Patents by Inventor Dah W. Tsang

Dah W. Tsang 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: 5528058
    Abstract: For IGBT, MCT or like devices, the substrate is formed with P+, N+ and N- layers and PN diffusions to define body and source regions in the N-layer and a MOS-gated channel at the upper surface. The N-layer is sized and doped (.about.10.sup.14 /cm.sup.3) to block reverse bias voltage. The N+ layer is >20 .mu.m thick and doped below .about.10.sup.17 /cm.sup.3 but above the N- doping to enhance output impedance and reduce gain at high V.sub.ce conditions. Or the N+ layer is formed with a thin (.about.5 .mu.m) highly doped (>10.sup.17 /cm.sup.3) layer and a thick (>20 .mu.m) layer of .about.10.sup.16 /cm.sup.3 doping. A platinum dose of 10.sup.13 to 10.sup.16 /cm.sup.3 is ion implanted and diffused into the silicon to effect lifetime control. Gate and source contacts and body and source diffusions have an inter-digitated finger pattern with complementary tapers to minimize current crowding and wide gate buses to minimize signal delay.
    Type: Grant
    Filed: October 13, 1994
    Date of Patent: June 18, 1996
    Assignee: Advanced Power Technology, Inc.
    Inventors: Douglas A. Pike, Jr., Dah W. Tsang, James M. Katana, Dumitru Sdrulla
  • Patent number: 5283202
    Abstract: For IGBT, MCT or like devices, the substrate is formed with P+, N+ and N- layers and PN diffusions to define body and source regions in the N-layer and a MOS-gated channel at the upper surface. The N-layer is sized and doped (.about.10.sup.14 /cm.sup.3) to block reverse bias voltage. The N+ layer is >20 .mu.m thick and doped below .about.10.sup.17 /cm.sup.3 but above the N- doping to enhance output impedance and reduce gain at high V.sub.ce conditions. Or the N+ layer is formed with a thin (.about.5 .mu.m) highly doped (>10.sup.17 /cm.sup.3) layer and a thick (>20 .mu.m) layer of .about.10.sup.16 /cm.sup.3 doping. A platinum dose of 10.sup.13 to 10.sup.16 /cm.sup.2 is ion implanted and diffused into the silicon to effect lifetime control. Gate and source contacts and body and source diffusions have an inter-digitated finger pattern with complementary tapers to minimize current crowding and wide gate buses to minimize signal delay.
    Type: Grant
    Filed: September 15, 1992
    Date of Patent: February 1, 1994
    Assignee: Advanced Power Technology, Inc.
    Inventors: Douglas A. Pike, Jr., Dah W. Tsang, James M. Katana, Dumitra Scrulla
  • Patent number: 5283201
    Abstract: A recessed gate power MOSFET is formed on a substrate (20) including a P-body layer (26), N-drain layer (24) and optional P+ layer (22) for IGBT. A trenching protective layer (30) formed on the substrate upper surface (28) is patterned to define exposed areas (46) as stripes or a matrix, and protected areas. Sidewall spacers (44) of predetermined thickness (52) with inner surfaces (48) contact the protective layer sidewalls. A first trench (50) is formed in substrate areas (46) with sidewalls aligned to the sidewall spacer outer surfaces (47) and extending depthwise through the P-body layer (26) to at least a predetermined depth (56). Gate oxide (60) is formed on the trench walls and gate polysilicon (62) refills the trench to a level (64) near substrate upper surface (28). Oxide (68) between sidewall spacers (44) covers polysilicon (62). Removing the protective layer exposes upper substrate surface (28') between spacer inner surfaces (48).
    Type: Grant
    Filed: August 7, 1992
    Date of Patent: February 1, 1994
    Assignee: Advanced Power Technology, Inc.
    Inventors: Dah W. Tsang, John W. Mosier, II, Douglas A. Pike, Jr., Theodore O. Meyer
  • Patent number: 5262336
    Abstract: For IGBT, MCT or like devices, the substrate is formed with P+, N+ and N- layers and PN diffusions to define body and source regions in the N-layer and a MOS-gated channel at the upper surface. The N-layer is sized and doped (.about.10.sup.14 /cm.sup.3) to block reverse bias voltage. The N+ layer is >20 .mu.m thick and doped below .about.10.sup.17 /cm.sup.3 but above the N- doping to enhance output impedance and reduce gain at high V.sub.ce conditions. Or the N+ layer is formed with a thin (.about.5 .mu.m) highly doped (>10.sup.17 /cm.sup.3) layer and a thick (>20 .mu.m) layer of .about.10.sup.16 /cm.sup.3 doping. A platinum dose of 10.sup.13 to .about.10.sup.16 /cm.sup.2 is ion implanted and diffused into the silicon to effect lifetime control. Gate and source contacts and body and source diffusions have an inter-digitated finger pattern with complementary tapers to minimize current crowding and wide gate buses to minimize signal delay.
    Type: Grant
    Filed: March 13, 1992
    Date of Patent: November 16, 1993
    Assignee: Advanced Power Technology, Inc.
    Inventors: Douglas A. Pike, Jr., Dah W. Tsang, James M. Katana
  • Patent number: 5190885
    Abstract: For IGBT, MCT or like devices, the substrate is formed with P+, N+ and N- layers and PN diffusions to define body and source regions in the N-layer and a MOS-gated channel at the upper surface. The N-layer is sized and doped (.about.10.sup.14 /cm.sup.3) to block reverse bias voltage. The N+ layer is >20 .mu.m thick and doped below .about.10.sup.17 /cm.sup.3 but above the N- doping to enhance output impedance and reduce gain at high V.sub.ce conditions. Or the N+ layer is formed with a thin (.about.5 .mu.m) highly doped (>10.sup.17 /cm.sup.3) layer and a thick (>20 .mu.m) layer of .about.10.sup.16 /cm.sup.3 doping. A platinum dose of 10.sup.13 to 10.sup.16 /cm.sup.2 is ion implanted and diffused into the silicon to effect lifetime control. Gate and source contacts and body and source diffusions have an inter-digitated finger pattern with complementary tapers to minimize current crowding and wide gate buses to minimize signal delay.
    Type: Grant
    Filed: March 13, 1992
    Date of Patent: March 2, 1993
    Assignee: Advanced Power Technology, Inc.
    Inventors: Douglas A. Pike, Jr., Dah W. Tsang, James M. Katana
  • Patent number: 5045903
    Abstract: A dopant-opaque layer of polysilicon is deposited on gate oxide on the upper substrate surface to serve as a pattern definer during fabrication of the device. It provides control over successive P and N doping steps used to create the necessary operative junctions within a silicon substrate and the conductive structures formed atop the substrate. A trench is formed in the upper silicon surface and a source conductive layer is deposited to electrically contact the source region as a gate conductive layer is deposited atop the gate oxide layer. The trench sidewall is profile tailored using a novel O.sub.2 -SF.sub.6 plasma etch technique. An oxide sidewall spacer is formed on the sides of the pattern definer and gate oxide structures, before depositing the conductive material. A planarizing layer is applied and used as a mask for selectively removing any conductive material deposited atop the oxide spacer.
    Type: Grant
    Filed: November 16, 1989
    Date of Patent: September 3, 1991
    Assignee: Advanced Power Technology, Inc.
    Inventors: Theodore O. Meyer, John W. Mosier, II, Douglas A. Pike, Jr., Theodore G. Hollinger, Dah W. Tsang
  • Patent number: 5019522
    Abstract: A dopant-opaque layer of polysilicon is deposited on gate oxide on the upper substrate surface to serve as a pattern definer during fabrication of the device. It provides control over successive P and N doping steps used to create the necessary operative junctions within a silicon substrate and the conductive structures formed atop the substrate. A trench is formed in the upper silicon surface and a source conductive layer is deposited to electrically contact the source region as a gate conductive layer is deposited atop the gate oxide layer. The trench sidewall is profile tailored using a novel O.sub.2 -SF.sub.6 plasma etch technique. An oxide sidewall spacer is formed on the sides of the pattern definer and gate oxide structure, before depositing the conductive material. A planarizing layer is applied and used as a mask for selectively removing any conductive material deposited atop the oxide spacer.
    Type: Grant
    Filed: January 2, 1990
    Date of Patent: May 28, 1991
    Assignee: Advanced Power Technology, Inc.
    Inventors: Theodore O. Meyer, John W. Mosier, II, Douglas A. Pike, Jr., Theodore G. Hollinger, Dah W. Tsang