Image sensor with an improved sensitivity
AssigneesSTMicroelectronics S.r.l., STMicroelectronics (Crolles 2) SAS
InventorsPerceval COUDRAIN, Philippe CORONEL, Xavier BELREDON
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Abstract
An embodiment of an image sensor comprising photosensitive cells, each photosensitive cell comprising at least one charge storage means formed at least partly in a substrate of a semiconductor material. The substrate comprises, for at least one first photosensitive cell, a portion of a first silicon and germanium alloy having a first germanium concentration, possibly zero, and for at least one second photosensitive cell, a portion of a second silicon and germanium alloy having a second germanium concentration, non-zero, greater than the first germanium concentration.
Claims42
An image sensor comprising photosensitive cells, each photosensitive cell comprising at least one charge storage means formed at least partly in a substrate of a semiconductor material, wherein the substrate comprises, for at least one first photosensitive cell, a portion of a first silicon and germanium alloy having a first germanium concentration, possibly zero, and for at least one second photosensitive cell, a portion (of a second silicon and germanium alloy having a second germanium concentration, non-zero, strictly greater than the first germanium concentration.
A method for manufacturing an image sensor comprising photosensitive cells, comprising the steps of:
- (a) providing a single-crystal silicon layer;
- (b) forming, at least partly in said layer, for at least one first photosensitive cell, a portion of a first silicon and germanium alloy having a first germanium concentration, possibly zero, and, for at least one second photosensitive cell, a portion of a second silicon and germanium alloy having a second non-zero germanium concentration strictly greater than the first germanium concentration;
- and
- (c) forming, for each photosensitive cell, a charge storage means at least partly in the layer.
An integrated circuit, comprising:
- a substrate;
- a layer disposed over the substrate and having a first region doped with a first concentration of germanium;
- and
- a first photo detector having a first portion disposed in the substrate beneath the first region of the layer.
The integrated circuit of 11 wherein:
- the first wavelength comprises one of a red, a green, and a blue wavelength;
- and
- the second wavelength comprises another of a red, a green, and a blue wavelength.
A system, comprising:
- an image sensor, including
- a substrate,
- a layer disposed over the substrate and having a first region doped with a first concentration of germanium, and
- a first photo detector having a first portion disposed in the substrate beneath the first region of the layer;
- and
- a controller coupled to the image sensor.
A photo cell, comprising:
- a photo detector;
- and
- a semiconductor region disposed over the photo detector and including germanium.
A method, comprising:
- forming a first semiconductor region having a first level of germanium;
- forming a second semiconductor region having a second level of germanium;
- forming a first photo detector in optical alignment with the first region of the layer;
- and
- forming a second photo detector in optical alignment with the second region of the layer.
Dependencies are inferred from the claim text.