Patents by Inventor Mohit Bhatnagar

Mohit Bhatnagar 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: 5780878
    Abstract: A lateral gate, vertical drift region transistor including a drain positioned on one surface of a substrate and a doped structure having a buried region therein positioned on the other surface of the substrate. The buried region defining a drift region in the doped structure extending vertically from the substrate and further defining a doped region in communication with the drift region and adjacent the surface of the doped structure. A source positioned on the doped structure in communication with the doped region. An insulating layer positioned on the doped structure with a metal gate positioned on the insulating layer so as to define an accumulation region extending laterally adjacent the control terminal and communicating with the drift region and the source.
    Type: Grant
    Filed: July 29, 1996
    Date of Patent: July 14, 1998
    Assignee: Motorola, Inc.
    Inventors: Mohit Bhatnagar, Charles E. Weitzel
  • Patent number: 5710455
    Abstract: A FET including a channel region and a drift region in a channel layer with a source in the channel region and a drain in the drift region. The current channel between the source and drain defining a straight transistor portion and a curved transistor portion. An oxide with a thin portion overlying the channel region and a thick portion overlying the drift region, and a gate on the thin oxide overlying the current channel. A drain field plate and a gate field plate on the thick oxide with spaced apart edges and a damaged region underlying the edges of the field plates only in the curved transistor portion to reduce electric fields at the edges of the field plates. Also, the current channel has a greater length and the edges are spaced apart farther in the curved transistor portions.
    Type: Grant
    Filed: July 29, 1996
    Date of Patent: January 20, 1998
    Assignee: Motorola
    Inventors: Mohit Bhatnagar, Charles E. Weitzel, Michael Zunino
  • Patent number: 5661312
    Abstract: A silicon carbide MOSFET (10) is formed to have a high breakdown voltage. A breakdown enhancement layer (20) is formed between a channel region (14) and a drift layer (12). The breakdown enhancement layer (20) has a lower doping concentration that increases the width of a depletion region (24) near a gate insulator (17). The increased depletion region width improves the breakdown voltage.
    Type: Grant
    Filed: March 30, 1995
    Date of Patent: August 26, 1997
    Assignee: Motorola
    Inventors: Charles E. Weitzel, Mohit Bhatnagar
  • Patent number: 5627385
    Abstract: A lateral silicon carbide transistor (10) utilizes a modulated channel region (18) to form an accumulation region that facilitates a low on-resistance. A doped region of the channel layer forms a channel insert (14) that also lowers the on-resistance of the transistor (10). Field plates (23,24) are utilized to facilitate providing a high breakdown voltage. A high resistance layer (29)between the field plates (23,24) also assists in increasing the breakdown voltage and decreasing on-resistance of the transistor (10).
    Type: Grant
    Filed: August 28, 1995
    Date of Patent: May 6, 1997
    Assignee: Motorola, Inc.
    Inventors: Mohit Bhatnagar, Charles E. Weitzel
  • Patent number: 5612232
    Abstract: A method of fabricating a semiconductor device including forming a Schottky contact on the surface of a substrate by patterning a layer of nickel to define a contact and annealing the nickel below approximately 600.degree. C. A trench is etched around the Schottky contact utilizing the Schottky contact as an etch mask and inert ions are implanted in the trench to form a damage region. The trench is passivated with a dielectric layer. An ohmic contact can be formed on the reverse side of the substrate prior to formation of the Schottky contact.
    Type: Grant
    Filed: March 29, 1996
    Date of Patent: March 18, 1997
    Assignee: Motorola
    Inventors: Christine Thero, Mohit Bhatnagar, Charles E. Weitzel
  • Patent number: 5569937
    Abstract: A lateral silicon carbide transistor (10) utilizes a modulated channel region (18) to form an accumulation region that facilitates a low on-resistance. A doped region of the channel layer forms a channel insert (14) that also lowers the on-resistance of the transistor (10). A damage termination layer (27) is utilized to facilitate providing a high breakdown voltage. Field plates (23,24) also assists in increasing the breakdown voltage and decreasing the on-resistance of the transistor (10).
    Type: Grant
    Filed: August 28, 1995
    Date of Patent: October 29, 1996
    Assignee: Motorola
    Inventors: Mohit Bhatnagar, Charles E. Weitzel, Christine Thero
  • Patent number: 5338945
    Abstract: A silicon carbide field effect transistor of the present invention includes a base and source region each formed by a series of amorphizing, implanting and recrystallizing steps. Moreover, the drain, base and source regions extend to a face of a monocrystalline silicon carbide substrate and the source and base regions comprise substantially monocrystalline silicon carbide formed from recrystallized amorphous silicon carbide, The source and base regions also have vertical sidewalls defining the p-n junction between the source/base and base/drain regions, respectively. The vertical orientation of the sidewalls arises from the respective implantation of electrically inactive ions into the substrate during the amorphizing steps for forming the base region in the drain and for forming the source region in the base region. The electrically inactive ions are selected from the group consisting of silicon, hydrogen, neon, helium, carbon and argon.
    Type: Grant
    Filed: February 15, 1994
    Date of Patent: August 16, 1994
    Assignee: North Carolina State University at Raleigh
    Inventors: Bantval J. Baliga, Mohit Bhatnagar
  • Patent number: 5322802
    Abstract: A silicon carbide field effect transfer of the present invention includes a base and source region each formed by a series of amorphizing, implanting and recrystallizing steps. Moreover, the drain, base and source regions extend to a face of a monocrystalline silicon carbide substrate and the source and base regions comprise substantially monocrystalline silicon carbide formed from recrystallized amorphous silicon carbide. The source and base regions also have vertical sidewalls defining the p-n junction between the source/base and base/drain regions, respectively. The vertical orientation of the sidewalls arises from the respective implantation of electrically inactive ions into the substrate during the amorphizing steps for forming the base region in the drain and for forming the source region in the base region. The electrically inactive ions are selected from the group consisting of silicon, hydrogen, neon, helium, carbon and argon.
    Type: Grant
    Filed: January 25, 1993
    Date of Patent: June 21, 1994
    Assignee: North Carolina State University at Raleigh
    Inventors: Bantval J. Baliga, Mohit Bhatnagar
  • Patent number: 5318915
    Abstract: A method for forming a p-n junction in silicon carbide includes the steps of amorphizing a portion of a monocrystalline silicon carbide substrate, implanting dopant ions into the amorphous portion of the substrate and then recrystallizing the amorphous portion to thereby form a substantially monocrystalline region including the dopant ions. In particular, the amorphizing step includes the steps of masking an area on the face of the monocrystalline silicon carbide substrate and then directing electrically inactive ions to the masked area so that an amorphous region in the substrate is formed. Accordingly, the amorphous region has sidewalls extending to the face that are substantially orthogonal to the bottom edge of the amorphous region. Once the amorphized region is defined, electrically active dopant ions are implanted into the amorphous region. The dopant ions are then diffused into the amorphous region and become uniformly distributed.
    Type: Grant
    Filed: January 25, 1993
    Date of Patent: June 7, 1994
    Assignee: North Carolina State University at Raleigh
    Inventors: Bantval J. Baliga, Dev Alok, Mohit Bhatnagar