Method of forming an elevated photodiode in an image sensor
View Patent ↗The invention provides an elevated photodiode for image sensors and methods of formation of the photodiode. Elevated photodiodes permit a decrease in size requirements for pixel sensor cells while reducing leakage, image lag and barrier problems typically associated with conventional photodiodes.
1. A method of forming a pixel sensor cell comprising:
forming a blocking layer on a first substrate layer and over at least one transistor gate;
forming a plurality of openings in the blocking layer;
growing an epitaxial layer of silicon in said plurality of openings;
etching said blocking layer after growing the epitaxial layer to form a sidewall on said at least one transistor gate.
2. The method according to claim 1 wherein said blocking layer is silicon dioxide.
3. The method according to claim 1 wherein said epitaxial layer in said plurality of openings is grown to a thickness of about 1000 §.
4. The method according to claim 1 wherein at least one of said plurality of openings is formed over a region where a photoconversion device is to be formed.
5. The method according to claim 1 wherein at least one of said plurality of openings is formed over a region where a source/drain region for a transistor having said at least one transistor gate is to be formed.
6. The method according to claim 1 further comprising etching said blocking layer to form sidewalls on a plurality of transistor gates.