Patents by Inventor Surinder Krishna

Surinder Krishna 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: 4958210
    Abstract: Premature avalanche breakdown resulting from high electric fields produced by metal interconnections crossing underlying high conductivity regions of an integrated circuit is eliminated by selectively providing discontinuities in the high conductivity regions underlying the metal interconnection paths.
    Type: Grant
    Filed: November 20, 1989
    Date of Patent: September 18, 1990
    Assignee: General Electric Company
    Inventors: Surinder Krishna, Manuel L. Torreno, Jr., Michael S. Adler
  • Patent number: 4804634
    Abstract: In a monolithic silicon integrated circuit fast diffusing impurities are incorporated into the collectors of the bipolar lateral transistors. The impurity level is controlled, using ion implantation, so that after device processing the lateral transistor collectors extend an additional increment into the base. This increment is doped with the fast diffusing impurity at a level that overcompensates the normal base impurity to the opposite conductivity type and conductivity about equal to that of the base. Thus the collector junction is moved towards the emitter and is symmetrical in terms of conductivity. This means that when the collector is reverse biased the depletion field extends about equally on both sides of the junction. This action greatly relieves the voltage gradient and stress so that collector junction voltage breakdown is enhanced. Since the collector junction is closer to the emitter the transistor current gain and frequency response are enhanced.
    Type: Grant
    Filed: December 14, 1987
    Date of Patent: February 14, 1989
    Assignee: National Semiconductor Corporation
    Inventors: Surinder Krishna, Amolak R. Ramde
  • Patent number: 4734382
    Abstract: A bipolar/CMOS process includes bipolar transistors having emitters formed in less than a minimal masking dimension. An opening is formed through a polycrystalline silicon layer deposited on a silicon substrate. After coating the sides of the opening with silicon dioxide, the intrinsic base region of the bipolar transistor and the emitter region are implanted. The extrinsic base is formed by outdiffusion from the polycrystalline silicon layer. The structure includes an epitaxial layer which is more strongly doped below its surface than at its surface to enhance the performance of CMOS transistors formed therein. Additionally, the bipolar and complementary MOS transistors are self-aligned to each other by the manner in which the buried layers are formed.
    Type: Grant
    Filed: February 20, 1987
    Date of Patent: March 29, 1988
    Assignee: Fairchild Semiconductor Corporation
    Inventor: Surinder Krishna
  • Patent number: 4648909
    Abstract: A fabrication process for integrated circuits having linear bipolar transistors and other circuit elements. The process defines collector contact 32, base 34, and isolation 36 regions in one masking operation. Subsequent masking layers of photoresist 40, 42, 46 are used to shield selected regions during implantation of exposed regions. Circuit density is improved through the use of aluminum doped isolation regions 36. The base region is doped in a single ion implantation step, which is followed by low temperature deposition of a covering oxide layer 48.
    Type: Grant
    Filed: November 28, 1984
    Date of Patent: March 10, 1987
    Assignee: Fairchild Semiconductor Corporation
    Inventors: Surinder Krishna, Kulwant Egan
  • Patent number: 4639274
    Abstract: A method for producing an improved capacitor in MOS technology utilizing a thin layer oxide dielectric to improve the active/parasitic capacitance ratio while maintaining a high breakdown voltage and a low leakage current.A polycrystalline silicon layer is formed over a silicon dioxide field region on a wafer of semiconductor silicon. Phosphorus ions are implanted in the polycrystalline silicon layer at an implant energy between approximately 80 and 100 keV. The surface of the polycrystalline silicon layer is oxidized to form an interpoly oxide, utilizing an oxidation temperature which, for the implant dosage of phosphorus ions used, is sufficient to make the interpoly oxide layer approximately 770 Angstroms thick. The structure is then annealed at a temperature of approximately 1100.degree. C. in oxygen and HCl. A second polycrystalline silicon layer is formed over the interpoly oxide layer, and the process completed in the conventional manner.
    Type: Grant
    Filed: November 28, 1984
    Date of Patent: January 27, 1987
    Assignee: Fairchild Semiconductor Corporation
    Inventor: Surinder Krishna
  • Patent number: 4581626
    Abstract: A gate turn-off (IGTO) thyristor having short turn-off times and high di/dt and dV/dt capabilities comprises an insulating layer overlying the inner region of the n2-emitter (cathode) region which includes a central region of greater resistivity than the n2-emitter cathode region for reducing turn-off current density of the device. The addition of an insulating layer and a central region of increased resistivity to the central portions of a base region of a bipolar transistor provides similar improved performance characteristics.
    Type: Grant
    Filed: April 9, 1979
    Date of Patent: April 8, 1986
    Assignee: General Electric Company
    Inventors: Surinder Krishna, E. Duane Wolley
  • Patent number: 4512816
    Abstract: A semiconductor substrate having an epitaxial layer on its upper surface is provided with a masking layer. Holes are photolithographically etched in the masking layer where isolation diffusion regions are to be formed. Then aluminum ions are implanted into the surface and diffused completely through the epitaxial layer so as to create tubs of epitaxial material that are PN junction isolated. Since aluminum is a fast diffuser, the diffusion time is greatly reduced, thereby reducing the up diffusion of buried N+ collector so that the original epitaxial layer can be made relatively thin. Lateral isolation diffusion is reduced, thereby substantially reducing the surface area required for isolation. Thus, the process is capable of increasing the component density in the completed integrated circuit.
    Type: Grant
    Filed: April 23, 1984
    Date of Patent: April 23, 1985
    Assignee: National Semiconductor Corporation
    Inventors: Amolak R. Ramde, Wadie N. Khadder, Surinder Krishna
  • Patent number: 4060821
    Abstract: A novel grid structure for a field controlled thyristor includes a current controlling grid structure interdigitated with a cathode structure in which the surface area of the cathode structure is substantially greater than that of the grid structure. High forward blocking voltage gain (anode voltage/grid voltage) and low on-state losses in a turn-off type field controlled thyristor are accomplished by providing a surface grid portion and a buried portion which are connected to the surface grid structure and substantially underlies the cathode structure. The buried grid structure is constructed in a manner to provide a high aspect ratio for the channel region.
    Type: Grant
    Filed: June 21, 1976
    Date of Patent: November 29, 1977
    Assignee: General Electric Co.
    Inventors: Douglas E. Houston, Surinder Krishna
  • Patent number: 4032961
    Abstract: Geometrical design criteria are disclosed for a Gate Modulated BiPolar Transistor, or GAMBIT, which is a three terminal variable negative resistance device. The GAMBIT is a planar, interdigited, integrated device whose electrical characteristics show a voltage controlled negative resistance between two of its terminals. The magnitude of the negative resistance is controlled by the variation of the applied bias to the third terminal.
    Type: Grant
    Filed: August 23, 1976
    Date of Patent: June 28, 1977
    Assignee: General Electric Company
    Inventors: B. Jayant Baliga, Douglas E. Houston, Surinder Krishna
  • Patent number: 3988771
    Abstract: Deep level impurities such, for example, as gold, platinum, silver, nickel and copper, are introduced into selected regions of semiconductor devices by directional solidification to reduce the charge recombination lifetime and therefore the turn-off time of the device.
    Type: Grant
    Filed: May 28, 1974
    Date of Patent: October 26, 1976
    Assignee: General Electric Company
    Inventor: Surinder Krishna
  • Patent number: 3988772
    Abstract: The minority carrier lifetime is drastically reduced in an integrated semiconductor power device by introducing deep level impurities such, for example, as gold, silver, platinum, nickel and copper into selected regions of the device by Thermal Gradient Zone Melting processing.
    Type: Grant
    Filed: May 28, 1974
    Date of Patent: October 26, 1976
    Assignee: General Electric Company
    Inventor: Surinder Krishna
  • Patent number: 3982269
    Abstract: A homogeneous integrated power structure embodies solid state control or signal devices and power devices integrated monolithically to achieve optimum physical characteristics of each device embodied therein at economical cost of manufacturing the same. The devices are electrically isolated from each other by a P-N junction isolation grid produced by the thermomigration of metal-rich wires through a semiconductor substrate by thermal gradient zone melting processing techniques.
    Type: Grant
    Filed: November 22, 1974
    Date of Patent: September 21, 1976
    Assignee: General Electric Company
    Inventors: Manuel L. Torreno, Jr., Bruno F. Kurz, deceased, Surinder Krishna
  • Patent number: 3979769
    Abstract: A Gate Modulated BiPolar Transistor, or GAMBIT, is a three terminal negative resistance device. A load is connected between the emitter and collector terminals and the magnitude of the negative resistance is controlled by the voltage on the gate terminal. An increase in the output voltage modulates the resistance of the gate which decreases the output current.
    Type: Grant
    Filed: October 16, 1974
    Date of Patent: September 7, 1976
    Assignee: General Electric Company
    Inventors: Douglas E. Houston, Surinder Krishna, Bantval Jayant Baliga
  • Patent number: 3945028
    Abstract: A plasma thyristor circuit is provided for generating high power, ultra-short duration electrical signals. A silicon semiconductor body has first, second and third impurity regions therein with a PN junction formed at the transition between the first and second or the second and third impurity regions. The second impurity region has an impurity concentration of less than about 5 .times. 10.sup.14 atoms/cm.sup.3, and a width of greater than about 80 microns. The ratio of the punch-through voltage of the second impurity region to the reverse breakdown voltage of the PN junction is between 0.3 and 0.7. Power sources apply both a reverse bias voltage across the body greater than said punch-through voltage and less than said reverse breakdown voltage, and a current to the body having a density greater than the saturation current density of the second impurity region.
    Type: Grant
    Filed: April 26, 1973
    Date of Patent: March 16, 1976
    Assignee: Westinghouse Electric Corporation
    Inventors: Surinder Krishna, Chang Kwei Chu