Disclosed is a curable coating composition that includes a compound having both hydroxy functionality and carbamate functionality of the structure ##STR1## wherein R is H or alkyl, a polyisocyanate crosslinking agents and an aminoplast crosslinking agent. The effective equivalents of the aminoplast crosslinking agent is equal to or less than the equivalents of carbamate functionality and the effective equivalents of polyisocyanate crosslinker is equal to or less than the equivalents of hydroxyl functionality. The carbamate-functional resin and the aminoplast crosslinking agent provide rheology control during the early part of the bake to cure an applied coating of the coating composition.

Basecoat-clearcoat coatings, or color-plus-clear composite coatings, are widely used, especially in the automotive industry, because of their exceptional appearance. Automotive coatings must not only have the desirable appearance properties of high gloss, depth of color, distinctiveness of image, and so on; but they must also be resistant to marring, scratching, etching, or spotting from environmental depositions, chalking, and other forms of film degradation. It is particularly critical in a color-plus-clear composite coating to have a clear coat layer that is resistant to film degradation.
In addition to the considerations of appearance and durability, a coating must be formulated to minimize the amount of regulated volatile organic compound emissions from the painting process. For a thermoset solventborne system this is usually accomplished by employing low molecular weight resins and crosslinking agents. One drawback to this approach is that such coatings systems have poorer rheological properties during application and the curing bake. When the coatings are heated in order to cause a reaction between the resins and crosslinking agents, the viscosity of the low molecular weight resins is reduced. These resins tend to flow on the coated substrate causing sagging, slumping, so-called fat edges, and other appearance problems before the coating has achieved a sufficient level of cure to prevent further movement.
Difficulties with controlling rheology have been a problem particularly with coatings compositions that are cured using blocked polyisocyanates as crosslinkers. Although coatings compositions using polyisocyanate crosslinkers are highly preferred for the excellent appearance and durability of the films they produce, such systems must usually be heated to temperatures of 290.degree. F. (143.degree. C.) and higher in order to de-block the polyisocyanate and thereby initiate cure. At these temperatures, the tendency of the low molecular weight principal resins to flow is increased. Thus, the coating composition flows more than is desirable before there is sufficient crosslinking to set up the coating film. The excessive flow leads to the appearance problems in the cured coating mentioned above.
In U.S. Pat. No. 5,342,888, Sudo describes the cure of hydroxyl-functional acrylic resins with a combination of blocked aliphatic polyisocyanates and alkyl-etherified melamine resins. According to Sudo, coatings from acrylic resins cured only with the alkyl-etherified melamine resin have poor resistance to acid rain deterioration, while such coatings cured only blocked polyisocyanates have good acid resistance but poor low-temperature cure and workability. Sudo teaches that the proportion of melamine resin to the blocked polyisocyanate must be from 50/50 to 95/5 by weight to avoid, on the one hand, inadequate cure and, on the other hand, poor acid resistance However, because the coating compositions of Sudo form coatings that still have a substantial amount of ether linkages from the aminoplast-hydroxy cure, such coatings will show significant deterioration from acid rain etching.
U.S. Pat. No. 4,102,847, Hartmann et al., and U.S. Pat. No. 4,892,906, Pham et al., disclose coating compositions similar to that of Sudo. Both the Hartmann and the Pham references teach hydroxy-functional resins cured with mixtures of melamine and isocyanate. Again, the coating compositions of these references form coatings with a substantial amount of ether linkages and thus will show significant deterioration from acid rain etching.
Carbamate-functional reactive diluents are described in WO 87/00851, Hoy et al.; U.S. Pat. No. 5,115,015, Richey, Jr., et al.; U.S. Pat. No. 4,814,382, Hoy et al.; U.S. Pat. No. 4,677,168, Hoy et al.; and U.S. Pat. No. 4,520,167, Blank et al. The carbamate-functional reactive diluents are low molecular weight compounds with one carbamate group. These materials are mono-functional in the systems disclosed and therefore cannot build up viscosity fast enough at the beginning of the cure cycle to prevent the sagging and other flow problems mentioned above.

High solids thermosetting compositions with dual cure mechanism


In some examples, a computer system may receive historical repair data and may extract features from the historical repair data for use as training data. The computer system may determine, from the historical repair data, a repair hierarchy including a plurality of repair levels which includes repair actions as one of the repair levels. Furthermore, the computer system may train the machine learning model, which performs multiple tasks for predicting values of individual levels of the repair hierarchy, by tuning parameters of the machine learning model using the training data.

When complex equipment experiences a failure, it may be difficult and time-consuming to determine the cause of the failure and a corresponding repair action for returning the equipment to a functioning condition. Furthermore, with aging technicians leaving the workforce in some industries, there may be a knowledge gap created in which newer technicians may not have sufficient experience to easily determine a cause of a failure and a suitable repair procedure for correcting the failure.

Equipment repair management and execution


A motorized reduction gear unit having a crank and connecting rod mechanism incorporated in it, but especially for use as a vehicle screen wiper drive unit, comprises a hollow casing having a cover plate, with, within the hollow interior of the casing, a toothed wheel which is rotatable about an axis. The toothed wheel carries a gudgeon pin parallel to the axis of rotation of the toothed wheel but eccentric with respect to the latter. The pin drives a crank and connecting rod system in which the crank and connecting rod are articulated together about a pivot pin, so that continuous rotary motion of the toothed wheel is converted into alternating rotary motion of an output shaft. It further includes a peripheral gasket disposed between the upper edge of the casing and the cover plate, together with a friction plate element in the form of a thickened friction portion disposed fixedly on the inner surface of the cover plate facing towards the casing. The peripheral gasket and the friction plate element together constitute a monobloc component.

Such a unit generally comprises an electric drive motor together with a speed reducing mechanism, in particular a mechanism of the worm type enclosed within the hollow casing by the cover plate.
The casing includes within its hollow interior, as is well known, a toothed wheel which is driven in rotation by the worm, and which actuates, via an eccentric gudgeon pin carried by this toothed wheel, a crank and connecting rod system which operates an output shaft, in such a way that the latter moves in alternating rotary motion. The output shaft extends through the base of the casing for connection with the screen wiper to be driven by it.
The crank and connecting rod system consists of an arm which is connected at one of its ends to the eccentric gudgeon pin carried by the toothed wheel. At its other end, this arm has a toothed sector which meshes with a second toothed sector. This second toothed sector is in turn fixed to the output shaft. In order that the two toothed sectors will remain in continuous engagement, they are linked together on either side by means of balance members, which also constitute the crank of the crank and connecting rod system.
However, such a motorised reduction gear unit has to be able to transmit very large forces. The crank and connecting rod system is subjected not only to forces transmitted by the toothed wheel in the axis of rotation of the connecting rod, which can cause the crank and connecting rod system stall, so as to give rise to axial displacement of the pivot of that system, but also to axial forces on the axis of the gudgeon pin, or on the axis of the output shaft itself.
It has previously been proposed, in a previous patent application of the present Applicants, namely French published patent application FR 2 667 670A, to immobilise against axial movement the eccentric gudgeon pin which is carried by the toothed wheel, by locating it against the cover plate by means of a friction plate which is fixed against the inner surface of the cover plate, and on which the end of the gudgeon pin engages. The same document also proposes the provision of a friction ring surrounding the end of the output shaft and disposed against the inner surface of the cover plate, being in engagement on one of the balance members that surround the output shaft.
These expedients avoid the situation in which the eccentric pin or the output shaft impact on the inner surface of the cover plate accidentally due to axial forces, so giving rise to noise. However, this problem still remains in connection with the crank and connecting rod system.
Accordingly, a simple and inexpensive way is sought to improve the operation of the pivotal connections at the eccentric gudgeon pin of the toothed wheel, and in the crank and connecting rod system.
In addition, in order to provide sealing against ingress of grease and dust into the flat joint between the cover plate and the casing, it is usual to arrange a gasket between the edge of the said cover plate and that of the casing. However, this gasket, which is currently made in a very fragile material, is a component which can easily become torn during assembly operations. In addition, because this component is very malleable, it is quite a delicate operation to fit it in place in the joint between the casing and the cover plate.

Motorized reduction gear unit comprising a hollow casing having a cover plate, especially for a screen wiping apparatus


An apparatus for the microbiological testing of pressurized liquids is disclosed which includes a completely closed container, at the base of which a membrane filter is sealed. Fitted upstream from the membrane is a built-in reading window and included downstream from the membrane, is a flange comprising a lip seal and a female threaded part. The apparatus may be used in conjunction with a microbiological testing process by screwing to the container a filtration support, taking and filtering the sample to be analyzed, and then substituting for the support an incubation cartridge for the subsequent development, in an incubator, of the colonies collected on the membrane.

In many industries, including the food, pharmaceutical and electronics industries, it is important to be able to check the microbiological quality of pressurized fluids, whether during transfer of such fluids through lines or whether such fluids are kept in storage tanks.
So far, the standard method used has been to sample, in aseptic conditions, a certain volume of liquid in a receptacle with the aid of a small sample valve and then to test this sample by the usual filtration method or the method described in U.S. Pat. No. 4,777,137 filed on Jan. 15, 1985 and assigned to Millipore Corporation.
It is easy to imagine the risks of "false positives" incurred by these samples and various transfer of samples. Moreover, these different operations waste time and cause delays in receiving the results of the analyses. The invention described below eliminates these risks because the filtration necessary for the analysis, as well as the placing of the filter in contact with the nutrient medium, which is necessary for the development of the microorganisms that are retained on the membrane, can be carried out in the field. Accordingly, this feature simplifies the operations hitherto necessary for the microbiological testing of these liquids.

Apparatus and method for the microbiological testing of pressurized liquids


A finned heat exchanger for increased heat transfer from liquid to air, includes of a plurality of stacked thin plates of conductive metal sheeting which are provided with stamped and drawn, slightly conical collars of elliptical, oval or other oblong cross section. The plates are stacked and assembled with the collars of each sheet forcefully pushed into the collars of the adjoining plate, thus effecting tightly closed ducts for the passage of the liquid. The thus-created ducts are arranged in rows and columns, wherein the long axes of the oblong cross section are inclined towards the center line of each column at an angle of 12.degree.-16.degree. to the left and to the right in alternate columns, and wherein the ducts in the rows are staggered in the direction of air flow, every second duct being disposed in forward direction by about half the length of the long axis of its cross section.

The invention relates to a finned-duct heat exchanger serving to transfer heat energy between a liquid flowing through the ducts and between air or gas caused to flow through the spaces between the fins. It relates particularly to a heat exchanger comprising a plurality of parallel closely stacked metal plates, each plate being provided with a plurality of protruding oblong conical collars, wherein the collars of each plate inserted into the collars of the adjoining sheet form continuous parallel ducts extending through the metal plates forming the fins of the heat exchanger. It furthermore relates to a heat exchanger wherein the axes of said oblong ducts are positioned at an angle to the direction of the flow of air or gas with the object of improving heat transfer and, on the other hand, reducing the flow resistance to the gas or air blown through the heat exchanger.
Although the heat exchanger to be described is suitable for any kind of gas flowing between the fins, including air, the expression "air" will be used in the following to describe any gaseous medium flowing through the exchanger, while the expression "liquid" will be used for any fluid, liquid or gaseous, made to flow through the ducts.
The inventor of the present heat exchanger is the owner of an inventor's certificate No. 983431, issued in USSR, disclosing a finned tube-less heat exchanger of the kind which has plurality of oblong finned ducts arranged in parallel rows perpendicular to the direction of air-flow, with their axes alternately inclined at equal angles to the direction of air-flow, thereby creating alternate converging and diverging air channels between pairs of adjoining ducts. Although this arrangement of ducts increases the heat transfer per unit area compared with the conventional finned-tube heat exchangers, it has the inherent drawback that certain portions of the air flow in reverse direction, mostly in the diverging air channel portions from higher to lower pressure zones, as illustrated in FIG. 1 of the drawings. This backflow results in stagnant air flow in the areas at the downstream ends of the ducts, where heat transfer is much lower than along the surfaces with rapid air flow. This type of flow evidently causes higher flow resistance and reduced heat transfer, and it is the main object of the present invention to obviate these drawbacks, as far as possible.
Tests with various arrangements of finned-tube heat exchangers are described in volume 182 of May 1966 of the Transactions of the ASME. These tests were carried out with oblong tubes having their axes aligned in the direction of air flow, and they showed that specific performance was the highest with staggered arrangement of the tubes, especially if turbulators were provided on the fins. These tests are quoted here, since a similar arrangement of ducts is employed in the heat exchanger of the present invention.
The present invention has the above-mentioned objects to reduce flow resistance and to increase heat transfer, and in addition to facilitate production of this kind of heat exchanger by obviating the necessity of sealing the connections between the duct portions of the metal plates by soldering or otherwise, as employed with the conventional type of tube-less heat exchangers.
The design of the heat exchanger according to the present invention is most suitable in the manufacture of radiators for motor vehicles, or of condensors and evaporators in air conditioning units, and in any other equipment designed for the exchange of heat energy between a gas and a liquid.


A multi-functional polymer defined by the formula(Q—RnZ—P2—Ywhere (Q—R)n is a functionality cluster, Q is a functional group, R is a multi-valent organic group, P2 is a long-chain polymer, n is an integer from about 2 to about 10, Y is a proton, a weak functional group, or a selective functional group, and Z is a branch point where the functionality clusters join the long-chain polymer.

In the art of making tires, it is desirable to employ rubber vulcanizates that demonstrate reduced hysteresis loss, i.e., less loss of mechanical energy to heat. Hysteresis loss is often attributed to polymer free ends within the cross-linked rubber network, as well as the disassociation of filler agglomerates.
Functionalized polymers have been employed to reduce hysteresis loss. The functional group of the functionalized polymer is believed to interact with a filler particle and thereby reduces the number of polymer free ends. Also, the interaction between the functional group and the filler particles reduces filler agglomeration, which thereby reduces hysteretic losses attributable to the disassociation of filler agglomerates.
One particularly useful functional group is tributyltin. Rubbery polymers containing a tributyltin functionality have produced rubber vulcanizates that demonstrate reduced hysteresis loss. These rubbery polymers have been prepared by anionic polymerization techniques whereby tin-lithio initiators, e.g., tributyltin lithium, have been employed as initiators.
Further reduction in hysteresis loss has been observed where the rubber polymers employed in the manufacture of tires contain functionalities at both the head and tail of the polymer. For example, polybutadiene and poly(styrene-co-butadiene) have been prepared by initiating their polymerization with a tin-lithio initiator, e.g., tributyltin lithium, and terminating the polymerization with alkyltin chlorides, which impart a tin functionality at the end of the polymer chain.
While polymers that have functionalities at both their head and tail have demonstrated the ability to provide filler-reinforced vulcanizates with advantageous hysteresis properties, the ability to process these polymers is reduced as compared to non-functional polymers. Namely, the ability to adequately mix filler particles into the rubber compound has proven to be problematic because it requires greater mixing energy and mixing time.
Because polymers that provide filler-reinforced vulcanizates with reduced hysteresis loss are important in the manufacture of tires, there is a need to overcome problems associated with prior art polymers.


Electronic device package on package (POP) technology is disclosed. A POP can comprise a first electronic device package including a heat source. The POP can also comprise a second electronic device package disposed on the first electronic device package. The second electronic device package can include a substrate having a heat transfer portion proximate the heat source that facilitates heat transfer from the heat source through a thickness of the substrate. The substrate can also have an electronic component portion at least partially about the heat transfer portion that facilitates electrical communication. In addition, the POP can comprise an electronic component operably coupled to the electronic component portion.

POP integrated circuit packaging is where two or more packages are stacked on a PCB. This arrangement provides a space savings on the PCB and has therefore become increasingly popular for small form factor applications due to the higher component density that can be provided in devices such as mobile phones, personal digital assistants (PDA), and digital cameras. Some POP configurations stack a memory package (e.g., DRAM, SRAM, FLASH, etc.) on a logic or processor package and are known as mixed logic-memory stacks. A logic or processor package can include processor and/or a system on a chip (SOC), which may integrate a CPU, a GPU, a memory controller, a video decoder, an audio decoder, a video encoder, a camera processor, system memory, and/or a modem onto a single chip.
Reference will now be made to the exemplary embodiments illustrated, and specific language will be used herein to describe the same. It will nevertheless be understood that no limitation of the scope or to specific invention embodiments is thereby intended.


In general, embodiments described herein relate to methods and systems for automating the configuration of network devices. More specifically, embodiments of the invention relate to using configuration commands that specify protocol-specified relationships in order to generate granular (or specific) filtering rules (also referred to as rules). The rules are subsequently programmed into the network device.

Network device configuration is a complex process. The complexity is the result of the network device having to support many different protocols and to send and receive network traffic from a large number of other network devices. Further, the networks in which the network devices are located are not statically configured. Rather, the configuration of the network may vary overtime. As a result, network administrators must routinely update the configuration of the network devices to address the changes in the network configuration. The traditional approach to configuring (or updating the configuration of) the network devices is a manual, time consuming, and error prone process. As a result, it is common for network devices to be misconfigured. This misconfiguration may, for example, expose the network devices (and, more broadly, the network) to malicious activity—e.g., distributed denial of service (DDOS) attacks and result in sub-optimal performance of the network.
For example, scenarios exist in which network devices in a network can be overwhelmed by a DDOS attack. The DDOS attack may be orchestrated by one or more of the malicious (or compromised) devices ("attacking devices") within or connecting to the network. The DDOS attacks generally take the form of hundreds, or thousands, of attacking devices sending network traffic to the network devices in the network. These attacking devices can aggregate an amount of network traffic that is large enough to overwhelm the network devices' ability to process legitimate network traffic. If the network devices are misconfigured, they can become overwhelmed and the overall operation of the network is negatively impacted.

System and method for managing a network device


A system for automatically charging fees when predetermined positions are passed, comprising a communication device (4) for dedicated short range communication (DSRC) that is intended for an at least temporarily stationary installation, and at least one mobile communication unit (7) for dedicated short range communication (DSRC); the DSRC communication device (4) provided to be stationarily installed is adapted for transmitting information identifying itself and thus, at least indirectly, its position of installation to the mobile DSRC communication unit (7).

1. Field of the Invention
The invention relates to a system for automatically charging fees when pre-determined positions are passed, e.g. for collecting road toll or parking fees, comprising a communication device for dedicated short range communication (DSRC) that is intended for an at least temporarily stationary installation, and at least one mobile communication unit for dedicated short range communication (DSRC).
2. Description of the Prior Art
Such a system is disclosed in WO 99/33027 A. In such a system, in particular for collecting tolls from motor vehicles, so-called "virtual" toll stations are used which enter into a bidirectional communication with vehicle-borne installations when the vehicles pass these stations. Information regarding the position of the vehicles is transmitted to the vehicle-borne device via a system such as GNSS (Global Navigation Satellite System), or GPS (Global Positioning System), respectively. The payment procedure is effected by linking the position information and the data stored in a device. The major disadvantage is that locating the vehicles is relatively imprecise and unreliable, and also the determination and the comparison with the virtual toll station is unsatisfactory; moreover, the devices required for this system are complex and expensive.
A quite similar system is described in WO 99/48052 A. This includes an identification of the vehicle-borne communication unit by means of, e.g., a smart card which is read out upon enquiry by the stationary toll station, thereby identifying the associated vehicle. The stationary toll station furthermore communicates with a central computer system so as to carry out the charging of the fees. However, this is rather complex as regards various identification and communication processes.
Moreover, from WO 99/66455 A a road-borne control for a toll device installed in a vehicle is known. For position determination, a GPS device is provided so that the road-borne control means can be recognized, or identified, respectively, by means of GPS at its respective site of installation.
A special dedicated short range communication method, in particular using microwaves, for communicating with a vehicle-borne unit (so-called "OBU"—On Board Unit) is disclosed in WO 99/25087 A, wherein a step-wise adjustment of the degree of modulation is effected in the modulation of a carrier wave. This, too, is a bidirectional communication between stationary installations (beacons) and vehicle-borne units, wherein nothing is said on obtaining an information regarding the position.


A well completion method provides for monitoring of reservoir pressure and saturation levels for two reservoirs from a single monitoring well. The well completion extends vertically through an upper and a lower reservoir. The well is cased, cemented, and perforated across the lower reservoir. A cement free zone is formed by cementing the casing string within the wellbore above an external casing packer above the upper reservoir. The casing string is perforated to allow fluid from the upper reservoir to flow through the cement free zone. A tubing string is landed and set within the casing string. The tubing string is sealed above and below the perforation at the cement free zone to prevent communication between fluid from the upper reservoir and the lower reservoir. The upper reservoir is monitored at the cement free zone, and the lower reservoir is monitored below an end of the tubing string.

1. Field of the Invention
The present invention relates in general to well monitoring and, in particular, to a well completion method to allow dual reservoir saturation and pressure monitoring.
2. Brief Description of Related Art
In conventional oil and gas production operations, a production well may be drilled into a subsurface fluid reservoir and completed for the production of reservoir fluid to the surface. Generally, a monitoring well may be drilled into the same reservoir as the production well. These monitoring wells provide information regarding the reservoir so that production may be controlled to maintain production at desired levels. The monitored information may include reservoir pressure, reservoir saturation levels, and the like.
The monitoring well will be drilled to the reservoir depth and completed by suspending a casing string within the wellbore. The annulus between the casing string and the wellbore will be cemented to secure the casing string within the wellbore. The casing string may be perforated at the reservoir location to allow fluid flow from the reservoir into the casing string. A tubing string will then be run and set to the casing string through the use of tubing packers so that an end of the tubing string is above the reservoir. A pressure monitoring gauge will be mounted to the end of the tubing string to monitor the reservoir pressure. Saturation and production logging may be performed through the perforated portions of the casing string located at the reservoir. Generally, pressure monitoring, saturation logging, and production logging occur proximate to, or below an end of the tubing string. In particular, saturation logging involves measurement of the pore volume of a reservoir formation that is filled by water, oil, and/or gas. Typically, acoustic or electromagnetic signals are passed into the formation through the monitoring well to generate saturation data. The signals must pass through the casing string wall and the cement layer to penetrate the formation.
Some production wells will be drilled through two reservoirs. In the corresponding production operations, reservoir fluid may be produced from both reservoirs. As a consequence, both reservoirs must be monitored. To obtain accurate pressure and saturation measurements, separate monitoring wells must be drilled to each reservoir. This is extremely costly and inefficient, essentially doubling the cost of reservoir monitoring.
Some attempts have been made to monitor two reservoirs from a single well. In these monitoring well completions, a single wellbore is drilled through both reservoirs. A casing string is then set and cemented in the wellbore. The cement layer in the annulus between the casing string and the wellbore will extend from the bottom of the well to the surface. The casing string is then perforated at both reservoirs. A tubing string is then run and set within the casing string. The tubing string will be set with a lower packer in between the reservoirs and an upper packer above the upper reservoir. Again, pressure monitoring, saturation logging, and production logging for the lower reservoir will all be conducted proximate to or below the end of the tubing string. However, this only provides accurate measurements of the lower reservoir.
Attempts have been made to conduct saturation logging operations across the upper reservoir. When this is attempted, the saturation logging signal must pass through the tubing string wall, an annulus between the tubing string and the casing string, the casing string wall, and the cement layer before entering the reservoir. The addition of the tubing string wall and annulus between the tubing string and the casing string may significantly decrease the strength of the saturation logging signals. As a consequence, the information generated during the saturation logging operations for the upper reservoir may be highly inaccurate. In addition, pressure monitoring is not possible due to the inability to isolate flow from the two reservoirs when a pressure gauge is used to monitor the upper reservoir. Therefore, there is a need for a well completion method that allows for accurate monitoring of pressure and saturation of more than one reservoir from the same well.

Completion method to allow dual reservoir saturation and pressure monitoring


A driver associated with a host peripheral component interconnect (PCI) device may be initiated, the host PCI device to be accessed by an application executed by a guest operating system (OS) of a guest using user space memory of the guest. A host page table switching instruction may be executed using the driver to cause a switch from a first host page table structure to a second host page table structure. The host PCI device may be accessed using the driver via a PCI alias address that is mapped to a host PCI address in the second host page table structure. Application code associated with the application may be prevented from accessing a host memory address in the second host page table structure.

Computer systems often include memory management features that provide memory protection. The memory management features may restrict particular processes from accessing particular portions of one or more devices. The devices may be physical devices, virtual devices, or a combination thereof. The restriction may be enforced using a combination of hardware features and kernel features that work together to provide or restrict an executing process from accessing memory resources. The memory resources are often separated into user space and kernel space and when a user space process attempts to access memory resources in kernel space the memory management features may generate a segmentation fault. The segmentation fault may indicate that an access violation occurred so that it can be handled accordingly. Device drivers often execute in kernel space and rely on the memory management features to protect memory associated with the device driver from being accessed by user space processes.

Efficient userspace driver isolation for virtual machines


Methods are disclosed for calculating cumulative exposure energy from a microlithography reticle, especially a reticle used for charged-particle-beam (CPB) microlithography. The methods provide an accuracy of results at least as high as conventional methods, but the subject methods can be performed using substantially less calculation time, even for complex patterns. The pattern features contained within a region and/or one or more size parameters of the region are evaluated according to specified rules. The region also is subdivided according to the specified rules. Subdivision produces subregions that also are evaluated according to the rules to determine whether to subdivide further or to cease further subdivision. The result is a branching structure for the region, containing multiple levels of subregions arranged in an hierarchical manner. As a result, e.g., a subregion distant from a cumulative-energy evaluation point (and that has little effect on the distribution position of elements therein) can be left relatively large, whereas a subregion near the evaluation point has a relatively large effect on the distribution position of the elements therein and hence is relatively small. From the branching structure, cumulative energy is calculated from the constituent subregions.

The present invention pertains to microlithography (projection-transfer of a pattern, defined by a reticle, onto a sensitive substrate) using an energy beam such as a charged particle beam (e.g., electron beam or ion beam). Microlithography in general is a key process used in the manufacture of microelectronic devices such as integrated circuits, displays, and the like. More specifically, the invention pertains to methods for determining proximity effects encountered with certain microlithography techniques, especially charged-particle-beam (CPB) microlithography. The methods involve determinations of cumulative exposure energy (exposure dose) at specific loci on a sensitive substrate. The results of such determinations are used for, inter alia, designing reticles that are less subject to proximity effects during use.
All conventional wafer-processing methods include at least one microlithography step, in which a pattern, defined on a mask or reticle, is transferred onto a sensitive substrate such as a semiconductor wafer. Typically, multiple xe2x80x9cchipsxe2x80x9d are formed on each wafer, and multiple microlithography steps are performed to form various patterned layers of the chips. As an energy medium for making the pattern transfer, a beam of electromagnetic radiation (e.g., light, X-rays) or of charged particles (e.g., electron beam, ion beam) is used. To be imprinted with the pattern, the substrate is coated with a suitable xe2x80x9cresist.xe2x80x9d With a xe2x80x9cpositivexe2x80x9d resist, regions that receive a cumulative exposure energy (dose) exceeding a threshold value are removed by developing the resist. With a xe2x80x9cnegativexe2x80x9d resist, regions that receive a cumulative exposure dose exceeding a threshold value are left on the wafer after development. Hence, in order to form a pattern properly on the substrate, it usually is necessary to calculate whether the cumulative exposure dose at each region of the substrate is higher than the specified threshold value. It also is necessary to configure the reticle so that the respective shapes of the regions where energy accumulates above the threshold value will form pattern elements having the intended profiles.
In charged-particle-beam (CPB) microlithography, xe2x80x9cproximity effectsxe2x80x9d frequently are encountered, in which the respective doses of exposure energy received at any of various loci on the wafer surface vary according to the respective distribution and configuration of pattern elements in the vicinity of the loci. I.e., the distribution and configuration of nearby pattern elements affect the manner in which charged particles of the beam are scattered as they encounter the substrate. Scattered charged particles can cause unintentional development of nearby regions of the resist in various ways, resulting in pattern elements being formed on the substrate having profiles that deviate substantially from the intended profiles of the elements. I.e., the profiles of the pattern elements as formed on the wafer unintentionally have different profiles than the corresponding elements as defined on the reticle.
In optical microlithography, proximity effects as summarized above generally do not occur. However, errors in the pattern as transferred to the substrate can occur due to light diffraction. Hence, in both optical and CPB microlithography, unavoidable differences can arise between the shapes of pattern elements as defined on the reticle versus the shapes of corresponding pattern elements as formed on the substrate.
Various methods have been considered for solving this problem. The methods generally involve changing and adjusting localized cumulative amounts of radiation dose received at the substrate so as to obtain the desired distribution of cumulative exposure energy at the surface of the substrate. For example, certain methods involve localized deformation of certain pattern elements as defined on the reticle.
A conventional method for calculating local cumulative exposure dose, leading to corresponding deformations of pattern elements as defined on the reticle to correct proximity effects in CPB microlithography, is discussed below, referring to FIGS. 20(a)-20(c). In FIG. 20(a), item 101 is a pattern element having a profile that is to be transferred to the substrate with minimal profile change. For convenience, the transfer magnification is unity. The edge of the pattern element 101 is divided into N segments S1-SN as shown in FIG. 20(b). The element as defined on the reticle is deformed deliberately by moving each of these segments a tiny amount in a direction perpendicular to the direction in which the edge of the segment extends. This is shown in FIG. 20(c), which depicts a magnified view of a portion of the pattern element 101 after moving certain segments. Specifically, FIG. 20(c) shows segments S1, S2, and SN. The desired outline of the pattern element to be formed on the substrate is denoted by the line 102. In FIG. 20(c), segments SN and S2 have been moved inward relative to the line 102 (thereby forming xe2x80x9cindentsxe2x80x9d), and the segment S1is moved outward (thereby forming a xe2x80x9cprojectionxe2x80x9d). A1, A2, AN denote respective points on the line 102 corresponding to centers of the respective edges ofxe2x80x9cpre-movexe2x80x9d segments S1, S2, SN. The points A1, A2, AN are points at which evaluations of cumulative exposure dose are made.
Referring further to FIG. 20(c), D1, D2, and DN are respective vectors indicating the magnitude and direction of movement of the edge of each respective segment S1, S2, SN. A respective vector D1-DN is assumed for each segment S1-SN in this manner, and the change in cumulative exposure dose occurring at each evaluation point A1-AN is calculated in accordance with the change in position of the edge of each segment according to the respective vector. That is, cumulative exposure energy (dose) is changed at each evaluation point Ai (i=1, 2, . . . , N) by moving the edge of the respective segment S1-SN according to the respective vector Dj (j=1, 2, . . . , N), and the change in cumulative exposure dose received at each evaluation point Ai (i=1, 2, . . . , N) can be determined from the respective vector.
Before actually moving each segment S1-SN, the cumulative exposure dose that would be received by the entire respective pattern element (e.g. as shown in FIG. 20(a)) after moving the segments is determined. Desirably, the total exposure dose received by the element after moving the segments is unchanged from the total exposure dose that otherwise would be received by the pattern element before moving the segments. Hence, for each element, the vectors Dj (j=1, 2, . . . , N) are re-determined in an iterative manner as required until the total exposure dose received by all the evaluation points Ai (i=1, 2, . . . , N) of the element is equal to the total that otherwise would be obtained if the respective pattern element were unchanged from that shown in FIG. 20(a).
In the method summarized above, the evaluation points Ai (i=1, 2, . . . , N) are positioned on the sensitive substrate to correspond to the center points of each xe2x80x9cpre-movexe2x80x9d segment S1-SN. Alternatively, the distribution of cumulative exposure dose may be evaluated along respective lines intersecting each segment at an angle, as described in U.S. Pat. No. 5,698,859, incorporated herein by reference. For example, the distribution of cumulative exposure dose can be evaluated along a line 103 perpendicularly intersecting segment S2 (FIG. 20(c)).
FIGS. 21(a)-21(b) show a second conventional method for calculating cumulative exposure dose, termed a xe2x80x9crepresentative figurexe2x80x9d method. This method achieves simplification of pattern-element figures by reducing the number of pattern-element figures referred to for calculating cumulative exposure energy (dose). I.e., the complex and fine pattern-element figures of, e.g., an LSI pattern are replaced (for analysis purposes) with simple figures each having xe2x80x9ccoarsexe2x80x9d pattern information that is the same as that of the original pattern-element figures in individual small regions of the pattern. For ease of discussion, the magnification of the image as formed on the substrate, relative to the pattern as formed on the reticle, is unity. In FIG. 21(a) xe2x80x9cPxe2x80x9d is a point at which cumulative exposure dose is calculated, xe2x80x9cFxe2x80x9d is a pattern element, and xe2x80x9c101xe2x80x9d denotes a reference region referred to for calculating the cumulative exposure dose. Only the pattern elements in the region 101 are assumed to have any effect on the cumulative exposure dose at the point P. The region 101 is divided into small regions 102 of a suitable size. (In this example, the region 101 is divided vertically and horizontally three times each, for a total of nine small regions 102. In actual practice each region 101 is divided into many more small regions 102 than nine.)
The total pattern-element area and centroid of the respective pattern element(s) in each small region 102 are calculated for each small region 102. Then, as shown in FIG. 21(b), a respective simplified figure Fxe2x80x2 (known as a xe2x80x9crepresentative figurexe2x80x9d) is created for each small region 102. Note that each small region 102 has a single representative figure. Each simplified figure Fxe2x80x2 has the same total pattern-element area and centroid as determined for the actual pattern element(s) in the respective small region 102 that may or may not contain pattern elements.
When calculating the cumulative exposure dose for each small region 102, the calculation is performed for each representative figure Fxe2x80x2 instead of having to calculate the dose for each pattern element F in the small region 102 and summing them for each small region 102. To form the small regions 102, the reference region 101 simply is divided equally, horizontally and vertically, into equal-area small regions 102.
The disadvantage with the first conventional method summarized above is that, with N divided segments, calculations must be performed N2 times. Hence, as N increases, the number of calculations increases geometrically, and calculation time correspondingly increases.
With the second conventional method summarized above, as the size of the small regions 102 increases, each small region encompasses more respective pattern elements that are replaced, for analysis purposes, by a respective representative figure, and calculation speed increases. However, simply increasing the size of the small regions does not take into account data concerning the distribution of pattern elements inside each small region 102. Consequently, the accuracy of the determined value of cumulative exposure dose received by each small region is less than obtainable if the representative figure method were not used. Conversely, if the size of the small regions 102 were to be decreased, then the accuracy of the exposure-dose calculations would increase, but there would be little to no difference between the number of original pattern elements and the number of representative figures. Hence, the benefit of improving calculation speed is lost.
In view of the shortcomings of the prior art as summarized above, an object of the invention is to provide improved methods for calculating cumulative exposure dose (energy) of defined regions of a reticle pattern. The methods provide a calculation accuracy at least as good as conventional methods but can be performed faster so as to accommodate the increasing number and complexity of pattern elements in contemporary microelectronic-device patterns. Other objects are to provide proximity-effect calculation methods utilizing such methods, reticle-design methods including such proximity-effect calculation methods, and microelectronic-device-fabrication methods utilizing reticles manufactured using such reticle-design methods.
A first aspect of the invention is directed to methods for determining a cumulative dose of exposure energy received by exposed portions of the sensitive substrate, as used in a microlithography method in which a pattern defined on a reticle is transferred to a sensitive substrate using an energy beam. According to one embodiment of such a method, in a first-level region of the reticle defining multiple pattern elements with respect to which cumulative exposure dose is to be determined, the total cumulative dose for the region is set initially to zero. Also, an evaluation point is selected in the region at which cumulative exposure dose is to be calculated. The region is divided in a branching manner into a second level of subregions each having a respective reference point from which distance measurements concerning the subregion are to be taken.
If a subregion has a size parameter that, in a ratio to a distance between the respective reference point and the evaluation point, is greater than a specified value xcfx86, then the following sub-steps are performed: (1) the subregion is not subdivided, (2) the pattern elements located in the subregion are converted into at least one corresponding representative figure, (3) based on the representative figure(s) in the subregion, a contribution of the subregion to the cumulative dose of exposure energy at the evaluation point is calculated, and (4) the contribution is added to the total cumulative dose for the evaluation point in the region. If a subregion contains a number of pattern elements that is no greater than a specified number m, then the following sub-steps are performed: (1) the subregion is not subdivided, (2) the pattern element(s) in the subregion are regarded as their own respective representative figure(s), (3) based on the representative figure(s) in the subregion, a contribution of the subregion to the cumulative dose of exposure energy at the evaluation point is calculated, and (4) the contribution is added to the total cumulative dose for the evaluation point in the region. The two conditional steps noted above in this paragraph can be performed in either order. If a subregion does not satisfy either of these conditional steps, then the subregion is subdivided in a branching manner into a next-lower (e.g., third) level of subregions, wherein each next-lower-level subregion has a respective reference point from which distance measurements concerning the subregion are to be taken. Then, the steps described in this paragraph are repeated for each of the next-lower-level subregions. After exhaustively subdividing the region as summarized above, the resulting cumulative exposure dose is regarded as the cumulative exposure dose for the evaluation point in the region.
This embodiment differs from the conventional xe2x80x9crepresentative figurexe2x80x9d method, in which the subject region is divided into identically sized subregions regardless of any specific characteristics of the region or of the distribution of pattern elements in the region. In this embodiment, in contrast, a subregion located distantly from the evaluation point has relatively little effect on the distribution of the pattern portion in the region. Hence, the more distant subregion can be larger than subregions nearer to the evaluation point. In contrast, a subregion located near the evaluation point has a relatively large effect on the distribution of the pattern portion in the region. Hence, the nearer subregion typically is relatively small. These differently sized subregions result from application of branching division according to the invention.
In other words, a region to be evaluated is subdivided according to specified rules. In applying the rules, decisions are made on whether to further subdivide a subregion. If the decision is to subdivide, then the subdivision is conducted according to the specified rules to produce subregions at the next lower level. In this manner, the region is divided into a respective group of subregions that are hierarchically related to each other according to the branching structure that was created.
In this embodiment, the decision criterion for whether to subdivide a region (or subregion) is the ratio of a size parameter of the region (or subregion) to the distance between the evaluation point and a xe2x80x9creference pointxe2x80x9d for the region (or subregion). The xe2x80x9cevaluation pointxe2x80x9d is a selected point in the region where the cumulative dose of exposure energy in the region is to be calculated. The xe2x80x9creference pointxe2x80x9d for the region or subregion can be, e.g., the center of the respective region or subregion. Representative size parameters include: (a) the area of the region or subregion, (b) the length of a side of the region or subregion (especially if the region or subregion is a regular polygon such as a square, etc.), and (c) the circumference of the region or subregion. An alternative distance parameter is the maximum distance between the evaluation point and the subject subregion.
If a subregion has a size parameter that, in a ratio to the distance between the respective reference point and the evaluation point, is smaller than the specified value xcfx86, and if the number of pattern elements contained in the subject subregion is no greater than m, then the respective pattern element(s) is regarded as the corresponding representative figure. The contribution of the subject subregion to the cumulative exposure energy for the evaluation point in the region is calculated using the representative figure. The contribution is added to the cumulative exposure energy, and no further subdivision of the subregion occurs. If the number of pattern elements contained in the subject subregion is larger than m, then the subregion is further subdivided in a branching manner into the next-lower-level of constituent subregions.
The simplest value of the number xe2x80x9cmxe2x80x9d is unity (1), which is useful for any pattern arrangement or size. A value of m=1 also is desired from the perspective of ensuring calculation accuracy.
The simplest manner of converting the pattern portion contained within a subject subregion into one or more representative figures is to convert the portion into a single representative figure. An exemplary method of making such a conversion is described in Oogi et al., xe2x80x9cHigh-speed Convolution System for Real-time time Proximity Effect Correction,xe2x80x9d Jap. J. Appl Phys. 37:6779-6784 (1998). If a subregion contains multiple pattern elements, then the subregion can be subdivided further into lower-level subregions each containing no more than one pattern element. The individual pattern elements in the lower-level subregions can be converted into respective representative figures.
In making the decision on whether to subdivide a region or subregion, a similar result is obtained regardless of which is performed first: (1) determining whether the size parameter of the region or subregion, in a ratio to a distance between the respective reference point and the selected evaluation point, is greater than a specified value xcfx86, or (2) determining whether the number of pattern elements contained in the subject region or subregion is no greater than a less than or equal to a specified number m.
In this embodiment, the steps of subdividing a subject region or subregion and determining cumulative exposure dose are performed simultaneously. Hence, at the time that a region is subdivided exhaustively and converted as required to corresponding representative figures according to the invention, calculation of the cumulative dose of exposure energy also is completed. Conventionally, calculating a contribution to exposure dose made by a representative figure is performed using a xe2x80x9crepresentative figurexe2x80x9d method as described in, for example, U.S. Pat. No. 5,863,682, incorporated herein by reference.
In another embodiment of a method according to the invention, in a first-level region of the reticle defining multiple pattern elements with respect to which cumulative exposure dose is to be determined, a total cumulative dose for a selected evaluation point in the region is initialized to zero. The region is divided in a branching manner into one or more sublevels of subregions as required until each of the subregions thus formed contains a respective number of pattern elements no greater than a specified number m. Such branching division creates a branching structure of subregions from the first level to an nh level, wherein each subregion has a respective reference point from which distance measurements concerning the respective subregion are to be taken.
If a subregion in an ith (1xe2x89xa6ixe2x89xa6n) level has a size parameter that, in a ratio to a distance between the respective reference point and the evaluation point, is greater than a specified value xcfx86, then the following sub-steps are performed: (1) pattern elements located in the subject subregion are converted into at least one corresponding representative figure, (2) based on the representative figure(s) in the subject subregion, a contribution of the subject subregion to the cumulative exposure dose is calculated, and (3) without regard to any contributions possibly made by (i+1)th or other lower-level subregions of the subject subregion, the contribution of the subject subregion is added to the total cumulative dose for the region. If the subregion in the ith level contains a number of pattern elements that is no greater than a specified number m, then the following sub-steps are performed: (1) the pattern element(s) in the subject subregion is regarded as its own respective representative figure(s), (2) based on the representative figure(s) in the subject subregion, a contribution of the subject subregion to the cumulative exposure dose is calculated, and (3) the contribution of the subject subregion is added to the cumulative dose for the evaluation point in the region. The two conditional steps noted above in this paragraph can be performed in either order. If a subregion does not satisfy either of these conditional steps, then the conditional steps are repeated for (i+1)th-level subregions of the subject subregion.
After performing the above for all applicable subregions of the region, then the resulting cumulative exposure dose is regarded as the cumulative exposure dose for the evaluation point in the region.
In the first embodiment summarized above, subdivision of a region and calculation of cumulative exposure energy were performed simultaneously, subregion-by-subregion as the subregions were designated. In the second embodiment, in contrast, complete branching division of a region is performed, until the number of pattern elements contained in each subregion is no greater than m. After the complete branching structure of the region is determined, representative figures are created for the pattern element(s) in the subregions thus formed, and respective contributions of the representative figures are calculated. The respective contributions are calculated in the same manner as in the first embodiment. Hence, the end result of the second embodiment is the same as with the first embodiment.
In yet another embodiment of a method according to the invention, a region of the reticle is selected that defines multiple pattern elements with respect to which cumulative exposure dose is to be determined. In the region, an evaluation point is identified at which cumulative exposure dose in the region is to be calculated. The region is subdivided in a branching manner into one or more sublevels of subregions. Each subregion has a respective reference point from which distance measurements concerning the respective subregion are to be taken
If a subregion has a size parameter that, in a ratio to a distance between the respective reference point and the evaluation point, is greater than a specified value xcfx86, then the subject subregion is not further subdivided, and any pattern elements located in the subject subregion are converted into at least one corresponding representative figure. If the subregion contains a number of pattern elements that is no greater than a specified number m, then the subject subregion is not further subdivided, and the pattern element(s) in the subregion is regarded as its own respective representative figure. The two conditional steps noted above in this paragraph can be performed in either order. If a subregion does not satisfy either of these conditional steps, then the subject subregion is subdivided in a branching manner into a next-lower level of subregions. The conditional steps are repeated for each of the next-lower-level subregions. After the region has been subdivided exhaustively according to the above, respective contributions of exposure energy from each of the subregions to a cumulative exposure dose for the region are calculated. The resulting cumulative exposure dose is regarded as the cumulative exposure dose for the evaluation point in the region.
In the first embodiment summarized above, subdivision of a region and calculation of cumulative exposure energy were performed simultaneously, subregion-by-subregion as the subregions were designated. In the third embodiment summarized above, subdivision of the region and creation of representative figures are performed first. After the representative figures are created, the cumulative energy at the evaluation point is determined by combining the individual contributions from each of the respective subregions. Hence, the result of this embodiment is similar to the result of the first embodiment.
In yet another embodiment of a method according to the invention, a subject region is divided in a branching manner into one or more sublevels of subregions as required until each of the subregions thus formed contains a respective number of pattern elements no greater than a specified number m. Hence, a branching structure is created of subregions from the first level to an nth level. Each subregion has a respective reference point from which distance measurements concerning the respective subregion are to be taken.
If a subregion in an ith (1xe2x89xa6ixe2x89xa6n) level has a size parameter that, in a ratio to a distance between the respective reference point and the selected evaluation point, is greater than a specified value xcfx86, then any pattern elements located in the subject subregion are converted into at least one corresponding representative figure. However, respective representative figures for pattern elements located in any lower-level subdivisions of the subject subregion are not created. If the subregion contains a number of pattern elements that is no greater than a specified number m, then the pattern element(s) in the subregion is regarded as its own respective representative figure. However, again, respective representative figures for pattern elements located in any lower-level subdivisions of the subject subregion are not created. If a subregion does not satisfy either of these conditional steps, respective representative figures are created for respective pattern elements contained in (i+1)th-level subregions of the subject subregion. With respect to all subregions of the subject region from the first level to the nth level, the individual exposure-dose contributions from the representative figures in the subregions are summed to yield a cumulative exposure dose for the evaluation point in the region.
In yet another embodiment, the region is divided in a branching manner into one or more sublevels of subregions as required until each of the subregions thus formed contains a respective number of pattern elements no greater than a specified number m. Thus, a branching structure of subregions is created from the first level to an nth level. For each subregion thus formed, if the subject subregion contains a number of pattern elements that is no greater than a specified number m, then the pattern element(s) in the subject subregion is regarded as its own respective representative figure(s). If the subject subregion contains a number of pattern elements that is greater than the specified number m, then the pattern elements located in the subject subregion are converted into at least one corresponding representative figure.
For each subregion formed as summarized above, if the subject subregion has a size parameter that, in a ratio to a distance between the respective reference point and the selected evaluation point, is greater than a specified value xcfx86, then a contribution of the subject subregion to the cumulative exposure dose at the evaluation point is calculated without considering any contribution of lower-level subregions of the subject subregion to the cumulative exposure dose. If the subject subregion contains a number of pattern elements that is no greater than the specified number m, then a contribution of the respective representative figure(s) to the cumulative exposure dose at the evaluation point is calculated without considering any contribution of lower-level subregions of the subject subregion to the cumulative exposure dose. Either conditional step can be performed first. If a subregion does not satisfy either of the conditional steps, then, in the calculation of the respective contribution of the subject subregion to cumulative exposure dose, contributions of lower-level subregions of the subject subregion are included. The individual calculated exposure-dose contributions from all the subregions of the region are summed to yield a cumulative exposure dose for the evaluation point in the region.
In this method, as in other methods summarized above, branching division of the region is performed until the respective number of pattern elements included in any subregion is less than or equal to a specified number m. Meanwhile, representative figures are formed in all subregions, including subregions at lower levels in which, in other embodiments summarized above, representative figures were not determined. It would appear that this would require excessive calculation time. However, if a similarly configured subregion appears at multiple places, the cumulative energy calculation for the evaluation point can be performed once for such a subregion and the results of the calculation used wherever the subject subregion occurs. Thus, calculation time can be reduced substantially for certain patterns.
In any of the methods summarized above, if the number of pattern elements included in a subregion is less than or equal to 1, instead of regarding the respective pattern element as its own representative figure, the pattern element can be converted into a respective representative figure having a simpler profile than the respective pattern element.
In any of the methods summarized above, if the number of pattern elements included in a subregion is no greater than a specified number m, then the respective pattern element can be regarded as its own representative figure. Alternatively, the pattern element can be converted into a respective representative figure having a relatively simple profile and usable for making cumulative-dose calculations, thereby simplifying the calculations.
In any of the methods summarized above, a pattern element can be divided into a combination of a core portion (e.g., having a relatively simple shape) and secondary portions located outside the core portion. One or more of the secondary portions can include portions having a negative shape. A separate cumulative energy calculation can be performed for the core portion (using conventional methods), with cumulative energy calculations for the secondary portions being performed using any of the above-summarized methods according to the invention. A cumulative exposure dose for a pattern element is obtained simply by adding the energy calculated for the respective secondary portions to the energy calculated for the respective core portion. This method variation can provide a more accurate and rapid determination of the respective exposure-dose contribution of, for example, a single complex pattern element present in a subregion. I.e., because the core portion has a simple profile, its contribution to cumulative exposure dose can be determined easily using conventional methods, saving the method according to the invention for calculating the respective contributions from the secondary portions.
Any of the processes summarized above can be recorded on a suitable computer-readable medium to allow automation of the method under the control of a computer. More than one method can be programmed on the same medium.
The foregoing and additional features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings.

Methods for calculating cumulative dose of exposure energy from regions of a microlithography reticle for use in correcting proximity effects


A circuit and method are given, to realize a high efficiency voltage multiplier for integrated circuits generating an internal and flexible positive or negative high voltage on-chip supply voltage from low external positive or negative supply voltages or ground. Applying multi-phase control signals to voltage boost internal nodes allows for eliminating threshold voltage drop losses and thus improves the voltage pumping gain compared to circuits with diode-configured FETs of prior art. Making use of voltage signals from antecedent stages in order to bias the bulk of MOS transistors fabricated in triple-well technology enables relaxing of the gate oxide stress within high order stage MOS transistors. Such a method, called leap-frog bulk potential tracking method, makes MOS transistors from different stages exhibit about the same body effect, which is very important because MOS transistors of higher order stages now show the same performance as MOS transistors from lower order stages. Important also in terms of efficiency as the charge sharing speed of high order MOS transistors always dominates the total charge pump performance and the driving force of pumped currents, thus also allowing for a greater number of serially connectable stages overall or a smaller number necessary for a certain targeted output voltage.

(1) Field of the Invention
The present invention relates in general to semiconductor voltage generator circuits, and particularly to capacitive voltage multiplier circuits using MOS transistors, even more particularly to voltage multiplier circuits using charge pumps manufactured as semiconductor integrated circuits.
(2) Description of the Prior Art
Recent developments in electronic devices for modern mobile and portable equipment for telecommunications and data processing have strengthened a tendency to an ever-continuing decrease of the applied supply voltages and furthermore to prefer components still needing one single supply voltage only. Portable devices are in general powered by batteries and weight and size of modern batteries play an important role in customer's acceptance, thus smaller devices with small batteries however furnishing low voltages only are in focus of current manufacturing and marketing strategies. Most modern integrated circuits utilizing a single power supply voltage incorporate on-chip circuitry to generate a "boosted" voltage having a magnitude greater than their own power supply voltage. Frequently this boosted voltage is used as a veritable power supply voltage for portions of the circuitry also contained on the integrated circuit and needing such higher voltages for their proper functioning. Common examples for integrated circuits comprising such portions are semiconductor memory devices of all kinds, such as Random Access Memory (RAM) circuits or special Non Volatile (NV)—RAM devices, like memory devices which make use of so-called 'floating gates' needing high voltages for their operation, like Flash-EPROM (Erasable Programmable Read-Only Memory) or E-EPROM (Electrically Erasable PROM) devices. Modern integrated memory devices using Magnetoresitive (MRAM) and Ferroelectric (FRAM) technologies are to be counted in also. Other types of circuits, e.g. for logic functions like EPLD (Erasable Programmable Logic Device) make also use of 'floating gates' and therefore need much higher voltages as their supply voltage VDD. Unlike many older devices, which required that two different power supply voltages be supplied, to operate the device (e.g., +5 and +12 volts), many contemporary devices now have only one single power supply voltage (usually called VDD: D as legacy from Drain) of (2.5-3.3) volts (relative to "ground" or VSS: S as legacy from Source). This VDD power supply voltage is typically utilized to power most of the device, within semiconductor memory devices also including the normal data read operation circuit parts. The higher voltage (frequently called VPP: P as legacy from Programming) is generated by an on-chip voltage generator having a typical value of +8 volts (again relative to VSS) rather than requiring a separate power supply voltage used for write operations within memory circuits. In many integrated circuits, such on-chip voltage generators are implemented as capacitive voltage multiplier circuits, largely because of the relative ease of implementing suitably large capacitors in a monolithic integrated circuit technology. These capacitive voltage multiplier circuits are usually called "charge pumps". Charge pumps are circuits that pump charge into capacitors to develop an output voltage higher than the supply voltage. Such voltage generators or voltage multipliers used to "pump" a voltage from a lower voltage level to a higher voltage level are well known. Typically, they are used in non-volatile memory arrays in which the high voltage is required to program or erase the non-volatile memory cells. The supplied voltage is the "low" voltage and the "high" voltage is used to program or erase the memory cells. In general, electronic devices built as integrated circuits for a capacitive voltage multiplier operation are made up of multiple stages essentially connected in series and comprising charge pumps in order to "pump" a voltage from a lower source level to a higher source level. Many charge pump circuit stages can thus be implemented serially to increase the voltages provided. Each stage contains a pair of diodes (or transistors configured as a diode) and two capacitors. The stages are driven by a pair of alternating clock signals. High voltage charge pumps are able to provide positive or negative high voltages.
FIG. 1A prior art shows the three (3)-stage design of a prior art single anti-phase clock voltage multiplier circuit. This circuit displays said serial connection of Charge Pump stages (CP/CPs) built with easy integrable components only: MOS transistors and MOS capacitors, whereby each MOS transistor is connected in a diode configuration and also each capacitor is implemented by a MOS transistor. Each CP-stage is comprised of two serially connected Charge Transfer stages (CT/CTs) e.g. CTs1 (11) and CTs2 (12). Each CT stage is made up of one diode connected MOS transistor, e.g. D1 (14a) or D2 (14b) and one charge storage MOS capacitor, e.g. C1 (13a) or C2 (13b). Each CT stage has input node and output node, e.g. CTs1 nodes N1 (24) and N2 (26), CTs2 nodes N2 and N3 (28) respectively. The above-mentioned stage count of three for the circuit is based on this definition. The exemplary CP-stage 10 shall thus be consisting of diodes D1 and D2 and its two corresponding capacitors C1 and C2 as first stage 10. Capacitors C1 and C2 supply the two complementary control (clock) signals BSTA (25a) and BSTB (25b) to nodes N1 and N2 respectively, whereby all odd numbered (or alternately even-numbered) CT stages are supplied by BSTA and all even numbered (or alternately odd-numbered) CT stages by BSTB, which is clocked in anti-phase to BSTA. The abbreviation BST shall hereby remind of BooST, the action which is crucial for the circuit and which gets controlled by these signals, the letters A and B are used persistently to designate complementary pairs of items. An input isolation diode DVDD (18) feeds supply voltage VDD at node NVDD (20) to input node N1 connected to D1 and C1. Output node N3 connected to D2 leads eventually to the following CP-stages, in our case however only one further CT stage is following, namely CTs3 (17), set-up by MOS capacitor C3 (15) and diode connected MOS transistor D3 (16), whereby capacitor C3 is again supplying said clock signal BSTA to one electrode of diode D3. The other electrode of said diode D3 is now furnishing the output voltage VPP 29 of the multiplier circuit to a final load capacitor Cload 19, also connected to VSS 28 or ground. For future reference: the voltages at the individual nodes 24, 26 and 28 corresponding to the diode-capacitor combinations D1-C1, D2-C2 and D3-C3 shall be designated as V1, V2 and V3 respectively. The drawing in FIG. 1A prior art shows a so-called Dickson CP circuit proposed by J. Dickson in IEEE Journal of Solid-State Circuits (see J. F. Dickson, "On-Chip High-Voltage Generation in MNOS Integrated Circuits Using an Improved Voltage Multiplier Technique", IEEE J. of Solid-state Circuits, vol. SC-11, No. 3, June, 1976, pp. 374-378, which is hereby incorporated by reference in its entirety). Dickson's architecture is a construction of diode-coupled switches and pumping capacitors responding to two complementary clock signals.
Referring now to FIG. 1A prior art again for a summary, the voltage multiplier circuit includes a plurality of serially connected CP-stages, one of which is labeled 10. Each CP-stage includes two CT stages, each made up of a diode D1 or D2 as charge transfer switch and a capacitor C1 or C2 as charge storage device, thus forming CTs1 and CTs2, each having an input node and an output node with corresponding voltages V1 at node N1, V2 at node N2 and V3 at node N3. A complementary pair of clock signals BSTA and BSTB is provided to drive the various pump stage capacitors C1 and C2. The input node N1 of the first serially-connected CP-stage is usually connected to the VDD power supply (at least for generating a boosted positive voltage) via an isolation diode DVDD, which may also be considered as part of another serially-connected CT stage, and the output voltage being VPP of the last CT stage, here CTs3, taken from output node NVPP (29) (which could otherwise be considered as output node of a last serially-connected CT stage) and measured over load capacitor Cload versus VSS or ground. Not previously mentioned are second order or side effects such as forward diode drop voltages or threshold voltages (V.sub.th) of the MOS-transistor diodes and parasitic stray capacitances (C.sub.s) formed in MOS circuits from said transistor drain and storage capacitor nodes versus ground. In practice, the diodes are frequently implemented as diode-connected MOSFETs, each with its gate terminal and drain terminal connected together to form one terminal of the diode, and its source terminal forming the other terminal of the diode. Also, the capacitors are frequently implemented as large area MOSFETs, each with its source terminal and drain terminal connected together to form one terminal of the capacitor, and its gate terminal forming the other terminal of the capacitor. Furthermore, the output voltage is usually somewhat less than this theoretical value, due to said stray capacitances, incomplete charge transfer, DC current flow provided into the output node, and other effects, which have been well studied in the literature and which shall be re-examined later. These have to be considered however in more detail because it is well known that voltage multiplier circuits based on Dickson's architecture fail to provide sufficient pumping efficiency when the power supply voltage VDD becomes very low, in which case their output gains for boosting voltages decrease to an unusable condition.
A time diagram of the anti-phase control clock signal of the circuit shown in FIG. 1A prior art is depicted in FIG. 1B prior art, displaying the voltage VBST for the two complementary clock signals BSTA and BSTB as a function of time t. These complementary control clock signals are usually driven with full VDD-level swings (i.e., transitioning between a low level of VSS and a high level of VDD). Consequently, each CP-stage boosts the voltage conveyed to its input node by an amount equal to VDD less a diode drop (assuming relatively negligible DC load current and ignoring second order effects).
In such a design the output voltage VPP 29 measured versus ground (VSS) is determined by the following equation, generalized for M stages and assuming no current load is required from the load capacitor Cload at output node 29:VPP=(VDD−V.sub.th)+M*(VBST*C/(C+C.sub.s)−V.sub.th)wherein:(VDD−V.sub.th) is the voltage at the input node N1 to the first CT or CP-stage of the voltage multiplier after the voltage has passed through the transistor DVDD, configured as diode;(V.sub.th) is the threshold voltage or forward diode drop voltage of each diode connected MOS transistor D(2n−1) and D(2n) in the multiplier; C is the capacitance of the coupling storage MOS capacitors C(2n−1) and C(2n) in the nth CT stage of the multiplier, with C(2n−1)=C(2n);(C.sub.s) is the stray capacitance versus ground (VSS) at the drain-capacitor node of each diode connected MOS transistor D(2n−1) and D(2n) in the multiplier; VBST is the voltage of the clock signals BSTA and BSTB, normally equaling VDD; M is the total number of stages of the multiplier; and n is a running index (1 . . . M). Typically, C/(C+C.sub.s) is about 85% and (V.sub.th) can vary from approximately 1 Volt to 2.5 Volt or higher depending on the degree of the body effect of the transistor, which varies from process to process. VBST typically is the same as VDD, When VDD is less than 3 V, the term VBST*C/(C+C.sub.s) is very close to V.sub.th. As already mentioned, this will severely degrade the pumping efficiency of the multiplier. Thus, the prior art tried to eliminate V.sub.th or its effect to obtain a larger gain, e.g. to get higher VBST on the gate of the transistors N, or to use multi-phase clock signals.
The voltage diagrams presented in FIG. 1C prior art depict three internal node voltages (V1, V2, and V3 at N1, N2, and N3 respectively) during operation of the voltage multiplier circuit of FIG. 1A prior art driven by the complementary clock signals BSTA and BSTB shown in FIG. 1B prior art under some premises: all forward diode voltage drops equal (V.sub.th), all stray capacitances are neglected, no load current is drawn from output node 29 with voltage VPP. The circuit from FIG. 1A prior art can provide a supply voltage minus threshold voltage as node voltage V1=(VDD−V.sub.th) to node N1. An increase at each stage of (.DELTA.V)=VBST is obtained. If VBST=VDD the voltage increment (.DELTA.V) reaches VDD. The output voltage VPP of the circuit can thus attain VPP=V1+3* (.DELTA.V−(V.sub.th))=(VDD−V.sub.th)+3* (.DELTA.V−(V.sub.th)). However, the amplitude VBST of clock pulses BSTA and BSTB, pump capacitance (C) of capacitors C1, C2, and C3, parasitic stray capacitance (Cs), and load current are factors that can limit the voltage gain achieved at each pump stage. Thus (.DELTA.V) is the voltage increment reached under these constraints. For a capacitor charge to be passed fully from a lower stage to a higher stage, the increase in voltage for the stage (.DELTA.V) must be greater than the transistor threshold voltage (V.sub.th), the forward diode drop voltage.
Notes:
V1, V2, and V3 are the pre-boost voltage levels of nodes N1, N2, and N3 respectively. V1+(.DELTA.V), V2+(.DELTA.V), and V3+(.DELTA.V) are the post-boost voltage levels of nodes N1, N2, and N3 respectively.
The circuit in this prior art scheme of FIG. 1A prior art has a number of disadvantages, some have been already mentioned above. Five major drawbacks shall be listed in the following:                First, its charge sharing process is not completely executed, which is owed to the threshold voltage of the diode connected MOS transistor, i.e. there is always one forward diode drop voltage difference between two adjacent charge sharing nodes, which thus reduces efficiency. In other words an internal voltage value of at least one threshold voltage drop higher than the desired output voltage must be generated.        Second, owed again to said threshold voltage drop we need more CP-stages connected in series to achieve a certain target voltage up to which we want the charges to be pumped to. The more CP-stages are connected in series the less pumping efficiency is obtained, or in other words, extra stages are required to reach said certain target voltage due to this lowered efficiency.        Third, owed to the body effect the threshold voltage of higher order CP-stage's will gradually increase. It is well known, that the body effect to which integrated NMOS transistors are subject to, will increase the threshold voltage of this NMOS transistor itself. This will also limit the number of serially connected CP-stages and thus a possible higher voltage generation, because said increased threshold voltage may be higher than the available external supply voltage VDD, especially in future very low VDD voltage supply applications. If the threshold voltage of diode connected NMOS transistors is higher than the boost voltage VDD, the NMOS diode cannot be turned on and no charge sharing process will be executed. In other words, when it comes to low supply voltage levels the circuit does not perform well.        Fourth, the charge sharing speed is rather slow because the diode-configured NMOS transistors are always working in saturation region. It is well known that the effective resistance of NMOS transistors in saturation region is very large. This will increase the charge sharing time and also reduce the magnitude of the pump current within the CP because the value of the CP's settlement current is reciprocal to the charge sharing time, i.e. the time during which two capacitors are connected together.        Fifth, the breakdown voltage of the diode connected MOS transistors must increase as CP output voltage increases, which signifies that the higher order MOS transistors oxide stress is gradually increased, which will decrease the rise time of the pumping circuit and also degrade reliability. It would be desirable to have a CP circuit that can efficiently develop a high positive or negative output voltage from a low input voltage without requiring higher breakdown voltage transistors.
At lower power supply voltages, the diode drop voltage lost within each CP-stage significantly affects the final output voltage achievable by such a CP circuit. Consequently, other approaches to design voltage multiplier circuits replace the diode type charge transfer device with a Charge Transfer Switch (CTS) device in each CP-stage. Additionally multi-phase control signal schemes are used, to more effectively control the pumping process. It is also desirable to more accurate control the CTS to reduce the forward voltage drop across the CTS when turned on to transfer charge from input to output, and to carefully control the time that the CTS is turned on to prevent back transfer of charge from output to input. A variety of solutions are found in the prior art for controlling a CTS device in attempt to simultaneously achieve these two competing goals. Nevertheless, additional improvements in CP circuits are desired. Moreover, such voltage generator circuits also may consume a significant amount of power relative to the remainder of the circuit, and thus increase the current that must be supplied by the user (e.g. by the VDD power supply). Consequently the unwanted increase in power dissipation increases the temperature of the die during operation. In a battery-powered environment, any increase in power consumed by a device has significant implications for battery life, and any additional heat generated is also more difficult to dissipate. Therefore continued improvements in CP circuits are needed. It is therefore a challenge for the designer of such circuits to achieve a higher efficiency solution. There are various patents referring to such solutions.
U.S. Pat. No. 5,886,887 (to Jenq) presents a voltage multiplier with low threshold voltage sensitivity including a voltage multiplier having a number of electrically-like stages. Each of the stages receives two input signals and a pump signal, whereby the stage has an MOS transistor with a first source/drain region and a second source/drain region and a gate. Each stage also has means for receiving a pump signal and for separately pumping the first source/drain region and the gate of the first transistor by the pump signal. The two input signals are supplied to the first source/drain region and the gate of the first transistor, respectively. A first output signal is supplied from the second source/drain region of the first transistor, and from the first source/drain region of the first transistor. A voltage signal is supplied as the input signal of the first stage and a clock signal having a first phase is supplied to the first stage as the pump signal of the first stage. The first and second output signals of the first stage are supplied to the second stage as the input signals of the second stage and a clock signal having a second phase different from the first phase is supplied to the second stage as the pump signal of the second stage.
U.S. Pat. No. 6,501,325 (to Meng) discloses low voltage supply higher efficiency cross-coupled high voltage charge pumps including an apparatus comprising a number of cross-coupled charge pump stages configured to generate an output voltage in response to (i) a supply voltage, (ii) a first signal, and (iii) a second signal, where the output voltage has a greater magnitude than the supply voltage.
U.S. Pat. No. 6,734,717 (to Min) describes a charge pump circuit which includes a first switch for connecting an input terminal to a first pumping node, a first pumping capacitor for boosting up a voltage level of the first pumping node in response to a first control signal, a second switch for connecting the first pumping node to an output terminal, a third switch for connecting the input terminal to a second pumping node, a second pumping capacitor for boosting up a voltage level of the second pumping node in response to a second control signal, and a fourth switch for connecting the second pumping node to the output terminal. The charge pump circuit decreases a loss of an output voltage and prevents malfunctions in MOS devices by preventing damages of gate oxides of the MOS devices due to excessively high voltage differences.
U.S. Pat. No. 7,023,260 (to Thorp et al.) teaches a charge pump circuit incorporating corresponding parallel charge pump stages and method therefore wherein an improved charge pump circuit efficiently utilizes multiple charge pump stages to produce output voltages much larger than the power supply voltage by incorporating, in some embodiments, two parallel strings of series-coupled charge pump stages. Each corresponding charge pump stage in one string is controlled at least by a node in the corresponding charge pump stage of the other string.
In the prior art, there are different technical approaches for achieving the goal of a higher efficiency operation for integrated voltage generator circuits. However these approaches use often solutions, which are somewhat technically complex and therefore also expensive in production. It would be advantageous to reduce the expenses in both areas.
Although the above-mentioned patents describe circuits and/or methods close to the field of the invention they differ in essential features from the circuit, the system and especially the method introduced here.

Charge pump circuit for high voltage generation


Communicating data by transforming images or other non-text data into subsets of text characters and communicating each subset in an electronic message that can carry only a limited number of text characters. An embodiment transforms portions of binary data of an image or other non-text data into subsets of hexadecimal data that represents text characters. The subsets of hexadecimal text character data are included in SMS messages that have a predefined maximum number of characters. A header is included in the SMS messages to identify the ordering of the data. The SMS messages are communicated to a receiving device that orders the messages, transforms each subset of hexadecimal text characters back into the binary data, and assembles the binary data into it prior form for rendering to a user of the receiving device. A server may process the SMS messages, such as by inserting additional SMS messages with advertising data.

People use a variety of electronic devices and software programs to communicate. To exchange data, people often use general purpose computing devices that run software programs such as electronic mail, instant messaging, voice over internet protocol (VOIP), and/or other communication systems. Cell phones and other limited-capability devices can also be used to communicate, but they often have inherent limitations and/or network constraints that make it difficult to use the communication systems of general purpose computing devices. Consequently, limited-capability devices often use specialized communication programs and protocols such as short message service (SMS), multimedia message service (MMS), and the like. These often have limits on message sizes, communication speeds, data types, and the like. However, users often desire the capability to communicate large amounts, and various types of data, without having to use a large and/or stationary general purpose computing device. For example, users often wish to exchange images, video, audio, and/or other large amounts of data that is difficult and/or expensive to communicate with limited-capability devices.
Some communication systems enable users to exchange somewhat larger amounts of text data. For example, a multipart SMS system can split long text messages into multiple SMS messages. A user typically enters a long string of text that is larger than an individual SMS message. After completing the string of text, a multipart SMS system generally breaks the text into parts that fit within SMS messages. However, this is generally limited to text data and string of text is typically limited to a predefined maximum number of characters. Other types of data and boundless amounts of data generally can not be communicated with such systems. It is with respect to these and other issues that embodiments of the present invention are directed.

Employing the SMS protocol as a transport layer protocol


A seal for a sliding glass window includes a sliding glass guide and an elastomeric channel member that is at least partially disposed within the sliding glass guide. Located between the elastomeric channel member and the sliding glass guide is an electroactive actuator that is operable to change its shape from a first shape to a second shape, or vice versa, when a voltage is applied thereto. The first shape of the electroactive actuator pushes the elastomeric channel member towards the sliding glass window and the second shape pulls the elastomeric channel member away from the sliding glass window.

The use of sliding glass windows is common, in particular with motor vehicles. Such windows use a motor in combination with a window switch to slide the window from a closed position to a plurality of open positions. Around the outer edge of at least part of the window pane is a seal that provides a desirable watertight and in some instances airtight seal around the window pane. The seal allows for an edge portion of the window pane to fit at least partially within and provides contact therebetween in order to prevent water, air and the like from passing between the seal and the window pane. However, the seal between the window and the seal material results in a frictional force that must be overcome when the window is moved from a stationary position. Thus the better the seal, the higher the friction between the seal material and the window, and thus the greater the power required to move the window. An increase in the power required to move the window is in contradiction to desirable lightweight motors that have minimal electrical, hydraulic or pneumatic input power requirements. As such, a seal that affords for a decrease in friction prior to moving the window from a stationary position would be desirable.

Seal having an electroactive actuator a for sliding glass window

Toyota Motor Engineering & Manufacturing North America, Inc.