Photo-sensor cross-section for increased quantum efficiency
First Claim
1. An integrated circuit having a photo-sensing element, the photo-sensing element comprising:
- (a) a first region formed within a substrate defining a horizontal substrate plane; and
(b) a second region located within the first region, wherein;
a cross-section of the photo-sensing element vertical to the substrate plane defines;
(1) a set of interior side-wall interfaces between the first region and the second region;
(2) a set of exterior side-wall interfaces between the first region and the substrate; and
(3) a set of one or more horizontal interfaces between the first region and the substrate, such that a horizontal line can be drawn through the vertical cross-section that would cross a first exterior side-wall interface, followed by a first interior side-wall interface, followed by a second interior side-wall interface, followed by a second exterior side-wall interface; and
the second region is contiguous with the substrate.
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Accused Products
Abstract
Photo-sensors, such as photo-diodes, are formed using regions with cross-sections that increase the overall quantum efficiency of the resulting photo-sensor. The cross-sections have additional (e.g., interior) side-wall interfaces, and, in some embodiments, an additional, relatively shallow bottom interface. The increased total side-wall area and any additional shallow bottom area increase the total photo-junction volume located near the surface of the device. As a result, a greater fraction of photons having relatively small absorption lengths (e.g., blue light) will be absorbed within a photo-junction, thereby increasing the quantum efficiency for those photons. The present invention enables photo-sensors to be implemented with more uniform spectral response.
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Citations
12 Claims
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1. An integrated circuit having a photo-sensing element, the photo-sensing element comprising:
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(a) a first region formed within a substrate defining a horizontal substrate plane; and
(b) a second region located within the first region, wherein;
a cross-section of the photo-sensing element vertical to the substrate plane defines;
(1) a set of interior side-wall interfaces between the first region and the second region;
(2) a set of exterior side-wall interfaces between the first region and the substrate; and
(3) a set of one or more horizontal interfaces between the first region and the substrate, such that a horizontal line can be drawn through the vertical cross-section that would cross a first exterior side-wall interface, followed by a first interior side-wall interface, followed by a second interior side-wall interface, followed by a second exterior side-wall interface; and
the second region is contiguous with the substrate. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for fabricating an integrated circuit having a photo-sensing element comprising:
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forming a first region formed within a substrate defining a horizontal substrate plane; and
forming a second region located within the first region, wherein;
a cross-section of the photo-sensing element vertical to the substrate plane defines;
a set of interior side-wall interfaces between the first region and the second region;
a set of exterior side-wall interfaces between the first region and the substrate; and
a set of one or more horizontal interfaces between the first region and the substrate, such that a horizontal line can be drawn through the vertical cross-section that would cross a first exterior side-wall interface, followed by a first interior side-wall interface, followed by a second interior side-wall interface, followed by a second exterior side-wall interface; and
the second region is contiguous with the substrate. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification