Patents by Inventor Al F. Tasch

Al F. Tasch has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 6319799
    Abstract: A heterojunction transistor with high mobility carriers in the channel region includes a source region and a drain region formed in a semiconductor body with the source region and the drain region comprising doped semiconductor alloys separated from the substrate by heterojunctions. A channel region is provided between the source region and the drain region comprising an undoped layer of an alloy of the semiconductor material and a deposited layer of material of the semiconductor body overlying the undoped layer. A gate electrode is formed on a gate oxide over the channel region. In fabricating the high mobility heterojunction transistor, the spaced source and drain regions are formed in the substrate by implanting dopant of conductivity type opposite to the substrate and a material in the alloy and then annealing the structure to form the alloy of the semiconductor material under the undoped layer.
    Type: Grant
    Filed: May 9, 2000
    Date of Patent: November 20, 2001
    Assignee: Board of Regents, The University of Texas System
    Inventors: Qiqing Ouyang, Al F. Tasch, Jr., Sanjay Kumar Banerjee
  • Patent number: 5393690
    Abstract: A semiconductor device and method of manufacture employs an improved insulating layer to laterally separate conductive layers or regions. A relatively thick insulating layer is anisotropically patterned to form an electrode having a thick insulating layer on its side walls. Subsequently defined conductive regions are separated from the electrode by a distance determined by the thickness of the insulating layer. In devices requiring multiple level polycrystalline silicon electrodes, shorts between electrodes are reduced; in MOS devices, operating parameters are improved due to decreased overlap of the gate electrode over the source or drain region, decreased contamination of the gate electrode during manufacture, and more uniform gate oxide definition along the active channel between the source and drain.
    Type: Grant
    Filed: January 21, 1993
    Date of Patent: February 28, 1995
    Assignee: Texas Instruments Incorporated
    Inventors: Horng-Sen Fu, Al F. Tasch, Jr., Pallab K. Chatterjee
  • Patent number: 5202574
    Abstract: A semiconductor device and method of manufacture employs an improved insulating layer to laterally separate conductive layers or regions. A relatively thick insulating layer is anistropically patterned to form an electrode having a thick insulating layer on its side walls. Subsequently defined conductive regions are separated from the electrode by a distance determined by the thickness of the insulating layer. In devices requiring multiple level polycrystalline silicon electrodes, shorts between electrodes are reduced; in MOS devices, operating parameters are improved due to decreased overlap of the gate electrode over the source or drain region, decreased contamination of the gate electrode during manufacture, and more uniform gate oxide definition along the active channel between the source and drain.
    Type: Grant
    Filed: August 21, 1992
    Date of Patent: April 13, 1993
    Assignee: Texas Instruments Incorporated
    Inventors: Horng-Sen Fu, Al F. Tasch, Jr., Pallab K. Chatterjee
  • Patent number: 5026575
    Abstract: The present invention involves the use of organocalcium precursors for the chemical vapor deposition of thin CaF.sub.2 films under exceptionally mild conditions. This method is based on utilizing an organocalcium compound and a source of fluorine in a chemical vapor deposition reaction to form CaF.sub.2.
    Type: Grant
    Filed: July 11, 1989
    Date of Patent: June 25, 1991
    Assignee: Board of Regents, The University of Texas System
    Inventors: Richard A. Jones, Alan H. Cowley, Al F. Tasch, Jr.
  • Patent number: 4763181
    Abstract: A non-charge-sensing high density dynamic random access memory (DRAM) cell using a trench capacitor as a vertical FET and two active field effect transistors (FETs). A particular bit line is shared by the cells on either side of it; the bit line on one side of a particular cell being used to write to the cell while the bit line on the other side of the cell is used to read from the cell. This dual use of bit lines, plus the use of a vertical FET transistor along one side of a trench capacitor, plus the avoidance for the need of a relatively large storage capacitor since the cell is not read by "dumping" or releasing its charge onto the bit line all aid in making this cell compact and suitable for high density memories. Since the substrate serves as the second source/drain region of the vertical FET, a separate line for this region is eliminated, also contributing substantially to a smaller cell size.
    Type: Grant
    Filed: December 8, 1986
    Date of Patent: August 9, 1988
    Assignee: Motorola, Inc.
    Inventor: Al F. Tasch, Jr.
  • Patent number: 4591891
    Abstract: A MOS read only memory, or ROM, is formed by a process compatible with standard P-channel or N-channel metal or silicon gate manufacturing methods. The ROM is programmed either after the protective nitride layer has been applied and patterned, usually the last step in the slice processing method before electrical testing of the devices, or after the electrical testing of the devices. All potential MOS transistors in the ROM array are initially at a logic "0" or a logic "1". An electron beam slice printing machine is used to program the selected transistors in the ROM array to change their logic state by exposing the gates of the selected transistors to an electron beam. The gates to be exposed are predetermined by a coding on a magnetic tape which corresponds to the desired ROM code. No electron beam mask is necessary since the beam only exposes in selected areas.
    Type: Grant
    Filed: June 5, 1978
    Date of Patent: May 27, 1986
    Assignee: Texas Instruments Incorporated
    Inventors: Pallab K. Chatterjee, Al F. Tasch, Jr.
  • Patent number: 4553316
    Abstract: A MESFET is fabricated using a self-aligned gate process. This process uses a vertical (anisotropic) etch to self-align the gate and source/drain. The vertical etch, in conjunction with a two-level insulator, creates a barrier between the gate and source/drain, so that when metal is deposited and reacted, and any excess removed, the gate is selfaligned with the source/drain, and contacts to the source/drain and gate are well isolated. The alignment obtained by this process is advantageous in that series channel resistance is reduced, and a more compact structure is attained for improvement in packing density.
    Type: Grant
    Filed: March 12, 1984
    Date of Patent: November 19, 1985
    Assignee: Texas Instruments Incorporated
    Inventors: Theodore W. Houston, Al F. Tasch, Jr., Henry M. Darley, Horng S. Fu
  • Patent number: 4455738
    Abstract: A MESFET is fabricated using a self-aligned gate process. This process uses a vertical (anisotropic) etch to self-align the gate and source/drain. The vertical etch, in conjunction with a two-level insulator, creates a barrier between the gate and source/drain, so that when metal is deposited and reacted, and any excess removed, the gate is self-aligned with the source/drain, and contacts to the source/drain and gate are well isolated. The alignment obtained by this process is advantageous in that series channel resistance is reduced, and a more compact structure is attained for improvement in packing density.
    Type: Grant
    Filed: December 24, 1981
    Date of Patent: June 26, 1984
    Assignee: Texas Instruments Incorporated
    Inventors: Theodore W. Houston, Al F. Tasch, Jr., Henry M. Darley, Horng S. Fu
  • Patent number: 4384301
    Abstract: A novel metal-oxide-semiconductor (MOS) field effect transistor having enhanced oxide thickness at the edge of the gate electrode and having metal silicide regions in the gate electrode and source and drain areas. The enhanced oxide thickness improves interconnect-to-interconnect breakdown voltage in multilevel interconnect devices as well as minimizing gate overlap of source and drain. The metal silicide regions reduce series resistance and improve device speed and packing density.
    Type: Grant
    Filed: October 9, 1981
    Date of Patent: May 17, 1983
    Assignee: Texas Instruments Incorporated
    Inventors: Al F. Tasch, Jr., Pallab K. Chatterjee, Horng-Sen Fu
  • Patent number: 4373165
    Abstract: A semiconductor read-only-memory (ROM) device having an array of punch-through devices as memory cells. The cells are formed at the crossing points of two pluralities of parallel elongated regions, the two pluralities being perpendicular to each other. One plurality is located in subsurface regions of a semiconductor body and is of a conductivity type opposite that of the surrounding body. The other plurality is located at a surface of the semiconductor body and is of the same conductivity type as the subsurface plurality. The device is programmed by implanting impurities of the same conductivity type as the semiconductor body between selected crossing points. No contacts exists in the array.
    Type: Grant
    Filed: September 14, 1981
    Date of Patent: February 8, 1983
    Assignee: Texas Instruments Incorporated
    Inventor: Al F. Tasch, Jr.
  • Patent number: 4355454
    Abstract: A method for fabricating a metal oxide semiconductor device having at least one level of polycrystalline silicon interconnects and novel insulation layers for multilevel interconnects. In one embodiment, the fabrication processing includes forming a layer of arsenic doped glass as a multilevel interconnect system insulating layer. In another embodiment, the method includes the formation of a multilevel interconnect system insulating layer which includes the formation of a layer of undoped silicon dioxide as a barrier layer and then forming a layer of arsenic doped glass upon the undoped layer.
    Type: Grant
    Filed: May 5, 1981
    Date of Patent: October 26, 1982
    Assignee: Texas Instruments Incorporated
    Inventors: Al F. Tasch, Jr., Horng-Sen Fu
  • Patent number: 4356040
    Abstract: A semiconductor device and method of manufacture employs an improved insulating layer to laterally separate conductive layers or regions. A relatively thick insulating layer is anisotropically patterned to form an electrode having a thick insulating layer on its side walls. Subsequently defined conductive regions are separated from the electrode by a distance determined by the thickness of the insulating layer. In devices requiring multiple level polycrystalline silicon electrodes, shorts between electrodes are reduced; in MOS devices, operating parameters are improved due to decreased overlap of the gate electrode over the source or drain region, decreased contamination of the gate electrode during manufacture, and more uniform gate oxide definition along the active channel between the source and drain.
    Type: Grant
    Filed: May 2, 1980
    Date of Patent: October 26, 1982
    Assignee: Texas Instruments Incorporated
    Inventors: Horng-Sen Fu, Al F. Tasch, Jr., Pallab K. Chatterjee
  • Patent number: 4354896
    Abstract: A method for patterning a submicrometer substrate element which is smaller than the reproducible resolution accuracy of optical lithography. A series of layers is deposited upon a top layer pattern using standard methods. An edge of the top layer is positioned at or near where the required submicrometer element is to be patterned. A cavity is formed in one of the intermediate layers by removing that intermediate layer in such a fashion that the layer underneath the edge of the top layer is removed. Next, a conformal layer is deposited upon the structure so that the conformal layer fills the cavity. Then the conformal layer is removed and each of the other layers is sequentially removed in such a fashion that only that portion of the conformal layer that occupied the cavity remains, together with any layers that occupy the space underneath the cavity. The remaining layers are the mask for further patterning.
    Type: Grant
    Filed: August 5, 1980
    Date of Patent: October 19, 1982
    Assignee: Texas Instruments Incorporated
    Inventors: William R. Hunter, Al F. Tasch, Jr., Thomas C. Holloway
  • Patent number: 4328511
    Abstract: The present invention is embodied in a dynamic random access memory (RAM) cell comprising a depletion mode field effect transistor structure with a p-n junction "gate" electrode. The cell can be programmed to two threshold voltage states providing constant current sensing. Cell programming is by application of appropriate signals to the transistor "gate" electrode and source. Reading is accomplished by sensing current through the transistor while the source is grounded. An intermediate voltage on the "gate" electrode prevents changes in the state of the cell.
    Type: Grant
    Filed: December 10, 1979
    Date of Patent: May 4, 1982
    Assignee: Texas Instruments Incorporated
    Inventors: Al F. Tasch, Jr., Geoff W. Taylor, Pallab K. Chatterjee
  • Patent number: 4319260
    Abstract: A metal oxide semiconductor device having at least one level of polycrystalline silicon interconnects and novel insulation layers for multilevel interconnects. In one embodiment a layer of arsenic doped glass replaces the conventional phosphorus doped glass insulation layer. In other embodiments a layer of arsenic doped glass upon an undoped layer of silicon dioxide provides the insulation layer. Slow diffusing source-drain impurities along with these insulation layers provide minimum lateral source-drain diffusion.
    Type: Grant
    Filed: September 5, 1979
    Date of Patent: March 9, 1982
    Assignee: Texas Instruments Incorporated
    Inventors: Al F. Tasch, Jr., Horng-Sen Fu
  • Patent number: 4272303
    Abstract: An MOS read only memory, or ROM, is formed by a process compatible with standard P-channel or N-channel metal or silicon gate manufacturing methods. The ROM is programmed either after the protective nitride layer has been applied and patterned, usually the last step in the slice processing method before electrical testing of the devices, or after the electrical testing of the devices. All potential MOS transistors in the ROM array are initially at a logic "0" or a logic "1". Selected transistors are programmed by implanting a "light" ion such as hydrogen or helium through the protective nitride layer and the electrode into the gate oxide, photoresist being used as an implant mask.
    Type: Grant
    Filed: July 9, 1979
    Date of Patent: June 9, 1981
    Assignee: Texas Instruments Incorporated
    Inventors: Pallab K. Chatterjee, Al F. Tasch, Jr.
  • Patent number: 4268950
    Abstract: An MOS read only memory, or ROM, is formed by a process compatible with standard silicon gate manufacturing methods. The ROM is programmed either after the top level of device interconnects has been patterned and sintered, usually the last step in the slice processing method before electrical testing of the devices, or after the electrical testing of the devices. All potential MOS transistors in the ROM array are initially at a logic "0" or a logic "1". Selected transistors are programmed by implanting ions of the appropriate impurity type through their gates and gate oxides into the silicon, using photoresist as an implant mask. Impurities are electrically activated by laser annealing, and residual oxide charge is removed by rf plasma anneal.
    Type: Grant
    Filed: June 5, 1978
    Date of Patent: May 26, 1981
    Assignee: Texas Instruments Incorporated
    Inventors: Pallab K. Chatterjee, Al F. Tasch, Jr.
  • Patent number: 4228445
    Abstract: A charge coupled device having geometries suitable for fabrication in high density packages (64,000 bits per chip-1,000,000 bits per chip) is comprised of a semiconductor substrate having dopant impurity atoms of a first type and a first surface. A charge transfer channel lies in the substrate near the first surface, and it is overlaid by an insulating layer of non-uniform thickness. A plurality of first and second electrodes lie on the insulating layer traversely to the channel. A well region of dopant impurity atoms of a second type opposite to the first type lies under each of the electrodes. The non-uniform insulating layer underlies each of the first electrodes by a first uniform thickness, underlies the second electrodes by a second uniform thickness, and separates the each of the first and second electrodes by approximately the second thickness. The second thickness is 20%-60% greater than the first thickness to greatly reduce inter-electrode shorts in high density packages.
    Type: Grant
    Filed: October 27, 1977
    Date of Patent: October 14, 1980
    Assignee: Texas Instruments Incorporated
    Inventors: Al F. Tasch, Jr., Pallab K. Chatterjee
  • Patent number: 4227202
    Abstract: A charge coupled device having geometries suitable for fabrication in high density packages (64,000 bits per chip--1,000,000 bits per chip) is comprised of a semiconductor substrate having dopant impurity atoms of a first type and a first surface. A charge transfer channel lies in the substrate near the first surface; and it is overlaid by an insulating layer of non-uniform thickness. A plurality of first and second electrodes lie on the insulating layer traversely to the channel. A barrier region of dopant impurity atoms of the first type lies under each of the electrodes. The non-uniform insulating layer underlies each of the first electrodes by a first uniform thickness, underlies the second electrodes by a second uniform thickness, and separates the each of the first and second electrodes by approximately the second thickness. The second thickness is 20%-60% greater than the first thickness to greatly reduce inter-electrode shorts in high density packages.
    Type: Grant
    Filed: October 27, 1977
    Date of Patent: October 7, 1980
    Assignee: Texas Instruments Incorporated
    Inventors: Al F. Tasch, Jr., Pallab K. Chatterjee
  • Patent number: 4203125
    Abstract: An MOS random access memory cell using the capacitance of a buried P-N junction as the storage element is formed by a process compatable with standard N-channel silicon gate manufacturing methods. The cell is fabricated using a method which consists of an implanted channel stopper underneath a thick field oxide, a buried, fully implanted charge storage element which also is the source of the cell transistor, self-aligned polysilicon gates, multilayer oxide and a thin film of metallization for interconnections. The vertical stacking of the charge storage and transfer elements and the increase in storage area to cell area ratio with the buried storage area provide a cell with very high packing density.
    Type: Grant
    Filed: July 3, 1978
    Date of Patent: May 13, 1980
    Assignee: Texas Instruments Incorporated
    Inventors: Pallab K. Chatterjee, Geoff W. Taylor, Al F. Tasch, Jr., Horng-Sen Fu