Multi-layered gate for a CMOS imager
First Claim
Patent Images
1. A pixel sensor cell for use in an imaging device, said pixel sensor cell comprising:
- a photosensitive region of a first conductivity type formed on a substrate;
a floating diffusion region of a second conductivity type formed in the substrate and spaced from said photosensitive region;
a first insulating layer formed on said substrate;
a first gate formed on said first insulating layer over said photosensitive region, said first gate comprising a first conductive layer on a first portion of said first insulating layer, a second insulating layer on the first conductive layer, and insulating spacers for defining structure in said substrate, said insulating spacers being formed on the sides of said first gate; and
a second gate formed on a second portion of said first insulating layer, said second portion of said first insulating layer overlying said structure in said substrate, and said second gate comprising a semitransparent conductive layer formed on said second insulating layer and extending at least partially over said first gate.
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Abstract
A multi-layered gate for use in a CMOS or CCD imager formed with a second gate at least partially overlapping it. The multi-layered gate is a complete gate stack having an insulating layer, a conductive layer, an optional silicide layer, and a second insulating layer, and has a second gate formed adjacent to it which has a second conductive layer that extends at least partially over the surface of the multi-layered gate. The multi-layered gate has improved insulation, thereby resulting in fewer shorts between the conductive layers of the two gates. Also disclosed are processes for forming the multi-layered gate and the overlapping gate.
370 Citations
66 Claims
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1. A pixel sensor cell for use in an imaging device, said pixel sensor cell comprising:
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a photosensitive region of a first conductivity type formed on a substrate;
a floating diffusion region of a second conductivity type formed in the substrate and spaced from said photosensitive region;
a first insulating layer formed on said substrate;
a first gate formed on said first insulating layer over said photosensitive region, said first gate comprising a first conductive layer on a first portion of said first insulating layer, a second insulating layer on the first conductive layer, and insulating spacers for defining structure in said substrate, said insulating spacers being formed on the sides of said first gate; and
a second gate formed on a second portion of said first insulating layer, said second portion of said first insulating layer overlying said structure in said substrate, and said second gate comprising a semitransparent conductive layer formed on said second insulating layer and extending at least partially over said first gate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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37. A pixel sensor cell for use in an imaging device, said pixel sensor cell comprising:
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a photosensitive region of a first conductivity type formed in a substrate;
a floating diffusion region of a second conductivity type formed in the substrate and spaced from said photosensitive region;
a first insulating layer formed on the substrate;
a first gate formed on said first insulating layer over said photosensitive region, said first gate comprising a first conductive layer on said first insulating layer, a second insulating layer on the first conductive layer, and insulating spacers formed on the sides of said first gate; and
a second gate formed on said first insulating layer, said second gate comprising a semitransparent conductive layer formed on said first insulating layer and extending at least partially over said first gate. - View Dependent Claims (38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51)
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52. A pixel sensor cell for use in an imaging device, said pixel sensor cell comprising:
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a photosensitive region of a first conductivity type formed in a substrate;
a floating diffusion region of a second conductivity type formed in the substrate and spaced from said photosensitive region;
a first insulating layer formed on the substrate;
a first gate formed on said first insulating layer over said photosensitive region, said first gate comprising a first conductive layer on said first insulating layer, a second insulating layer on the first conductive layer, and insulating spacers formed on the sides of said first gate; and
a second gate formed on said second insulating layer, said second gate comprising a semitransparent conductive layer formed on said second insulating layer and extending at least partially over said first gate. - View Dependent Claims (53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66)
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Specification