Patents by Inventor Shih Tzung Su
Shih Tzung Su 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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Patent number: 11289596Abstract: A split gate power device is disclosed having a trench containing a U-shaped gate that, when biased above a threshold voltage, creates a conductive channel in a p-well. Below the gate is a field plate in the trench, coupled to the source electrode, for spreading the electric field along the trench to improve the breakdown voltage. The top gate poly is initially formed relatively thin so that it can be patterned using non-CMP techniques, such as dry etching or wet etching. As such, the power device can be fabricated in conventional fabs not having CMP capability. In one embodiment, the thin gate has vertical and lateral portions that create conductive vertical and lateral channels in a p-well. In another embodiment, the thin gate has only vertical portions along the trench sidewalls for minimizing surface area and gate capacitance.Type: GrantFiled: February 5, 2020Date of Patent: March 29, 2022Assignee: MaxPower Semiconductor, Inc.Inventors: Jun Zeng, Kui Pu, Mohamed N. Darwish, Shih-Tzung Su
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Publication number: 20220052170Abstract: A vertical trench MOSFET is formed with deep P-shield regions below portions of each gate trench. The deep P-shield regions are effectively downward extensions of the P-body/well, and are electrically coupled to the top source electrode. The P-shield regions abut the bottom portions and lower sides of the gate trenches, so that those small portions of the gate trench do not create N-channels and do not conduct current. Accordingly, each trench comprises an active gate portion that creates an N-channel and a small non-active portion that abuts the P-shield regions. The spacing of the P-shield regions along each gate trench is selected to achieve the desired electric field spreading to protect the gate oxide from punch-through. No field plate trenches are needed to be formed in the active area of the MOSFET. The deep P-shield regions are formed by implanting P-type dopants through the bottom of the trenches.Type: ApplicationFiled: August 5, 2021Publication date: February 17, 2022Inventors: Jun Zeng, Mohamed N. Darwish, Shih-Tzung Su
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Publication number: 20200273987Abstract: A split gate power device is disclosed having a trench containing a U-shaped gate that, when biased above a threshold voltage, creates a conductive channel in a p-well. Below the gate is a field plate in the trench, coupled to the source electrode, for spreading the electric field along the trench to improve the breakdown voltage. The top gate poly is initially formed relatively thin so that it can be patterned using non-CMP techniques, such as dry etching or wet etching. As such, the power device can be fabricated in conventional fabs not having CMP capability. In one embodiment, the thin gate has vertical and lateral portions that create conductive vertical and lateral channels in a p-well. In another embodiment, the thin gate has only vertical portions along the trench sidewalls for minimizing surface area and gate capacitance.Type: ApplicationFiled: February 5, 2020Publication date: August 27, 2020Inventors: Jun Zeng, Kui Pu, Mohamed N. Darwish, Shih-Tzung Su
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Patent number: 10157983Abstract: In one embodiment, a power MOSFET or IGBT cell includes an N-type drift region grown over the substrate. An N-type layer, having a higher dopant concentration than the drift region, is then formed over the drift region. A P-well is formed over the N-type layer, and an N+ source/emitter region is formed in the P-well. A gate is formed over the P-well's lateral channel and has a vertical extension into a trench. A positive gate voltage inverts the lateral channel and increases the vertical conduction in the N-type layer along the sidewalls of the trench to reduce on-resistance. A vertical shield field plate is also in the trench and may be connected to the gate. The field plate laterally depletes the N-type layer when the device is off to increase the breakdown voltage. Floating P-islands in the N-type drift region increase breakdown voltage and reduce the saturation current.Type: GrantFiled: February 12, 2018Date of Patent: December 18, 2018Assignee: MAXPOWER SEMICONDUCTOR INC.Inventors: Jun Zeng, Mohamed N. Darwish, Wenfang Du, Richard A. Blanchard, Kui Pu, Shih-Tzung Su
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Publication number: 20180261666Abstract: In one embodiment, a power MOSFET or IGBT cell includes an N-type drift region grown over the substrate. An N-type layer, having a higher dopant concentration than the drift region, is then formed over the drift region. A P-well is formed over the N-type layer, and an N+ source/emitter region is formed in the P-well. A gate is formed over the P-well's lateral channel and has a vertical extension into a trench. A positive gate voltage inverts the lateral channel and increases the vertical conduction in the N-type layer along the sidewalls of the trench to reduce on-resistance. A vertical shield field plate is also in the trench and may be connected to the gate. The field plate laterally depletes the N-type layer when the device is off to increase the breakdown voltage. Floating P-islands in the N-type drift region increase breakdown voltage and reduce the saturation current.Type: ApplicationFiled: February 12, 2018Publication date: September 13, 2018Inventors: Jun Zeng, Mohamed N. Darwish, Wenfang Du, Richard A. Blanchard, Kui Pu, Shih-Tzung Su
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Patent number: 9947779Abstract: In one embodiment, a power MOSFET cell includes an N+ silicon substrate having a drain electrode. An N-type drift layer is grown over the substrate. An N-type layer, having a higher dopant concentration than the drift region, is then formed along with a trench having sidewalls. A P-well is formed in the N-type layer, and an N+ source region is formed in the P-well. A gate is formed over the P-well's lateral channel and has a vertical extension into the trench. A positive gate voltage inverts the lateral channel and increases the vertical conduction along the sidewalls to reduce on-resistance. A vertical shield field plate is also located next to the sidewalls and may be connected to the gate. The field plate laterally depletes the N-type layer when the device is off to increase the breakdown voltage. A buried layer and sinker enable the use of a topside drain electrode.Type: GrantFiled: July 28, 2017Date of Patent: April 17, 2018Assignee: MaxPower Semiconductor Inc.Inventors: Jun Zeng, Mohamed N. Darwish, Kui Pu, Shih-Tzung Su
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Publication number: 20170330962Abstract: In one embodiment, a power MOSFET cell includes an N+ silicon substrate having a drain electrode. An N-type drift layer is grown over the substrate. An N-type layer, having a higher dopant concentration than the drift region, is then formed along with a trench having sidewalls. A P-well is formed in the N-type layer, and an N+ source region is formed in the P-well. A gate is formed over the P-well's lateral channel and has a vertical extension into the trench. A positive gate voltage inverts the lateral channel and increases the vertical conduction along the sidewalls to reduce on-resistance. A vertical shield field plate is also located next to the sidewalls and may be connected to the gate. The field plate laterally depletes the N-type layer when the device is off to increase the breakdown voltage. A buried layer and sinker enable the use of a topside drain electrode.Type: ApplicationFiled: July 28, 2017Publication date: November 16, 2017Inventors: Jun Zeng, Mohamed N. Darwish, Kui Pu, Shih-Tzung Su
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Patent number: 9761702Abstract: In one embodiment, a power MOSFET cell includes an N+ silicon substrate having a drain electrode. An N-type drift layer is grown over the substrate. An N-type layer, having a higher dopant concentration than the drift region, is then formed along with a trench having sidewalls. A P-well is formed in the N-type layer, and an N+ source region is formed in the P-well. A gate is formed over the P-well's lateral channel and has a vertical extension into the trench. A positive gate voltage inverts the lateral channel and increases the vertical conduction along the sidewalls to reduce on-resistance. A vertical shield field plate is also located next to the sidewalls and may be connected to the gate. The field plate laterally depletes the N-type layer when the device is off to increase the breakdown voltage. A buried layer and sinker enable the use of a topside drain electrode.Type: GrantFiled: August 18, 2016Date of Patent: September 12, 2017Assignee: MaxPower SemiconductorInventors: Jun Zeng, Mohamed N. Darwish, Kui Pu, Shih-Tzung Su
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Publication number: 20160359029Abstract: In one embodiment, a power MOSFET cell includes an N+ silicon substrate having a drain electrode. An N-type drift layer is grown over the substrate. An N-type layer, having a higher dopant concentration than the drift region, is then formed along with a trench having sidewalls. A P-well is formed in the N-type layer, and an N+ source region is formed in the P-well. A gate is formed over the P-well's lateral channel and has a vertical extension into the trench. A positive gate voltage inverts the lateral channel and increases the vertical conduction along the sidewalls to reduce on-resistance. A vertical shield field plate is also located next to the sidewalls and may be connected to the gate. The field plate laterally depletes the N-type layer when the device is off to increase the breakdown voltage. A buried layer and sinker enable the use of a topside drain electrode.Type: ApplicationFiled: August 18, 2016Publication date: December 8, 2016Inventors: Jun Zeng, Mohamed N. Darwish, Kui Pu, Shih-Tzung Su
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Patent number: 9461127Abstract: A power MOSFET cell includes an N+ silicon substrate having a drain electrode. A low dopant concentration N-type drift layer is grown over the substrate. An N-type layer, having a higher dopant concentration than the drift region, is then formed and etched to have sidewalls. A P-well is formed in the N-type layer, and an N+ source region is formed in the P-well. A gate is formed over the P-well's lateral channel and has a vertical extension next to the top portion of the sidewalls. A positive gate voltage inverts the lateral channel and increases the conduction along the sidewalls to reduce on-resistance. A vertical shield field plate is also located next to the sidewalls and extends virtually the entire length of the sidewalls. The field plate laterally depletes the N-type layer when the device is off to increase the breakdown voltage.Type: GrantFiled: October 1, 2015Date of Patent: October 4, 2016Assignee: MaxPower Semiconductor, Inc.Inventors: Jun Zeng, Mohamed N. Darwish, Kui Pu, Shih-Tzung Su
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Publication number: 20160027880Abstract: A power MOSFET cell includes an N+ silicon substrate having a drain electrode. A low dopant concentration N-type drift layer is grown over the substrate. An N-type layer, having a higher dopant concentration than the drift region, is then formed and etched to have sidewalls. A P-well is formed in the N-type layer, and an N+ source region is formed in the P-well. A gate is formed over the P-well's lateral channel and has a vertical extension next to the top portion of the sidewalls. A positive gate voltage inverts the lateral channel and increases the conduction along the sidewalls to reduce on-resistance. A vertical shield field plate is also located next to the sidewalls and extends virtually the entire length of the sidewalls. The field plate laterally depletes the N-type layer when the device is off to increase the breakdown voltage.Type: ApplicationFiled: October 1, 2015Publication date: January 28, 2016Inventors: Jun Zeng, Mohamed N. Darwish, Kui Pu, Shih-Tzung Su
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Patent number: 9184248Abstract: A power MOSFET cell includes an N+ silicon substrate having a drain electrode. A low dopant concentration N-type drift layer is grown over the substrate. An N-type layer, having a higher dopant concentration than the drift region, is then formed and etched to have sidewalls. A P-well is formed in the N-type layer, and an N+ source region is formed in the P-well. A gate is formed over the P-well's lateral channel and has a vertical extension next to the top portion of the sidewalls. A positive gate voltage inverts the lateral channel and increases the conduction along the sidewalls to reduce on-resistance. A vertical shield field plate is also located next to the sidewalls and extends virtually the entire length of the sidewalls. The field plate laterally depletes the N-type layer when the device is off to increase the breakdown voltage.Type: GrantFiled: February 6, 2015Date of Patent: November 10, 2015Assignee: MaxPower Semiconductor Inc.Inventors: Jun Zeng, Mohamed N. Darwish, Kui Pu, Shih-Tzung Su
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Publication number: 20150221765Abstract: A power MOSFET cell includes an N+ silicon substrate having a drain electrode. A low dopant concentration N-type drift layer is grown over the substrate. Alternating N and P-type columns are formed over the drift layer with a higher dopant concentration. An N-type layer, having a higher dopant concentration than the drift region, is then formed and etched to have sidewalls. A P-well is formed in the N-type layer, and an N+ source region is formed in the P-well. A gate is formed over the P-well's lateral channel and next to the sidewalls as a vertical field plate. A source electrode contacts the P-well and source region. A positive gate voltage inverts the lateral channel and increases the conduction along the sidewalls. Current between the source and drain flows laterally and then vertically through the various N layers. On resistance is reduced and the breakdown voltage is increased.Type: ApplicationFiled: July 22, 2014Publication date: August 6, 2015Inventors: Jun Zeng, Mohamed N. Darwish, Kui Pu, Shih-Tzung Su
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Publication number: 20150221731Abstract: A power MOSFET cell includes an N+ silicon substrate having a drain electrode. A low dopant concentration N-type drift layer is grown over the substrate. An N-type layer, having a higher dopant concentration than the drift region, is then formed and etched to have sidewalls. A P-well is formed in the N-type layer, and an N+ source region is formed in the P-well. A gate is formed over the P-well's lateral channel and has a vertical extension next to the top portion of the sidewalls. A positive gate voltage inverts the lateral channel and increases the conduction along the sidewalls to reduce on-resistance. A vertical shield field plate is also located next to the sidewalls and extends virtually the entire length of the sidewalls. The field plate laterally depletes the N-type layer when the device is off to increase the breakdown voltage.Type: ApplicationFiled: February 6, 2015Publication date: August 6, 2015Inventors: Jun Zeng, Mohamed N. Darwish, Kui Pu, Shih-Tzung Su
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Patent number: 9093522Abstract: A power MOSFET cell includes an N+ silicon substrate having a drain electrode. A low dopant concentration N-type drift layer is grown over the substrate. Alternating N and P-type columns are formed over the drift layer with a higher dopant concentration. An N-type layer, having a higher dopant concentration than the drift region, is then formed and etched to have sidewalls. A P-well is formed in the N-type layer, and an N+ source region is formed in the P-well. A gate is formed over the P-well's lateral channel and next to the sidewalls as a vertical field plate. A source electrode contacts the P-well and source region. A positive gate voltage inverts the lateral channel and increases the conduction along the sidewalls. Current between the source and drain flows laterally and then vertically through the various N layers. On resistance is reduced and the breakdown voltage is increased.Type: GrantFiled: July 22, 2014Date of Patent: July 28, 2015Assignee: MaxPower Semiconductor, Inc.Inventors: Jun Zeng, Mohamed N. Darwish, Kui Pu, Shih-Tzung Su
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Patent number: 8581341Abstract: Semiconductor power devices, and related methods, wherein a recessed contact makes lateral ohmic contact to the source diffusion, but is insulated from the underlying recessed field plate (RFP). Such an insulated RFP is here referred to as an embedded recessed field plate (ERFP).Type: GrantFiled: April 19, 2011Date of Patent: November 12, 2013Assignee: MaxPower Semiconductor, Inc.Inventors: Mohamed N. Darwish, Jun Zeng, Shih-Tzung Su, Richard A. Blanchard
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Patent number: 8294235Abstract: A MOSFET switch which has a low surface electric field at an edge termination area, and also has increased breakdown voltage. The MOSFET switch has a new edge termination structure employing an N-P-N sandwich structure. The MOSFET switch also has a polysilicon field plate configuration operative to enhance any spreading of any depletion layer located at an edge of a main PN junction of the N-P-N sandwich structure.Type: GrantFiled: April 12, 2011Date of Patent: October 23, 2012Assignee: MaxPower Semiconductor, Inc.Inventors: Jun Zeng, Mohamed N. Darwish, Shih-Tzung Su
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Publication number: 20120187473Abstract: A MOSFET switch which has a low surface electric field at an edge termination area, and also has increased breakdown voltage. The MOSFET switch has a new edge termination structure employing an N-P-N sandwich structure. The MOSFET switch also has a polysilicon field plate configuration operative to enhance any spreading of any depletion layer located at an edge of a main PN junction of the N-P-N sandwich structure.Type: ApplicationFiled: April 12, 2011Publication date: July 26, 2012Applicant: MAXPOWER SEMICONDUCTOR INC.Inventors: Jun Zeng, Mohamed N. Darwish, Shih-Tzung Su
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Publication number: 20110254088Abstract: Semiconductor power devices, and related methods, wherein a recessed contact makes lateral ohmic contact to the source diffusion, but is insulated from the underlying recessed field plate (RFP). Such an insulated RFP is here referred to as an embedded recessed field plate (ERFP).Type: ApplicationFiled: April 19, 2011Publication date: October 20, 2011Applicant: MAXPOWER SEMICONDUCTOR INC.Inventors: Mohamed N. Darwish, Jun Zeng, Shih-Tzung Su, Richard A. Blanchard
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Patent number: 7923804Abstract: A MOSFET switch which has a low surface electric field at an edge termination area, and also has increased breakdown voltage. The MOSFET switch has a new edge termination structure employing an N-P-N sandwich structure. The MOSFET switch also has a polysilicon field plate configuration operative to enhance any spreading of any depletion layer located at an edge of a main PN junction of the N-P-N sandwich structure.Type: GrantFiled: February 9, 2009Date of Patent: April 12, 2011Assignee: MaxPower Semiconductor Inc.Inventors: Jun Zeng, Mohamed N. Darwish, Shih-Tzung Su