Patents by Inventor Tiesheng Li

Tiesheng Li 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: 8288229
    Abstract: Fabricating a semiconductor device includes forming a hard mask on the substrate having a top substrate surface; forming a gate trench in the substrate, through the hard mask; depositing gate material in the gate trench; removing the hard mask to leave a gate structure; implanting a body region; implanting a source region; forming a source body contact trench having a trench wall and a trench bottom; and disposing an anti-punch through implant along at least a section of the trench wall but not along the trench bottom.
    Type: Grant
    Filed: March 9, 2011
    Date of Patent: October 16, 2012
    Assignee: Alpha & Omega Semiconductor Limited
    Inventors: Anup Bhalla, Sik K. Lui, Tiesheng Li
  • Publication number: 20120193631
    Abstract: This invention discloses a semiconductor wafer for manufacturing electronic circuit thereon. The semiconductor substrate further includes an etch-back indicator that includes trenches of different sizes having polysilicon filled in the trenches and then completely removed from some of the trenches of greater planar trench dimensions and the polysilicon still remaining in a bottom portion in some of the trenches having smaller planar trench dimensions.
    Type: Application
    Filed: March 27, 2012
    Publication date: August 2, 2012
    Inventors: Yu Wang, Tiesheng Li, Sung-Shan Tai, Hong Chang
  • Publication number: 20120161225
    Abstract: The present technology discloses a semiconductor die integrating a MOSFET device and a Schottky diode. The semiconductor die comprises a MOSFET area comprising the active region of MOSFET, a Schottky diode area comprising the active region of Schottky diode, and a termination area comprising termination structures. Wherein the Schottky diode area is placed between the MOSFET area and the termination area such that the Schottky diode area surrounds the MOSFET area.
    Type: Application
    Filed: December 28, 2010
    Publication date: June 28, 2012
    Inventors: Tiesheng Li, Lei Zhang
  • Patent number: 8193061
    Abstract: This invention discloses a semiconductor wafer for manufacturing electronic circuit thereon. The semiconductor substrate further includes an etch-back indicator that includes trenches of different sizes having polysilicon filled in the trenches and then completely removed from some of the trenches of greater planar trench dimensions and the polysilicon still remaining in a bottom portion in some of the trenches having smaller planar trench dimensions.
    Type: Grant
    Filed: April 18, 2011
    Date of Patent: June 5, 2012
    Assignee: Alpha & Omega Semiconductor Incorporated
    Inventors: Yu Wang, Tiesheng Li, Sung-Shan Tai, Hong Chang
  • Publication number: 20120104467
    Abstract: According to one embodiment, a self-aligned trench structure junction gate field-effect transistor (JFET) includes a silicon substrate, two or more trenches having a P-type polysilicon gate region near a bottom portion of the trench and an interlayer dielectric layer (ILDL) above the P-type polysilicon gate region, a channel region separating each trench including epitaxial silicon, an N+ source region above the channel region extending between a top of each trench, and a source metal above the N+ source region. In another embodiment, a self-aligned trench structure JFET includes a silicon substrate, two or more trenches having an N-type polysilicon gate region near a bottom portion of the trench and an ILDL above the N-type polysilicon gate region, a channel region separating each trench including epitaxial silicon, a P+ source region above the channel region extending between a top of each trench, and a source metal above the P+ source region.
    Type: Application
    Filed: October 29, 2010
    Publication date: May 3, 2012
    Applicant: Monolithic Power Systems, Inc.
    Inventors: Tiesheng Li, Ognjen Milic, Lei Zhang
  • Patent number: 8169801
    Abstract: Voltage converters with integrated low power leaker device and associated methods are disclosed herein. In one embodiment, a voltage converter includes a switch configured to convert a first electrical signal into a second electrical signal different than the first electrical signal. The voltage converter also includes a controller operatively coupled to the switch and a leaker device electrically coupled to the controller. The controller is configured to control the on and off gates of the switch, and the leaker device is configured to deliver power to the controller. The leaker device and the switch are formed on a first semiconductor substrate, and the controller is formed on second semiconductor substrate separate from the first semiconductor substrate.
    Type: Grant
    Filed: May 28, 2009
    Date of Patent: May 1, 2012
    Assignee: Monolithic Power Systems, Inc.
    Inventors: Michael R. Hsing, Ognjen Milic, Tiesheng Li
  • Publication number: 20120098058
    Abstract: A semiconductor device and a method for forming the semiconductor device wherein the semiconductor comprises: a trench MOSFET, formed on a semiconductor initial layer, comprising a well region, wherein the semiconductor initial layer has a first conductivity type and wherein the well region has a second conductivity type; an integrated Schottky diode next to the trench MOSFET, comprising a anode metal layer contacted to the semiconductor initial layer; a trench isolation structure, coupled between the trench MOSFET and integrated Schottky diode, configured to resist part of lateral diffusion from the well region; wherein the well region comprises an overgrowth part which laterally diffuses under the trench isolation structure and extends out of it.
    Type: Application
    Filed: October 21, 2011
    Publication date: April 26, 2012
    Inventors: Lei Zhang, Tiesheng Li
  • Patent number: 8163618
    Abstract: This invention discloses a new switching device supported on a semiconductor that includes a drain disposed on a first surface and a source region disposed near a second surface of said semiconductor opposite the first surface. The switching device further includes an insulated gate electrode disposed on top of the second surface for controlling a source to drain current. The switching device further includes a source electrode interposed into the insulated gate electrode for substantially preventing a coupling of an electrical field between the gate electrode and an epitaxial region underneath the insulated gate electrode. The source electrode further covers and extends over the insulated gate for covering an area on the second surface of the semiconductor to contact the source region. The semiconductor substrate further includes an epitaxial layer disposed above and having a different dopant concentration than the drain region.
    Type: Grant
    Filed: February 9, 2010
    Date of Patent: April 24, 2012
    Assignee: Alpha and Omega Semiconductor Incorporated
    Inventors: Anup Bhalla, Daniel Ng, Tiesheng Li, Sik K. Lui
  • Publication number: 20120001176
    Abstract: A semiconductor device wafer includes a test structure. The test structure includes a layer of material having an angle-shaped test portion disposed on at least a portion of a surface of the semiconductor wafer. A ruler marking on the surface of the semiconductor wafer proximate the test portion is adapted to facilitate measurement of a change in length of the test portion.
    Type: Application
    Filed: September 13, 2011
    Publication date: January 5, 2012
    Applicant: ALPHA & OMEGA SEMICONDUCTOR, LTD.
    Inventors: Yingying Lou, Tiesheng Li, Yu Wang, Anup Bhalla
  • Publication number: 20110227147
    Abstract: RESURF effect devices with both relatively deep trenches and relatively deep implants are described herein. Also, methods of fabricating such devices are described herein. A RESURF effect device may include alternating regions of first and second conductivity types where each of the second regions includes an implant region formed into a trench region of the second region.
    Type: Application
    Filed: March 19, 2010
    Publication date: September 22, 2011
    Inventors: Tiesheng Li, Michael R. Hsing, Deming Xiao
  • Patent number: 8021563
    Abstract: A method for determining the depth etch, a method of forming a shielded gate trench (SGT) structure and a semiconductor device wafer are disclosed. A material layer is formed over part of a substrate having a trench. The material fills the trench. A resist mask is placed over a test portion of the layer of material. The resist mask does not cover the trench. The layer of material is isotropically etched. An etch depth may be determined from a characteristic of etching of the material underneath the mask. Such a method may be used for forming SGT structures. The wafer may comprise a layer of material disposed on at least a portion of a surface of semiconductor wafer; a resist mask comprising an angle-shaped test portion disposed over a portion of the layer of material; and a ruler marking on the surface of the substrate proximate the test portion.
    Type: Grant
    Filed: March 23, 2007
    Date of Patent: September 20, 2011
    Assignee: Alpha & Omega Semiconductor, Ltd
    Inventors: Yingying Lou, Tiesheng Li, Yu Wang, Anup Bhalla
  • Patent number: 8008151
    Abstract: A method of fabricating a semiconductor device comprises forming a hard mask on a substrate having a top substrate surface, forming a trench in the substrate, through the hard mask, depositing gate material in the trench, where the amount of gate material deposited in the trench extends beyond the top substrate surface, and removing the hard mask to leave a gate structure that extends substantially above the top substrate surface.
    Type: Grant
    Filed: November 9, 2007
    Date of Patent: August 30, 2011
    Assignee: Alpha and Omega Semiconductor Limited
    Inventors: Sung-Shan Tai, Tiesheng Li, Anup Bhalla, Hong Chang, Moses Ho
  • Publication number: 20110207276
    Abstract: Fabricating a semiconductor device includes forming a hard mask on the substrate having a top substrate surface; forming a gate trench in the substrate, through the hard mask; depositing gate material in the gate trench; removing the hard mask to leave a gate structure; implanting a body region; implanting a source region; forming a source body contact trench having a trench wall and a trench bottom; and disposing an anti-punch through implant along at least a section of the trench wall but not along the trench bottom.
    Type: Application
    Filed: March 9, 2011
    Publication date: August 25, 2011
    Applicant: ALPHA & OMEGA SEMICONDUCTOR LIMITED
    Inventors: Anup Bhalla, Sik K. Lui, Tiesheng Li
  • Publication number: 20110198588
    Abstract: This invention discloses a semiconductor wafer for manufacturing electronic circuit thereon. The semiconductor substrate further includes an etch-back indicator that includes trenches of different sizes having polysilicon filled in the trenches and then completely removed from some of the trenches of greater planar trench dimensions and the polysilicon still remaining in a bottom portion in some of the trenches having smaller planar trench dimensions.
    Type: Application
    Filed: April 18, 2011
    Publication date: August 18, 2011
    Inventors: Yu Wang, Tiesheng Li, Sung-Shan Tai, Hong Chang
  • Patent number: 7977193
    Abstract: A trench-gate metal oxide semiconductor field-effect transistor includes a field plate that extends into a drift region of the transistor. The field plate is configured to deplete the drift region when the transistor is in the OFF-state. The field plate is formed in a field plate trench. The field plate trench may be formed using a self-aligned etch process. The conductive material of the field plate and gate of the transistor may be deposited in the same deposition process step. The conductive material may be etched thereafter to form the field plate and the gate in the same etch process step.
    Type: Grant
    Filed: October 20, 2010
    Date of Patent: July 12, 2011
    Assignee: Monolithic Power Systems, Inc.
    Inventors: Donald R. Disney, Tiesheng Li, Lei Zhang
  • Patent number: 7932148
    Abstract: This invention discloses an improved trenched metal oxide semiconductor field effect transistor (MOSFET) device that includes a trenched gate surrounded by a source region encompassed in a body region above a drain region disposed on a bottom surface of a substrate. The MOSFET cell further includes a shielded gate trench (SGT) structure below and insulated from the trenched gate. The SGT structure is formed substantially as a round hole having a lateral expansion extended beyond the trench gate and covered by a dielectric liner layer filled with a trenched gate material. The round hole is formed by an isotropic etch at the bottom of the trenched gate and is insulated from the trenched gate by an oxide insulation layer. The round hole has a lateral expansion beyond the trench walls and the lateral expansion serves as a vertical alignment landmark for controlling the depth of the trenched gate.
    Type: Grant
    Filed: February 9, 2009
    Date of Patent: April 26, 2011
    Assignee: Alpha & Omega Semiconductor, Ltd
    Inventors: Hong Chang, Sung-Shan Tai, Tiesheng Li, Yu Wang
  • Patent number: 7928507
    Abstract: This invention discloses a semiconductor wafer for manufacturing electronic circuit thereon. The semiconductor substrate further includes an etch-back indicator that includes trenches of different sizes having polysilicon filled in the trenches and then completely removed from some of the trenches of greater planar trench dimensions and the polysilicon still remaining in a bottom portion in some of the trenches having smaller planar trench dimensions.
    Type: Grant
    Filed: December 9, 2009
    Date of Patent: April 19, 2011
    Assignee: Alpha & Omega Semiconductor, Inc.
    Inventors: Yu Wang, Tiesheng Li, Sung-Shan Tai, Hong Chang
  • Patent number: 7923774
    Abstract: A semiconductor device includes a drain, a body disposed over the drain, a source embedded in the body, a gate trench extending through the source and the body into the drain, a gate disposed in the gate trench, a source body contact trench extending through the source into the body, a conductive contact layer disposed along at least a portion of a source body contact trench sidewall and in contact with at least a portion of the source, and a trench filling material disposed in the source body contact trench and overlaying at least a portion of the conductive contact layer.
    Type: Grant
    Filed: March 31, 2009
    Date of Patent: April 12, 2011
    Assignee: Alpha & Omega Semiconductor Limited
    Inventors: Anup Bhalla, Sik Lui, Tiesheng Li
  • Publication number: 20110057259
    Abstract: A method for forming a thick bottom oxide in the bottom of a trench used in a vertical MOSFET. Initially, an n-type substrate has an n-type epitaxial layer grown thereon. A top portion of the n-type epitaxial layer is implanted with p-type dopants to provide a p-layer. A trench is then etched into the p- and n-type epitaxial layer. A high density plasma chemical vapor deposition (HDPCVD) process is used to either partially or fully fill the trench. Any oxide on the top surface of the p-layer is then removed, such as by using a chemical mechanical polishing step. Then, an isotropic etching step, such as a wet etch, is used to remove the silicon dioxide from the trench, while leaving a thick bottom oxide at the bottom of the trench. The HDPCVD process utilizes minimal thermal budget to form the thick bottom oxide.
    Type: Application
    Filed: September 4, 2009
    Publication date: March 10, 2011
    Inventor: Tiesheng Li
  • Patent number: 7879676
    Abstract: Trench gate MOSFET devices may be formed using a single mask to define gate trenches and body contact trenches. A hard mask is formed on a surface of a semiconductor substrate. A trench mask is applied on the hard mask to predefine a body contact trench and a gate trench. These predefined trenches are simultaneously etched into the substrate to a first predetermined depth. A gate trench mask is next applied on top of the hard mask. The gate trench mask covers the body contact trenches and has openings at the gate trenches. The gate trench, but not the body contact trench, is etched to a second predetermined depth. Conductive material of a first kind may fill the gate trench to form a gate. Conductive material of a second kind may fill the body contact trench to form a body contact.
    Type: Grant
    Filed: July 30, 2010
    Date of Patent: February 1, 2011
    Assignee: Alpha & Omega Semiconductor Incorporated
    Inventors: Yeeheng Lee, Hong Chang, Tiesheng Li, John Chen, Anup Bhalla