Patents by Inventor Amitava Bose

Amitava Bose 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).

  • Publication number: 20070200184
    Abstract: A power metal-oxide-semiconductor field effect transistor (MOSFET) (100) incorporates a stepped drift region including a shallow trench insulator (STI) (112) partially overlapped by the gate (114) and which extends a portion of the distance to a drain region (122). A silicide block extends from and partially overlaps STI (112) and drain region (122). The STI (112) has a width that is approximately 50% to 75% of the drift region.
    Type: Application
    Filed: February 24, 2006
    Publication date: August 30, 2007
    Inventors: Ronghua Zhu, Amitava Bose, Vishnu Khemka, Todd Roggenbauer
  • Publication number: 20070200136
    Abstract: The present disclosure relates to isolated Zener diodes (100) that are substantially free of substrate current injection when forward biased. In particular, the Zener diodes (100) include an “isolation tub” structure that includes surrounding walls (150, 195) and a base (130) formed of semiconductor regions. In addition, the diodes (100) include silicide block (260) extending between anode (210) and cathode (220) regions. The reduction or elimination of substrate current injection overcomes a significant shortcoming of conventional Zener diodes that generally all suffer from substrate current injection when they are forward biased. Due to this substrate current injection, the current from each of a conventional diode's two terminals is not the same.
    Type: Application
    Filed: February 28, 2006
    Publication date: August 30, 2007
    Inventors: Ronghua Zhu, Vishnu Khemka, Amitava Bose, Todd Roggenbauer
  • Patent number: 7244989
    Abstract: A semiconductor component and method of manufacture, including an insulated gate bipolar transistor (IGBT) (100, 200, 300, 400) that includes a semiconductor substrate (110, 210, 310, 410) having a first conductivity type and buried semiconductor region (115, 215, 315, 415) having a second conductivity type located above the semiconductor substrate. The IGBT further includes a first semiconductor region (120, 220, 320, 420) having the first conductivity type located above the buried semiconductor region, a second semiconductor region (130, 230, 330, 430) having the first conductivity type located above the first semiconductor region, a third semiconductor region (140, 240, 340, 440) having the second conductivity type located above the first semiconductor region, an emitter (150, 250, 350, 450) having the first conductivity type disposed in the third semiconductor region, and a collector (170, 270, 370, 470) having the first conductivity type disposed in the third semiconductor region.
    Type: Grant
    Filed: June 2, 2005
    Date of Patent: July 17, 2007
    Assignee: Freescale Semiconductor, Inc.
    Inventors: Vishnu K. Khemka, Amitava Bose, Ronghua Zhu
  • Publication number: 20070096225
    Abstract: A semiconductor device may include first, second, and third semiconductor layers. The first and third layers may have a first dopant type, and the second layer may have a second dopant type. A first region within the third semiconductor layer may have the second dopant type. A second region between the first region and the second semiconductor layer may have the first dopant type. A third region above the second region may have the first dopant type. A fourth semiconductor region adjacent to the third region may have a first concentration of the second dopant type. A source contact region may have a second concentration of the second dopant type adjacent to the third semiconductor region and adjacent to the fourth semiconductor region. The second concentration may be higher than the first concentration.
    Type: Application
    Filed: October 31, 2005
    Publication date: May 3, 2007
    Inventors: Vishnu Khemka, John Pigott, Ronghua Zhu, Amitava Bose, Randall Gray, Jeffrey Braun
  • Publication number: 20070045767
    Abstract: Structure and method are provided for semiconductor devices. The devices include trenches filled with highly doped polycrystalline semiconductor, extending from the surface into the body of the device for, among other things: (i) reducing substrate current injection, (ii) reducing ON-resistance and/or (iii) reducing thermal impedance to the substrate. For isolated LDMOS devices, the resistance between the lateral isolation wall (tied to the source) and the buried layer is reduced, thereby reducing substrate injection current. When placed in the drain of a lateral device or in the collector of a vertical device, the poly-filled trench effectively enlarges the drain or collector region, thereby lowering the ON-resistance. For devices formed on an oxide isolation layer, the poly-filled trench desirably penetrates this isolation layer thereby improving thermal conduction from the active regions to the substrate. The poly filled trenches are conveniently formed by etch and refill.
    Type: Application
    Filed: August 25, 2005
    Publication date: March 1, 2007
    Inventors: Ronghua Zhu, Vishnu Khemka, Amitava Bose
  • Patent number: 7180158
    Abstract: A semiconductor component and method of manufacture, including an insulated gate bipolar transistor (IGBT) (100) including a semiconductor substrate (110) having a first conductivity type and buried semiconductor region (115) having a second conductivity type located above the semiconductor substrate. The IGBT further includes a plurality of first semiconductor regions (120) having the first conductivity type, a plurality of second semiconductor regions (130) having the first conductivity type, and a plurality of third semiconductor regions (140) having the second conductivity type. A sinker region (142) having the second conductivity type is disposed in a third semiconductor region and a first semiconductor region during manufacture to define the plurality of regions and tie the buried semiconductor region to the plurality of third semiconductor regions.
    Type: Grant
    Filed: June 2, 2005
    Date of Patent: February 20, 2007
    Assignee: Freescale Semiconductor, Inc.
    Inventors: Vishnu K. Khemka, Amitava Bose, Ronghua Zhu
  • Publication number: 20060273402
    Abstract: A semiconductor component and method of manufacture, including an insulated gate bipolar transistor (IGBT) (100, 200, 300, 400) that includes a semiconductor substrate (110, 210, 310, 410) having a first conductivity type and buried semiconductor region (115, 215, 315, 415) having a second conductivity type located above the semiconductor substrate. The IGBT further includes a first semiconductor region (120, 220, 320, 420) having the first conductivity type located above the buried semiconductor region, a second semiconductor region (130, 230, 330, 430) having the first conductivity type located above the first semiconductor region, a third semiconductor region (140, 240, 340, 440) having the second conductivity type located above the first semiconductor region, an emitter (150, 250, 350, 450) having the first conductivity type disposed in the third semiconductor region, and a collector (170, 270, 370, 470) having the first conductivity type disposed in the third semiconductor region.
    Type: Application
    Filed: June 2, 2005
    Publication date: December 7, 2006
    Inventors: Vishnu Khemka, Amitava Bose, Ronghua Zhu
  • Publication number: 20060273428
    Abstract: A semiconductor component and method of manufacture, including an insulated gate bipolar transistor (IGBT) (100) including a semiconductor substrate (110) having a first conductivity type and buried semiconductor region (115) having a second conductivity type located above the semiconductor substrate. The IGBT further includes a plurality of first semiconductor regions (120) having the first conductivity type, a plurality of second semiconductor regions (130) having the first conductivity type, and a plurality of third semiconductor regions (140) having the second conductivity type. A sinker region (142) having the second conductivity type is disposed in a third semiconductor region and a first semiconductor region during manufacture to define the plurality of regions and tie the buried semiconductor region to the plurality of third semiconductor regions.
    Type: Application
    Filed: June 2, 2005
    Publication date: December 7, 2006
    Inventors: Vishnu Khemka, Amitava Bose, Ronghua Zhu
  • Publication number: 20060267089
    Abstract: A semiconductor component and method of manufacture, including an insulated gate bipolar transistor (IGBT) (100, 200) that includes a semiconductor substrate (110) having a first conductivity type and buried semiconductor region (115) having a second conductivity type located above the semiconductor substrate. The IGBT further includes a first semiconductor region (120) having the first conductivity type located above the buried semiconductor region, a second semiconductor region (130) having the second conductivity type located above at least a portion of the first semiconductor region, an emitter (150) having the second conductivity type disposed in the second semiconductor region, and a collector (170) having the second conductivity type disposed in the first semiconductor region. A sinker region (140) is provided to electrically tie the buried semiconductor region (115) to the second semiconductor region (130).
    Type: Application
    Filed: May 31, 2005
    Publication date: November 30, 2006
    Inventors: Vishnu Khemka, Amitava Bose, Ronghua Zhu
  • Patent number: 7141860
    Abstract: An LDMOS transistor has a Schottky diode inserted at the center of a doped region of the LDMOS transistor. A Typical LDMOS transistor has a drift region in the center. In this case a Schottky diode is inserted at the center of this drift region which has the effect of providing a Schottky diode connected from source to drain in the forward direction so that the drain voltage is clamped to a voltage that is lower than the PN junction threshold, thereby avoiding forward biasing the PN junction. An alternative is to insert the Schottky diode at the well in which the source is formed, which is on the periphery of the LDMOS transistor. In such case the Schottky diode is formed differently but still is connected from source to drain in the forward direction to achieve the desired voltage clamping at the drain.
    Type: Grant
    Filed: June 23, 2004
    Date of Patent: November 28, 2006
    Assignee: Freescale Semiconductor, Inc.
    Inventors: Vishnu K. Khemka, Vijay Parthasarathy, Ronghua Zhu, Amitava Bose
  • Publication number: 20060261382
    Abstract: Methods and apparatus are provided for reducing substrate leakage current of lateral RESURF diode devices. The diode device (60, 60?, 100) comprises first (39) and second (63) surface terminals overlying a semiconductor substrate (22) coupled to P (38, 32, 26) and N (24, 30, 46) type regions providing the diode action. An unavoidable parasitic vertical device (54, 92) permits leakage current to flow from the first terminal (39) to the substrate (22). This leakage current is reduced by having the diode device second terminal (63) comprise both N (46) and P (62) type regions coupled together by the second terminal (63). This forms a shorted base-collector lateral transistor (72) between the first (39) and second (63) terminals to provide the diode function. The gain of this lateral transistor (72) increases the proportion of first terminal (39) current that flows to the second terminal (63) rather than the substrate (22).
    Type: Application
    Filed: May 19, 2005
    Publication date: November 23, 2006
    Inventors: Vishnu Khemka, Ronghua Zhu, Amitava Bose
  • Publication number: 20060261408
    Abstract: Methods and apparatus are provided for reducing substrate leakage current of RESURF LDMOSFET devices.
    Type: Application
    Filed: February 28, 2006
    Publication date: November 23, 2006
    Inventors: Vishnu Khemka, Amitava Bose, Todd Roggenbauer, Ronghua Zhu
  • Publication number: 20060246670
    Abstract: A Schottky device having a plurality of unit cells, each having a Schottky contact portion, surrounded by a termination structure that causes depletion regions to form in a vertical and horizontal direction, relative to a surface of the device, during a reverse bias voltage condition.
    Type: Application
    Filed: April 29, 2005
    Publication date: November 2, 2006
    Applicant: Freescale Semiconductor, Inc.
    Inventors: Vishnu Khemka, Vijay Parthasarathy, Ronghua Zhu, Amitava Bose
  • Publication number: 20060244081
    Abstract: In one embodiment, semiconductor device 10 comprises a diode which uses isolation regions (34, 16, and 13) and a plurality of dopant concentrations (30, 20, 24, and 26) which may be used to limit the parasitic current that is injected into the semiconductor substrate (12). Various biases on the isolation regions (34, 16, and 13) may be used to affect the behavior of semiconductor device (10). In addition, a conductive layer (28) may be formed overlying the junction between anode (42) and cathode (40). This conductive layer (28) may decrease the electric field in selected regions in order to increase the maximum voltage that may be applied to cathode (40).
    Type: Application
    Filed: June 27, 2006
    Publication date: November 2, 2006
    Applicant: Freescale Semiconductor, Inc.
    Inventors: Ronghua Zhu, Amitava Bose, Vishnu Khemka, Vijay Parthasarathy
  • Patent number: 7095092
    Abstract: In one embodiment, semiconductor device 10 comprises a diode which uses isolation regions (34, 16, and 13) and a plurality of dopant concentrations (30, 20, 24, and 26) which may be used to limit the parasitic current that is injected into the semiconductor substrate (12). Various biases on the isolation regions (34, 16, and 13) may be used to affect the behavior of semiconductor device (10). In addition, a conductive layer (28) may be formed overlying the junction between anode (42) and cathode (40). This conductive layer (28) may decrease the electric field in selected regions in order to increase the maximum voltage that may be applied to cathode (40).
    Type: Grant
    Filed: April 30, 2004
    Date of Patent: August 22, 2006
    Assignee: Freescale Semiconductor, Inc.
    Inventors: Ronghua Zhu, Amitava Bose, Vishnu K. Khemka, Vijay Parthasarathy
  • Patent number: 7071518
    Abstract: A regular Schottky diode or a device that has a Schottky diode characteristic and an MOS transistor are coupled in series to provide a significant improvement in leakage current and breakdown voltage with only a small degradation in forward current. In the reverse bias case, there is a small reverse bias current but the voltage across the Schottky diode remains small due the MOS transistor. Nearly all of the reverse bias voltage is across the MOS transistor until the MOS transistor breaks down. This transistor breakdown, however, is not initially destructive because the Schottky diode limits the current. As the reverse bias voltage continues to increase the Schottky diodes begins to absorb more of the voltage. This increases the leakage current but the breakdown voltage is a somewhat additive between the transistor and the Schottky diode.
    Type: Grant
    Filed: May 28, 2004
    Date of Patent: July 4, 2006
    Assignee: Freescale Semiconductor, Inc.
    Inventors: Vijay Parthasarathy, Vishnu K. Khemka, Ronghua Zhu, Amitava Bose
  • Publication number: 20060014342
    Abstract: A semiconductor component comprises a first semiconductor region (110, 310), a second semiconductor region (120, 320) above the first semiconductor region, a third semiconductor region (130, 330) above the second semiconductor region, a fourth semiconductor region (140, 340) above the third semiconductor region, a fifth semiconductor region (150, 350) above the second semiconductor region and at least partially contiguous with the fourth semiconductor region, a sixth semiconductor region (160, 360) above and electrically shorted to the fifth semiconductor region, and an electrically insulating layer (180, 380) above the fourth semiconductor region and the fifth semiconductor region. A junction (145, 345) between the fourth semiconductor region and the fifth semiconductor region forms a zener diode junction, which is located only underneath the electrically insulating layer. In one embodiment, a seventh semiconductor region (170) circumscribes the third, fourth, fifth, and sixth semiconductor regions.
    Type: Application
    Filed: July 14, 2005
    Publication date: January 19, 2006
    Applicant: Freescale Semiconductor, Inc.
    Inventors: Vishnu Khemka, Vijay Parthasarathy, Ronghua Zhu, Amitava Bose, Todd Roggenbauer
  • Publication number: 20060001057
    Abstract: A conductive layer includes a first portion that forms a Schottky region with an underlying first region having a first conductivity type. A second region of a second conductivity type underlies the first region, where the second conductivity type is opposite the first conductivity type. A third region of the first conductivity type immediately underlies the second region and is electrically coupled to a cathode of the device.
    Type: Application
    Filed: June 30, 2004
    Publication date: January 5, 2006
    Inventors: Vishnu Khemka, Vijay Parthasarathy, Ronghua Zhu, Amitava Bose
  • Publication number: 20050285188
    Abstract: An LDMOS transistor has a Schottky diode inserted at the center of a doped region of the LDMOS transistor. A Typical LDMOS transistor has a drift region in the center. In this case a Schottky diode is inserted at the center of this drift region which has the effect of providing a Schottky diode connected from source to drain in the forward direction so that the drain voltage is clamped to a voltage that is lower than the PN junction threshold, thereby avoiding forward biasing the PN junction. An alternative is to insert the Schottky diode at the well in which the source is formed, which is on the periphery of the LDMOS transistor. In such case the Schottky diode is formed differently but still is connected from source to drain in the forward direction to achieve the desired voltage clamping at the drain.
    Type: Application
    Filed: June 23, 2004
    Publication date: December 29, 2005
    Inventors: Vishnu Khemka, Vijay Parthasarathy, Ronghua Zhu, Amitava Bose
  • Publication number: 20050275055
    Abstract: A regular Schottky diode or a device that has a Schottky diode characteristic and an MOS transistor are coupled in series to provide a significant improvement in leakage current and breakdown voltage with only a small degradation in forward current. In the reverse bias case, there is a small reverse bias current but the voltage across the Schottky diode remains small due the MOS transistor. Nearly all of the reverse bias voltage is across the MOS transistor until the MOS transistor breaks down. This transistor breakdown, however, is not initially destructive because the Schottky diode limits the current. As the reverse bias voltage continues to increase the Schottky diodes begins to absorb more of the voltage. This increases the leakage current but the breakdown voltage is a somewhat additive between the transistor and the Schottky diode.
    Type: Application
    Filed: May 28, 2004
    Publication date: December 15, 2005
    Inventors: Vijay Parthasarathy, Vishnu Khemka, Ronghua Zhu, Amitava Bose