Patents by Inventor Pallab K. Chatterjee

Pallab K. Chatterjee 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: 4683486
    Abstract: A dRAM cell and array of cells, together with a method of fabrication, are disclosed wherein the cell includes one field effect transistor and one storage capacitor with both the transistor and the capacitor formed in a trench in a substrate. The transistor source, channel, and drain and one capacitor plate are formed in a layer of material inserted into the trench and insulated from the substrate; the gate and other capacitor plate are formed in the substrate trench sidewall. In preferred embodiments bit lines on the substrate surface connect to the inserted layer, and word lines on the substrate surface are formed as diffusions in the substrate which also form the gate. The trenches and cells are formed in the crossings of bit lines and word lines; the bit lines and the word lines form perpendicular sets of parallel lines.
    Type: Grant
    Filed: September 24, 1984
    Date of Patent: July 28, 1987
    Assignee: Texas Instruments Incorporated
    Inventor: Pallab K. Chatterjee
  • Patent number: 4673962
    Abstract: DRAM cells and arrays of cells on a semiconductor substrate, together with methods of fabrication, are disclosed wherein the cells are formed in pairs or quartets by excavating a trench or two trenches through the cell elements to split an original cell into two or four cells during the fabrication. The cells include vertical field effect transistors and capacitors along the trench sidewalls with word lines and bit lines crossing over the cells.
    Type: Grant
    Filed: March 21, 1985
    Date of Patent: June 16, 1987
    Assignee: Texas Instruments Incorporated
    Inventors: Pallab K. Chatterjee, Ashwin H. Shah
  • Patent number: 4604727
    Abstract: A memory including various selectively configurable peripherals which provide on-chip low-level control features and a configuration RAM storing bits which both provide unclocked full logic-level outputs to control the selectively configurable peripherals and can also be accessed and read out. That is, each cell in the configuration RAM has two output modes: a digital continuous output, which is provided as a continuous control signal to various peripheral circuits and a selectable analog output which is used to read the information stored in the configuration RAM.
    Type: Grant
    Filed: August 31, 1983
    Date of Patent: August 5, 1986
    Assignee: Texas Instruments Incorporated
    Inventors: Ashwin H. Shah, Pallab K. Chatterjee, James D. Gallia, Shivaling S. Mahant-Shetti
  • 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: 4554572
    Abstract: A CMOS device configuration in which a complete CMOS inverter is contained in the space normally required for a single NMOS transistor of equivalent geometry. A first polysilicon layer of normal thickness and N+ doping is used for the N channel gate, and a second polysilicon layer is deposited conformally over the oxide which encapsulates the first polysilicon layer. The second polysilicon layer is thin and doped p-type. The second layer is only lightly doped initially, and is then doped more heavily by a low-energy implantation. The portions of the second poly layer which are adjacent to the sidewalls of the gate level in first poly will be shielded from the heavy implantation, and will therefore provide relatively lightly doped p-type channel regions, to form a pair of PMOS polysilicon transistors addressed by the N+ first poly gate electrode. Preferably the channel doping of these polysilicon transistors is at least 10.sup.17.
    Type: Grant
    Filed: June 17, 1983
    Date of Patent: November 19, 1985
    Assignee: Texas Instruments Incorporated
    Inventor: Pallab K. Chatterjee
  • 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: 4379306
    Abstract: A charge coupled device is disclosed which includes a plurality of stages having increased charge storage capacity and decreased leakage current. Each stage is comprised of a semiconductor substrate of a first-type conductivity having a first surface. A charge transfer channel extends through the stage. An insulating layer of non-uniform thickness lies on the first surface. The insulating layer has at least two spaced apart relatively thick portions traversing the channel, and has relatively thin portions traversing the channel throughout the spaces between the spaced apart thick portions. Phase electrodes traverse the channel such that each phase electrode overlies one relatively thick portion and one adjacent relatively thin portion of the insulating layer. A shallow dopant layer of a second-type conductivity lies throughout the channel relatively near to the first surface.
    Type: Grant
    Filed: August 26, 1977
    Date of Patent: April 5, 1983
    Assignee: Texas Instruments Incorporated
    Inventors: Pallab K. Chatterjee, Aloysious F. Tasch, Jr.
  • Patent number: 4365261
    Abstract: A charge coupled device is disclosed which includes a plurality of stages having increased charge storage capacity and decreased leakage current. Each stage is comprised of a semiconductor substrate of a first-type conductivity having a first surface. An insulating layer of uniform thickness lies on the first surface. A charge transfer channel extends through each stage. Phase electrodes lie on the insulating layer transversely to the channel. The semiconductor substrate under each phase electrode is divided into a barrier region and an adjacent well region bounded by the channel. A shallow dopant layer of the first-type conductivity lies in each of the barrier regions relatively near to the first surface. A buried channel dopant layer of a second-type conductivity lies in the well regions and the barrier regions under and relatively near to the shallow first-type conductivity dopant layer.
    Type: Grant
    Filed: August 26, 1977
    Date of Patent: December 21, 1982
    Assignee: Texas Instruments Incorporated
    Inventors: Pallab K. Chatterjee, Aloysious F. Tasch, Jr.
  • Patent number: 4364076
    Abstract: A charge coupled device memory is disclosed which includes a plurality of stages having increased charged storage capacity and decreased leakage current. Each stage is comprised of a semiconductor substrate of a first-type conductivity having a first surface. An insulating layer of uniform thickness lies on the first surface. A charge transfer channel extends through each stage. Phase electrodes lie on the insulating layer transversely to the channel. The semiconductor substrate under the phase electrodes is divided into barrier regions and adjacent well regions bounded by the channel. A dopant layer of a second-type conductivity lies in each of the well regions relatively near to the first surface. An enhanced first-type conductivity dopant layer lies in the well regions and the barrier regions relatively far from the surface having a doping which is greater than the doping of the first-type conductivity semiconductor substrate.
    Type: Grant
    Filed: August 26, 1977
    Date of Patent: December 14, 1982
    Assignee: Texas Instruments Incorporated
    Inventors: Pallab K. Chatterjee, Aloysious F. Tasch, Jr.
  • 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: 4353082
    Abstract: A random access memory device which is comprised of a matrix of individual MOS random access memory cells, the individual cells utilizing a sense region formed by a diffused layer of heavily doped silicon material underlying the storage and transfer regions, the storage region being formed at the surface of the device and containing a double implant for increasing the storage capacity of the cell, the transfer region being formed along the edge of a V-groove anisotropical etch which extends from the surface of the device adjacent the storage region and into the diffused sense region. In one embodiment first and second layers of polycrystalline silicon separated by an insulating layer and deposited at the surface of the cell act as the storage and transfer gates, respectively, the first layer overlying the storage region adjacent the V-groove and the second layer lying within the V-groove and partially overlapping the first layer.
    Type: Grant
    Filed: July 29, 1977
    Date of Patent: October 5, 1982
    Assignee: Texas Instruments Incorporated
    Inventor: Pallab K. Chatterjee
  • 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: 4291391
    Abstract: The present invention is embodied in a method of operating a dynamic random access memory (RAM) array having individual depletion mode metal-oxide-semiconductor (MOS) transistors as the memory cells. The cells can be programmed to two threshold states providing constant current sensing. Cell programming is by application of appropriate signals to the transistor gate electrode and source. Reading is accomplished by grounding the source and sensing current through the transistor. An intermediate voltage on the gate electrode prevents changes in the state of the cell.
    Type: Grant
    Filed: September 14, 1979
    Date of Patent: September 22, 1981
    Assignee: Texas Instruments Incorporated
    Inventors: Pallab K. Chatterjee, Geoffrey W. Taylor
  • 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
  • Patent number: 4153904
    Abstract: A semiconductor device having a p-n junction characterized by low electric field crowding and a resulting high avalanche breakdown voltage requirement. The semiconductor device is comprised of a semiconductor substrate having impurity atoms of one type and a first surface. A first doped region lies in said substrate at said first surface and has dopant atoms of a type opposite to said one type. A second doped region lies in said substrate at said first surface adjacent the entire perimeter of said first doped region. The second doped region extends laterally away from said first doped region, and has dopant atoms of the same type as and of less density than said dopant atoms of said first doped region.
    Type: Grant
    Filed: October 3, 1977
    Date of Patent: May 8, 1979
    Assignee: Texas Instruments Incorporated
    Inventors: Al F. Tasch, Jr., Horng-Sen Fu, Pallab K. Chatterjee
  • Patent number: 4152779
    Abstract: In a microelectronic, metal-oxide-semiconductor dynamic random access memory cell having an MOS capacitance signal storage region, leakage current has been found to have a critical dependence upon the voltage level at which the storage gate is operated (V.sub.STORE). The leakage rate undergoes a sharp transition to a low state below a certain critical V.sub.STORE. This transition is due to the shutting off of the leakage from the periphery and field region around the cell. Consequently, maximum refresh time is achieved by modifying the cell to permit operation of the storage gate below the critical voltage, which may be at or near ground level. For an n-channel cell, permanently shifting the flatband voltage at the silicon-oxide interface of the storage capacitor in the negative direction can generate a potential well for charge storage with a very small V.sub.STORE.
    Type: Grant
    Filed: April 6, 1978
    Date of Patent: May 1, 1979
    Assignee: Texas Instruments Incorporated
    Inventors: Al F. Tasch, Jr., Pallab K. Chatterjee, Horng-Sen Fu, Geoffrey W. Taylor