Dual EPI active pixel cell design and method of making the same
AssigneeInternational Business Machines Corporation
InventorsTerence B. Hook, Hon-Sum P. Wong
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Abstract
The present invention is a dual epi active pixel sensor cell having a p− region of dual thickness and a method of making the same. The dual epi active pixel sensor cell produces a sensor with improved noise and latch-up reduction and improved red absorption. The thin p− epi region is positioned in the logic region for improved latch-up immunity. The thick p− epi is position in the pixel region for improved red absorption.
Claims11
A method of making an active pixel sensor device comprising the steps of:
- (a) providing a p type wafer substrate having a p+ region and a p− epitaxy region wherein a portion of said p+ and p− epitaxy region defines a logic region and another portion of said p+ and p− epitaxy regions defines a pixel region;
- (b) implanting a p+ region in said p− epitaxy region positioned in said logic region;
- and
- (c) creating a p− epitaxy layer on said substrate above said logic and pixel regions to form a thin p− region in said logic region and a thick p− region in said pixel region.
A method of making an active pixel sensor device comprising the steps of:
- (a) providing a p+ wafer substrate region wherein a portion of said p+ region defines a logic region and another portion of said p+ region defines a pixel region;
- (b) etching said pixel region;
- (c) growing p− silicon in said pixel region;
- and
- (d) creating a p− epitaxy layer on said substrate above said logic and pixel regions to form a thin p− region in said logic region and a thick p− region in said pixel region.
A method of making an active pixel sensor device comprising the steps of:
- (a) providing a semiconductor substrate doped at a first concentration;
- (b) forming a doped layer having a surface positioned above the substrate, the doped layer being doped at a second concentration and extending a first distance below the surface in a logic region and a second distance below the surface in a pixel region, the second distance being greater than the first distance;
- (c) constructing at least one photosensitive device in the doped layer in the pixel region and at least one logic device in the doped layer in the logic region.
Dependencies are inferred from the claim text.