Patents by Inventor Karthik Padmanabhan
Karthik Padmanabhan 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).
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Publication number: 20190165169Abstract: A method for forming a lateral superjunction MOSFET device includes forming a semiconductor body including a lateral superjunction structure and a first column connected to the lateral superjunction structure. The MOSFET device includes the first column to receive current from the channel when the MOSFET is turned on and to distribute the channel current to the lateral superjunction structure functioning as the drain drift region. In some embodiment, the MOSFET device includes a second column disposed in close proximity to the first column. The second column disposed near the first column is used to pinch off the first column when the MOSFET device is to be turned off and to block the high voltage being sustained by the MOSFET device at the drain terminal from reaching the gate structure. In some embodiments, the MOSFET device further includes termination structures for the drain, source and body contact doped region fingers.Type: ApplicationFiled: January 30, 2019Publication date: May 30, 2019Inventors: Madhur Bobde, Lingpeng Guan, Karthik Padmanabhan, Hamza Yilmaz
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Patent number: 10276387Abstract: A semiconductor device includes a superjunction structure formed using simultaneous N and P angled implants into the sidewall of a trench. The simultaneous N and P angled implants use different implant energies and dopants of different diffusion rate so that after annealing, alternating N and P thin semiconductor regions are formed. The alternating N and P thin semiconductor regions form a superjunction structure where a balanced space charge region is formed to enhance the breakdown voltage characteristic of the semiconductor device.Type: GrantFiled: February 2, 2017Date of Patent: April 30, 2019Assignee: Alpha and Omega Semiconductor IncorporatedInventors: Karthik Padmanabhan, Madhur Bobde, Lingpeng Guan, Lei Zhang, Hamza Yilmaz
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Patent number: 10243072Abstract: A method for forming a lateral superjunction MOSFET device includes forming a semiconductor body including a lateral superjunction structure and a first column connected to the lateral superjunction structure. The MOSFET device includes the first column to receive current from the channel when the MOSFET is turned on and to distribute the channel current to the lateral superjunction structure functioning as the drain drift region. In some embodiment, the MOSFET device includes a second column disposed in close proximity to the first column. The second column disposed near the first column is used to pinch off the first column when the MOSFET device is to be turned off and to block the high voltage being sustained by the MOSFET device at the drain terminal from reaching the gate structure. In some embodiments, the MOSFET device further includes termination structures for the drain, source and body contact doped region fingers.Type: GrantFiled: May 4, 2018Date of Patent: March 26, 2019Assignee: Alpha and Omega Semiconductor IncorporatedInventors: Madhur Bobde, Lingpeng Guan, Karthik Padmanabhan, Hamza Yilmaz
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Publication number: 20190006461Abstract: A semiconductor device includes a semiconductor body having a base region incorporating a field stop zone where the base region and the field stop zone are both formed using an epitaxial process. Furthermore, the epitaxial layer field stop zone is formed with an enhanced doping profile to realize improved soft-switching performance for the semiconductor device. In some embodiments, the enhanced doping profile formed in the field stop zone includes varying, non-constant doping levels. In some embodiments, the enhanced doping profile includes one of an extended graded doping profile, a multiple stepped flat doping profile, or a multiple spike doping profile. The epitaxial layer field stop zone of the present invention enables complex field stop zone doping profiles to be used to obtain the desired soft-switching characteristics in the semiconductor device.Type: ApplicationFiled: June 29, 2017Publication date: January 3, 2019Inventors: Lei Zhang, Karthik Padmanabhan, Lingpeng Guan, Jian Wang, Lingbing Chen, Wim Aarts, Hongyong Xue, Wenjun Li, Madhur Bobde
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Publication number: 20180254342Abstract: A method for forming a lateral superjunction MOSFET device includes forming a semiconductor body including a lateral superjunction structure and a first column connected to the lateral superjunction structure. The MOSFET device includes the first column to receive current from the channel when the MOSFET is turned on and to distribute the channel current to the lateral superjunction structure functioning as the drain drift region. In some embodiment, the MOSFET device includes a second column disposed in close proximity to the first column. The second column disposed near the first column is used to pinch off the first column when the MOSFET device is to be turned off and to block the high voltage being sustained by the MOSFET device at the drain terminal from reaching the gate structure. In some embodiments, the MOSFET device further includes termination structures for the drain, source and body contact doped region fingers.Type: ApplicationFiled: May 4, 2018Publication date: September 6, 2018Inventors: Madhur Bobde, Lingpeng Guan, Karthik Padmanabhan, Hamza Yilmaz
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Patent number: 9991380Abstract: A lateral superjunction MOSFET device includes multiple transistor cells connected to a lateral superjunction structure, each transistor cell including a conductive gate finger, a source region finger, a body contact region finger and a drain region finger arranged laterally within each transistor cell. Each of the drain region fingers, the source region fingers and the body contact region fingers is a doped region finger having a termination region at an end of the doped region finger. The lateral superjunction MOSFET device further includes a termination structure formed in the termination region of each doped region finger and including one or more termination columns having the same conductivity type as the doped region finger and positioned near the end of the doped region finger. The one or more termination columns extend through the lateral superjunction structure and are electrically unbiased.Type: GrantFiled: June 23, 2017Date of Patent: June 5, 2018Assignee: Alpha and Omega Semiconductor IncorporatedInventors: Madhur Bobde, Lingpeng Guan, Karthik Padmanabhan, Hamza Yilmaz
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Publication number: 20170365710Abstract: A lateral superjunction MOSFET device includes multiple transistor cells connected to a lateral superjunction structure, each transistor cell including a conductive gate finger, a source region finger, a body contact region finger and a drain region finger arranged laterally within each transistor cell. Each of the drain region fingers, the source region fingers and the body contact region fingers is a doped region finger having a termination region at an end of the doped region finger. The lateral superjunction MOSFET device further includes a termination structure formed in the termination region of each doped region finger and including one or more termination columns having the same conductivity type as the doped region finger and positioned near the end of the doped region finger. The one or more termination columns extend through the lateral superjunction structure and are electrically unbiased.Type: ApplicationFiled: June 23, 2017Publication date: December 21, 2017Inventors: Madhur Bobde, Lingpeng Guan, Karthik Padmanabhan, Hamza Yilmaz
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Patent number: 9722073Abstract: A lateral superjunction MOSFET device includes a gate structure and a first column connected to the lateral superjunction structure. The lateral superjunction MOSFET device includes the first column to receive current from the channel when the MOSFET is turned on and to distribute the channel current to the lateral superjunction structure functioning as the drain drift region. In some embodiment, the MOSFET device includes a second column disposed in close proximity to the first column. The second column disposed near the first column is used to pinch off the first column when the MOSFET device is to be turned off and to block the high voltage being sustained by the MOSFET device at the drain terminal from reaching the gate structure. In some embodiments, the lateral superjunction MOSFET device further includes termination structures for the drain, source and body contact doped region fingers.Type: GrantFiled: February 23, 2016Date of Patent: August 1, 2017Assignee: Alpha and Omega Semiconductor IncorporatedInventors: Madhur Bobde, Lingpeng Guan, Karthik Padmanabhan, Hamza Yilmaz
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Publication number: 20170148632Abstract: A semiconductor device includes a superjunction structure formed using simultaneous N and P angled implants into the sidewall of a trench. The simultaneous N and P angled implants use different implant energies and dopants of different diffusion rate so that after annealing, alternating N and P thin semiconductor regions are formed. The alternating N and P thin semiconductor regions form a superjunction structure where a balanced space charge region is formed to enhance the breakdown voltage characteristic of the semiconductor device.Type: ApplicationFiled: February 2, 2017Publication date: May 25, 2017Inventors: Karthik Padmanabhan, Madhur Bobde, Lingpeng Guan, Lei Zhang, Hamza Yilmaz
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Patent number: 9595609Abstract: A semiconductor device includes a superjunction structure formed using simultaneous N and P angled implants into the sidewall of a trench. The simultaneous N and P angled implants use different implant energies and dopants of different diffusion rate so that after annealing, alternating N and P thin semiconductor regions are formed. The alternating N and P thin semiconductor regions form a superjunction structure where a balanced space charge region is formed to enhance the breakdown voltage characteristic of the semiconductor device.Type: GrantFiled: September 21, 2015Date of Patent: March 14, 2017Assignee: Alpha and Omega Semiconductor IncorporatedInventors: Karthik Padmanabhan, Madhur Bobde, Lingpeng Guan, Lei Zhang, Hamza Yilmaz
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Publication number: 20160380097Abstract: A lateral superjunction MOSFET device includes a gate structure and a first column connected to the lateral superjunction structure. The lateral superjunction MOSFET device includes the first column to receive current from the channel when the MOSFET is turned on and to distribute the channel current to the lateral superjunction structure functioning as the drain drift region. In some embodiment, the MOSFET device includes a second column disposed in close proximity to the first column. The second column disposed near the first column is used to pinch off the first column when the MOSFET device is to be turned off and to block the high voltage being sustained by the MOSFET device at the drain terminal from reaching the gate structure. In some embodiments, the lateral superjunction MOSFET device further includes termination structures for the drain, source and body contact doped region fingers.Type: ApplicationFiled: February 23, 2016Publication date: December 29, 2016Inventors: Madhur Bobde, Lingpeng Guan, Karthik Padmanabhan, Hamza Yilmaz
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Patent number: 9530885Abstract: In some embodiments, a normally on high voltage switch device (“normally on switch device”) incorporates a trench gate terminal and buried doped gate region. In other embodiments, a surface gate controlled normally on high voltage switch device is formed with trench structures and incorporates a surface channel controlled by a surface gate electrode. The surface gate controlled normally on switch device may further incorporate a trench gate electrode and a buried doped gate region to deplete the conducting channel to aid in the turning off of the normally on switch device. The normally on switch devices thus constructed can be readily integrated with MOSFET devices and formed using existing high voltage MOSFET fabrication technologies.Type: GrantFiled: June 10, 2015Date of Patent: December 27, 2016Assignee: Alpha and Omega Semiconductor IncorporatedInventors: Madhur Bobde, Hamza Yilmaz, Daniel Calafut, Karthik Padmanabhan
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Patent number: 9508805Abstract: A termination structure for a semiconductor power device includes a plurality of termination groups formed in a lightly doped epitaxial layer of a first conductivity type over a heavily doped semiconductor substrate of a second conductivity type. Each termination group includes a trench formed in the lightly doped epitaxial layer of the first conductivity type. All sidewalls of the trench are covered by a plurality of epitaxial layers of alternating conductivity types disposed on two opposite sides and substantially symmetrical with respect to a central gap-filler layer disposed between two innermost epitaxial layers of an innermost conductivity type as the first conductivity type.Type: GrantFiled: July 28, 2014Date of Patent: November 29, 2016Assignee: ALPHA AND OMEGA SEMICONDUCTOR INCORPORATEDInventors: Lingpeng Guan, Madhur Bobde, Hamza Yilmaz, Karthik Padmanabhan
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Patent number: 9450045Abstract: A fabrication method to form a lateral superjunction structure in a semiconductor device uses N and P type ion implantations into a base epitaxial layer. In some embodiments, the base epitaxial layer is an intrinsic epitaxial layer or a lightly doped epitaxial layer. The method performs simultaneous N and P type ion implantations into the base epitaxial layer. The epitaxial and implantation processes are repeated successively to form multiple implanted base epitaxial layers on a semiconductor base layer. After the desired number of implanted base epitaxial layers is formed, the semiconductor structure is subjected to annealing to form a lateral superjunction structure including alternate N and P type thin semiconductor regions. In particular, the alternating N and P type thin superjunction layers are formed by the ion implantation process and subsequent annealing. The fabrication method of the present invention ensures good charge control in the lateral superjunction structure.Type: GrantFiled: June 23, 2015Date of Patent: September 20, 2016Assignee: Alpha and Omega Semiconductor IncorporatedInventors: Madhur Bobde, Lingpeng Guan, Karthik Padmanabhan, Hamza Yilmaz
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Patent number: 9397154Abstract: This invention discloses a semiconductor power device formed in a semiconductor substrate of a first conductivity type comprises an active cell area and a termination area surrounding the active cell area and disposed near edges of the semiconductor substrate. The termination area includes a plurality of trenches filled with a conductivity material forming a shield electrode and insulated by a dielectric layer along trench sidewalls and trench bottom surface wherein the trenches extending vertically through a body region of a second conductivity type near a top surface of the semiconductor substrate and further extending through a surface shield region of the first conductivity type. A dopant region of the second conductivity type disposed below the surface shield region extending across and surrounding a trench bottom portion of the trenches.Type: GrantFiled: August 31, 2015Date of Patent: July 19, 2016Assignee: Alpha and Omega Semiconductor IncorporatedInventors: Karthik Padmanabhan, Madhur Bobde
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Patent number: 9312381Abstract: A lateral superjunction MOSFET device includes a gate structure, a first column connected to the lateral superjunction structure and a second column disposed in close proximity to the first column. The lateral superjunction MOSFET device includes the first column to receive current from the channel when the MOSFET is turned on and to distribute the channel current to the lateral superjunction structure functioning as the drain drift region. The second column disposed near the first column is used to pinch off the first column when the MOSFET device is to be turned off and to block the high voltage being sustained by the MOSFET device at the drain terminal from reaching the gate structure. In some embodiments, the lateral superjunction MOSFET device further includes termination structures for the drain, source and body contact doped region fingers.Type: GrantFiled: June 23, 2015Date of Patent: April 12, 2016Assignee: Alpha and Omega Semiconductor IncorporatedInventors: Madhur Bobde, Lingpeng Guan, Karthik Padmanabhan, Hamza Yilmaz
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Publication number: 20160099307Abstract: This invention discloses a semiconductor power device formed in a semiconductor substrate of a first conductivity type comprises an active cell area and a termination area surrounding the active cell area and disposed near edges of the semiconductor substrate. The termination area includes a plurality of trenches filled with a conductivity material forming a shield electrode and insulated by a dielectric layer along trench sidewalls and trench bottom surface wherein the trenches extending vertically through a body region of a second conductivity type near a top surface of the semiconductor substrate and further extending through a surface shield region of the first conductivity type. A dopant region of the second conductivity type disposed below the surface shield region extending across and surrounding a trench bottom portion of the trenches.Type: ApplicationFiled: August 31, 2015Publication date: April 7, 2016Inventors: Karthik Padmanabhan, Madhur Bobde
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Publication number: 20160087095Abstract: A semiconductor device includes a superjunction structure formed using simultaneous N and P angled implants into the sidewall of a trench. The simultaneous N and P angled implants use different implant energies and dopants of different diffusion rate so that after annealing, alternating N and P thin semiconductor regions are formed. The alternating N and P thin semiconductor regions form a superjunction structure where a balanced space charge region is formed to enhance the breakdown voltage characteristic of the semiconductor device.Type: ApplicationFiled: September 21, 2015Publication date: March 24, 2016Inventors: Karthik Padmanabhan, Madhur Bobde, Lingpeng Guan, Lei Zhang, Hamza Yilmaz
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Patent number: 9171949Abstract: A semiconductor device includes a superjunction structure formed using simultaneous N and P angled implants into the sidewall of a trench. The simultaneous N and P angled implants use different implant energies and dopants of different diffusion rate so that after annealing, alternating N and P thin semiconductor regions are formed. The alternating N and P thin semiconductor regions form a superjunction structure where a balanced space charge region is formed to enhance the breakdown voltage characteristic of the semiconductor device.Type: GrantFiled: September 24, 2014Date of Patent: October 27, 2015Assignee: Alpha and Omega Semiconductor IncorporatedInventors: Karthik Padmanabhan, Madhur Bobde, Lingpeng Guan, Lei Zhang, Hamza Yilmaz
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Patent number: 9153653Abstract: This invention discloses a semiconductor power device formed in a semiconductor substrate of a first conductivity type comprises an active cell area and a termination area surrounding the active cell area and disposed near edges of the semiconductor substrate. The termination area includes a plurality of trenches filled with a conductivity material forming a shield electrode and insulated by a dielectric layer along trench sidewalls and trench bottom surface wherein the trenches extending vertically through a body region of a second conductivity type near a top surface of the semiconductor substrate and further extending through a surface shield region of the first conductivity type. A dopant region of the second conductivity type disposed below the surface shield region extending across and surrounding a trench bottom portion of the trenches.Type: GrantFiled: December 6, 2013Date of Patent: October 6, 2015Assignee: Alpha and Omega Semiconductor, Inc.Inventors: Karthik Padmanabhan, Madhur Bobde