Front side implanted guard ring structure for backside illuminated image sensor
First Claim
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1. A method of forming a backside illuminated image sensor, the method comprising:
- ion-implanting a guard ring structure of a predetermined depth in a front-side surface of a semiconductor substrate, the guard ring structure forming a two-dimensional array of pixels, each pixel of the array of pixels separated from an adjacent pixel by the guard ring structure;
forming at least one image sensing element on the front-side surface of the semiconductor substrate, the at least one image sensing element being formed in a pixel of the array of pixels and surrounded by the guard ring structure; and
reducing a thickness of the semiconductor substrate to a predetermined thickness by removing material from the back-side surface of the semiconductor substrate, wherein the thickness of the semiconductor substrate is reduced until the guard ring structure is co-planar with a back-side surface of the semiconductor substrate, whereby the guard ring structure extends from the front-side surface to the back-side surface of the semiconductor substrate having the reduced thickness.
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Abstract
An image sensor includes a semiconductor substrate, a guard ring structure in the substrate, and at least one pixel surrounded by the guard ring structure. The guard ring structure is implanted in the substrate by high-energy implantation.
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Citations
20 Claims
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1. A method of forming a backside illuminated image sensor, the method comprising:
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ion-implanting a guard ring structure of a predetermined depth in a front-side surface of a semiconductor substrate, the guard ring structure forming a two-dimensional array of pixels, each pixel of the array of pixels separated from an adjacent pixel by the guard ring structure; forming at least one image sensing element on the front-side surface of the semiconductor substrate, the at least one image sensing element being formed in a pixel of the array of pixels and surrounded by the guard ring structure; and reducing a thickness of the semiconductor substrate to a predetermined thickness by removing material from the back-side surface of the semiconductor substrate, wherein the thickness of the semiconductor substrate is reduced until the guard ring structure is co-planar with a back-side surface of the semiconductor substrate, whereby the guard ring structure extends from the front-side surface to the back-side surface of the semiconductor substrate having the reduced thickness. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An image sensor, comprising:
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a semiconductor substrate, the substrate having a front-side surface and a back-side surface opposite the front-side surface; a plurality of image sensing elements formed on the front-side surface of the substrate; and an ion-implanted guard ring structure separating each of the image sensing elements from other image sensing elements, wherein the guard ring structure extends from the front-side surface of the substrate up to the back-side surface of the substrate and a surface of the guard ring is co-planar with the back-side surface of the substrate. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A method of fabricating an image sensor device, comprising:
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forming a guard ring structure in a semiconductor substrate via ion implantation, said guard ring structure dividing the substrate into a two-dimensional array of pixels each pixel of the array of pixels separated from an adjacent pixel by the guard ring structure, wherein a surface of the guard ring structure is co-planar with a back-side surface of the substrate; forming a plurality of image sensing elements in the substrate, each of the image sensing elements being in one pixel of the two-dimensional array of pixels and surrounded by the guard ring structure; and annealing the substrate with the guard ring structure and image sensing elements formed therein. - View Dependent Claims (18, 19, 20)
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Specification