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US 8,076,197 B2Granted
Image sensor and method for fabricating the same
AssigneeIntellectual Ventures II LLC
InventorHan-Seob Cha
Life of this patent
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Abstract
A CMOS image sensor includes a substrate including silicon, a silicon germanium (SiGe) epitaxial layer formed over the substrate, the SiGe epitaxial layer formed through epitaxial growth and doped with a predetermined concentration level of impurities, an undoped silicon epitaxial layer formed over the SiGe epitaxial layer by epitaxial growth, and a photodiode region formed from a top surface of the undoped silicon epitaxial layer to a predetermined depth in the SiGe epitaxial layer.
Claims28
A method, comprising:
- growing a first epitaxial layer over a substrate of an image sensor;
- doping the first epitaxial layer with a predetermined concentration level of impurities;
- growing an undoped second epitaxial layer over the first epitaxial layer;
- and
- using an ion implantation process to form a photodiode region from a top surface of the undoped second epitaxial layer to a predetermined depth in the first epitaxial layer.
2 more elements
A method, comprising:
- using a first epitaxial growth process to form a first SiGe epitaxial layer on a substrate of an image sensor such that the first SiGe epitaxial layer has a Ge concentration that varies based on distance from a top surface of the substrate;
- using a second epitaxial growth process to form a second SiGe epitaxial layer over the first SiGe epitaxial layer;
- using a third epitaxial growth process to form a third SiGe epitaxial layer over the second SiGe epitaxial layer;
- using another epitaxial growth process to form a silicon epitaxial layer over the third SiGe epitaxial layer;
- and
- using an ion implanting process to form a photodiode region in the silicon epitaxial layer and the third SiGe epitaxial layer.
3 more elements
A method, comprising:
- forming a silicon germanium (SiGe) epitaxial layer on a top surface of a substrate of an image sensor such that a germanium (Ge) concentration gradually increases over a portion of the SiGe epitaxial layer in a direction away from the top surface of the substrate;
- forming a silicon (Si) epitaxial layer on the SiGe epitaxial layer;
- and
- implanting a photodiode region into the Si epitaxial layer and the SiGe epitaxial layer.
1 more element
Dependencies are inferred from the claim text.