Backside structure for BSI image sensor
First Claim
1. A method for forming an image sensor, comprising:
- forming an anti-reflective coating over and in direct contact with a first semiconductor surface of a semiconductor, the semiconductor supporting a photodiode adjacent to a second surface of the semiconductor opposite the first surface of the semiconductor, wherein the anti-reflective coating is a single material with a constant thickness throughout the anti-reflective coating;
forming an etching stop layer in direct physical contact with the single material;
forming a buffer oxide over the etching stop layer; and
selectively removing a portion of the buffer oxide through etching, the etching stop layer protecting the anti-reflective coating during the etching.
1 Assignment
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Accused Products
Abstract
An embodiment method for forming an image sensor includes forming an anti-reflective coating over a surface of a semiconductor supporting a photodiode, forming an etching stop layer over the anti-reflective coating, forming a buffer oxide over the etching stop layer, and selectively removing a portion of the buffer oxide through etching, the etching stop layer protecting the anti-reflective coating during the etching. An embodiment image sensor includes a semiconductor disposed in an array region and in a periphery region, the semiconductor supporting a photodiode in the array region, an anti-reflective coating disposed over a surface of the semiconductor, an etching stop layer disposed over the anti-reflective coating, a thickness of the etching stop layer over the photodiode in the array region less than a thickness of the etching stop layer in the periphery region, and a buffer oxide disposed over the etching stop layer in the periphery region.
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Citations
20 Claims
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1. A method for forming an image sensor, comprising:
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forming an anti-reflective coating over and in direct contact with a first semiconductor surface of a semiconductor, the semiconductor supporting a photodiode adjacent to a second surface of the semiconductor opposite the first surface of the semiconductor, wherein the anti-reflective coating is a single material with a constant thickness throughout the anti-reflective coating; forming an etching stop layer in direct physical contact with the single material; forming a buffer oxide over the etching stop layer; and selectively removing a portion of the buffer oxide through etching, the etching stop layer protecting the anti-reflective coating during the etching. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for forming an image sensor, comprising:
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forming an anti-reflective coating over and in direct contact with a surface of a semiconductor, wherein the anti-reflective coating is dielectric material throughout the anti-reflective coating and the semiconductor supporting a photodiode for a back-side image sensor; forming an etching stop layer over and in direct contact with the anti-reflective coating; forming a buffer oxide over and in direct contact with the etching stop layer; forming a metal shield over and in direct contact with the buffer oxide; disposing a mask over and in direct contact with a portion of the metal shield to define a periphery region and an array region, the array region including the photodiode; and removing the metal shield and the buffer oxide in the array region through etching, the etching stop layer protecting the anti-reflective coating in the array region during the etching. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A method for forming an image sensor, comprising:
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providing a substrate, the substrate having an array area and a periphery area, the substrate having a photosensitive element along a first surface of the substrate in the array area; forming an anti-reflective coating in direct physical contact with a second surface of the substrate, wherein the anti-reflective coating comprises a single material throughout the anti-reflective coating and the second surface is a surface of semiconductor material; forming an etching stop layer in direct physical contact with the anti-reflective coating; forming a buffer oxide layer over the etching stop layer, wherein the buffer oxide layer has a high etch selectivity relative to the etching stop layer; forming a metal shield over the buffer oxide layer; forming a patterned mask over the metal shield, the patterned mask exposing at least a portion of the array area; and removing the metal shield from the array area. - View Dependent Claims (18, 19, 20)
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Specification