Superposed multi-junction color APS

• US 6,455,833 B1
• Filed: 03/09/2000
• Issued: 09/24/2002
• Est. Priority Date: 03/09/1999
• Status: Active Grant

• Current Assignee: Aptina Imaging Corporation (ON Semiconductor Corporation)
• Original Assignee: Micron Technology, Inc.
• Inventors: Berezin, Vladimir
• Primary Examiner(s): PYO, KEVIN K
• Application Number:
  US09/522,286
• Time in Patent Office: 929 Days
• Field of Search: 250/208.1, 250/226, 250/214.1, 250/216, 257/431, 257/440, 257/443, 257/461, 348/272, 348/274, 348/276, 348/277, 348/308
• US Class Current: 250/208.1
• CPC Class Codes: G01J 3/50 using electric radiation detectors
• CPC Class Codes: H01L 27/14647 Multicolour imagers having a stacked pixel-element structure, e.g. npn, npnpn or MQW elements

Abstract

A CMOS image sensor obtains color through the use of two or three superposed layers. Each pixel in the image sensor includes a plurality of superposed photosensitive p-n junctions with individual charge integration regions. The combination of each of the superposed layers provides increased sensitivity and resolution of a single chip color imager.

Claims

1. A photosensor comprising:

a first charge collection region having a first absorption length; and

a second charge collection region having a second absorption length, wherein the first charge collection region and the second charge collection region are superposed;

wherein each of the first and second charge collection regions is connected to an individually controlled, dedicated reset transistor and an individually controlled, dedicated output transistor.

2. The photosensor of claim 1, further comprising a third charge collection region having a third absorption length, wherein the third charge collection region is superposed with the first and second charge collection region, wherein the third charge collection regions is connected to an individually controlled, dedicated reset transistor and an individually controlled, dedicated output transistor.

3. The photosensor of claim 1, wherein the first charge collection region is sensitive to light of a first color.

4. The photosensor of claim 1, wherein the second charge collection region is sensitive to light of a second color.

5. The photosensor of claim 2, wherein the third charge collection region is sensitive to light of a third color.

6. The photosensor of claim 1, wherein the photosensor uses a 4:

2;

2 sampling standard.

7. A method of generating color in an active pixel sensor comprising:

generating light of a first color in a first charge collection region;

generating light of a second color in a second charge collection region;

outputting the light with an individually controlled, dedicated reset transistor and an individually controlled, dedicated output transistor for each of the first and second charge collection regions; and

superposing the light of the first color with the light of the second color.

8. The method of claim 7, further comprising:

generating light of a third color in a third charge collection region;

outputting the light with an individually controlled, dedicated reset transistor and an individually controlled, dedicated output transistor for the third charge collection region; and

superposing the light of the third color with the light of the first and second color.