Patents by Inventor Mahalingam Bhaskaran

Mahalingam Bhaskaran 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: 9520441
    Abstract: A method for fabricating a back-illuminated imager which has a pinned back surface is disclosed. A first insulator layer is formed overlying a mechanical substrate. A conductive layer is deposited overlying the first insulator layer. A second insulator layer is formed overlying the conductive layer to form a first structure, an interface being formed between the conductive layer and the second insulator layer, the conductive layer causing band bending proximal to the interface such that the interface is electrically pinned. Hydrogen is implanted in a separate device wafer to form a bubble layer. A final insulator layer is formed overlying the device wafer to form a second structure. The first structure and the second structure are bonded to form a combined wafer. A portion of the combined wafer is removed underlying the bubble layer to expose a seed layer comprising the semiconductor material substantially overlying the second insulator layer.
    Type: Grant
    Filed: May 15, 2009
    Date of Patent: December 13, 2016
    Assignee: SRI INTERNATIONAL
    Inventors: Pradyumna Kumar Swain, David Jay Cheskis, Mahalingam Bhaskaran
  • Patent number: 8946818
    Abstract: A method for fabricating a back-illuminated semiconductor imaging device on a semiconductor-on-insulator substrate, and resulting imaging device is disclosed. The device includes an insulator layer; a semiconductor substrate, having an interface with the insulator layer; an epitaxial layer grown on the semiconductor substrate by epitaxial growth; and one or more imaging components in the epitaxial layer in proximity to a face of the epitaxial layer, the face being opposite the interface of the semiconductor substrate and the insulator layer, the imaging components comprising junctions within the epitaxial layer; wherein the semiconductor substrate and the epitaxial layer exhibit a net doping concentration having a maximum value at a predetermined distance from the interface of the insulating layer and the semiconductor substrate and which decreases monotonically on both sides of the profile from the maximum value within a portion of the semiconductor substrate and the epitaxial layer.
    Type: Grant
    Filed: April 15, 2010
    Date of Patent: February 3, 2015
    Assignee: SRI International
    Inventors: Peter Alan Levine, Pradyumna Swain, Mahalingam Bhaskaran
  • Patent number: 8652937
    Abstract: A back-illuminated semiconductor imaging device on a semiconductor-on-insulator substrate is disclosed. The device includes an insulator layer, a semiconductor substrate having an interface with the insulator layer, an epitaxial layer grown on the semiconductor substrate; and one or more imaging components in the epitaxial layer. The semiconductor substrate and the epitaxial layer exhibit a net doping concentration profile having a maximum value at a predetermined distance from the interface which decreases monotonically on both sides of the profile. The doping profile between the interface with the insulation layer and the peak of the doping profile functions as a “dead band” to prevent dark current carriers from penetrating to the front side of the device.
    Type: Grant
    Filed: March 13, 2012
    Date of Patent: February 18, 2014
    Assignee: SRI International
    Inventors: Levine Peter Alan, Pradyumna Swain, Mahalingam Bhaskaran
  • Publication number: 20120190150
    Abstract: A back-illuminated semiconductor imaging device on a semiconductor-on-insulator substrate is disclosed. The device includes an insulator layer, a semiconductor substrate having an interface with the insulator layer, an epitaxial layer grown on the semiconductor substrate by epitaxial growth; and one or more imaging components in the epitaxial layer. The semiconductor substrate and the epitaxial layer exhibit a net doping concentration profile having a maximum value at a predetermined distance from the interface which decreases monotonically on both sides of the profile. The doping profile between the interface with the insulation layer and the peak of the doping profile functions as a “dead band” to prevent dark current carriers from penetrating to the front side of the device.
    Type: Application
    Filed: March 13, 2012
    Publication date: July 26, 2012
    Inventors: Peter Alan Levine, Pradyumna Swain, Mahalingam Bhaskaran
  • Patent number: 8178914
    Abstract: A method for fabricating a back-illuminated semiconductor imaging device on a semiconductor-on-insulator substrate is disclosed. The substrate includes an insulator layer and an epitaxial layer overlying the insulator layer. A bond pad region is formed extending into the epitaxial layer to a surface of the insulator layer. A bond pad is fabricated partially overlying the bond pad region. At least one imaging component is fabricated partially overlying and extending into the epitaxial layer. A passivation layer is fabricated overlying the epitaxial layer, the bond pad, and the at least one imaging component. A handle wafer is bonded to the passivation layer. A portion of the insulator layer and a portion of the bond pad region is etched to expose a portion of the bond pad.
    Type: Grant
    Filed: October 15, 2009
    Date of Patent: May 15, 2012
    Assignee: SRI International
    Inventors: Peter Alan Levine, Pradyumna Kumar Swain, Mahalingam Bhaskaran
  • Patent number: 7985612
    Abstract: A method and resulting device for reducing crosstalk in a back-illuminated imager is disclosed, comprising providing a substrate comprising an insulator layer and a seed layer substantially overlying the insulator layer, an interface being formed where the seed layer comes in contact with the insulator layer; forming an epitaxial layer substantially overlying the seed layer, the epitaxial layer defining plurality of pixel regions, each pixel region outlining a collection well for collecting charge carriers; and forming one of an electrical, optical, and electrical and optical barrier about the outlined collection well extending into the epitaxial layer to the interface between the seed layer and the insulator layer.
    Type: Grant
    Filed: June 4, 2008
    Date of Patent: July 26, 2011
    Assignee: SRI International
    Inventors: Pradyumna Kumar Swain, Mahalingam Bhaskaran
  • Patent number: 7932575
    Abstract: A method for fabricating a back-illuminated semiconductor imaging device on a semiconductor-on-insulator substrate, and resulting imaging device is disclosed. The method for manufacturing the imaging device includes the steps of providing a substrate comprising an insulator layer, and an epitaxial layer substantially overlying the insulator layer; fabricating at least one imaging component at least partially overlying and extending into the epitaxial layer; forming a plurality of bond pads substantially overlying the epitaxial layer; fabricating a dielectric layer substantially overlying the epitaxial layer and the at least one imaging component; providing a handle wafer; forming a plurality of conductive trenches in the handle wafer; forming a plurality of conductive bumps on a first surface of the handle wafer substantially underlying the conductive trenches; and bonding the plurality of conductive bumps to the plurality of bond pads.
    Type: Grant
    Filed: April 28, 2009
    Date of Patent: April 26, 2011
    Assignee: SRI International
    Inventors: Mahalingam Bhaskaran, Pradyumna Kumar Swain, Peter Levine, Norman Goldsmith
  • Patent number: 7855128
    Abstract: A method for fabricating a back-illuminated semiconductor imaging device on an ultra-thin semiconductor-on-insulator substrate (UTSOI) is disclosed. The UTSOI substrate is formed by providing a handle wafer comprising a mechanical substrate and an insulator layer substantially overlying the mechanical substrate. A donor wafer is provided. Hydrogen is implanted in the donor wafer to form a bubble layer. The donor wafer is doped with at least one dopant to form a doped layer proximal to the bubble layer. The handle wafer and the donor wafer are bonded between the insulator layer of the handle wafer and a surface of the donor wafer proximal to the doped layer to form a combined wafer having a portion substantially underlying the bubble layer. The portion of the combined wafer substantially underlying the bubble layer is removed so as to expose a seed layer. An epitaxial layer is grown substantially overlying the seed layer, wherein at least one dopant diffuse into the epitaxial layer.
    Type: Grant
    Filed: May 27, 2009
    Date of Patent: December 21, 2010
    Assignee: Sarnoff Corporation
    Inventors: Rui Zhu, Peter Alan Levine, Pradyumna Kumar Swain, Mahalingam Bhaskaran
  • Patent number: 7804113
    Abstract: An anti-blooming structure for a back-illuminated imager is disclosed. In one embodiment, the anti-blooming structure is formed in a substrate of a first conductivity type having a back side and a front side, comprising a channel region of a second conductivity type formed in the substrate; a barrier region of the first conductivity type positioned in the substrate substantially overlying the channel region and proximal to the front side of the substrate; and a drain region of the second conductivity type positioned substantially overlying the barrier region, wherein when light impinges on the back side of the substrate the light generates charge carriers that collect in the channel region, the charge carriers passing through the barrier region into the drain region when a potential corresponding to the collected charge carriers in the channel region is about equal to the potential corresponding to the barrier region.
    Type: Grant
    Filed: September 5, 2007
    Date of Patent: September 28, 2010
    Assignee: Sarnoff Corporation
    Inventors: Pradyumna Kumar Swain, Mahalingam Bhaskaran
  • Patent number: 7777229
    Abstract: A method for fabricating a back-illuminated semiconductor imaging device and resulting imaging device is disclosed, which includes the steps providing a substrate having a front surface and a back surface; growing an epitaxial layer substantially overlying the front surface of the substrate; forming at least one barrier layer substantially within the epitaxial layer; fabricating at least one imaging structure overlying and extending into the epitaxial layer, the imaging structure at least one charge transfer region, the at least one barrier layer substantially underlying the at least one charge transfer region, wherein light incident on the back surface of the substrate generates charge carriers which are diverted away from the at least one charge transfer region by the at least one barrier layer. At least a portion of the epitaxial layer is grown using an epitaxial lateral overgrowth technique.
    Type: Grant
    Filed: August 24, 2007
    Date of Patent: August 17, 2010
    Assignee: Sarnoff Corporation
    Inventors: Pradyumna Kumar Swain, Mahalingam Bhaskaran, Peter Levine, Norman Goldsmith
  • Publication number: 20100200944
    Abstract: A method for fabricating a back-illuminated semiconductor imaging device on a semiconductor-on-insulator substrate, and resulting imaging device is disclosed. The device includes an insulator layer; a semiconductor substrate, having an interface with the insulator layer; an epitaxial layer grown on the semiconductor substrate by epitaxial growth; and one or more imaging components in the epitaxial layer in proximity to a face of the epitaxial layer, the face being opposite the interface of the semiconductor substrate and the insulator layer, the imaging components comprising junctions within the epitaxial layer; wherein the semiconductor substrate and the epitaxial layer exhibit a net doping concentration having a maximum value at a predetermined distance from the interface of the insulating layer and the semiconductor substrate and which decreases monotonically on both sides of the profile from the maximum value within a portion of the semiconductor substrate and the epitaxial layer.
    Type: Application
    Filed: April 15, 2010
    Publication date: August 12, 2010
    Inventors: Peter Alan Levine, Pradyumna Swain, Mahalingam Bhaskaran
  • Patent number: 7723215
    Abstract: A method for fabricating a back-illuminated semiconductor imaging device on a semiconductor-on-insulator substrate, and resulting imaging device is disclosed. The device includes an insulator layer; a semiconductor substrate, having an interface with the insulator layer; an epitaxial layer grown on the semiconductor substrate by epitaxial growth; and one or more imaging components in the epitaxial layer in proximity to a face of the epitaxial layer, the face being opposite the interface of the semiconductor substrate and the insulator layer, the imaging components comprising junctions within the epitaxial layer; wherein the semiconductor substrate and the epitaxial layer exhibit a net doping concentration having a maximum value at a predetermined distance from the interface of the insulating layer and the semiconductor substrate and which decreases monotonically on both sides of the profile from the maximum value within a portion of the semiconductor substrate and the epitaxial layer.
    Type: Grant
    Filed: May 23, 2007
    Date of Patent: May 25, 2010
    Assignee: Sarnoff Corporation
    Inventors: Peter Alan Levine, Pradyumna Swain, Mahalingam Bhaskaran
  • Publication number: 20100032783
    Abstract: A method for fabricating a back-illuminated semiconductor imaging device on a semiconductor-on-insulator substrate, and resulting imaging device is disclosed.
    Type: Application
    Filed: October 15, 2009
    Publication date: February 11, 2010
    Inventors: Pradyumna Kumar Swain, Mahalingam Bhaskaran, Peter Alan Pal Levine
  • Publication number: 20090294883
    Abstract: A method for fabricating a back-illuminated imager which has a pinned back surface is disclosed. A first insulator layer is formed overlying a mechanical substrate. A conductive layer is deposited overlying the first insulator layer. A second insulator layer is formed overlying the conductive layer to form a first structure, an interface being formed between the conductive layer and the second insulator layer, the conductive layer causing band bending proximal to the interface such that the interface is electrically pinned. Hydrogen is implanted in a separate device wafer to form a bubble layer. A final insulator layer is formed overlying the device wafer to form a second structure. The first structure and the second structure are bonded to form a combined wafer. A portion of the combined wafer is removed underlying the bubble layer to expose a seed layer comprising the semiconductor material substantially overlying the second insulator layer.
    Type: Application
    Filed: May 15, 2009
    Publication date: December 3, 2009
    Inventors: Pradyumna Kumar Swain, David Jay Cheskis, Mahalingam Bhaskaran
  • Publication number: 20090298260
    Abstract: A method for fabricating a back-illuminated semiconductor imaging device on an ultra-thin semiconductor-on-insulator substrate (UTSOI) is disclosed. The UTSOI substrate is formed by providing a handle wafer comprising a mechanical substrate and an insulator layer substantially overlying the mechanical substrate. A donor wafer is provided. Hydrogen is implanted in the donor wafer to form a bubble layer. The donor wafer is doped with at least one dopant to form a doped layer proximal to the bubble layer. The handle wafer and the donor wafer are bonded between the insulator layer of the handle wafer and a surface of the donor wafer proximal to the doped layer to form a combined wafer having a portion substantially underlying the bubble layer. The portion of the combined wafer substantially underlying the bubble layer is removed so as to expose a seed layer. An epitaxial layer is grown substantially overlying the seed layer, wherein at least one dopant diffuse into the epitaxial layer.
    Type: Application
    Filed: May 27, 2009
    Publication date: December 3, 2009
    Inventors: Rui Zhu, Peter Alan Levine, Pradyumna Kumar Swain, Mahalingam Bhaskaran
  • Patent number: 7622342
    Abstract: A method for fabricating a back-illuminated semiconductor imaging device on a semiconductor-on-insulator substrate, and resulting imaging device is disclosed. A substrate which includes an insulator layer and an epitaxial layer substantially overlying the insulator layer is provided. At least one bond pad region is formed extending into the epitaxial layer to a surface of the insulator layer. At least one bond pad is fabricated at least partially overlying the at least one bond pad region. At least one imaging component is fabricated at least partially overlying and extending into the epitaxial layer. A passivation layer is fabricated substantially overlying the epitaxial layer, the at least one bond pad, and the at least one imaging component. A handle wafer is bonded to the passivation layer. The at least a portion of the insulator layer and at least a portion of the bond pad region is etched to expose at least a portion of the at least one bond pad.
    Type: Grant
    Filed: January 28, 2008
    Date of Patent: November 24, 2009
    Assignee: Sarnoff Corporation
    Inventors: Pradyumna Kumar Swain, Mahalingam Bhaskaran, Peter Levine
  • Publication number: 20090256227
    Abstract: A method for fabricating a back-illuminated semiconductor imaging device on a semiconductor-on-insulator substrate, and resulting imaging device is disclosed. The method for manufacturing the imaging device includes the steps of providing a substrate comprising an insulator layer, and an epitaxial layer substantially overlying the insulator layer; fabricating at least one imaging component at least partially overlying and extending into the epitaxial layer; forming a plurality of bond pads substantially overlying the epitaxial layer; fabricating a dielectric layer substantially overlying the epitaxial layer and the at least one imaging component; providing a handle wafer; forming a plurality of conductive trenches in the handle wafer; forming a plurality of conductive bumps on a first surface of the handle wafer substantially underlying the conductive trenches; and bonding the plurality of conductive bumps to the plurality of bond pads.
    Type: Application
    Filed: April 28, 2009
    Publication date: October 15, 2009
    Inventors: Mahalingam Bhaskaran, Pradyumna Kumar Swain, Peter Levine, Norman Goldsmith
  • Publication number: 20090206377
    Abstract: A method and resulting device for reducing crosstalk in a back-illuminated imager is disclosed, comprising providing a substrate comprising an insulator layer and a seed layer substantially overlying the insulator layer, an interface being formed where the seed layer comes in contact with the insulator layer; forming an epitaxial layer substantially overlying the seed layer, the epitaxial layer defining plurality of pixel regions, each pixel region outlining a collection well for collecting charge carriers; and forming one of an electrical, optical, and electrical and optical barrier about the outlined collection well extending into the epitaxial layer to the interface between the seed layer and the insulator layer.
    Type: Application
    Filed: June 4, 2008
    Publication date: August 20, 2009
    Inventors: Pradyumna Kumar Swain, Mahalingam Bhaskaran
  • Patent number: 7547622
    Abstract: A method for fabricating CCD imaging structures is disclosed, comprising the steps of providing a silicon substrate; growing a dielectric layer substantially overlying the silicon substrate; depositing a first layer of polysilicon substantially overlaying the dielectric layer; removing at least a portion of the first layer of polysilicon to form a plurality of polysilicon gates and first predetermined inter-gate gaps, each of plurality of the polysilicon gates having a predetermined line width; depositing a second layer of polysilicon of a predetermined thickness substantially overlaying the plurality of polysilicon gates and the first predetermined inter-gate gaps; removing at least a portion of the second layer of polysilicon from between gates of the plurality of polysilicon gates to define a plurality of non-overlapping polysilicon gates and second predetermined inter-gate gaps that expose the dielectric layer, the second predetermined inter-gate gaps being smaller than the first predetermined inter-gate
    Type: Grant
    Filed: October 4, 2007
    Date of Patent: June 16, 2009
    Assignee: Sarnoff Corporation
    Inventors: Pradyumna Kumar Swain, David Arthur Furst, Mahalingam Bhaskaran
  • Patent number: 7541256
    Abstract: A method for fabricating a back-illuminated semiconductor imaging device on a semiconductor-on-insulator substrate, and resulting imaging device is disclosed. The method for manufacturing the imaging device includes the steps of providing a substrate comprising an insulator layer, and an epitaxial layer substantially overlying the insulator layer; fabricating at least one imaging component at least partially overlying and extending into the epitaxial layer; forming a plurality of bond pads substantially overlying the epitaxial layer; fabricating a dielectric layer substantially overlying the epitaxial layer and the at least one imaging component; providing a handle wafer; forming a plurality of conductive trenches in the handle wafer; forming a plurality of conductive bumps on a first surface of the handle wafer substantially underlying the conductive trenches; and bonding the plurality of conductive bumps to the plurality of bond pads.
    Type: Grant
    Filed: July 18, 2007
    Date of Patent: June 2, 2009
    Assignee: Sarnoff Corporation
    Inventors: Pradyumna Kumar Swain, Peter Levine, Mahalingam Bhaskaran, Norman Goldsmith