An electrical signal interconnect assembly has first and second high speed coaxial interconnects with each interconnect having a male and female side. One of the male and female side of the first interconnect is floatably mounted on the assembly with the other side mounted on an electrical instrument. The second coaxial interconnect is mounted on a mechanical alignment facility having coarse and fine mechanical alignment portions with the coarse mechanical alignment portion including a closely mating pocket and body. One of the male and female side of the interconnect is mounted on the pocket with the other side mounted on the body. One of the pocket and body is mounted on the interconnect assembly and the other of the pocket and body is mounted on the electrical instrument. A coaxial cable electrically connects the two coaxial interconnects together in the interconnect assembly.

The present invention relates generally to electrical signal interconnect assemblies and more particularly to a signal interconnect assembly for routing an electrical signal from a signal output to a signal input of a test and measurement instrument, such as oscilloscope, waveform generator, spectrum analyzers, network analyzers and the like.
Test and measurement instruments, such as oscilloscopes, have one or more input signal connectors for coupling one or more measurement probes to the instrument. Typical input signal connectors include BNC and SMA connectors. These types of connectors couple electrical signals from the measurement probe that acquires the signals from a device under test to circuitry within the instrument.
Measurement testing of optical component and assemblies has become an important requirement for oscilloscopes with the increased use of these devices in the electronics industry. The oscilloscope is provided with an optical-to-electrical (O/E) converter that receives an optical signal from the optical device under test via an optical cable. The O/E converter converts the optical signal to an electrical signal and couples the electrical signal via one of the electrical signal input connectors to the oscilloscope. An important requirement for such an oscilloscope and O/E converter system is the calibration of the oscilloscope-O/E converter combination. That is the O/E converter and the oscilloscope are calibrated as a combined unit to produce an optical reference receiver measurement system having a frequency response that matches a 4th order Bessel-Thompson frequency response. Such an optical reference receiver measurement system is well suited for measuring the characteristics of telecommunication system optical components and assemblies.
A limitation on the above described oscilloscope optical reference receiver system is that the calibration of the system is maintained only with the O/E converter calibrated with the oscilloscope. If the different O/E converter is used with the oscilloscope or the O/E converter is used with a different oscilloscope, the optical signal measurement system provides a normal or average response and not a reference receiver response. Customers who switch O/E converters between oscilloscopes loss the 4th order Bessel-Thompson frequency response of calibrated reference receiver.
One solution to this problem is to build the O/E converter into the oscilloscope and couple the output of the O/E converter directly to input circuitry of one of the channels in the oscilloscope. One drawback to this solution is the loss of one oscilloscope channel that could be used for making other types of measurements. A second solution would be to add a precision, high frequency relay switch prior to the input circuitry of the selected oscilloscope input channel. This allows the channel to be used as a standard signal input as well as providing the input from the O/E converter. A drawback to this solution is that the relay switch would introduce additional loss into the channel and possibly generate anomalies, such as reflections, into the measured signal.
What is needed is an interconnect solution for coupling the output of an internal O/E converter in a measurement instrument, such as an oscilloscope, that does not reduce the number of available input channels to instrument nor increase signal loss in the channel.
Accordingly, the present invention is to an electrical signal interconnect assembly useable as a signal routing adapter with a measurement instrument, such as an oscilloscope, for coupling an output signal from an O/E converter internally disposed within the instrument to an input signal connector on the instrument. The electrical signal interconnect assembly has first and second high speed coaxial interconnects with each coaxial interconnect having a central signal conductor and a surrounding shield conductor. Each of the coaxial interconnects have a male side including a male shield contact mateable with a female side having a shield sleeve defining a chamber including a contact facility having a compliant portion operable to flexibly grip the male shield contact. One of the male and female mating sides of the first coaxial interconnect is selected and floatingly attached to one side of a panel over a first aperture formed in the panel. The panel has a second aperture over which a mechanical alignment facility is attached on the same side of the panel as the first coaxial interconnect. The mechanical alignment facility has coarse and fine mechanical alignment portions with the coarse mechanical alignment portion including a closely mating pocket and body. The pocket has a rim and a floor recessed below the rim such that the rim provides a first angular displacement limit of the body. The fine mechanical alignment portion includes a notch defined in one of the pocket and body and a key closely mating with the notch defined in the other of the pocket and body such that the notch provides a second angular displacement limit of the body. One of the male and female mating sides of the second coaxial interconnect is selected and attached to one of the pocket and body. A coaxial cable having a cental signal conductor and a surrounding shield conductor is attached to the corresponding cental signal conductors and a surrounding shield conductors of the first and second coaxial interconnects on the opposing side of the panel.
The first and second interconnects are preferably blind mating interconnects with the associated mating sides of the first and second coaxial interconnects and one of the pocket and body mounted on an electrical instrument and coupled to circuitry in the instrument. In the preferred embodiment, the female mating sides of the interconnects are connected to the instrument. The electrical signal interconnect assembly further includes a separate electronic data interconnect having a first side connected to the pocket and a second side connected to the body. At least one side of the data interconnect includes compliant contacts operable to contact a corresponding set of contacts on the other side, over a range of depths with which the body is inserted into the pocket. In the preferred embodiment, one side of the data interconnect includes pogo pins contained within the pocket, and the other side includes a fixed contact surface.
A housing is attached to the opposing side of the panel with the housing having a base with depending sidewalls positioned against the opposing side of the panel. The base may include cantilever spring members disposed on the base with each cantilever spring member having a fixed end attached to the base a flexible free end with the free ends defining an aperture. In one embodiment, the cantilever spring members extend above the base in a direction opposite the sidewalls. In a second and preferred embodiment, the base includes an aperture with the cantilever spring members disposed adjacent to the aperture and extending below the base in the same direction as the sidewalls. Preferably, the cantilever spring members are integrally formed with the housing.
The objects, advantages and novel features of the present invention are apparent from the following detailed description when read in conjunction with appended claims and attached drawings.


A shoppping cart basket bumper provides a sheet of resilient material that overlaps a substantial surface of a shopping cart basket. The bumper sheet is firmly attached to the outer face of the basket utilizing a structure positioned along the inner face of the basket that is fastened through openings in the basket to the sheet. The bumper can include rails and slots for holding advertising placards on each of the inside and outside exposed sides of the basket.

A substantial amount of damage to vehicles is caused each year by unattended and carelessly directed shopping carts in store parking lots. Shopping carts have a tendency to roll into the sides of vehicles causing dings, scrapes and small dents to vehicle body work. A large number of such impacts occur when shopping carts roll front end first into vehicles. The alignment of the wheels of the shopping cart and the distribution of its weight make front-on impacts quite likely.
In an attempt to minimize damage from front on impacts, existing shopping cart designs often incorporate the small bumpers of hard plastic along the bottom front corners of the shopping cart basket. While these bumpers can reduce damage from scraping of the basket against painted surfaces such as display cases and vehicle body work, they are too hard to effectively absorb impact energy in a cart-to vehicle collision. Hence, such bumpers do not substantially reduce the damage caused to vehicles by shopping cart impacts.
It is therefore an object of the present invention to provide a more effective bumper system over, preferably, the front of a shopping cart basket to more efficiently absorb energy generated from impacts. It is a further object of this invention to provide a bumper for shopping carts that can be attached to existing basket structures without significant alteration to the basket. It is yet another object of this invention to provide a shopping cart bumper that is easily manufactured and that is adaptable to fit a wide variety of shopping cart basket shapes without substantial alteration of the basket or bumper.


Structure and method for securing a molding compound to a leadframe paddle is disclosed. Half-holes are etched in the top surface of the leadframe paddle. Moreover, each side of the leadframe paddle is provided with a respective anchor. A die is then attached to the top surface of the leadframe paddle. During the molding process, the molding compound covers the die, the anchors, and fills the half-holes in the top surface of the leadframe paddle. The half-holes cause the molding compound to be locked into the paddle. The half-holes also increase the interface surface area between the molding compound and the top surface of the leadframe paddle. Moreover, during the molding process, the molding compound will encapsulate the anchors provided on each side of the die. When the molding compound hardens around the anchors, the molding compound is reinforced and held in place by the anchors. In essence, the anchors act as supports that extend in four directions within the molding compound to hinder both upward and downward movement of the molding compound. Accordingly, the half-holes and anchors result in a better adhesion of the molding compound to the top surface of the leadframe paddle.

1. Field of the Invention
The present invention is generally in the field of semiconductor packaging. More specifically, the invention is in the field of leadframe packaging.
2. Background Art
A leadframe is used in the fabrication of plastic molded enclosures, also referred to as a xe2x80x9cmolded packagexe2x80x9d in this application. The leadframe is fabricated from a metal such as copper and comprises a paddle which is secured to the body of the leadframe by four tie-bars. The paddle is situated at the center of the leadframe. The leadframe also comprises a number of leads which are secured to the frame.
A die is attached to the top surface of the paddle in a manner known in the art. Respective first ends of respective bond wires are then bonded to respective die bonding pads. Respective second ends of each bond wire are then spanned to respective inner leads in the leadframe and bonded thereto for making the desired electrical connections. In a subsequent stage of the assembly process, the leadframe is placed in a mold cavity in a transfer molding machine and the entire die, bond wires, die bonding pads, and top surface of the paddle are encapsulated in a molding compound.
In an xe2x80x9cexposedxe2x80x9d paddle leadframe based molded package, the bottom of the paddle is not encapsulated in molding compound. The metal on the bottom of the paddle of the leadframe is left exposed in order to attach the bottom of the paddle to the printed circuit board during a re-flow solder process.
The top surface of the paddle is usually silver-plated copper, while the exposed copper bottom of the paddle is usually left unplated. Typical molding compounds have poor adhesion to silver. Therefore, the typical molding compound adheres poorly to the top of the paddle. As a result, most of the protection against separation of the molding compound from the top of the paddle is provided by the four edges along the sides of the paddle. However, the protection provided by the edges of the paddle against separation of the molding compound from the top of the paddle is usually insufficient. Therefore, separation of the molding compound from the top of the paddle may still occur.
It is known in the field of leadframe packaging that poor adhesion of the molding compound to the paddle of the leadframe in an exposed paddle leadframe based molded package is a serious concern. As discussed above, poor adhesion of the molding compound to the silver-plated top of the paddle and insufficient adhesion along the edges of the paddle may result in the separation of the molding compound from the surface of the paddle of the leadframe. This separation is generally referred to as xe2x80x9cdelamination.xe2x80x9d
Delamination can occur during the re-flow process when the bottom of the paddle is soldered to the printed circuit board. The exposed bottom of the paddle is brought into contact with solder on the surface of the printed circuit board. The solder is heated to a temperature of approximately 120 degrees centigrade. At approximately this temperature, the solder becomes molten and the bottom of the paddle of the leadframe is then brought into contact with the molten solder. When the solder cools, a secure connection of the paddle to the printed circuit board will result.
However, there are problems with this process. During the re-flow process, as the temperature rises, a point is reached where the temperature is not yet high enough for the solder to melt, but is high enough to result in an expansion of the copper bottom of the paddle. Because the top of the paddle is encapsulated in molding compound, some support for the paddle in the upward direction is provided. This support on top of the paddle hinders any upward expansion. However, the bottom of the paddle is not encapsulated. As a result, the paddle expands primarily in a downward direction. Because the molding compound has some support from the top and edges of the paddle it tends to stay fixed as the bottom of the paddle pulls downward. This downward expansion of the paddle and the essentially fixed position of the molding compound can lead to a separation of the top surface of the paddle from the molding compound.
One effect of delamination is that the bond wires may be broken. A first end of each bond wire is bonded to a die bonding pad on the die. As discussed above, the die is attached to the top surface of the paddle. The bond wires bonded to the die are encapsulated in the molding compound during the molding process. As stated above, the molding compound tends to stay fixed as the paddle expands downward. Therefore, the bond wires also stay fixed. Thus, in response to the paddle being pulled downward, the bond wires may break. As a result of the problem described above, there are many unusable molded packages in the leadframe assembly process which cause a significant decrease in the yield.
Thus, it is seen that there is a need in the art for a method of providing better adhesion between the molding compound and the top of the paddle in an exposed leadframe based molded package.
The present invention is structure and method for securing a molding compound to a leadframe paddle. According to the invention""s structure and method, improved adhesion between the molding compound and the top surface of the leadframe paddle in an exposed leadframe based molded package is achieved.
According to the invention, half-holes are etched in the top surface of the leadframe paddle. Moreover, according to the invention, each side of the leadframe paddle is provided with a respective anchor. A die is then attached to the top surface of the leadframe paddle. During the molding process, the molding compound covers the die, the anchors, and fills the half-holes in the top surface of the leadframe paddle. The half-holes cause the molding compound to be locked into the paddle. The half-holes also increase the interface surface area between the molding compound and the top surface of the leadframe paddle.
Moreover, during the molding process, the molding compound will encapsulate the anchors provided on each side of the die. When the molding compound hardens around the anchors, the molding compound is reinforced and held in place by the anchors. In essence, the anchors act as supports that extend in four directions within the molding compound to hinder both upward and downward movement of the molding compound. Accordingly, the invention""s half-holes and anchors result in a better adhesion of the molding compound to the top surface of the leadframe paddle.


This is a charging assembly that is useful in marking processes with an electrostatically charged surface. The assembly includes, besides the charger, a controller and an electric field probe. Charge and current flows can be detected by the probe and corrected immediately after detection of flaws by the probe and conveyed to the controller. If flaws in the charger are determined by the probe, corrections are made to the output by a controller; this is done before a final copy or print is made. The term flaws as used means any non-uniform appearing region in the printed image or any otherwise unacceptable defect. The probe is enabled to detect and indicate flaws and the controller which is in communication with the probe takes corrective action on the flaws. The probe used is a novel probe having two sensing elements surrounded by one or more reference electrodes.

In an electrostatographic process, a system is used whereby a uniform electrostatic charge is placed upon a reusable photoconductive surface. The charged photoconductive surface is then exposed to a light image of an original to selectively dissipate the charge to form a latent electrostatic image of the original on the photoreceptor. The latent image is developed by depositing finely divided marking and charged particles (toner) upon the photoreceptor surface. The charged toner is electrostatically attached to the latent electrostatic image areas to create a visible replica of the original. The toned developed image is then transferred from the photoconductor surface to a final image support material, such as paper, and the toner image is fixed thereto by heat and pressure to form a permanent copy corresponding to the original.
In Xerographic systems of this type, a photoreceptor surface is generally arranged in a drum or belt configuration to move in an endless path through the various processing stations of the Xerographic process. The photoconductive or photoreceptor surface is generally reusable whereby the toner image is transferred to the final support material, and the surface of the photoreceptor is prepared to be used once again for another reproduction of an original. In this endless path, several stations of corona charging are traversed. These charging stations may involve one or a cluster of chargers including dicorotron or other corotron units.
Several methods and devices are known for applying an electrostatic charge to the photosensitive member such as the use of electron-emitting pins, an electron-emitting grid, single corona-charging structures and single or multiple dicorotron wire assemblies. These will be referred to as "chargers" throughout this disclosure and claims. In recent development of multifunctional Xerographic machines where copiers can provide several functions, the need for several reliable chargers or charging assemblies exists in order to assure that high quality final copies are produced.
Usually, in electrostatographic or electrostatic copy processes, as those above noted, a number of chargers such as corotrons, scorotrons, or dicorotrons are used at several various stations around the photoreceptor. For example, the chargers are used at the station that places a uniform charge on the photoreceptor, at a transfer station, at a cleaning station, etc. In today's high speed copiers, it is important that all corotrons (or chargers) are controlled for efficient and uniform charging. Generally, one structure of a dicorotron charger uses a thin, glass-coated wire mounted in an elongated U-shaped housing between two insulating anchors called "insulators". These support the wire in the U-shaped housing in a spring-tensioned manner in a singular plane. This dicorotron unit or assembly, as above noted where aluminum usually comprises the housing, is in one embodiment an elongated U-shaped shield. The wire or corona-generating electrode is typically a highly conductive, elongated wire situated in close proximity to the photoconductive surface to be charged.
As earlier noted, the charging of the photoreceptor or other surfaces is necessary for the proper reliable operation of the Xerographic machine.
Charging devices historically come in several forms including wires, pins, grids, and the like and are generally referred to as corotrons, scorotrons and dicorotrons; all will be referred to in this disclosure as "chargers" or a source of "corona" discharge. These charging devices typically use high voltages to create a corona which contains electrons and/or ions for deposit on a surface.
Non-uniform charging caused by dirty wires or an otherwise faulty charger cause the appearance of a printed copy to appear blurry or have areas where the image is entirely missing (deleted). Corrective means and specifically automated and continuous corrective means for countermining the effects of dirty chargers, faulty chargers, or improperly installed chargers are seriously needed.
With the advent of high speed xerography reproduction machines wherein printers can produce at a rate in excess of three thousand copies per hour, the need for corotrons or dicorotrons at many processing stations is needed in a reliable and dependable manner in order to utilize the full capabilities of the reproduction machine. These corotron systems must operate flawlessly to virtually eliminate unacceptable print quality and machine shutdowns due to corotron malfunctions.
Generally, in electrostatographic or electrostatic printing processes, a number of corotrons or dicorotrons are used at various stations around the photoreceptor. For example, the dicorotrons are used at the station that places an initial uniform charge on the photoreceptor, at a transfer station to control the charge on the backside of the media receiving the toned image, at a cleaning station where reduction of the intensity of the electrostatic forces between the photoreceptor and toner is required and at a plurality of other related processes. In today's high speed printers, it is important that all corotrons (or dicorotrons) are in perfect working order since one corotron malfunction can easily render the entire printing process useless. Some high speed printers including color printers use several dicorotron units. In one embodiment, as many as sixteen corotron or dicorotron units are used. So, maintaining each corotron or dicorotron unit in perfect working order is essential to the proper functioning of these complex fast color printers. It is common to use one or several corona-generating device(s) ("corotron" or "dicorotron") for depositing the electrostatic at the above-noted stations. Generally, the structure of a dicorotron uses a thin, glass-coated wire mounted between two insulating anchors or end blocks called "anchors" which support the wire in a highly tensioned manner in a singular plane. In this disclosure, the term "anchors" includes insulator, end blocks, insulating anchors, etc. These anchors are installed between flexible holders or clamps or anchor inserts that maintain the anchors in place. These anchor inserts are fixed at two opposite ends of a U-shaped dicorotron "housing" or "shells" or "shield". The wire or corona-generating electrode is typically a highly conductive elongated wire situated in close proximity to the photoconductive surface to be charged. Often, the corona discharge electrode is coated with a dielectric material such as glass, for glass coating improves charging uniformity throughout the electrode's life. Since the wire electrode is comprised of a thin outer glass brittle coating, it may be easily damaged or dirtied, or contaminated as earlier noted. In some instances even very gentile handling or cleaning of this electrode often results in fracture of the glass coating which could cut or injure the user, cause damage to surrounding parts, or cause contamination to the printer itself. While cleaning sometimes corrects problems in this corona electrode, it is sometimes necessary to replace the wire due to degradation in the corona performance or even in breakage of the electrode which could occur during the cleaning.
If the flaws in the charger are determined by a suitable sensing device such as a field probe, particularly a high resolution field probe and subsequent corrections are made to the output by a suitable controller before the final copy or print is made, a high advance in electrostatic marking systems will be accomplished. Since the output from a charger can vary across the length, width, and area of the charging element, precise control of the output over vary small, local areas of the charger to achieve a uniform output across the entire area of the charger device is needed. Irregularities or non-uniformities in the local output of a charger over a width of as little as a few micron or less, or over an area of about 10 square microns, or less can cause flaws within and thereby adversely impact upon the quality of a xerographic print. Controllers of the type integral close feedback loop controllers, or proportional, or a proper combination of them, can process the sensed charge surface and provide actionable information sequentially distributed to various actuators. The actuators considered include controlling the output of the charge device, which, depending on the type of charge device, can be accomplished by changing the voltage input to each of the charging elements of the charge device. Considered distributed controller schemes include multiobjective distributed controllers using other actuators to compensate for the flaws in the charger, like modulating pixel to pixel the laser exposure in order to compensate for the charge variability across the charged photoreceptor surface, or by replacing the faulted charging device. In a process color reprographic machine, for example a CMYK printer, the controller scheme described above is repeated for each color. But this concept is extended to other xerographic base machines, for example, machines printing black and one or more highlight colors, five or more process color machines, and so on. By the term "flaws in a charger" is meant non uniform charging or contaminated or dirty wires or faulty corotron (charger) installation which would result in perturbation, including a microscopic perturbation or disturbance, in the output corona or ion stream. By the term "flaws in a print" is meant any undesired, non-uniform appearing region in the printed image, any void region within the printed image or otherwise unacceptable defect such as a jagged line that is visible or otherwise detected by the end-user.

This patent is subject to a terminal disclaimer.


This invention relates to compounds which are inhibitors of elastase, particularly human neutrophil elastase, and to novel processes for making the same. As inhibitors of human neutrophil elastase, the compounds are useful in the treatment of a patient afflicted with a neutrophil associated inflammatory disease.

This invention relates to compounds which are inhibitors of elastase, particularly human neutrophil elastase, useful for a variety of physiological and end-use applications, and to processes for making said inhibitors.
Human neutrophil elastase has been implicated as an agent contributing to the tissue destruction associated with a number of inflammatory diseases such as chronic bronchitis, cystic fibrosis, and rheumatoid arthritis. J. L. Malech and J. I. Gallin, New Engl. J. Med., 317(11), 687 (1987). Elastase possesses a broad range of proteolytic activity against a number of connective tissue macromolecules including elastin, fibronectin, collagen, and proteoglycan. The presence of the enzyme elastase may contribute tc the pathology of these diseases.
Normal plasma contains large quantities of protease inhibitors that control a variety of enzymes involved in connective tissue turnover and inflammation. For example, .alpha.-1-proteinase inhibitor (.alpha.-1-P.sub.1) is a serine protease inhibitor that blocks the activity of elastase. .alpha.-1-P.sub.1 has received considerable interest because reduction in plasma levels to less than 15% of normal is associated with the early development of emphysema. In addition to plasma derived protease inhibitors, secretory fluids, including bronchial, nasal, cervical mucus, and seminal fluid contain an endogenous protease inhibitor called secretory leukoprotease inhibitor (SLP.sub.1) that can inactivate elastase and is believed to play an important role in maintaining the integrity of the epithelium in the presence of inflammatory cell proteases. In certain pathological states .alpha.-1-P.sub.1 and SLP.sub.1 are inactivated by neutrophil oxidative mechanisms allowing the neutrophil proteases to function in an essentially inhibitor-free environment. For example, bronchial lavage fluids from patients with adult respiratory distress syndrome (ARDS) have been found to contain active elastase and .alpha.-1-P.sub.1 that had been inactivated by oxidation.
In addition to oxidative mechanisms, neutrophils possess non-oxidative mechanisms for eluding inhibition by antiproteases. Neutrophils from patients with chronic granulomatous disease are capable of degrading endothelial cell matrices in the presence of excess .alpha.-1-P.sub.1. There is considerable in vitro evidence that stimulated neutrophils can tightly bind to their substrates such that serum antiproteases are effectively excluded from the microenvironment of tight cell-substrate contact. The influx of large numbers of neutrophils to an inflammatory site may result in considerable tissue damage due to the proteolysis that occurs in this region.
Applicants have determined that elastase is one of the primary neutrophil proteases responsible for cartilage matrix degeneration as measured by the ability of neutrophil lysate, purified elastase and stimulated neutrophils to degrade cartilage matrix proteoglycan. Furthermore, applicants have previously discovered peptide derivatives useful as elastase inhibitors, exerting valuable pharmacological activities. For example, peptide derivatives useful as elastase inhibitors wherein the terminal carboxyl group has been replaced by a pentafluoroethylcarbonyl (--C(O)C.sub.2 F.sub.5)group and in which the N-terminal amino acid is substituted with various protecting groups are disclosed in European Patent Application OPI No. 0529568, inventors Peet et al., with a publication date of Mar. 3, 1993 and European Patent Application OPI No. 0410411, inventors Bey et al., with a publication date of Jan. 30, 1991. Because of new processes for making perfluoroalkylcarbonyl peptides, Applicants have recently discovered heptafluoropropylcarbonyl and nonaflurobutylcarbonyl moieties of elastase inhibitors.

Perfluoroalkyl ketone inhibitors of elastase and processes for making the same


A method, apparatus and program product automatically generate a grayscale lithography mask file (76) from a three dimensional (3D) model (72) of a desired topography, e.g., as generated by a three dimensional computer aided design (CAD) tool (70).

Semiconductor fabrication routinely relies on a number of fabrication processes to manufacture integrated circuit devices, or chips. Photolithography, for example, is routinely used in the creation of patterned layers of various materials on the surface of a substrate such as a semiconductor wafer. For example, in order to create a layer of conductive wires on the surface of a substrate, a thin film of metal may be deposited across the substrate followed by the deposition of a temporary layer of a photosensitive material referred to as photoresist. Photolithography is then used to form a desired geometric pattern in the photoresist by exposing the photoresist to light projected through an optical mask having apertures matching the desired geometric pattern. Exposure of the photoresist to light modifies the chemical properties of the exposed portions such that when the photoresist is developed, selected portions of the photoresist material are removed and an area of the surface of the substrate corresponding to the desired geometric pattern is accessible through the photoresist. Etching may then be performed to remove the portions of the thin film not covered by the photoresist, followed by removal of the remaining photoresist material, leaving a thin film of metal patterned according to the desired geometric pattern.
Optical masks used in photolithography are typically generated using computer software, and are often manufactured themselves using a photolithographic process that etches apertures into an opaque film disposed on a transparent substrate. The geometric patterns for the masks are typically stored in electronic form as mask files, which are fed to a stepper or scanner to pattern the mask with the desired geometric pattern.
In addition, an alternative photolithography technique referred to as maskless lithography eliminates the use of an optical mask, and instead scans a narrow beam over the photoresist to directly write the desired geometric pattern into the photoresist. As with the mask files used to create optical masks, the electronic data that controls the maskless lithography process to write a desired geometric pattern into the photoresist is also referred to as a mask file, and is generated using computer software.
A common feature of traditional mask-based and maskless photolithography is that they are typically binary processes. Put another way, with both mask-based and maskless photolithography, the photoresist layer is effectively opaque for any areas of a substrate that are covered by the photoresist material, while for areas where the photoresist material has been removed, the underlying areas of the substrate are fully exposed for subsequent processes such as etching.
Grayscale lithography, in contrast, is a technique used to expose different areas of a photosensitive substrate to various intensities of light. By controlling the amount of light each region of the substrate is exposed to, the depth at which photoresist is developed can be carefully controlled. This process can result in the creation of complex three dimensional (3D) structures in photoresist simply from using a single exposure lithographic technique, which may then be copied to an underlying substrate using an etching technique such as deep reactive-ion etching (DRIE) to generate a topography including complex three dimensional shapes on the surface of a substrate. Grayscale lithography is of particular interest for use in fabricating microelectromechanical systems (MEMS) such as micro- or nano-scale sensors and actuators, microfluidics, and microoptical components like microlenses, diffractive elements or hybrids.
While grayscale lithography provides an extremely versatile tool for MEMS fabrication, grayscale lithography is a relatively underutilized process. In part, the underutilization of grayscale lithography is due to time and effort required to create mask files suitable for defining complex 3D topographies, e.g., to control a maskless laser lithography system such as a laser pattern generator. Many such systems utilize mask files that define multiple layers, with each layer corresponding to a different level of exposure, and with geometric objects defined in each layer to define the desired three dimensional profile. Particularly for complex topographies, the manpower required to generate the mask files can be cost and time prohibitive. In addition, in many instances, the calculations required to generate the mask files are too complex to be completed by hand.
Therefore, a significant need exists in the art for an improved method for creating mask files used in connection with grayscale lithography.

Automated generation of mask file from three dimensional model for use in grayscale lithography

University of Louisville Research Foundation, Inc.


A method for forming P-type gallium nitride is disclosed in the invention. In this method, Mg--H can be completly discomposed by use of an annealing process, thereby entirely dissociating the hydrogen atoms from the gallium nitride, while the nitrogen atoms are not dissociated from the gallium nitride. Therefore, the P-type gallium nitride having high conductivity is obtained and V.sub.N gap defects created in the gallium nitride do not occur. During the annealing process, nitrogen flux is added around the gallium nitride to prevent decomposition of the gallium nitride. The above-mentioned nitrogen flux can be generated by use of RF plasma, electron cyclotron resonance (ECR) or ion beam. Furthermore, since a forward current is provided across the P--N junction of the gallium nitride, the Mg--H inside the magnesium-doped gallium nitride can be decomposed by just increasing the temperature to 175.degree. C. Therefore, in the invention, when a diode structure is manufactured with gallium nitride, the hydrogen atoms can be dissociated from the gallium nitride in a low-temperature process, thereby activating the magnesium (acceptor), such that the conductivity of the P-type gallium nitride is further increased and V.sub.N gap defects caused by a high-temperature process are prevented.

1. Field of the Invention
The invention relates to a method for forming a P-type gallium nitride.
2. Description of the Related Art
Currently, in all materials used for manufacturing luminescent devices which can emit blue, purple or ultraviolet light rays, gallium nitride has the best potential, because the gallium nitride has a direct energy gap structure and its energy gap is about 3.39 eV at a room temperature. In the prior art, a hetero-epitaxial growing process performed on a sapphire substrate is used to form single-crystal gallium nitride. However, since there are great differences between the gallium nitride and sapphire substrate in lattice match and coefficient of thermal expansion, it is very difficult to grow gallium nitride of high quality and high planarization. Nevertheless, this problem can be overcome by depositing an AlN layer to function as a buffer layer on the sapphire substrate before the gallium nitride is grown. Therefore, the planarization, crystal quality and electric properties of the gallium nitride layer can be improved.
In order to further improve the efficiency of an LED which emits blue light, and manufacture an LED with gallium nitride, development and research of P-type gallium nitride is urgently necessary. Growing gallium nitride doped with magnesium (Mg) is disclosed in Jpn. J. Appl. Phys. Vol. 28, No. 12, Dec. 1989, pp. L2112-L2114 by Hiroshi Amano, et al., wherein a low-energy electron beam process is performed after the magnesium-doped gallium nitride is grown, so that the formed magnesium-doped gallium nitride has a hole concentration on the order of 2.times.10.sup.16 cm.sup.-3, a hole mobility on the order of 8cm.sup.2 /Vxs, and a resistivity on the order of 35 .OMEGA..times.cm. However, P-type gallium nitride having the above-mentioned data can not be sufficiently utilized to manufacture a blue light ray-emitting and high power LED. To resolve this problem, annealing magnesium-doped gallium nitride at a temperature on the order of 700.degree. C. is disclosed in Jpn. J. Appl. Phys. Vol. 31 (1992), Pt. 2, No. 2B, pp. L139-L142 by Shuji Nakamura et al., wherein hydrogen can be dissociated from the Mg--H to activate the magnesium (acceptor), such that the formed P-type gallium nitride has a low impedance, and wherein this P-type gallium nitride has a resistivity on the order of 2 .OMEGA..times.cm, a hole concentration on the order of 3.times.10.sup.17 cm.sup.-3, and a hole mobility on the order of 10 cm.sup.2 /V-s.
Generally, the annealing temperature should be kept in a range of 700.degree..about.800.degree. C. If the temperature is below 700.degree. C., the Mg--H is not easily decomposed completely. Furthermore, if the hydrogen atoms can not be completely dissociated from the gallium nitride, once the temperature is lowered, the dissociated hydrogen atoms can combine with the magnesium into Mg--H immediately. As a result, the magnesium can not be activated and the resistance is increased. On the other hand, if the temperature is higher than 700.degree.C., the nitrogen atoms inside the gallium nitride are dissociated, resulting in V.sub.N gap defects.

Method for forming P-type gallium nitride

Industrial Technology Research Institute


A print head of this invention has a plurality of heater boards, and each heater board has a plurality of heating resistors, driver circuits corresponding to the heating resistors, one shiftregister for inputting serial data, a data latch circuit for latching print data input from the shift register, a pre-heat data latch circuit for latching selection data of selecting one or several of pre-heat signals input from the shift register, and a pre-heat selection circuit for selecting one or a plurality of pre-heat signals in accordance with the selection data latched in the pre-heat data latch circuit. In a print operation, one or several of the plurality of input pre-heat signals are selected to pre-heat the heating resistors, and when a main heat signal is input thereafter, the heating resistors are driven in accordance with the print data latched by the data latch circuit, thus performing the print operation.

The present invention relates to a print head comprising heating resistors as electro-thermal conversion elements, and a print apparatus using the same.
Ink-jet print methods have received a lot of attention owing to their advantageous features, i.e., since they can reduce noise upon printing to a negligible level, allows high-speed printing, can print an image on a so-called normal paper sheet by fixing an ink without requiring any special processing, and so on.
Of these methods, an ink-jet method described in Japanese Patent Publication No. 54-51837 and DOLS (German Laid-Open) No. 2843064 has a feature different from other ink-jet print methods in that heat energy is applied to a liquid to obtain a driving force for ejecting liquid droplets. More specifically, in the print method disclosed in the above-mentioned references, a liquid undergoes a change in state accompanied by an abrupt increase in volume upon application of heat energy, and a liquid is ejected from orifices at the distal end of an ink-jet head by the force based on the change in state, thus forming flying liquid droplets. The liquid droplets become attached to a recording medium to attain printing.
In particular, the ink-jet print method disclosed in DOLS No. 2843064 above can be very effectively applied to a so-called drop-on-demand print method. Furthermore, since a full-line type ink-jet print head having a high-density multi-orifice structure can be easily realized, an image with a high resolution and high image quality can be obtained at high speed.
An ink-jet print head of an apparatus applied to this print method includes a print head board which comprises orifices arranged for ejecting a liquid, liquid ejection portions having liquid channels each including a heat applying portion as a portion for applying heat energy to a liquid for ejecting a liquid droplet, and electro-thermal conversion elements (heating resistors) as means for generating heat energy.
In recent years, as the above-mentioned print head board, one, in which an array of a plurality of heating resistors, drivers which have a one-to-one correspondence with these heating resistors and drive the heating resistors in correspondence with image data, a shift register which has the same number of bits as the heating resistors and parallelly outputs serially input image data to the drivers, and a latch circuit for temporarily storing data output from the shift register are arranged on a single circuit board, has been developed.
FIG. 12 shows the circuit arrangement of such a conventional print head board 300. Referring to FIG. 12, reference numeral 301 denotes an array of heating resistors; 302, power transistors serving as drivers; 303, a latch circuit; and 304, a shift register. Reference numeral 305 denotes a clock signal which is used for shift-inputting data in the shift register 304. Reference numeral 306 denotes serial image data input to the shift register 304. Reference numeral 307 denotes a latch signal; and 308, a heat pulse signal for externally controlling the ON times of the power transistors 302. Reference numeral 309 denotes a logic power supply; and 310, ground. Reference numeral 311 denotes a power supply (VH) input for driving the heating resistors 301.
In a printer apparatus having the head including the print head board with the above-mentioned arrangement, the serial data 306 is serially input to the shift register 304. The image data set in the shift register 304 is latched by the latch circuit 303 in response to the latch signal 307. When the heat pulse signal 308 is input, power transistors 302 corresponding to data "1" of the image data are set in the ON state. In this manner, the corresponding heating resistors 301 are energized and driven, ink in the liquid channels of the driven heating resistors 301 is heated, and the ink drops are ejected from the orifices, thus achieving printing.
Upon consideration of energy required for forming bubbles in a liquid portion contacting the heating resistor 301, if a heat dissipation condition remains the same, the energy corresponds to the product of required input energy per unit area of the heating resistor 301 and the area of the heating resistor 301. For this reason, the voltage applied across both ends of the heating resistor 301, and the current and time (pulse width) flowing through the heating resistor 301 can be set to obtain the above-mentioned energy. In practical use, the voltage can be set to be almost constant by the power supply of the printer apparatus main body. However, as for the current, the resistances of the heating resistors 301 have different values depending on lots and boards due to a variation in film thickness of the heating resistor 301 in the manufacture of the board. Therefore, when the application pulse width is constant, and the resistance of the heating resistor 301 becomes higher than a setting value, the current value decreases, and the application energy becomes insufficient. As a result, the ink cannot form bubbles. On the contrary, when the resistance of the heating resistor 301 becomes small, and the current value flowing through the heating resistor becomes larger than the setting value, excessive energy is input, resulting in burning and short service life of the heating resistor 301. In order to prevent this problem, a sensor 314 always monitors the resistance value of the heating resistor 301, and the power supply voltage or the application pulse width is changed based on the detected resistance value, so as to apply constant energy.
Next, upon consideration of the ejection amount of a liquid droplet to be ejected, the ejection amount is associated with the bubble formation volume of an ink. Since the bubble formation volume of the ink changes depending on the temperature of the heating resistor 301 and the ambient temperature, a pulse (pre-heat pulse) having energy low enough not to eject an ink is applied before an applying of a heat pulse for ejection, so as to adjust the temperature of the heating resistors 301 by the pulse width and timing of the pre-heat pulse. In this manner, a liquid droplet of a predetermined amount is ejected, and a desired print quality is maintained.
According to the above-mentioned prior art, correction of a variation in resistance value of each heating resistor 301 and temperature control of the board can be realized by changing the width of the heat pulse, and the width and timing of the pre-heat pulse to be applied to the heating resistors 301 is changed under the control of the printer apparatus main body by feeding back signals from the sensor 314 for monitoring the resistance value and a temperature sensor 315 for monitoring the temperature, and for outputting the heat signal. However, the ink ejection amounts vary depending on nozzles due to a variation in area of orifice apertures, a variation in thickness of the protection films of the heating resistors 301, and the like in the manufacture in addition to the above-mentioned factors even when the same energy is applied to the heating registers 301. Such variations results in density nonuniformity, stripes, and the like on printed matter, and hence ejection amount control for each nozzle or several nozzles is required.
When a plurality of print head boards are connected in series with each other to form a multi-nozzle ink-jet head to meet demand for an increase in the number of nozzles of an ink-jet head, since each of the print head boards has the heating resistors 301 having different resistance value from those of other print head board, the heat pulse width for ejecting an ink must be changed in each board to generate almost the same energy in the respective boards. As described above, when the print head is constituted by a plurality of boards, the print density difference between adjacent boards becomes conspicuous in addition to the above-mentioned orifice area. For this reason, it becomes more important to correct the ejection amount of ink in units of nozzles (heating resistors) in the board than in the case of a print head constituted by a single board.

Print head, and print pre-heat method and apparatus using the same


An apparatus and method for cleaning the interior of a vacuum chamber of a plasma reactor which includes introducing an etchant gas through inlet ports into the vacuum chamber and applying RF power to a RF plasma excitation apparatus so as to ignite and sustain a plasma within the chamber. The frequency of the RF signal is less than 1 MHz. Alternately, an apparatus and method for cleaning the aforementioned vacuum chamber where at least two different RF power signals can be employed. In one embodiment of this alternate method the step of applying RF power involves providing a first and second RF signal, where each signal exhibits a different frequency. The first RF signal is of a higher frequency and provided to ignite a plasma within the chamber, and thereafter terminated, whereas the second RF signal is of a lower frequency, less than 1 MHz, and provided to sustain the plasma. In another embodiment, the step of applying RF power again comprises providing separate RF signals, where each signal exhibits a different frequency. However, in this embodiment, the signals are used to generate a mixed frequency RF excitation field from the RF plasma excitation apparatus to ignite and sustain a plasma within the chamber. Here again, the first RF signal is of a higher frequency and the second RF signal is of a lower frequency, i.e. less than 1 MHz.

1. Technical Field
The invention relates to devices and methods for cleaning the interior surfaces of either a chemical vapor deposition (CVD) reactor or etch reactor using a plasma etch process to remove unwanted depositions.
2. Background Art
Reactors can perform various semiconductor processes on semiconductor substrates (often referred to as wafers), including dielectric etching and chemical vapor deposition (CVD). A reactor can employ purely chemical processes to perform CVD or etching, or else (depending upon the type of reactor), can perform radio frequency (RF) plasma CVD or plasma etching. The present description does not concern the process employed to carry out etching or CVD on a wafer but rather concerns a process for cleaning the interior surfaces of the reactor. Typically, during processing, unwanted depositions form on the interior surfaces of the reactor's vacuum chamber. For example, in a reactor used to perform chemical vapor deposition of silicon dioxide films, silicon dioxide (SiO.sub.2) residue forms over the interior surfaces of the chamber. In RF plasma CVD reactors having RF electrodes inside the chamber, the electrodes themselves can become contaminated with silicon dioxide. Other materials can contaminate the chamber interior surfaces, depending upon the type of process performed by the reactor. For instance, silicon carbide (SiC), silicon nitride (Si.sub.3 N.sub.4), and various silicon oxynitride (Si.sub.x O.sub.y N.sub.z) deposits are also possibilities.
Unwanted depositions such as those described above, if allowed to build up on the interior surfaces of the reactor chamber, can inhibit the performance of the reactor. For example, in a CVD reactor, such unwanted depositions change the deposition rate from one wafer to the next, reduce the deposition uniformity across the surface of a given substrate, and change the layer stresses so that a consistent stress level cannot be maintained between successive thin film layers. In addition, these depositions could eventually flake off as conditions within the reactor chamber change during processing, thereby forming particulates. These particles may fall onto the wafer being processed, thereby damaging devices formed thereon and reducing the yield.
Preferably, the foregoing difficulties are generally avoided by cleaning the reactor chamber interior shortly before inserting a wafer to be processed into the chamber. In a reactor equipped with RF plasma excitation electrodes and/or an RF plasma excitation antenna, silicon dioxide deposits are typically cleaned by the introduction of an etchant gas, such as ethyl hexafluoride (C.sub.2 F.sub.6), into the chamber. The etchant gas is ignited into a plasma by the RF excitation apparatus of the reactor. For high-rate CVD RF plasma reactors, an RF excitation field of 13.56 MHz is typically employed to ignite the plasma and is used during both wafer processing and chamber clean operations. In fact, a 13.56 MHz RF field with C.sub.2 F.sub.6 etchant gas is the most often used combination in performing RF plasma cleaning operations involving silicon dioxide deposits. The C.sub.2 F.sub.6 gas, when ignited as a plasma, produces a radical CF.sub.3 in the following reaction: EQU C.sub.2 F.sub.6 +energy from plasma.fwdarw.2CF.sub.3,
the CF.sub.3 providing the fluorine reactant species for etching of silicon dioxide deposits.
In the case of silicon nitride or silicon oxynitride deposits, the cleaning operation is typically performed using carbon tetrafluoride (CF.sub.4) or carbon hexafluoroethane and the like, along with an oxygen source such as oxygen or nitrous oxide and the like.
One problem with current cleaning processes is that the unwanted deposits on the interior chamber surfaces typically vary in thickness from one location to the next. Therefore, it is difficult to remove the unwanted deposit uniformly. Some of the interior chamber surfaces will still have remaining deposits, when others have been completely cleaned. One solution to this problem would be to perform the cleaning process for a long enough period of time to ensure all the deposits are removed. However, this would further reduce the productive cycle of the reactor, forcing it to spend more time in the unproductive cleaning process rather than in processing wafers. In addition, prolonged plasma cleaning operations can result in significant damage to cleaned chamber surfaces. The extra time required to ensure that all the chamber surfaces are thoroughly cleaned can cause varying degrees of damage to the first-cleaned surfaces.
Another problem with the use of C.sub.2 F.sub.6, and related etchant gases such as CF.sub.4, is that they are so-called "greenhouse" gases. The U.S. Environmental Protection Agency has ordered the reduction of all such gases which contribute to the depletion of the ozone layer and support the greenhouse effect. This means limiting or curtailing the use of the most widely employed etchant gases for reactor chamber cleaning.
Of course, other "non-greenhouse" gases are available to perform the aforementioned cleaning operation. For example, nitrogen-fluorine based etchant gases, such as NF.sub.3, provide one alternative. NF.sub.3 is a very aggressive etchant gas because it produces more fluorine in the plasma than the aforementioned "greenhouse" gases. Therefore, the interior surfaces of the reactor chamber are cleaned much faster. However, there are drawbacks to using NF.sub.3. One characteristic property of NF.sub.3 is that it is strongly electronegative (more so than CF.sub.4 or C.sub.2 F.sub.6) and therefore tends to reduce the population of free electrons in the plasma, due to its great affinity for electrons. The problem is that at RF excitation frequencies in the megahertz range (such as, for example, 13.56 MHz), a depleted electron population causes insufficient coupling between the RF signal and the plasma to sustain the plasma. This is primarily because at such high frequencies, the electrons are the only charged particles in the plasma with sufficient charge-to-mass ratio to be able to follow the rapid RF field oscillations. Thus, it is the electrons which kinetically couple the energy from the RF field to the ions and radicals in the plasma. The result is that as NF.sub.3 begins to reduce the electron population in the plasma, portions of the plasma become unstable, and flickering or collapsing of the plasma may be observed. Such plasma instability occurs at temperatures below 1000 degrees C and at chamber pressures between 0.005 and 10 Torr and at RF excitation frequencies on the order of 13.56 MHz. However, these are the very parameters preferred for current plasma cleaning operations. Plasma instabilities make the cleaning process uncertain, since plasma flickering results in the plasma density being reduced in various regions of the chamber for varying durations. This makes cleaning process control problematic, and the chamber may not be entirely cleaned at the conclusion of a given chamber cleaning process. With such instabilities, the effective plasma "on" time throughout the chamber is uncertain and so it is not possible to predict the required clean time with reasonable accuracy for consistent repetitive chamber clean operations. As a result, the specified chamber clean time is typically increased above that which would normally be necessary if the plasma was stable. This increased cleaning time can result in the damage to the first-cleaned chamber surfaces, as discussed previously, as well as increased processing downtime. And finally, it is noted that NF.sub.3 is a relatively expensive gas, as compared to other etchant species which are employed in plasma cleaning operations, thus making its use costly.
Another example of a "non-greenhouse" gas that could be employed for chamber cleaning is sulfur hexafluoride (SF.sub.6). However, when this etchant gas is used at the typical pressures and excitation frequencies, it exhibits an extremely poor cleaning performance. Due to this inefficiency, large quantities of the gas are required, along with long cleaning times. Thus, the expense of using this gas is high and wafer throughput is low.
As is evident from the above discussion, devices and methods for cleaning the interior surfaces of a plasma CVD or etch reactor are needed which will reduce or eliminate the need to employ "greenhouse gases", and alleviate the problems associated with the aforementioned alternate etchant gases. In addition, it is desired to reduce the cleaning times, without sacrificing the thoroughness of the cleaning, so as to improve the throughput of the plasma reactor.

Plasma cleaning of a CVD or etch reactor using a low or mixed frequency excitation field


Methods for converting two-dimensional images into three-dimensional images employing various interactive image processing tools that allow a user to apply any number or combination of image pixel repositioning depth contouring effects, algorithms or the like to create three-dimensional images.

1. Field of the Invention
The present invention relates to methods for conforming objects to a common depth perspective for converting two-dimensional images into three-dimensional images.
2. Description of the Related Art
In order for a three-dimensional image that is rendered from a two-dimensional image to appear realistic it often needs to include many smooth and complex transitions of depth. Unfortunately, known tools within graphic software packages or software filter plug-ins are not specifically designed to convert two-dimensional images into three-dimensional images and, consequently, do not facilitate an accurate true and believable re-creation of a three-dimensional image.
Moreover, known graphics-related software and methods for manipulating images do not provide tools that are capable of facilitating the individual conversion of a large number of two-dimensional images into three-dimensional images in a way that is practical or in a way that can be accomplished within a practical time realm. In order to be able to process a large number of images (as in the hundreds of thousands of frames in the typical motion picture) in a way that is practical and not time prohibitive, tools not yet known to exist would be required. Thus, it would be desirable to be able to provide methods for conforming objects to a common depth perspective for converting two-dimensional images into three-dimensional images in a manner that addresses the afore-described deficiencies of existing image processing software and methods.

Method for conforming objects to a common depth perspective for converting two-dimensional images into three-dimensional images


A method for making a light weight circuit module includes steps of providing a substrate, drilling through holes in the substrate and plating the through holes with a metal. The substrate is a rigid planar substrate and having metallization on both sides. The method also includes steps of drilling through holes in the substrate and plating the through holes with a metal. The method also includes steps of preparing a patterned photoresist layer on at least one of the two sides, etching the metallization on the at least one side in accordance with the patterned photoresist layer, drilling support holes, filling the support holes with a material chemically distinct from the substrate, stripping the patterned photoresist layer from the at least one side and chemically removing the substrate from the metallization.

Portability and ease of use are important for many new electronic products offering communications capabilities, data processing facilities and data entry and storage arrangements. Providing these and other features in a user-friendly and convenient package requires additional sophistication in circuit design and places a premium on performance as compared to weight of the product.
Conventional printed circuit cards provide a rugged and robust vehicle for realizing electronic circuitry of almost arbitrary complexity and sophistication. However, printed circuit cards invest substantial mass in the card itself, typically a fiberglass and epoxy matrix. It has been especially uneconomical and impractical to provide lightweight printed wiring boards wherein the ratio of the mass of the active circuitry to the mass of the product approached unity.
This problem is exacerbated in products having functional requirements sufficiently different as to preclude forming the product from a single monolithic circuit. For example, a handheld telephone requires digital circuitry for accomplishing dialing, memory functions such as speed dialing and cryptographic or other techniques for foiling unauthorized use. Also required are radio frequency circuits, operating in the neighborhood of a GigaHertz, which are not amenable to monolithic cointegration with power-efficient digital circuits using present-day integrated circuit fabrication capabilities. In such products, it is extremely desirable to reduce the weight of elements incorporated to interconnect distinct functional blocks having immiscible design requirements.
What is needed is a method for reducing the mass of the interconnections required between circuitries having functional differences presently precluding their cointegration in monolithic form.

Method for manufacturing a light weight circuit module


A method and apparatus for adaptively enabling a PB frames mode for video data processing. If the PB frames mode is enabled for a given pair of video pictures, and if the motion compensated prediction error for the B-picture in the most recently encoded PB frame is greater than the motion compensated prediction error for the P-picture in same PB frame multiplied by a constant, the PB frames mode is disabled for the PB frame. Otherwise, the PB frames mode remains enabled. If the PB frame is disabled by the PB decision logic, it may remain disabled until certain encoding parameters are met.

(1) Field of the Invention
The present invention is related to the field of video coding, more specifically, the present invention is a method and an apparatus for adaptively enabling and disabling PB frames mode in an H.263 video coder.
(2) Related Art
The ITU-T H.263 standard (ITU-T std. H.263-1995, published March 1996) is a standard for a coded representation which can be used for compressing the moving picture component of audio-visual services at low bit rates. The coding algorithm of the H.263 is a hybrid of inter-picture prediction which utilizes temporal redundancy, and transform coding of the remaining signal to reduce spatial redundancy.
There are numerous different optional modes in H.263 including a PB frames mode in which two pictures are coded as one unit. The term "PB" stems from P-picture and B-picture. A PB-frame comprises one P-picture predicted from the previous decoded P-picture and one B-picture predicted from both the previous decoded P-picture and the P-picture currently being decoded. With this option, portions of the B-picture maybe bi-directionally predicted from the past and future pictures.
There are various trade-offs in selecting an optional mode provided by H.263. Because the modes are optional, it is not necessary for the decoder to support any of the optional modes. If a decoder supports a given mode, the encoder has the option to enable or disable that given mode.
Currently, few methods exist for determining whether to enable or disable an optional mode for H.263. Typically, an optional mode is enabled at the beginning of a video data sequence and stays on throughout the entire length of the video data sequence. The disadvantage of this method is that with some types of video, the optional mode results in decreased video quality. For other types of video, the increase in video quality does not justify the increase in the computational overhead associated with the optional mode being enabled.
Therefore a method and an apparatus are desirable for allowing a feedback mechanism to determine whether to enable or disable an optional mode to produce the best video quality given a video data sequence.

Method and apparatus for adaptively enabling and disabling PB frames in an H.263 video coder


Silicon germanium regions are formed adjacent gates electrodes over both n-type and p-type regions in an integrated circuit. A hard mask patterned by lithography then protects structures over the p-type region while the silicon germanium is selectively removed from over the n-type region, even under remnants of the hard mask on sidewall spacers on the gate electrode. Silicon germanium carbon is epitaxially grown adjacent the gate electrode in place of the removed silicon germanium, and source/drain extension implants are performed prior to removal of the remaining hard mask over the p-type region structures.

Leading edge technologies require high performance operation at low-power. Epitaxial growth of silicon germanium carbon (often signified by any of "Si(Ge)(C)," "SiGe(C)" or "SiGe:C") layers can be an attractive solution to boost device performance. However n-channel metal oxide semiconductor (NMOS) and p-channel MOS (PMOS) transistors within complementary MOS (CMOS) designs require different epitaxies, creating challenges in protecting one type of transistor while performing epitaxy on the other transistor type. Conventional methods require patterning and the use of additional spacers on either NMOS or PMOS devices, which degrades device performance, makes integration very difficult, and leads to defects on the resulting circuits.
There is, therefore, a need in the art for an improved process for the epitaxial deposition of silicon germanium carbon layers during fabrication of CMOS integrated circuits.

Dual EPI CMOS integration for planar substrates

International Business Machines Corporation


A sputtering system for the depositing or etching of insulating, conducting, or semiconducting thin films is disclosed, in which the sputtering plasma is irradiated with a transverse, adjustable ultraviolet emission produced by an ultraviolet optical cavity containing a lamp discharge. The cavity irradiates the sputtering plasma volume with a sufficiently high optical flux to enact significant changes in the film produced. This effect is enabled by the device geometry, which, in the preferred embodiment, provides uniquely high efficiency and stability in the optical coupling between the lamp discharge and the sputtering plasma, resulting in the ability to significantly alter ionized and excited state populations within or above the sputtering plasma. The design also allows the operator to significantly control the volume and species involved in the optical interaction. A novel ultraviolet source for materials processing is also disclosed.

1. Field of the Invention
The present invention relates generally to vapor deposition methods and, in particular, a plasma sputtering apparatus by which thin or thick films of insulating, semiconductor, or conductive materials are formed. Potential applications exist in the fabrication of integrated circuits, optical elements, optoelectronic devices, and other such products requiring well-controlled physical properties in these same films. According to another aspect, the present invention relates generally to the field of ultraviolet light sources.
2. Description of the Related Art
In one aspect, the invention relates generally to the treatment of dispersed photoabsorbing media, such as gases, with ultraviolet radiation. An equipment geometry for this purpose, in fluid treatment, utilizes a flow-through geometry, wherein the media to be processed passes through a processing tube constructed of ultraviolet-transmitting materialxe2x80x94such as fused silicaxe2x80x94and wherein the tube is surrounded with one or several ultraviolet lamps, thereby creating a high radiative flux within the photoabsorbing media. The coupling efficiency of the ultraviolet radiation to the media may then be increased, by placing this coaxial arrangement within a reflective cavity. This latter reflective cavity becomes increasingly necessary as the extinction distance of the ultraviolet within the media becomes much greater than the relevant physical dimension of the apparatus, and the ultraviolet radiation must make many passes through the media before it is appreciably absorbed.
When the extinction distance is orders of magnitude longer than the relevant cavity dimension, the coupling efficiency of this ultraviolet source becomes inherently limited by parasitic losses within the reflective cavity, which xe2x80x9cstealxe2x80x9d the ultraviolet radiation away before it can be absorbed by the dispersed media. Similarly to a laser source, such losses can be largely attributed to a combination of the mirror quality, diffraction losses, and the propagation of the ultraviolet along optical paths which xe2x80x9cwalk offxe2x80x9d the cavity mirrors in so-called xe2x80x9cend-lossesxe2x80x9d. Unlike a laser, however, retention within the reflective cavity of these lamp sources is not greatly increased through the establishment of high-retention lasing modes that dominate the photoemission process. In addition, as clearance restrictions require the aforementioned processing tube to be increasingly short in lengthxe2x80x94or of increasingly smaller aspect ratioxe2x80x94the end-losses of the commensurately shorter reflective cavity become a serious limitation to the coupling efficiency of the processing apparatus. Conversely, ultraviolet radiation that is allowed to leak from the reflective cavity may adversely interact with other parts of the process. These sort of requirements have been partially dealt with in past fusion research, at least when using longer optical wavelengths, by implementing a laser cavity. In this approach, the photoabsorbing media is passed through the laser cavity itself. However, this approach becomes far more difficult for other, similarly configured, materials processes that require ultraviolet radiation; in part, because these latter processes would typically require much more economical solutions than those afforded fusion research, whereas, capital and maintenance costs for a high-power ultraviolet laser are likely to be prohibitively high.
The problems encountered with irradiating low absorption cross-section dispersed media become increasingly acute with lower pressure processes, wherein the dispersed media would typically be some gas or vapor which is rarified to a degree consistent with the level of vacuum. In these latter vacuum processes, one encounters situations wherein the absorbing constituent may have a vapor pressure of only 10xe2x88x926 atmospheres, with extinction distances in the range of 102 to 103 meters. At the same time, these vacuum processes will frequently involve one or several critical material surfaces that interact with the process quite differently when irradiated with the ultraviolet radiation. These same critical surfaces will typically be modified during the process, so that the result of irradiating these surfaces will change, as well. For instance, a thin film forming on one of these material surfaces can dramatically alter the absorption, scatter, or reflection of the ultraviolet radiation as its thickness increases. In ultraviolet-enhanced physical vapor deposition (PVD) processes, including reactive processes utilizing PVD sources, these issues have not been adequately addressed.
A prevalent PVD means in industry for the deposition of high quality thin films is through the utilization of sputtering techniques. The term xe2x80x9csputteringxe2x80x9d refers to a group of mechanisms by which material is ejected from a solid, or sometimes a liquid, target surface into a vapor form; this latter effect being due, at least in part, in either physical or chemical sputtering, to the kinetic energy transferred to the target atoms or molecules by bombarding particles. These mechanisms are utilized in sputter deposition processes categorized generally as laser sputtering, ion beam sputtering, glow discharge (or diode) sputtering, and magnetron glow discharge sputtering. The present invention, in its preferred embodiment, concerns primarily plasma sputtering, and, in particular, magnetron plasma sputtering. The magnetic confinement of the sputtering plasma in the magnetron sputtering process allows for a far greater range of mean free paths than the earlier, capacitively coupled diode plasma sputtering process. Its high deposition rate, combined with its versatility in depositing a wide range of materials under a great range of conditions, has made magnetron plasma sputtering a preferred thin film deposition technique for many industrial applications.
Yet, there are several aspects of plasma sputtering which are seen as significant barriers in utilizing the technique for future industrial applications. Most commercially available plasma sputter sources provide a small proportion of ionized species to the depositing film ( less than 5%). Most of the energy supplied for non-equilibrium growth is supplied by the thermal velocities of the depositing species. The thermal distribution of these velocities is necessarily broad, allowing little control over specific growth processes at the film growth interface. Because the energy supplied by the depositing species is kinetic, it is often difficult to provide high energies to the growth interface with out simultaneously causing subsurface damage, due to the recoil and implantation of the bombarding atoms.
Several modifications have been devised to render greater control over plasma sputtering processes wherein, as in the present invention, excited state and ion populations in the gas/vapor phase are increased and manipulated by means external to the sputtering plasma. This is most commonly accomplished by injecting electrons into the sputtering plasma to increase the plasma density and ion population, while simultaneously allowing a decrease of the target voltage. A resulting benefit is the ability to introduce a high proportion of relatively low energy ions to either etch or deposit on the substrate. This method has been made popular in the well-established triode and tetrode sputtering configurations, wherein electrons are usually supplied by a thermionic filament. This latter art has been found to work well for the deposition of metals, but is not compatible with reactive processes where electron emitting surfaces are prone to modification.
In recent years, plasma sputtering processes have also been developed that increase ionization through the utilization of secondary coils or antennas for RF or microwave excitation of the plasma. This latter prior art has also been found useful in the deposition of metals. However, difficulties arise, in that resonance conditions are effected by the inevitable modification of the process chamber surfaces during deposition, especially when depositing insulating or semi-insulating materials; also, these latter developments offer little resolution of the plasma species to be ionized.
The use of sources of UV/optical energy in conjunction with sputtering plasmas is relatively limited compared to the prior art concerning electron sources. In various instances, plasma sputtering experiments have been conducted utilizing the geometry set forth in U.S. Pat. No. 4,664,769 issued May 12, 1987 by Cuomo et al. This patent teaches a method wherein a UV source is directed onto a sputtering target during the magnetron sputtering process. The UV wavelength used is of an energy of or exceeding the photoelectric threshold of the target material, thereby causing the target to emit photoelectrons into the sputtering plasma. This photoelectric addition of electrons is found to increase plasma density, lower the cathode voltage required to sustain a discharge, as well as to increase the ion flux to the substrate, enabling modification of the film properties. As this work focuses on the irradiation of the sputtering target, its operation is contradictory to the goals of the present invention.
The use of UV/optical sources with magnetron sputtering plasmas in later work has consisted of efforts wherein a UV source, usually a laser, is directed upon the substrate being processed. These experiments are conducted in order to promote and study various surface reactions and solid phase transformations at the substrate surface, sometimes with a reactive gas injected at the substrate. As such, these accounts deal with UV interactions with the substrate surface and do not anticipate the present invention.
The use of UV/optical radiation sources in combination with processing plasmas has consisted mostly of the research conducted in relatively higher pressure photo-enhanced and plasma-enhanced chemical vapor deposition (CVD) processes. In the relevant accounts, ultraviolet radiation, usually from a laser, irradiates the substrate upon which the thin film is being deposited. This work in CVD was originated by Hargis, Gee, et al, and reported in the publications, xe2x80x9cLaser-plasma interactions for the deposition and etching of thin-film materialsxe2x80x9d, wherein is described the mechanism by which laser-produced UV activates the top monolayers which are plasma-deposited on the substrate.
This initial work utilizing both plasmas and UV radiation sources in CVD has continued. Researchers have since found that the plasmas used for plasma-enhanced CVD and plasma-enhanced chemical etching may be simultaneously or separately used as a photochemical UV source. The interaction of UV with these plasma-enhanced CVD and chemical etch processes has been found to take place primarily in surface modifications, such as in photo-activation of heterogeneous surface reactions at the substrate surface; because of this, these process geometries must incorporate means for illuminating the substrate surface which is being modified. Any photo-activated gas-phase reactions which might, in addition to the surface interactions, occur in these CVD and chemical etching plasmas would be essentially non-existent in the low-pressure, higher power density sputtering plasmas; nor are such gas phase reactions a necessary element of the present invention.
While the use of UV sources is a promising route for enhancing and controlling film growth and etching processes in plasma processing, the aforementioned prior art has had little impact on sputtering deposition/etching applications. Reasons for this are viewed, in the present invention, in light of the highly non-equilibrium thermodynamic mechanisms inherent in plasma sputtering technology. While the plasma sputter source provides a reliable means for depositing many materials under a wide range of conditions, consistently achieving a specific resultant film structure and composition, within relatively tight tolerances, remains a formidable challenge. Introducing additional energy sources to the sputtering plasma further complicates issues of stability and repeatability.
The prior art invariably utilizes process-altered surfaces which receive UV energy, namely the sputtering target or the substrate; but, in addition, chamber walls and fixturing. Any solid surfaces which might potentially receive UV radiation must act as a transmitting, reflecting, absorbing, or scattering surface. Because these process surfaces tend to be altered during the deposition process, the interaction of the UV source with the deposition process is also altered. As the reflectivity, scattering, and absorption occurring at these surfaces changes with process time, plasma-related mechanisms occurring throughout the process volume, such as secondary electron emission, gas/vapor photo-excitation, radiant heating, and photon-assisted sputtering, can all be dramatically altered. Hence, UV radiation incident on a growing film, or on the sputtering target, can interact with the deposition process in an unstable fashion.
Another problem arises in the use, in previous experiments, of UV (and other) sources which interact, in particular, with magnetron plasmas in a highly asymmetric geometry. The relative stability and repeatability of a conventional magnetron plasma source is due, in great part, to the maintenance of a symmetrically uniform magnetic and electric field for containment of the magnetron plasma. For example, a rectangular magnetron is more prone to arcing, in D.C. reactive sputtering, than a circular magnetron, due to its lower symmetry. As such, any UV source which is made to interact with a magnetron plasma should preserve the magnetron""s symmetry, if stable, repeatable performance is to be maintained.
The terms xe2x80x9cplasmaxe2x80x9d and xe2x80x9cdischargexe2x80x9d both refer herein to the general sense of an electrically or electromagnetically sustained, photo-emitting, gas/vapor discharge, wherein quasineutrality of the gas/vapor may not necessarily exist. While the term xe2x80x9cplasmaxe2x80x9d has been used more restrictively, and certainly more inclusively, than in the definition offered herein, the latter definition is consistent with current-day usage in the semiconductor industry, vapor deposition sciences, and other areas where the present invention might find application. The two terms are utilized differently in the present disclosure as a means of clearly differentiating between the sputtering xe2x80x9cplasmaxe2x80x9d of the preferred embodiment, and the photoemitting xe2x80x9cdischargexe2x80x9d of the disclosed ultraviolet lamp source.
In disclosing the present invention, the terms xe2x80x9ccavityxe2x80x9d, xe2x80x9creflective cavityxe2x80x9d, and xe2x80x9coptical cavityxe2x80x9d, will all refer to the common and general sense of a predetermined structure for confining propagation of optical radiation between reflective surfaces. Also, the use of the term xe2x80x9cvaporxe2x80x9d will herein refer to any gaseous or vapor-like substance, as distinguished from a solid or liquid. This includes atoms, molecules, ions, clusters, and other such dispersed substances which may traverse the process space of a processing chamber.
The previously cited problems, as recognized by the present invention, are addressed herein, in part, through the development of a novel ultraviolet processing apparatus that provides both highly efficient coupling and well-controlled interactions with dispersed photoabsorbing media, such a vapors. According to one aspect of the present invention, a narrow-band UV source has been developed which represents a significant departure from previous incoherent or coherent light sources used in materials processing. The UV source disclosed herein utilizes an optical cavity which allows unusually high retention without requiring the establishment of optical gain. Unlike a conventional laser, light is not coupled through a partially reflective mirror to a medium external to the cavity, but instead, is coupled directly to dispersed photoabsorbing process media present in the central process space within the optical cavity. Since the process media is, in the preferred embodiment, a vapor with a necessarily low photo-absorption cross section, the xe2x80x9cactivexe2x80x9d losses in the cavity can be very low, allowing the cavity radiation density to increase proportionally, thereby increasing total absorption. The radiation density is also increased by virtue of the large effective numerical aperture achieved, as the symmetric cavity focuses the optical energy to a relatively small process space at the center of the cavity. As a quasi-monochromatic source, the reflective cavity is designed to be capable of higher efficiency and higher average radiation density than available ultraviolet-emitting lasers. Compared to previous UV lamps, the UV source developed herein can maintain relatively high overall efficiency in the both the generation of high radiation densities, and the utilization of the generated UV photons for a selected photo-absorption process. This efficiency is enabled through a configuration that delimits the process volume, in part, through the use of thin film optical interference means.
In accordance with the illustrated preferred embodiment, the present invention also provides a sputtering apparatus and method for the deposition of material on a workpiece, using intense ultraviolet (UV) radiation, including vacuum ultraviolet (VUV; xcex less than 200 nm) radiation, to irradiate vapor constituents of a sputtering process. In particular, the sputtering apparatus disclosed herein allows a very high degree of optical coupling, as well as a high symmetry and a high selectibility of optical coupling, between a high power, UV-producing lamp discharge and the sputtering plasma.
In its first preferred embodiment the invention includes a central circular magnetron electrode for sustaining the sputtering plasma, a peripheral optical aperture located above the electrode, a separate concentric volume containing means for generating high power, narrow-band UV emission, a concentric reflective cavity, means for positioning a workpiece to receive depositing species, and optical interference and collimation means for both spatial and spectral control of the UV emission within the sputtering plasma. The sputter source described herein utilizes the aforementioned UV processing apparatus, which confines UV radiation to propagate within a planar process space above the sputtering target (xe2x80x9cabove the targetxe2x80x9d will, throughout this text, refer to the side of the target exposed to vacuum). The energy and radiation density of the UV radiation produced by the disclosed UV apparatus is sufficient to ionize a vapor or gas constituent of the sputtering plasma.
Whereas the use of UV radiation offers the potential for highly resolved interactions with specific plasma species, prior plasma sputtering art utilizing UV has not been developed significantly as a production method. Prior art plasma sputtering experiments utilizing ultraviolet energy for altering plasma sputtering processes have invariably required direct illumination of a processing surface, namely, the target or workpiece; many of these interactions are found in the present invention to be inherently unstable and difficult to control in a sputtering environment. These latter UV-surface interactions also tend to dominate the photo-absorption process, especially at the low pressures used in sputtering processes, thereby severely limiting the proportion of the UV radiation actually absorbed through UV-vapor interactions. In the present invention, through the efficient containment of UV spectral emissions, effective collimation of the UV, and a symmetric distribution of UV about the sputtering plasma""s major axis of symmetry, a high density of UV radiation is available for stable and repeatable photo-excitation and/or photo-ionization of the gas/vapor-phase plasma species; at the same time, the interactions of this UV energy with the target, workpiece, or other process-altered surfaces, are profoundly reduced. Another related advantage of the UV source of the present invention, in its capacity as a UV-assisted processing apparatus, is the possibility of reducing UV-induced damage at the workpiece being processed.
The present invention provides a new and versatile method for fabricating thin film structures by enacting a greater degree of control over both the sputtering plasma parameters, and the nature of plasma-emitted particles, than conventional plasma sputtering processes. One advantage of the present invention is that it introduces a means for increasing ion densities in a repeatable, low-cost method. The present invention, in its preferred embodiment, offers distinct advantages over the prior art as a method for producing high ion densities in or above the sputtering plasma. This increase in ion density is achieved by using well-resolved, photo-ionizing UV-plasma interactions, in a configuration which substantially reduces the interaction of ionizing radiation with any process-altered surface. A resulting advantage is the introduction of a both repeatable and highly tailorable process for increasing ion densities in and/or above the sputtering plasma.
Another advantage of the present invention is the increased control allowed in achieving specific compositional or structural characteristics in the thin (or thick) film structures formed. The selective and reproducible ionization of a specific species in, or above, the sputter plasma allows control over the kinetic and chemical energies of those specific atomic or molecular species at the growth front of the film. The ability to control ion fluxes, chemical energy, and kinetic energies in vapor depostion are powerful tools in controlling the microstructure and crystallinity of a deposited film. Because of the thermodynamic non-equilibrium nature of the sputtering process, it may produce material phases and phase combinations not possible in more thermodynamically equilibrium processes, such as evaporation or the earlier diode sputtering. This is due to the energies supplied by the depositing atoms, and their reactions, at the growth interface, being representative of temperatures far exceeding that of the bulk temperature of the workpiece. Hence greater latitude in controlling these energies via mean free path (i.e., pressure) and ionization greatly increases the latitude available in achieving a particular film structure. At the lower sputtering pressures possible with higher ion densities, the resultant films deposited will also tend to contain less contamination by the sputtering gas (e.g., argon). This will, in turn, minimize structural defects induced by these gases, enhancing the use of sputtering as an epitaxial technique.
Higher ion fluxes in sputtering also greatly enable the effort to perform so-called metallic-mode reactive sputtering, wherein the target remains metallic during deposition and the reacted product is formed at the workpiece, as chemical activity of the metal atoms at the workpiece is greatly enhanced. This latter method is important for high-rate sputtering of dielectrics, as well as providing a promising technique in sputter epitaxy. Other objects related to the present invention follow.
An object of the present invention is to provide a means for increasing the density of ionized and excited species in or above a sputtering plasma.
A further object of the invention is to provide a means of selectively activating desired transitions in the sputtering plasma, and thereby enacting a change in the properties of the deposited film.
Another object of the invention is to provide a means of irradiating the sputtering plasma and/or adjacent vapor with a high density of UV energy, in a manner which isolates the volume and nature of UV interaction.
Another object of the invention is to provide ionizing UV energy to plasma species without producing UV-induced damage at an adjacent workpiece.
Yet another object of the present invention is to provide a means of inducing a greater degree of self-sputtering of the target material, and thereby lowering the background pressure of inert gas required to sustain the plasma.
Another object of the present invention is to provide a self-contained means of irradiating dispersed photoabsorbing media.
Another object of the invention is to provide a novel, plasma-sustained ion source for the development of sputter-assisted processes.