallel with a reference face, the position of each hub bolt cannot be detected. When the number of hub bolts varies, i.e., when the kind of a vehicle to be assembled is changed, the method cannot rapidly meet such a situation.
Further, all the recognized points which have been detected, must be combined to produce polygons, and each of the produced polygons must be compared with the standard polygon. Therefore, the conventional wheel mounting method is time-consuming for their computation, and thus, has suffered from low productivity.


Systems for providing electrical power to one or more wind turbine electrical components is provided comprising an electrical grid and an auxiliary power source for providing electrical power, and one or more wind turbines. Each of the wind turbines includes a wind turbine generator, one or more electrical components, a main voltage transformer for connecting the wind turbine generator to the grid and a switchgear arranged between the main voltage transformer and a point of connection to the grid. One or more switches for alternately connecting either said electrical grid or said auxiliary power source to the switchgears of the wind turbines are provided. The switchgears comprise a switchgear voltage transformer, the switchgear voltage transformer includes primary and secondary windings, the primary windings receiving power from the electrical grid or auxiliary power source, and the secondary windings delivering electrical power to the wind turbine electrical components.

Wind turbines may be arranged together forming a wind park, with a single point of connection, i.e. the PCC ("Point of Common Coupling"). Wind parks may comprise a substation including e.g. wind park transformers that convert power from the wind park voltage to a grid voltage. Such a substation may further include wind park control systems e.g. a supervisory control and data acquisition system (SCADA).
Wind parks may be arranged on land ("onshore"), or in the water ("offshore"), either as a plurality of floating wind turbines or wind turbines on pillars fixed in the sea bed.
It is known to provide an auxiliary power source, such as e.g. a diesel generator for supplying power to wind turbines when a connection with the grid is lost. Connection with the grid may be lost during planned maintenance, or during installation, but also during normal operation in case of a problem in the grid.
In a wind turbine, electrical components may be categorized into three levels, as follows: Level 1 electrical components are those components which are considered critical. These level 1 components are required to operate continuously, even during stand-by situations, i.e. when a wind turbine is disconnected from the electrical grid, and no electrical power is thus available.
Level 1 components may include components related to communication, and control and manoeuver of the gas insulated switchgear (GIS). It may further include air conditioning systems, sensors, PLCs, beacons and protective systems among others. The power required for these components may e.g. be around 15 kVA.
Level 2 electrical components may include those components which are less critical; these components may be required to operate only occasionally during stand-by situations. Level 2 components may include lubrication pumps, lighting systems, the service lift, pitch and yaw systems among others. The power required for these components may amount to e.g. around 30 kVA.
Finally, level 3 electrical components may not be required to operate during stand-by situations. Level 3 components may include e.g. cooling fans and pumps among others.
So at least for the level 1 components and at least occasionally for the level 2 components, electrical power supply must be available even in case of grid loss.
A plurality of auxiliary power generators, e.g. diesel generators, may be installed at individual wind turbines to be able to supply power to each wind turbine individually. If an auxiliary power generator is provided for each individual wind turbine, a problem is the high cost involved.
Alternatively, at least one more powerful auxiliary power generator may be provided at the central substation supplying all wind turbines simultaneously. If one auxiliary diesel generator is provided for a wind park, the logistics involved in providing fuel to each of the generators can be troublesome, in particular in the case of an offshore wind park.
Having a single more powerful auxiliary diesel generator providing electrical power to all wind turbines in the case of grid loss however may also have other disadvantages. One technical problem may be that the auxiliary diesel generator is over-dimensioned to take into account the in-rush of current at start-up, and the power losses associated with the reactive loads on the one or more transformers within each wind turbine.
One known approach is represented in FIG. 1. Reference sign 100 indicates the electrical grid, and reference sign 200 refers to an auxiliary power generator, for example a diesel generator. A switch 150 may be provided to alternatively connect the wind turbines either to the electrical grid or to the auxiliary power generator.
Each wind turbine may comprise a circuit breaker, which is commonly arranged in a gas insulated switchgear 900 for power ranges relevant to this sort of implementation, and a main wind turbine transformer 300. The main transformer may convert power from 66 kV as delivered from the grid or from the auxiliary power generator to 0.9 kV, the voltage level of the generator 600 of the wind turbine. The rating of the main transformer may be e.g. 6500 kVA.
A secondary wind turbine transformer 400 will further transform the power from 0.9 kV to the voltage level required by the electrical components of the wind turbine, such as e.g. lighting systems, pitch systems, pumps, cooling fans, etc. This voltage level may be 0.4 kV. The rating of the secondary wind turbine transformer may be e.g. 200 kVA in order to be able to feed electrical components of all levels (levels 1, 2 & 3).
The electrical components may be divided into level 1 components 800, which always need power supply and for which an interruption of the operation cannot be accepted and level 2 and 3 components 700, for which interruption of the operation is not necessarily problematic. To this effect, an uninterruptible power supply 500 (UPS) may be added to the level 1 critical electrical components' circuit. Additionally, circuit breakers may be arranged both for the level 1 circuit and for the levels 2 and 3 components. The circuit breaker 250 may be opened in case of grid loss, and only selectively closed so that only power is delivered to those components when needed.
In the event of an interruption of the power supply from the main grid 100, the uninterruptable power supply associated with the level 1 critical electrical components may continue to function for e.g. approximately 30 minutes. However beyond these 30 minutes, the auxiliary power generator will have to deliver the required power via the transformers.
At least one problem related with this kind of arrangement is the major power losses in the main transformer 300.
In examples of the present invention, at least some of the aforementioned problems are at least partially resolved.

System for providing electrical power to a wind turbine component


A method for storing data in a memory may include when the data may be obtained under a variable condition, determining a cell corresponding to an area of the variable condition from an entire memory area, storing the data in the cell and dividing the cell storing the data into a plurality of cells, and whenever a new data may be obtained under a new variable condition, determining a new cell corresponding to an area of the new variable condition under which the new data may be obtained, from the plurality of cells of the entire memory area and repeating storing of the new data and dividing of the new cell.

1. Field of the Invention
The present invention relates to a method for storing data in a memory. More particularly, it relates to a method for storing data in a memory, which can efficiently store a learning value, calculated based on each variable condition by a control unit of a vehicle, in a memory area.
2. Description of Related Art
In general, a control hydraulic pressure, a major parameter for controlling an automatic transmission, is determined as a function such as a vehicle speed, oil temperature, input torque, etc. and is controlled to an appropriate hydraulic pressure by controlling a solenoid valve based on the determined value during speed change.
However, this data is determined to obtain the best result in a normal transmission having a central hydraulic deviation, and the distribution of hydraulic pressures in a large number of mass-produced transmissions cannot be covered only by the normally determined value.
To overcome this problem, a transmission control unit (TCU) of the vehicle typically performs a learning control to calculate an offset value with respect to a hydraulic pressure value under each condition, thus achieving a predetermined target shift feeling under each operating condition.
The learning control in the vehicle is performed by the control unit under certain rules to optimally control the transmission, engine, etc., based on a driver's driving habit or tendency. During operation of the vehicle, when a predetermined learning condition is satisfied, a series of processes of calculating, storing and controlling a learning value are performed.
Also, in the control of the engine using a plurality of sensors, an engine control unit (ECU) controls the injection time (i.e., fuel amount) of an injector using self-learning data, thus optimally controlling the injector. Here, the control values according to sensor values are appropriately compensated by the learning.
For example, the learning control is used in air-fuel ratio correction, knocking correction, idle RPM correction, Throttle Position Sensor ("TPS") deterioration correction, etc., and the learning control is performed by slightly adjusting the information in a lookup table of the ECU.
Meanwhile, in order to perform the above-described learning control in the vehicle, a process in which a microprocessor of the control unit stores the learning value, calculated under each condition, in a specific area of a memory in real time, is required. Here, the memory area in which the learning value is to be stored is determined based on the conditions (such as various sensor values as parameters or other operating conditions) and then stored in the corresponding memory area.
However, conventionally, the storing of the learning values has the following drawbacks.
For example, in the case of the transmission control unit, it is very difficult to differentiate the conditions such as the vehicle speed, oil temperature, input torque, etc., under which the learning values are stored, due to limitations in the capacity of the internal memory for storing the learning values. Accordingly, a learning memory of 4×4 or 6×6 in size is typically used with respect to a single shift class.
Here, the same learning cell in the memory is shared under slightly different conditions, and thus different learning values calculated under different conditions may be stored in the same learning cell. As a result, the accuracy is significantly reduced when the stored learning values are applied to the corresponding control.
Therefore, when a memory having a very large capacity is used, it is possible to determine a learning value storing area with an increased size (e.g., 1000×1000 cells) for storing the learning values, but the number of learning times increases geometrically, which significantly reduces the speed of storing the learning values, thereby reducing the convergence efficiency of the learning values.
FIG. 1 is a diagram showing a conventional method for storing learning values, in which a learning value storing area of a memory is divided into a plurality of virtual cells, and the problems associated with the conventional method will be described in more detail with reference to FIG. 1 below.
Typically, in the control unit of the vehicle such as the Engine Control Unit ("ECU"), Transmission Control Unit ("TCU"), etc., the learning values are stored in a memory having a predetermined cell capacity (m×m). When a learning value data under each condition is obtained while a virtual memory space, in which the learning value data is to be stored, is divided into a plurality of predetermined cells, the learning value data is stored in a cell at a position corresponding to the condition.
Referring to FIG. 1, it can be seen that the memory area is pre-divided into a plurality of cells according to X and Y conditions. When a learning value according to the X and Y conditions is obtained, a cell at a position corresponding to the X and Y conditions is determined (i.e., a learning value storing area is determined), and the learning value is stored in the corresponding cell.
Here, in a state where the learning value is pre-stored in a specific cell under the same condition, if another learning value under a slightly different condition is obtained, the obtained learning value is overwritten in the same cell.
That is, even when different learning values A, B and C under different X and Y conditions are obtained, if the X and Y conditions, under which learning values A, B and C are obtained, are designated to the same unit cell area, the last learning value (e.g., learning value C) is overwritten in the previous learning value (e.g., learning value B) stored in the same cell without distinguishing the conditions.
To solve this problem, it is necessary to subdivide the learning cell into a plurality of smaller cells such that the learning values obtained under different X and Y conditions can be stored in the respective areas. However, if the number of cells increases, a significant number of learning times is required to store the learning values in the respective cells.
For example, if the memory area is divided into 1,000,000 virtual cells, at least 1,000,000 learning times are required.
As such, in order to store most of the learning values obtained under various conditions in the respective areas of the learning memory corresponding to the respective conditions, it is necessary to further subdivide the storing areas of the learning memory divided for the respective conditions (i.e., an increase in m). If so, a significant number of learning times is required to store all of the learning values in the subdivided memory areas, and thus significantly reducing the convergence efficiency of the learning values.
To improve the efficiency of storing the learning values, it is necessary to reduce the number of cells divided in the learning memory. However, if so, the learning values obtained under slightly different conditions are stored in the same learning memory area (i.e., the same learning cell) by overwriting as mentioned above, and thus the difference between the conditions is not distinguishable from the stored learning values.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.


A switchover system and method is described. The invention preferably operates in a data packet switching system for transmitting through a switching arrangement data packets that comprise at least a data packet identifier. The switching arrangement comprises at least an active switch card associated to a backup switch card. And the active switch card and the backup switch card receive simultaneously at least a data packet and transmit it to a network adapter device. The switchover system comprises active and backup means for respectively storing at an active and backup data packet address the transmitted at least data packet. It also comprises switchover detecting means coupled to the active and backup storing means for detecting a switchover event, and control means coupled to the active and backup storing means and to the switchover detecting means for setting the backup storing means when a switchover event is detected.

Local Area Networks (LAN) such as Ethernet or token-ring networks, are generally interconnected through hubs. The hub is a system made of LAN adapters that communicate together through a switch card containing a switch engine. Such a switch engine can be either a shared memory switch or a crossbar switch.
The shared memory switch is a device wherein the data packets received by the input ports are stored into a memory at address locations determined by queues containing the packet destination addresses; the packets to be transmitted on the output ports as the destination addresses are de-queued.
Although such a switch enables the transfer of data packets it may present a bottleneck due to the hardware requirement of the many output ports, and may stop the data packet transfer from one adapter to another one due to hardware failure. In this particular case all data packets stored in the switch memory will be lost. This particular failure will have an impact on data transfer and on customer applications at the end of the adapter.
Any hardware failure on any switch system is damageable on the data packet transfer, and one of the solutions to prevent any hardware failure is to duplicate the switch system.
This solution consists of having duplicated synchronized switch cards, where one switch is active and the other one is backup. Both switches operate in parallel meaning that they receive/transmit the same data packets from/to the LAN adapters and receive the same commands issued from a Control Point of the switching system. When the active switch receives a switchover command from the Control Point, the active switch stops transferring data to the adapter. At the same time the backup switch receiving the same command becomes the active switch for all the attached adapters and takes over the data transfer. The major problem of those existing active/backup switches configurations is the loss or the duplication of data packets during the switchover operation, because the two switches are not in reality fully data packet synchronized.
Therefore there is a need for a switchover system that avoids loss or duplication of data packets during the switchover process.

Switchover system and method in a data packet switching network

International Business Machines Corporation


An inductor comprises a drum core which comprises a sintered magnetic material and has a winding axis and a pair of collars in a plate shape provided on both ends of the winding axis. The inductor further comprises a coil conductor wound on the winding axis of the drum core, the coil conductor is covered on an outer periphery thereof with a composite magnetic material in a sheet form containing a resin and magnetic powder, and the composite magnetic material in a sheet form is adhered to the outer periphery of the coil conductor except at least for inner surfaces of the pair of collars of the drum core facing each other.

1. Field of the Invention
The present invention relates to an inductor used in various kinds of compact thin electronic equipments, and a method for producing the inductor, and more specifically, the invention relates to an inductor having a structure containing a coil conductor wound on a drum core and a composite magnetic material in a sheet form covering the outer periphery of the coil conductor, and a method for producing the inductor.
2. Description of Related Technology
An inductor using a drum core generally has a magnetic material covering an outer periphery of a coil conductor wound on the drum core in order to meet requirement on producing electronic equipments having a small size and a low profile. For example, JP-A-9-120926 proposes an inductor 110 shown in FIGS. 13A and 13B produced in such a manner that a coil wire 113 wound in a hollow shape is placed to straddle on a pair of lead frames 116a and 116b, a lead end and a tail end of the coil wire 113 are conductively connected to the lead frames 116a and 116b, respectively, and a magnetic powder molding material 111 containing magnetic powder and a resin is molded under pressure onto the periphery of the coil wire 113. JP-A-2001-185421 proposes a magnetic device 210 (220) shown in FIGS. 14A and 14B produced in such a manner that magnetic members 212a, 212b and 212c (222a, 222b and 222c) formed, for example, of a ferrite sintered body are placed in a drum form, a coil conductor 213 (223) is wound on the magnetic member 212c (222c) in a rod shape, and the members are embedded in a composite magnetic member 211 (221).
In recent years, there are increasing tendencies of decrease in size and thickness of electronic equipments. Accordingly, an inductor having a small size and a low profile is demanded for the electronic equipments. However, a composite magnetic material containing a resin and magnetic powder can provide an apparent magnetic permeability μ′ of only about 10. Therefore, there is such a problem that the inductor 110 disclosed in JP-A-9-120926, in which the circumferences, including the inner circumference, of the wire coil 113 in a hollow shape are surrounded with the magnetic powder molding material 111 having a low magnetic permeability cannot provide a high inductance unless the number of turns of the wire coil is increased.
In the magnetic device 210 disclosed in JP-A-2001-185421, the composite magnetic member 211 containing a magnetic powder and a thermosetting resin is adhered to the magnetic member 212 corresponding to the collar of the drum core. Accordingly, a large residual stress remains inside the magnetic member 212 due to hardening of the resin contained in the magnetic member 211, so as to have such a problem that the apparent magnetic permeability μ′ of the magnetic member 212 is decreased due to the presence of the residual stress to fail to provide a high inductance. Furthermore, there is another problem that a difference in linear expansion coefficient occurring between the composite magnetic member 211 and the magnetic member 212 formed, for example, of a ferrite sintered body induces cracks in the magnetic member 212 associated with an internal stress formed upon reflow soldering or a heat cycle test and the aforementioned residual stress.

Inductor using drum core and method for producing the same


A conveyor roller cleaning device is mounted on the body of an image forming apparatus for cleaning the peripheral surface of a conveyor roller rotatably mounted on the body of the apparatus. The device includes an elastic member adapted to be pressed into contact with the roller, an attaching member provided at the tip end thereof with the elastic member, a drive source for driving the roller and drive control device for controlling the drive source. The attaching member is rotatable around the base end thereof between a setting position in which the elastic member is pressed into contact with the roller and a retreat position in which the elastic member is retracted away from the roller. The attaching member is maintained at the setting position by a reaction force corresponding to the pressing-contact force of the elastic member to the roller. The drive control device is adapted such that, before paper to be conveyed reaches the roller, the roller is rotated in a predetermined direction for a predetermined period of time to produce, between the peripheral surface of the roller and the elastic member, a frictional force by which the attaching member is biased toward the setting position.

The present invention relates to a conveyor roller cleaning device in which an elastic member is adapted to be pressed into contact with a conveyor roller for cleaning the same.
Generally, an image forming apparatus, such as a copying machine or the like, incorporates a conveyor roller cleaning device for cleaning a conveyor roller disposed in a paper conveyor unit for conveying a transfer sheet. In such a conveyor roller cleaning device, an elastic member is pressed into contact with the conveyor roller at the peripheral surface thereof, thus removing paper powder sticking to the conveyor roller.
This elastic member is attached to the tip end of an attaching member which is rotatable around its own base. When set to a setting position, the attaching member causes the elastic member to be pressed into contact with the conveyor roller. The attaching member set to the setting position, is maintained thereat by a reaction force corresponding to the pressing-contact force of the elastic member toward the conveyor roller.
In the conveyor roller cleaning device, at the time of clearing a jam or other maintenance processing the attaching member is rotated from the setting position and retracted to a retreat position where the attaching member does not get in the way of the maintenance processing.
However, there are instances where the attaching member is not securely set to the setting position after the maintenance processing has been executed with the attaching member moved to the retreat position. More specifically, although it is required that a predetermined pushing force to the attaching member in order to resist a reaction force be applied corresponding to the pressing-contact force for pressingly contacting the elastic member to the conveyor roller, the service engineer often fails to do so.
If the attaching member is not securely set to the setting position after completion of the maintenance processing, it is not assured that a sufficient pressing-contact force of the elastic member to the conveyor roller is provided. This results in poor cleaning. Such poor cleaning may take place not only after the maintenance processing has been executed, but also when the attaching member is not securely set.


An airbag module for a vehicle includes a gas generator for generating a gas and a multi-chamber airbag operatively connected to the gas generator for receiving the gas. The airbag defines a first inflation chamber, at least one second inflation chamber, at least one third inflation chamber and a fourth inflation chamber. The airbag includes internal vents configured to allow selective communication between the first chamber and each of the at least one second chamber and the at least one third chamber and selective communication between the at least one second chamber and the fourth chamber. The internal vents are configured to maintain a higher pressure in selective chambers by restricting ability of the gas to escape the selective chamber. The order of internal venting between the respective inflation chambers controls the pressure and timing of inflation of the multi-chamber airbag.

Exemplary embodiments herein relate to motor vehicle supplemental restraint systems, and more particularly, to a multi-chamber knee airbag for protecting an occupant from colliding with an object such as an interior panel in front of a seat in the event of a vehicle collision.
Vehicles generally provide some kind of supplemental restraint system. Often, these supplemental restraint systems take the form of inflatable devices or restraints. In some cases, an inflatable restraint system includes a leg protection device having an airbag deployed in front of the vehicle occupant to receive the legs of the occupant in the event of a vehicle collision so as to protect the vehicle occupant.
In one known leg protection device, a single chamber is formed inside the airbag. The occupant sitting on a vehicle seat may assume various sitting postures, for example, with knees apart and/or with legs extending sideways. The positions of the knees may be often spaced apart from a center of the seat. Therefore, the airbag of the leg protection device is designed to rapidly spread in the vehicle lateral direction after start of inflation. Having a single chamber, a dimension of the inflated airbag in a vehicle longitudinal direction (hereinafter, sometimes referred to as a thickness of an airbag) tends to be large. Therefore, sufficient inflation of the airbag can provide a large thickness for receiving the occupant's legs. However, if the airbag is designed to expand laterally as well, the inflation volume can become so large that a gas generator or inflator having a significantly large generating capacity is required.
In another known leg protection device, the airbag includes multiple chambers which are separated by partitions formed inside the airbag. The partitions have through ports or holes for the gas to flow between the chambers. Since the multi-chamber airbag has a relatively large volume, the gas generator is required to have a large capacity to quickly inflate the chambers located on a periphery of the airbag, resulting in relatively poor gas efficiency. Further, it can be difficult to control stiffness of different sections of the known airbag for different sized occupants.


The present invention provides a lacrimal duct tube that can be preferably used for the treatment of lacrimal duct obstruction, in particular, sheath guided endoscopic probing having been frequently performed in recent years, the lacrimal duct tube being excellent in passage through a lesion in the lacrimal duct, operability in the lacrimal duct, and manipulation of the endoscope inserted into the lumen of the tube, and providing a sufficient viewing field of the endoscope. The present invention relates to a lacrimal duct tube, including: a pair of tubular members that each has an opening at one end and a hole in a side wall communicating with a lumen; and a connection member that connects other ends of the tubular members, wherein the tubular members each include a plurality of resin portions different in Shore hardness, at least one of the resin portions is positioned between the opening and the hole and forms a lumen wall of the tubular member, and the lumen wall has a Shore hardness of 57D or more.

Treatment methods for lacrimal duct obstruction resulting in epiphora include: (i) probing by a lacrimal duct bougie, (ii) placement of a lacrimal duct tube; (iii) dacryocystorhinostomy (DCR); (iv) lacrimal canaliculization; (v) nasolacrimal duct plastic surgery; (vi) lacrimal caruncle moving surgery, and the like.
The probing by a lacrimal duct bougie in (i) is intended to insert a narrow tube called bougie into a lacrimal duct to open an obstructed site and reconstruct a flow path for a lacrimal fluid. This method is conducted as a first treatment in many cases due to its ease of execution and minimal invasiveness. The treatments (iii) dacryocystorhinostomy (DCR), (iv) lacrimal canaliculization, (v) nasolacrimal duct plastic surgery, and (vi) lacrimal caruncle moving surgery are highly effective but relatively invasive because of the need for creation of incisions in a patient's face or drilling holes in bones, and thus are conducted as a last resort.
Lacrimal duct tube for use in the treatment method (ii) is, after the probing by a lacrimal duct bougie (i), placed for maintaining of a flow path and reconstruction of tissues. The placement of a lacrimal duct tube (ii) is easy, less invasive, and highly effective as compared to the foregoing treatment methods (iii) to (vi), and thus is widely performed all over the world. Among such instruments, there is widely available a lacrimal duct tube in which a central part of the tube is formed by a narrow and soft tube or rod and both sides of the tube are formed by hard and thick tubes, as disclosed in Patent Document 1 (for example, refer to FIG. 1).
The lacrimal duct tube includes a tube and a pair of bougies that is inserted from incisions at both sides of the tube, and the bougies are operated to guide the tube into a lacrimal duct and place the tube there. As shown in FIG. 2 of Patent Document 1, a lacrimal duct is formed by lacrimal puncta (21 and 22), lacrimal canaliculi (23 and 24), a lacrimal sac (26), a nasolacrimal duct (27), and others. The lacrimal duct tube is inserted into the lacrimal duct.
However, to insert the lacrimal duct tube, it is necessary to fumble for intra-lacrimal duct operations. The bougies are blindly operated and thus may break through the tube or make a hole at a site other than in the normal lacrimal duct (creating a temporary path), which results in poor therapeutic outcomes. Accordingly, to solve the foregoing problem, the inventor of the present invention has suggested in the past a lacrimal duct intubation instrument in which an opening is formed at the tip of lacrimal duct tube, a reinforcement body is arranged and held in the vicinity of the opening, and the position of the reinforcement body is adjusted within a predetermined distance from the opening (refer to Patent Document 1).
In the recent year's field of lacrimal duct obstruction treatment, surgeries have been newly conducted based on a sheath guided endoscopic probing. At these surgeries, a sheath as an outer casing made of Teflon (registered trademark) or polyurethane covering a lacrimal endoscope was advanced ahead of the lacrimal endoscope in the lacrimal duct to observe from behind that the tip of the sheath opens the obstructed site in the lacrimal duct. This technique is also excellent in allowing exact tube insertion by using the sheath as a guide for tube insertion. Specifically, as shown in FIG. 11(a), a sheath 30 attached to a lacrimal endoscope 29 is inserted into an obstructed site 32 in the inferior nasal meatus 28 of the lacrimal duct 31 from the upper lacrimal punctum 21 through the upper lacrimal canaliculus 23 and passed through the obstructed site 32, and then the lacrimal endoscope 29 is removed. Next, as shown in FIG. 11(b), a lacrimal duct tube 33 is connected to the sheath 30, and the sheath 30 is pulled from the side opposite to the connection side of the lacrimal duct tube 33 to let the lacrimal duct tube 33 pass through the lacrimal duct 31. Then, as shown in FIG. 11(c), the sheath 30 is removed to place the lacrimal duct tube 33 in the lacrimal duct 31.
Next, although not shown, a sheath 30 different from the sheath 30 attached to the lacrimal endoscope 29 is inserted into the obstructed site 32 in the inferior nasal meatus 28 of the lacrimal duct 31 from the lower lacrimal punctum 22 through the lower lacrimal canaliculus 24 into which the lacrimal duct tube 33 is not inserted, and after the sheath 30 is passed through the obstructed site 32, the lacrimal endoscope 29 is removed. Then, an end of the lacrimal duct tube 33 not passing through the obstructed site 32 is connected to the sheath 30, and the sheath 30 is pulled from the side opposite to the connection side of the lacrimal duct tube 33 to let the other end of the lacrimal duct tube 33 pass through the lacrimal duct 31. Finally, the sheath 30 is removed to place the lacrimal duct tube 33 in the lacrimal duct 31.
However, according to the foregoing method, there is the need for a step of connecting the sheath inserted into the patient's lacrimal duct to the lacrimal duct tube. In addition, occurrence of the disconnection may result in an unsuccessful surgery. Thus, there is room for improvement in the method to secure manipulation of the instruments and reduce complexity of the operation.
Meanwhile, instead of using such a sheath, a lacrimal endoscope may be inserted into a lacrimal duct tube. For example, as lacrimal duct tubes usable with a lacrimal endoscope therein, there are known: 1) a lacrimal duct intubation instrument as described in Patent Document 1 that has an opening at the extreme end of a lacrimal duct tube and a reinforcement body arranged and held in the vicinity of the opening, the position of the reinforcement body being adjusted to be at a predetermined distance from the opening; and 2) a lacrimal duct treatment tool including a lacrimal duct placement main body that has an outer diameter allowing insertion into the lacrimal duct and is formed from a flexible material and a sheath part composed of a flexible cylindrical body that is provided at the lower end of the lacrimal duct placement main body and is formed from a harder material than that for the lacrimal duct placement main body (refer to Patent Document 2).
However, in the case of using the sheath guided endoscopic probing, the 1) lacrimal duct intubation instrument has a complicated tube structure, and the reinforcement body cannot be significantly smaller in diameter, and the extreme end of the tube is difficult to harden and thus tends to be slightly weak in pressing force (pushability). In addition, when performing operations with the 1) lacrimal duct intubation instrument, it is necessary to carefully operate the endoscope inserted into the tube because friction between the lacrimal duct tube and the endoscope becomes large.
The 2) lacrimal duct treatment tool is entirely long, which tends to make it difficult to perform smooth operations in general. In addition, it is necessary to separate the lacrimal duct treatment tool main body and the sheath part after placement of the tool in the lacrimal duct.


(i) As a primary reaction, m-cresol is allowed to react with propionaldehyde in the presence of an acid catalyst and thereby yields a polymer having a weight average molecular weight Mw of 200 to 500 and a molecular weight distribution Mw/Mn of 1.7 or less, and (ii) as a secondary reaction, the polymer is allowed to react with 3,4-xylenol and formaldehyde and thereby yields a novolak resin having an Mw of 1000 to 20000. By adding a specific photosensitizer, the novolak resin yields a positive photoresist composition.

1. Field of the Invention
The present invention relates to a novolak resin that exhibits excellent sensitivity, definition and short margin (the difference between optimum exposure time period Eop and minimum exposure time period Es) and is advantageously used in positive photoresist compositions for i-line lithography, as well as to a production process of the novolak resin and to a positive photoresist composition using the novolak resin.
2. Description of the Related Art
As positive photoresist composition for i-line (365 nm) lithography, compositions each comprising an alkali-soluble novolak resin and a 1,2-naphthoquinonediazido-group-containing compound are excellent in sensitivity, definition and heat resistance and are widely used in, for example, the manufacture of semiconductor integrated circuits (ICs).
The density of such ICs becomes denser and denser with advance of semiconductor technologies, and demands have been made on photoresist materials that can form ultrafine resist patterns of not more than half a micron with good shapes.
Such photoresist materials should have a higher sensitivity to improve throughput and should have a satisfactory short margin (Eop-Es) to improve yields.
The short margin (Eop-Es) is the difference between the minimum exposure time period (Es) to reproduce separated resist patterns and the exposure time period (Eop) to reproduce patterns in exact accordance with set dimensions of a mask pattern. A larger short margin means a smaller change rate in pattern dimensions depending on exposure conditions. Photoresist materials having a larger short margin exhibit improved yields and are easy to handle.
However, conventional positive photoresist compositions do not satisfy all the required characteristics including sensitivity, definition, short margin and pattern shape upon the formation of ultrafine resist patterns of not more than half a micron. For example, positive photoresist compositions exhibiting a higher sensitivity may cause reduced resist films after development and may have an insufficient definition, pattern shape and short margin. In contrast, those exhibiting a higher definition may have a deteriorated sensitivity.
Conventional alkali-soluble novolak resins for use in the positive photoresist compositions are generally prepared using two or more types of phenols as raw materials. Among them, novolak resins prepared by using m-cresol and p-cresol as essential ingredients are excellent in balance between sensitivity and definition and are widely used.
However, p-cresol is a monomer having low reactivity, and a substantial portion of p-cresol used in the reaction remains as unreacted monomers or as dimers, trimers and other low molecular weight fractions in the resulting product resin, and these substances cause scum in patterning of resists and cause deteriorated the characteristics as the resist.
For these reasons, resist compositions containing novolak resins prepared by using highly reactive 3,4-xylenol instead of lowly reactive p-cresol have been proposed.
For example, Japanese Patent Laid-Open No. 4-365046 discloses a positive photoresist composition comprising a novolak resin and a naphthoquinonediazidosulfonyl ester having a specific structure. The novolak resin is obtained by condensation of formaldehyde with phenols including m-cresol and at least one selected from p-cresol, xylenols and trimethylphenols.
Japanese Patent Laid-Open No. 5-88364 discloses a positive photoresist composition containing a novolak resin prepared by polycondensation of formaldehyde with a phenol mixture comprising 5% to 50% by mole of 3,4-xylenol and 95% to 50% by mole of m-cresol.
Japanese Patent Laid-Open No. 5-204146 discloses a positive photoresist composition containing a polycondensation product (a novolak resin) of an alkyl-substituted phenolic compound with an aldehyde mixture containing formaldehyde and a lower-alkyl-group-containing aldehyde, such as propionaldehyde. The molar ratio of formaldehyde to the lower-alkyl-group containing aldehyde in the aldehyde mixture is 1/99 to 99/1.
Japanese Patent Laid-Open No. 8-234420 mentions a positive photoresist composition containing an alkali-soluble novolak resin that has a weight average molecular weight Mw of from 2000 to 15000 and is prepared by reaction of m-cresol, 3,4-xylenol and formaldehyde in xcex3-butyrolactone.
These conventional photoresist compositions are, however, still insufficient in the aforementioned required characteristics upon the formation of ultrafine resist patterns of not more than half a micron, although they are suitable for the formation of patterns of about 0.6 xcexcm.
Accordingly, an object of the present invention is to provide a positive photoresist composition that satisfies all the required characteristics of sensitivity, definition, short margin and pattern shape even in the formation of ultrafine resist patterns of not more than half a micron.
Another object of the present invention is to provide a novolak resin that is suitable for the preparation of the positive photoresist composition, and a process for producing the novolak resin.
After intensive investigations to accomplish the above objects, the present inventors have found that a positive photoresist composition including an alkali-soluble novolak resin having a specific structure and a naphthoquinonediazidosulfonyl ester of a phenol compound having a specific structure satisfies all the required characteristics of sensitivity, definition, short margin and pattern shape even in the formation of ultrafine resist patterns of not more than half a micron. The present invention has been accomplished based on these findings.
Specifically, the present invention provides, in one aspect, a novolak resin including constitutional units represented by following Formulae (I), (II) and (III) in the molecule:
The present invention provides, in another aspect, a novolak resin that has a weight average molecular weight Mw of from 1000 to 20000 and is a reaction product of a polymer having constitutional units represented by following Formulae (I) and (II) in the molecule with 3,4-xylenol and formaldehyde:
In the novolak resin just mentioned above, the polymer is preferably a reaction product of m-cresol and propionaldehyde.
In a further aspect, the present invention provides a process for producing a novolak resin. The process includes the steps of (i) allowing, as a primary reaction, propionaldehyde to react with m-cresol in the presence of an acid catalyst to thereby yield a polymer, where the amount of propionaldehyde is 0.1 to 0.5 mole per mole of m-cresol; and (ii) allowing, as a secondary reaction, the polymer to react with 3,4-xylenol and formaldehyde to thereby yield a novolak resin having a weight average molecular weight Mw of from 1000 to 20000, where the amounts of 3,4-xylenol and formaldehyde are 0.1 to 0.5 mole per mole of m-cresol and 1 to 5 moles per mole of propionaldehyde, respectively.
The present invention provides, in another aspect, a positive photoresist composition. The positive photoresist composition includes (A) the aforementioned novolak resin and (B) a naphthoquinonediazidosulfonyl ester of a phenol compound represented by following Formula (IV):
wherein R1, R2, R3, R4, R5, R6, R7 and R8 are each independently a hydrogen atom, a halogen atom, an alkyl group having from 1 to 6 carbon atoms, an alkoxy group having from 1 to 6 atoms, or a cycloalkyl group; a, b and c are each independently an integer from 1 to 3; and m is 2 or 3.
In the positive photoresist composition, the phenol compound represented by Formula (IV) may be a linear tetranuclear phenol compound represented by following Formula (V):
Alternatively, the phenol compound represented by Formula (IV) may be a linear pentanuclear phenol compound represented by following Formula (VI):
The naphthoquinonediazidosulfonyl ester (B) is preferably a mixture of a naphthoquinonediazidosulfonyl ester of the linear tetranuclear phenol compound represented by Formula (V) and a naphthoquinonediazidosulfonyl ester of the linear pentanuclear phenol compound represented by Formula (VI).
The positive photoresist composition may further include (C) a phenol compound represented by following Formula (VII):
The present invention provides such a positive photoresist compositions that satisfies all the required characteristics of sensitivity, definition, short margin and pattern shape even in the formation of ultrafine resist patterns of not more than half a micron.
The invention also provides novolak resins useful for the preparation of the positive photoresist composition and the production process of the novolak resins.
Novolak Resins (A)
Novolak resins for use as the ingredient (A) in the present invention are novolak resins each having the constitutional units represented by Formulae (I), (II) and (III), respectively, in the molecule. The constitutional unit of Formula (I) is a constitutional unit formed by a reaction of two of the ortho positions and the para position of m-cresol with propionaldehyde. The constitutional unit of Formula (II) is a constitutional unit formed by a reaction of all the ortho positions and the para position of m-cresol with propionaldehyde. The constitutional unit of Formula (III) is a constitutional unit formed by a reaction of the two ortho positions of 3,4-xylenol with formaldehyde.
By using these novolak resins each having the constitutional units in the molecule, the resulting positive photoresist compositions can satisfy all the required characteristics of sensitivity, definition, short margin and pattern shape.
The novolak resins are preferably prepared by a process which includes the steps of (i) allowing, as a primary reaction, propionaldehyde to react with m-cresol in the presence of an acid catalyst to thereby yield a polymer, where the amount of propionaldehyde is 0.1 to 0.5 mole per mole of m-cresol; and (ii) allowing, as a secondary reaction, the polymer to react with 3,4-xylenol and formaldehyde to thereby yield a novolak resin, where the amounts of 3,4-xylenol and formaldehyde are 0.1 to 0.5 mole per mole of m-cresol and 1 to 5 moles per mole of propionaldehyde, respectively.
When a novolak resin is prepared in a similar manner as above, except that 3,4-xylenol is used instead of m-cresol in the step (i) and that m-cresol is used instead of 3,4-xylenol in the step (ii), the resulting novolak resin has constitutional units represented by the following formulae:
This novolak resin induces significant film reduction after development and is not suitable for the preparation of positive photoresist compositions having high definition and excellent short margin, although it has a high sensitivity.
Likewise, when a novolak resin is synthetically prepared by allowing a phenol mixture containing m-cresol and 3,4-xylenol to react with an aldehyde mixture containing formaldehyde and propionaldehyde, that is, allowing the four ingredients to react with one another at once, the resulting novolak resin is not suitable for the preparation of positive photoresist compositions having high sensitivity and definition.
In the preparation of the novolak resins of the present invention, the polymer obtained by the primary reaction is preferably a polymer having the constitutional units represented by Formulae (I) and (II) in the molecule, having a weight average molecular weight Mw of from 200 to 500 and having a molecular weight distribution Mw/Mn of less than or equal to 1.7, where Mn is a number average molecular weight. With this polymer, 3,4-xylenol is condensed with the aid of formaldehyde to thereby constitute the novolak resin.
The weight average molecular weight Mw and the number average molecular weight Mn as used herein are molecular weights in terms of polystyrene as determined by gel permeation chromatography (GPC).
The amount of propionaldehyde in the step (i) is preferably 0.1 to 0.5 mole, and typically preferably 0.2 to 0.4 mole, per mole of m-cresol. If the amount of propionaldehyde is less than the above range, the resulting positive photoresist composition may have deteriorated definition. If it exceeds the above range, the positive photoresist composition may have deteriorated sensitivity and pattern shape (i.e., the pattern may have an insufficiently vertical profile).
Acid catalysts for use in the step (i) include those generally used in the preparation of novolak resins, of which p-toluenesulfonic acid is preferred to yield a high reaction rate.
The amount of the acid catalyst is preferably from 0.1% by millimole to 100% by millimole, and typically preferably from 1% by millimole to 10% by millimole, relative to the total moles of phenolic monomers used in the preparation of the novolak resin.
The reaction in the step (i) is preferably performed in an organic solvent such as xcex3-butyrolactone.
The polymer prepared in the step (i) preferably has a molecular weight distribution Mw/Mn of less than or equal to 1.7 and a weight average molecular weight Mw of from about 200 to about 500 to yield a positive photoresist composition having high sensitivity and definition. The weight average molecular weight Mw of the polymer is more preferably from about 200 to about 300.
The amount of 3,4-xylenol used in the step (ii) is preferably from 0.1 to 0.5 mole and more preferably from 0.1 to 0.3 mole per mole of m-cresol used in the step (i). If the amount of 3,4-xylenol is less than the above range, the resulting positive photoresist composition may have insufficient definition. If it exceeds the above range, the positive photoresist composition may have deteriorated sensitivity and pattern shape (i.e. the pattern may have an insufficiently vertical profile).
The amount of formaldehyde used in the step (ii) is preferably from 1 to 5 moles and more preferably from 2 to 4 moles per mole of propionaldehyde used in the step (i). If the amount of formaldehyde is less than the above range, the resulting positive photoresist composition may have insufficient definition. If it exceeds the above range, the resulting positive photoresist composition may have insufficient sensitivity.
In addition to 3,4-xylenol, one or more types of phenols can be used as a third component in the step (ii).
In this case, the amounts and the types of such additional phenols as the third component are not specifically limited, as long as the compositional ratio of m-cresol to 3,4-xylenol is within the predetermined range and the characteristics of the positive photoresist composition of the present invention are not deteriorated.
In the step (i), the reaction time of the primary reaction between m-cresol and propionaldehyde is preferably more than or equal to 2 hours. If the reaction time is less than 2 hours, the core polymer formed from m-cresol and propionaldehyde may have a broad molecular weight distribution, i.e. a high Mw/Mn. Accordingly, the novolak resin obtained in the subsequent step (ii) may have insufficient characteristics and the resulting positive photoresist composition may exhibit insufficient total performances including definition, short margin, sensitivity and pattern shape (sufficient vertical profile). The reaction time of the primary reaction is preferably from about 4 hours to about 8 hours to achieve satisfactory industrial productivity.
In the step (ii), 3,4-xylenol is added to a solution mainly containing the core polymer prepared in the step (i), followed by dropwise addition of formalin (an aqueous solution of formaldehyde) at elevated temperatures to thereby start the reaction (the secondary reaction).
The reaction time of the secondary reaction is preferably from about 2 hours to about 4 hours. Within this range, the novolak resin may have a desired molecular weight and may become suitable for the preparation of positive photoresist compositions having satisfactory sensitivity, definition, short margin and vertical profile of the resist pattern. The reaction time of the secondary reaction may exceed 4 hours, but an excessively long reaction time is not desirable to yield high productivity.
The secondary reaction may be started by adding 3,4-xylenol to the solution immediately after the completion of the primary reaction, followed by dropwise addition of formalin. Alternatively, the secondary reaction may be started by cooling the reaction solution is cooled to around room temperature and stopping stirring after the completion of the primary reaction, and then adding 3,4-xylenol to the reaction solution, followed by dropwise addition of formalin.
For example, after the completion of the primary reaction, 3,4-xylenol is added before the solution is cooled, followed by cooling of the resulting mixture and stopping of stirring. Next, the mixture is raised in temperature again, followed by dropwise addition of formalin to thereby start the secondary reaction (polymerization).
Alternatively, the reaction solution is cooled after the completion of the primary reaction, 3,4-xylenol is then added to the solution, the reaction solution is then raised in temperature, followed by dropwise addition of formalin to thereby start the secondary reaction (polymerization).
Upon the start of the secondary reaction, formalin is preferably added dropwise to the reaction system at sufficiently elevated temperatures to avoid homopolymerization of formaldehyde.
The primary and secondary reactions are preferably performed at about 90xc2x0 C. to 100xc2x0 C. However, the primary reaction is preferably performed initially at 40xc2x0 C. to 50xc2x0 C. for 0.5 to 1 hour and is then performed at 90xc2x0 C. to 100xc2x0 C. for higher safety in the manufacture, since propionaldehyde has a boiling point of about 47xc2x0 C.
Even if the primary reaction is performed at 90xc2x0 C. to 100xc2x0 C. from the beginning, the characteristics of the resulting resin do not have significant differences from those prepared in the aforementioned manner.
The concentrations of the total monomers in the reaction solutions of the primary and secondary reactions are preferably controlled within a range from 10% to 60% by weight using an organic solvent such as xcex3-butyrolactone. If the total monomer concentration is less than 10% by weight, it may take a long time for the resulting polymer to achieve a target molecular weight, and a purification process, for example, to remove the reaction solvent may become difficult. If it exceeds 60% by weight, the resulting resin may cause clogging of piping during sampling or transportation to thereby deteriorate workability.
The novolak resins of the present invention may be prepared by xe2x80x9cbulk polymerizationxe2x80x9d without the use of an organic solvent such as xcex3-butyrolactone, but is preferably prepared by the above polymerization technique in an organic solvent. According to the polymerization technique, the reaction uniformly proceeds and invites less by-products.
The thus-prepared novolak resins have an Mw of preferably from 1000 to 20000 and more preferably from 2000 to 15000 to yield positive photoresist compositions having high definition and sensitivity.
Where necessary, unreacted materials and low molecular weight fractions should preferably be removed from the novolak resin by conventional purification, fractionation or other techniques to thereby yield a novolak resin having a high molecular weight and a low molecular weight distribution. The techniques for the removal are not specifically limited, but such unreacted materials and low molecular weight fractions are preferably removed in the following manner. The novolak resin solution is dissolved in methyl amyl ketone (MAK), and the resultant solution is washed with water to remove a catalyst and unreacted materials. To the residual is added a poor solvent such as hexane or heptane, or a hexane-MAK or heptane-MAK mixture, and the resultant mixture is stirred and then allowed to stand to separate a poor solvent layer containing low molecular weight fractions as an upper layer, and an MAK layer containing high molecular weight fractions as a lower layer. The lower layer is extracted and thereby yields a novolak resin having a higher molecular weight.
The positive photoresist composition of the present invention may further comprise additional alkali-soluble resins in addition to the aforementioned novolak resins within ranges not adversely affecting the objects of the invention.
Such additional alkali-soluble resins include, but are not limited to, condensates of aromatic hydroxy compounds and aldehydes or ketones, polyhydroxystyrenes and derivatives thereof. Such aromatic hydroxy compounds include, but are not limited to, phenol; p-cresol, o-cresol, and other cresols; 2,3-xylenol, 2,5-xylenol, 3,5-xylenol, and other xylenols; m-ethylphenol, p-ethylphenol, o-ethylphenol, 2,3,5-trimethylphenol, 2,3,5-triethylphenol, 4-tert-butylphenol, 3-tert-butylphenol, 2-tert-butylphenol, 2-tert-butyl-4-methylphenol, 2-tert-butyl-5-methylphenol, and other alkyl-substituted phenols; p-methoxyphenol, m-methoxyphenol, p-ethoxyphenol, m-ethoxyphenol, p-propoxyphenol, m-propoxyphenol, and other alkoxy-substituted phenols; o-isopropenylphenol, p-isopropenylphenol, 2-methyl-4-isopropenylphenol, 2-ethyl-4-isopropenylphenol, and other isopropenyl-substituted phenols; phenylphenol, and other aryl-substituted phenols; 4,4xe2x80x2-dihydroxybiphenyl, bisphenol A, resorcinol, hydroquinone, pyrogallol, and other polyhydroxyphenols. The aldehydes include, but are not limited to, formaldehyde, paraformaldehyde, trioxane, acetaldehyde, butyraldehyde, trimethylacetaldehyde, acrolein (acrylaldehyde), crotonaldehyde, cyclohexanealdehyde, furfural, furylacrolein, benzaldehyde, terephthalaldehyde, phenylacetaldehyde, xcex1-phenylpropylaldehyde, xcex2-phenylpropylaldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, p-hydroxybenzaldehyde, o-methylbenzaldehyde, m-methylbenzaldehyde, p-methylbenzaldehyde, o-chlorobenzaldehyde, m-chlorobenzaldehyde, p-chlorobenzaldehyde and cinnamaldehyde. The ketones include, for example, acetone, methyl ethyl ketone, diethyl ketone and diphenyl ketone. Each of these compounds can be used alone or in combination.
The condensate of the aromatic hydroxy compound with the aldehyde or ketone can be prepared in the presence of an acidic catalyst according to a conventional technique.
The polyhydroxystyrenes and derivatives thereof include, but are not limited to, vinylphenol homopolymers, and copolymers of vinylphenol and a copolymerizable comonomer. Such comonomers include, for example, acrylic acid derivatives, acrylonitrile, methacrylic acid derivatives, methacrylonitrile, styrene, xcex1-methylstyrene, p-methylstyrene, o-methylstyrene, p-methoxystyrene, p-chlorostyrene, and other styrene derivatives.
The amount of these additional alkali-soluble resins is preferably less than or equal to 50% by weight and typically preferably less than or equal to 30% by weight relative to the weight of the novolak resin (A).
Naphthoquinonediazidosulfonyl Esters (B)
The positive photoresist composition of the present invention comprises the ingredient (A) and a specific naphthoquinonediazidosulfonyl ester (B). Naphthoquinonediazidosulfonyl esters of the phenol compounds represented by Formula (IV) are used as the ingredient (B).
Among these ingredients (B), naphthoquinonediazidosulfonyl esters of the linear tetranuclear phenol compound represented by Formula (V) and naphthoquinonediazidosulfonyl esters of the linear pentanuclear phenol compound represented by Formula (VI) are preferred. The ingredient (B) is more preferably a mixture containing the naphthoquinonediazidosulfonyl ester of the linear tetranuclear phenol compound represented by Formula (V) and the naphthoquinonediazidosulfonyl ester of the linear pentanuclear phenol compound represented by Formula (VI).
The naphthoquinonediazidosulfonyl esters can be prepared by subjecting, for example, a 1,2-naphthoquinonediazidosulfonyl halide and the phenol compound to condensation reaction for the complete esterification or partial esterification. The condensation reaction can be generally performed in an organic solvent in the presence of a basic condensing agent. Such organic solvents include, for example, dioxane, N-methylpyrrolidone and dimethylacetamide, and such basic condensing agents include, for example, triethylamine, alkali metal carbonates, and alkali metal hydrogencarbonates. In the resulting naphthoquinonediazidosulfonyl ester, preferably equal to or more than 50% and more preferably equal to or more than 60% of the total moles of hydroxyl groups of the phenol compound is esterified with 1,2-naphthoquinonediazido-4 (or 5)-sulfonyl halide. In other words, the naphthoquinonediazidosulfonyl ester has an average esterification rate of preferably equal to or more than 50% and more preferably equal to or more than 60%. By using such a naphthoquinonediazidosulfonyl ester, the resulting positive photoresist composition can have a higher definition.
In addition to the above naphthoquinonediazidosulfonyl esters, the positive photoresist composition of the present invention may further comprise additional naphthoquinonediazidosulfonyl esters within ranges not adversely affecting the objects of the present invention.
For example, conventional compounds used as photosensitizers in positive photoresist compositions can be used as the additional naphthoquinonediazidosulfonyl esters. Such compounds include, but are not limited to, naphthoquinonediazidosulfonyl esters of 2,4-bis(3,5-dimethyl-4-hydroxybenzyl)-5-hydroxyphenol, 2,6-bis(3,5-dimethyl-4-hydroxybenzyl)-4-methylphenol, 2,6-bis(2,5-dimethyl-4-hydroxybenzyl)-4-methylphenol, and other linear trinuclear compounds.
The positive photoresist composition of the present invention may further comprise a sensitizer (intensifier) as an ingredient (C) according to necessity. The phenol compounds represented by Formula (VII) are preferred as the ingredient (C). By adding the ingredient (C), the positive photoresist composition of the present invention can have a higher sensitivity.
Conventional sensitizers (intensifiers) can also be used in addition to, or instead of, the phenol compounds represented by Formula (VII) within ranges not adversely affecting the objects of the present invention. Such sensitizers (intensifiers) include, but are not limited to, bis(4-hydroxy-2,3,5-trimethylphenyl)-2-hydroxyphenylmethane, 1,4-bis[1-(3,5-dimethyl-4-hydroxyphenyl)isopropyl]benzene, 2,4-bis(3,5-dimethyl-4-hydroxyphenylmethyl)-6-methylphenol, bis(4-hydroxy-3,5-dimethylphenyl)-2-hydroxyphenylmethane, bis(4-hydroxy-2,5-dimethylphenyl)-2-hydroxyphenylmethane, bis(4-hydroxy-3,5-dimethylphenyl)-3,4-dihydroxyphenylmethane, 1-[1-(3-methyl-4-hydroxyphenyl)isopropyl]-4-[1,1-bis(3-methyl-4-hydroxyphenyl)ethyl]benzene, 2,6-bis[1-(2,4-dihydroxyphenyl)isopropyl]-4-methylphenol, 4,6-bis[1-(4-hydroxyphenyl)isopropyl]resorcin, 4,6-bis(3,5-dimethoxy-4-hydroxyphenylmethyl)pyrogallol, 4,6-bis(3,5-dimethyl-4-hydroxyphenylmethyl)pyrogallol, 2,6-bis(3-methyl-4,6-dihydroxyphenylmethyl)-4-methylphenol, 2,6-bis(2,3,4-trihydroxyphenylmethyl)-4-methylphenol, 1,1-bis(4-hydroxyphenyl)cyclohexane, 6-hydroxy-4a-(2,4-dihydroxyphenyl)-9-1xe2x80x2-spirocyclohexyl-1,2,3,4,4a,9a-hexahydroxanthene and 6-hydroxy-5-methyl-4a-(2,4-dihydroxy-3-methylphenyl)-9-1xe2x80x2-spirocyclohexyl-1,2,3,4,4a,9a-hexahydroxanthene.
The amount of the sensitizer (intensifier) (C) is preferably from 5% to 50% by weight and more preferably from 10% to 35% by weight, relative to the weight of the novolak resin (A).
The amount of the ingredient (B) in the positive photoresist composition of the present invention is preferably from 10% to 60% by weight and more preferably from 20% to 50% by weight relative to the total weight of the novolak resin (A) and the ingredient (C) added according to necessity. If the amount of the ingredient (B) is excessively small, the resulting positive photoresist composition may not yield images in exact accordance with the pattern and may exhibit deteriorated transfer property. If the amount is excessively large, the resulting positive photoresist composition may exhibit a deteriorated sensitivity, may yield a nonuniform resist film and may exhibit a deteriorated definition.
By comprising the specific ingredients (A) and (B), and where necessary the ingredient (C), the positive photoresist composition of the present invention satisfies all the required characteristics of sensitivity, definition, short margin and pattern shape even in the formation of ultrafine resist patterns of not more than half a micron.
To further improve definition, exposure margin and film residual rate, the positive photoresist composition of the present invention may further comprise about 0.01% to about 10% by weight each of p-toluenesulfonyl chloride (PTSC), 4,4xe2x80x2-bis(diethylamino)benzophenone, 1,4-bis[1-(2-methyl-4-hydroxy-5-cyclohexylphenyl)isopropyl]benzene, and/or 1,3-bis[1-(2-methyl-4-hydroxy-5-cyclohexylphenyl)isopropyl]benzene.
Where necessary, the composition of the present invention may further comprise any of compatible additives including, for example, ultraviolet absorbents for inhibition of halation and surfactants for prevention of striation within ranges not adversely affecting the objects of the invention. Such ultraviolet absorbents include, for example, 4-dimethylamino-2xe2x80x2,4xe2x80x2-dihydroxybenzophenone, 5-amino-3-methyl-1-phenyl-4-(4-hydroxyphenylazo)pyrazole, 4-dimethylamino-4xe2x80x2-hydroxyazobenzene, 4-diethylamino-4xe2x80x2-ethoxyazobenzene, 4,4xe2x80x2-diethylaminoazobenzene and curcumin. The surfactants include, but are not limited to, Fluorad FC-430 and FC-431 (trade names, available from Fluorochemical-Sumitomo 3M Co.), EFTOP EF122A, EF122B, EF122C and EF126 (trade names, available from Tohkem Products Corporation) and other fluorine-containing surfactants.
The positive photoresist composition of the present invention is preferably used as a solution prepared by dissolving each of the ingredients (A) and (B), as well as the ingredient (C) and other additional ingredients added according to necessity, in an appropriate solvent. Such solvents include those conventionally used in positive photoresist compositions, such as acetone, methyl ethyl ketone, cyclohexanone, methyl amyl ketone, methyl isoamyl ketone, 2-heptanone and other ketones; ethylene glycol, propylene glycol, diethylene glycol, ethylene glycol monoacetate, propylene glycol monoacetate, diethylene glycol monoacetate, or monomethyl ethers, monoethyl ethers, monopropyl ethers, monobutyl ethers or monophenyl ethers of these compounds, and other polyhydric alcohols and derivatives thereof; dioxane and other cyclic ethers; and ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate, and other esters. Each of these solvents can be used alone or in combination. Of these solvents, preferred solvents are acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, 2-heptanone and other ketones; and ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate and other esters.
Practically, the positive photoresist composition of the present invention may preferably be used, for example, in the following manner: Each of the ingredients (A) and (B), as well as the ingredient (C) and other additional ingredients added according to necessity, is dissolved in an appropriate solvent as mentioned above to yield a coating solution; the coating solution is then applied, using a spinner or the like, onto a substrate such as a silicon wafer, and is then dried to form a photosensitive layer; next, the photosensitive layer is irradiated and is exposed with a light source emitting light of a wavelength of around 365 nm, such as a low-pressure mercury lamp, a high-pressure mercury lamp or an ultra-high-pressure mercury lamp, through a desired mask pattern; and the exposed portions of the film are then dissolved and removed by dipping the substrate in a developer solution, for example, an alkaline aqueous solution such as a 1% to 10% by weight tetramethylammonium hydroxide (TMAH) aqueous solution, thus forming an image being in exact accordance with the mask pattern.

Novolak resin, production process thereof and positive photoresist composition using the novolak resin


A method and an apparatus for applying a therapeutic substance to body tissue are provided in which ultrasonic radiation is used. The method allows the application of medication to be tailored to the needs of an individual patient. In particular, the timing, duration, intensity, and concentration of the application of medication can be adjusted according to individual requirements. Side effects of tissue adjacent to tissue in need o. The invention described herein was made in the course of work under a grant from the National Institute of Health.

This invention relates to the application of a therapeutic substance or of a medication to body tissue. In particular, ultrasonic radiation is used in the application of the therapeutic substance.
Medication may be applied to a target body tissue systemically. However, tissue other than the target tissue is also exposed to the medication which may cause harmful side effects. As a result of diffusion of medication into other tissue during systemic application, the concentration of medication that may be applied to the target tissue is limited.
Accordingly, an object of the invention is to provide a method for applying medication so that higher concentrations of medication may be applied to the target tissue.
A further object of the invention is to provide such an application method to minimize side effects in adjacent tissue.
A further object of the invention is to provide a method whereby medication is locally applied to target tissue and selective heat is simultaneously, locally applied to the same target tissue. Application of heat to elevate the temperature of the target tissue to a non-toxic level can enhance the efficacy of certain mediations. Selective delivery of ultrasound radiation can produce the desirable local temperature elevation.
A further object of the invention is to provide such an application method so that timing, duration, and intensity of the application of medication are tailored to suit the needs of an individual patient.
A further object of the invention is to provide an apparatus for applying therapeutic substance to body tissue.

Local application of medication with ultrasound


A molecular device is provided. The molecular device comprises a junction formed by a pair of crossed electrodes where a first electrode is crossed by a second electrode at a non-zero angle and at least one connector species including at least one switchable moiety and connecting the pair of crossed electrode in the junction. The junction has a functional dimension ranging in size from microns to nanometers. The molecular device further includes a buffer layer comprising nanocrystals interposed between the connector species and the second electrode.

Crossbar molecular electronic devices (CMED) typically consist of a top and bottom electrode, between which a layer of organic molecules is sandwiched in a planar configuration on an insulating substrate. The particular chemical and electronic properties of an organic molecule define the functionality of the CMED and to date, arrays of such devices have been made demonstrating programmable resistor logic, diode logic, and bistable switching, depending on the choice of the respective molecule.
One challenge with the construction of CMEDs is the fabrication of the top conducting electrode onto the molecular layer. The material for this electrode (usually a metal) is conventionally deposited by thermal or sputter deposition sources positioned with a line-of-sight to the substrate bearing the bottom electrode/molecular layer array. The problem with such sources is that they impart a high kinetic energy to the metal atoms, allowing them to either penetrate the molecular layer and short the device and/or undergo chemical reaction with the organic layer that unpredictably changes its chemical and electronic properties.
One approach to addressing this problem involves chilling the substrate bearing the bottom electrode/molecular layer array in a chamber filled with sub-Torr pressures of an inert gas to moderate the kinetic energies of incoming metal atoms that would originate from sources that do not have a direct line of sight to the substrate. Such an approach, while effective, can be inefficient, time-consuming, and costly, as most of the top electrode source material is wasted.
Thus, there remains a need for a mechanism for protecting the molecular layer during fabrication of the top electrode.

Nanocrystal protective layer for crossbar molecular electronic devices

Hewlett-Packard Development Company, L.P.


A vehicle 1000 has two pipings 60 and 62 arranged to discharge an exhaust gas from a fuel cell stack 10 to the outside of the vehicle 1000. An outlet provided at an end of the piping 60 is located at an underfloor position in a rear portion of the vehicle 1000, while an outlet provided at an end of the piping 62 is located at a roof rear end of the vehicle 1000. When the outlet provided at the end of the piping 60 is blocked or when there is a potential for such blockage, the outlet provided at the end of the piping 62 is used to discharge the exhaust gas from the fuel cell stack 10 to the outside of the vehicle 1000. This arrangement ensures continuous drive of the vehicle 1000 even in a specific environment where any of various obstructing objects as the cause of blockage of the outlet is present in the surroundings of the vehicle 1000.

In a vehicle equipped with fuel cells, a motor is driven with electric power generated by the fuel cells, and the driving power of the motor is used to rotate an axle with wheels and drive the vehicle. One proposed structure of such a vehicle has exhaust piping with an outlet to discharge the exhaust gas from the fuel cells to the outside of the vehicle. This outlet is generally located at an underfloor position in a rear portion of the vehicle main body, like the conventional vehicle driven with the output power of an internal combustion engine (see, for example, Japanese Patent Laid-Open No. 2002-289237). This arrangement of the outlet enables the exhaust gas from the fuel cells and water produced by power generation or by electrochemical reaction of hydrogen with oxygen (hereafter the exhaust gas and the produced water may collectively be referred to as 'exhaust fluid') to be discharged directly onto the road surface. One known gas discharge structure for vehicle-installed fuel cells is disclosed in, for example, Japanese Patent Laid-Open No. 2003-219512.
In the prior art structure disclosed in Japanese Patent Laid-Open No. 2002-289237, however, during drive of the vehicle equipped with the fuel cells on the water-covered road, the outlet may be blocked by the water, soil, sand, and other equivalent substances present on the road surface. Such blockage of the outlet may interfere with the smooth discharge of the exhaust gas and the produced water and stop power generation by the fuel cells to eventually prevent further run of the vehicle. The water, soil, sand, and other equivalent substances flowed into the outlet may run through the piping to reach the inside of the fuel cells and cause malfunction of the fuel cells.
This problem is not characteristic of the vehicle equipped with fuel cells but is commonly found in various moving bodies equipped with fuel cells and configured to be driven on the road surface with electric power generated by the fuel cells as the driving power source. Typical examples of such moving bodies include air craft and boats and ships, in addition to the vehicles.


In various embodiments, the invention provides enhanced structures, devices, and techniques that allow fluids and liquid products, such as cosmetics, to dispense in a more even, smoother, and more predictable manner from fluid containers. In one embodiment, a plug is inserted into the nozzle of a squeeze tube. The plug has embossments on its surface that form longitudinal openings for the tube's fluid contents to dispense in a controlled fashion. In one embodiment, a plug is positioned within at least a portion of the interior of the nozzle of a fluid container. The plug includes a tip and a base having at least one longitudinal opening structured to create a pathway for communicating fluid from the fluid repository to the dispensing orifice on at least a portion of an outside surface of the plug upon application of a threshold fluid pressure.

In the world of high quality consumer products, it is important to have product designs and packages that function effectively for their intended purposes. With respect to the cosmetics industry, for example, it is especially important to provide fluid containers that can meet consumer needs by efficiently and cleanly dispensing fluids such as creams, oils, make-up, and other types of cosmetics.
However, many current package and container designs for fluid containers suffer from deficiencies in how they deliver an appropriate dosage of fluid and how they maintain a clear and open path for fluid to flow. An insufficient dosage of fluid does not provide enough product to meet the needs of the consumer. On the other hand, an excess dosage generates extra product that cannot be readily used by the consumer. This extra product creates a clean-up problem for the consumer who must decide how to dispose of the extra fluid that has been dispensed. Also, such extra product can cause undesirable clogging of the dispensing orifice of a fluid container. In certain situations, fluid product within a container dries, cracks, and leaves residue in what may have been promoted or marketed as a "premium" package that commanded a commensurately "premium" price but which has now caused consumer dissatisfaction.
In view of the issues afflicting existing product designs and packages, including within the cosmetics industry, enhanced product dispensing and dosaging technology is needed. Fluid dispensing structures, devices, and techniques are needed that can dispense fluid in an even, smooth and predictable manner, without causing significant dripping or substantial clogging of the dispensing orifice of a fluid container.

Enhanced dispensing and dosaging techniques for fluid containers


A fine structure T-shaped electrode is fabricated using a phase shift method. A photoresist layer is formed on a semiconductor substrate and the photoresist layer is exposed to an exposure light having a first wavelength through a photomask which has a desired pattern of a base shifting layer whereby the phase of the exposure light is shifted by 180 degrees. The photoresist layer is then exposed to another exposure light having a second wavelength that is different from the first wavelength through the photomask. The photoresist is developed to form a T-shaped resist cavity and a metal layer is deposited over the resist layer formed on the semiconductor substrate. All the metal layer is removed except for the areas covering the T-shaped photoresist pattern. The T-shaped electrode is also formed by disposing a photoresist layer on a semiconductor substrate. The photoresist is exposed to an exposure light through a photomask which has a desired pattern of a phase shift layer whereby the phase of the exposure light is reversed and the light blocking layer to block the exposure light are formed at a certain fixed distance from and in parallel with the edge of said phase shifting layer pattern and are also formed inside as well as outside of the phase shifting layer pattern. The photoresist is developed to form a T-shaped photoresist cavity. A metal layer is deposited over the photoresist pattern formed on the semiconductor substrate. All of the metal layer is then removed except for the areas covering the T-shaped photoresist pattern.

This invention relates to a method of fabricating a fine structure electrode and particularly to a method of fabricating a T-shaped fine structure electrode.
As the integration density and the performance enhancement of semiconductive devices is progressing more and more in recent years, the pattern dimensions are becoming finer and finer, entering into a sub-micron range. At present optical lithography is generally employed to form patterns in the process of fabricating semiconductive devices. However, in fabricating a device like HEMT (high electron mobility transistor) that requires a fine structure electrode of about 0.3 .mu.m as the gate electrode, electron-beam lithography is usually used. The optical lithography has had 0.5 .mu.m as the pattern limit and for a finer structure electrode fabrication, electron-beam lithography and X-ray lithography have been effectively used.
On the other hand, in recent photolithography technology utilizing a projection exposure, research activity has been carried out aggressively on a fine resist pattern forming technology, namely, a so-called phase shifting method. This phase shifting method aims to form a fine pattern of less than 0.5 .mu.m by using existing projection exposure equipment with an improvement applied to a photomask. More specifically stating, this method employs a phase shifting layer that can have the phase of a part of the exposure light after passage of the photomask shifted and can improve the resolving power of the projection exposure method. A brief explanation about the principle of this method is made with the help of FIG. 1(a) through (d) and FIG. 2(a) through (d) in the following:
FIG. 1(a) through (d) show a widely known projection exposure method that uses an ordinary photomask 32 consisting only of a light blocking layer 31 and FIG. 2(a) through (d) shows the projection exposure that uses a phase shifting method using a phase shifting layer 33.
When a photomask 32 with non-phase shifting layer 33 is used as in FIG. 1(a), the phase direction of the light passing through the transparent area of the photomask 32 is not changed as in FIG. 1(b).
Therefore, when a resist pattern having dimensions close to the resolution limit to cause a light diffraction as in FIG. 1(c) is to be formed, the amplitudes of the lights passing through the transparent areas adjacent to each other overlap at the surface of a wafer and the light intensity contrast between the transparent area and the light blocking area observed at the surface of the wafer becomes not as pronounced as described in FIG. 1(d).
On the other hand, when a photomask 34 having a phase shifting layer 33 is used as shown in FIG. 2(a), the phase of the light passing through a transparent area incorporated with the phase shifting layer 33 is turned by 180 degrees against the phase of the light passing the area with no phase shifting layer 33 as shown FIG. 2(b). Thus, if one of the two adjacent areas is covered with a phase shifting layer 33, the amplitudes of the light passing through these transparent areas that are situated almost within a distance of the resolving limit from each other become zero at the surface of the wafer near the intermediate point between the two transparent areas due to the offsetting effect as shown in FIG. 2(d).
Consequently, the resolution power of a projection exposure method is enhanced by employing a phase shifting method whereby the contrast in the light intensity between the areas on the wafer corresponding to the transparent area and the light blocking area of the photomask is enhanced as shown in FIG. 2(d). The phase shifting method as explained in the foregoing is particularly effective in a repetitive formation of a pattern like a line and space pattern.
In contrast to this, as a way to apply the phase shifting method to a pattern of non-repetitive type like the gate pattern of HEMT, there is a method to utilize the end areas of a phase shifting layer of transparent type.
FIG. 3(a) through (d) show the case of a projection exposure wherein the end area of a phase shifting layer of transparent type is utilized. When a photomask 36 with a phase shifting layer 35 is used as in FIG. 3(a), the phase of the light passing through the transparent area with a phase shifting layer 35 formed on it is shifted by 180 degrees at the end of the phase shifting layer 35 as shown in FIG. 3(b). At the surface of a wafer, the light amplitudes overlap due to a diffraction and the light amplitudes near the end of the phase shifting layer are offset to zero as shown in FIG. 3(c). Thus, it is possible to form a fine pattern by having the light intensity reduced to zero at the end of the phase shifting layer 35 as shown in FIG. 3(d).
As described in the foregoing, use of a phase shifting method makes it possible to form a sub-half-micron resist pattern by an ordinary projection exposure method that otherwise has been so far considered impossible.
FIG. 4(a) through (e) show, in cross-sectional views, a process chart of the production method that utilizes a phase shifting method in fabricating a HEMT having a conventional fine structure electrode of T-shaped gates. According to FIG. 4, item 41 is a semiconductor substrate, item 42 is an active area, item 43 is a source drain ohmic electrode, item 44 is a negative photoresist, item 45 is a photomask with a transparent type phase shifting layer 46, item 47 is a fine structure cavity, item 48 is a photoresist, item 49 is a T-shaped resist cavity and item 50 is a gate electrode.
As shown in FIG. 4(a), an active area 42 is formed by mesa etching on a semiconductor substrate 41 having a HEMT structure grown by a MBE method and a source drain ohmic electrode 43 is formed on the foregoing active area 42. Next, as shown in FIG. 4(b), a negative photoresist 44 is applied to all of the surface and this negative photoresist 44 is then developed after it is exposed by a projection exposure to light through a photomask 45 having a transparent type phase shifting layer 46 to form a fine structure cavity 47 of 0.3 .mu.m as shown in FIG. 4(c). Then, as shown in FIG. 4(d), a photoresist 48 is applied to all of the surface and a photoresist cavity of about 0.8 .mu.m is formed by a projection exposure on the foregoing fine structure cavity 47 with an exact position alignment to complete the T-shaped resist cavity 49. After that, as shown in FIG. 4(e), a gate metal such as Ti/Pt/Au for example is applied to all of the surface by deposition and the T-shaped gate electrode 50 is formed by a lift-off method to complete an HEMT.
In the case of a fine structure gate HEMT, a reduction in the gate length causes an increase in the gate resistance with a resultant adverse effect imposed to the device's performance. Thus, it is desirable to make the gate electrode into a T-shape in order to reduce the gate resistance. However, according to conventional phase shifting technology, it is desirable to employ a two-layer resist method in forming a fine structure T-shaped resist cavity for fabricating a fine structure T-shaped gate electrode with a resultant complicated production process and also a problem of pattern defects due to a misalignment of positions at the time of forming an upper-layer cavity.

Method of fabricating a fine structure electrode

Matsushita Electric Industrial Co., Ltd.