Pixel sensor cell for use in an imaging device
First Claim
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1. A pixel sensor cell for use in an imaging device, said pixel sensor cell comprising:
- a substrate;
a first gate oxide layer formed over at least a portion of said substrate;
a first gate formed over said first gate oxide layer, said first gate comprising a first conductive layer formed over said first gate oxide layer, an insulating layer formed over the first conductive layer, a barrier metal layer formed over the first conductive layer, and insulating spacers formed on the sides of said first gate;
a second gate oxide layer separate from said first gate oxide layer formed over at least a portion of said substrate, wherein said second gate oxide layer is adjacent to an insulating spacer of said first gate and adjacent to said first gate oxide layer; and
a second gate formed over said second gate oxide layer, said second gate comprising a second conductive layer formed over said second gate oxide 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.
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Citations
41 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 substrate;
a first gate oxide layer formed over at least a portion of said substrate;
a first gate formed over said first gate oxide layer, said first gate comprising a first conductive layer formed over said first gate oxide layer, an insulating layer formed over the first conductive layer, a barrier metal layer formed over the first conductive layer, and insulating spacers formed on the sides of said first gate;
a second gate oxide layer separate from said first gate oxide layer formed over at least a portion of said substrate, wherein said second gate oxide layer is adjacent to an insulating spacer of said first gate and adjacent to said first gate oxide layer; and
a second gate formed over said second gate oxide layer, said second gate comprising a second conductive layer formed over said second gate oxide 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)
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36. A pixel sensor cell for use in an imaging device, said pixel sensor cell comprising:
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a substrate;
a first insulating layer formed over at Least a portion of said substrate;
a multi-layered transfer gate stack formed over said first insulating layer, said multi-layered transfer gate stack comprising a first conductive layer formed over said first insulating layer, a second insulating layer formed over the first conductive layer, a barrier metal layer formed over the first conductive layer, and insulating spacers formed on sides of said multi-layered transfer gate stack;
a photogate implant region formed self-aligned to an edge of said multi-layered transfer gate stack;
a gate oxide layer separate from said first insulating layer formed over at least a portion of said substrate and said photogate implant region, wherein said gate oxide layer is adjacent to an insulating spacer of said multi-layered transfer gate stack and adjacent to said first insulating layer; and
a semi-transparent photogate conductor formed over at least a portion of said multi-layered transfer gate stack, said photogate implant region and said gate oxide layer. - View Dependent Claims (37)
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38. A pixel sensor cell for use in an imaging device, said pixel sensor cell comprising:
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a substrate;
a first gate oxide layer formed over at least a portion of said substrate;
a multi-layered photogate formed over said first gate oxide layer, said multi-layered photogate comprising a first conductive layer formed over said first gate oxide layer, an insulating layer formed over the first conductive layer, and insulating spacers formed on sides of said multi-layered photogate;
a second gate oxide layer separate from said first gate oxide layer formed over at least a portion of said substrate and self-aligned to an edge of at least one insulating spacer, and adjacent to said first gate oxide layer; and
a transfer gate formed over at least a portion of said multi-layered photogate, said transfer gate comprising a second conductive layer formed over at least a portion of said second gate oxide layer and said multi-layered photogate, wherein said transfer gate further comprises a barrier metal layer formed over said second conductive layer. - View Dependent Claims (39)
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40. A pixel sensor cell for use in an imaging device, said pixel sensor cell comprising:
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a substrate;
a first gate oxide layer formed over at least a portion of said substrate;
a first gate formed over said first gate oxide layer, said first gate comprising a first conductive layer formed over said first gate oxide layer, an insulating layer formed over the first conductive layer, and insulating spacers formed on the sides of said first gate;
a second gate oxide layer separate from said first gate oxide layer formed over at least a portion of said substrate, wherein said second gate oxide layer is adjacent to an insulating spacer of said first gate and adjacent to said first gate oxide layer; and
a second gate formed over said second gate oxide layer, said second gate comprising a second conductive layer formed over said second gate oxide layer and extending at least partially over said first gate, wherein a barrier metal layer is formed over the second conductive layer.
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41. A pixel sensor cell for use in an imaging device, said pixel sensor cell comprising:
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a substrate;
a first insulating layer formed over at least a portion of said substrate;
a multi-layered transfer gate stack formed over said first insulating layer, said multi-layered transfer gate stack comprising a first conductive layer formed over said first insulating layer, a second insulating layer formed over the first conductive layer, a silicide layer formed over said first conductive layer, and insulating spacers formed on sides of said multi-layered transfer gate stack;
a photogate implant region formed self-aligned to an edge of said multi-layered transfer gate stack;
a gate oxide layer separate from said first insulating layer formed over at least a portion of said substrate and said photogate implant region, wherein said gate oxide layer is adjacent to an insulating spacer of said multi-layered transfer gate stack and adjacent to said first insulating layer; and
a semi-transparent photogate conductor formed over at least a portion of said multi-layered transfer gate stack, said photogate implant region and said gate oxide layer.
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Specification