Sarnoff Corporation

Sri International

Mahalingam Bhaskaran

Pradyumna Kumar Swain

Peter Alan Levine

Norman Goldsmith

Rui Zhu

David Jay Cheskis

Levine Peter Alan

David Arthur Furst

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.

Method for electronically pinning a back surface of a back-illuminated imager fabricated on a UTSOI wafer

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. 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.

Dark current reduction in back-illuminated imaging sensors

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.

Methods of fabricating back-illuminated imaging sensors

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.

Method of fabricating back-illuminated imaging sensors

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. The seed layer and the epitaxial layer of the device have a net dopant concentration profile which has an initial maximum value at the interface of the seed layer and the insulator layer and which decreases monotonically with increasing distance from an interface within an initial portion of the semiconductor substrate and the epitaxial layer.

Method and device for reducing crosstalk in back illuminated imagers

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.

Method of fabricating back-illuminated imaging sensors using a bump bonding technique

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. At the completion of the growing of the epitaxial layer, there exists a net dopant concentration in the seed layer and the epitaxial layer which has maximum value at or near an interface between the seed layer and the insulator layer.

Back-illuminated imager using ultra-thin silicon on insulator substrates

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. In a second embodiment, a drain region of the second conductivity type is positioned substantially extending into at least a portion of the front side of the substrate; a barrier region of the first conductivity type positioned substantially underlying about the drain region; and a channel region of the second conductivity type positioned substantially underlying and about the barrier region. The channel region, the barrier region, and the drain region are formed by ion implantation.

Anti-blooming structures for back-illuminated imagers

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. The barrier layer can be a high energy implant formed substantially within the epitaxial layer, an optical shield made of an optically opaque material surrounded by oxide on all sides, or a combination of both. The imaging structure can be a CCD or CMOS imaging structure.

Method and apparatus for reducing smear in back-illuminated imaging sensors

Dark current reduction in back-illuminated imaging sensors and method of fabricating same

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.

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 gaps.

Fabrication of CCD image sensors using single layer polysilicon

A method for fabricating a back-illuminated semiconductor imaging device on a thin semiconductor-on-insulator substrate, and resulting imaging device. Resulting device has a monotonically varying doping profile which provides a desired electric field and eliminates a dead band proximate to the backside surface.

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Lawrenceville, NJ, United States of America

Mahalingam Bhaskaran