CMOS image sensor and fabricating method thereof

• US 20060001043A1
• Filed: 06/29/2005
• Published: 01/05/2006
• Est. Priority Date: 07/01/2004
• Status: Abandoned Application

• Current Assignee: DONGBU ELECTRONICS CO., LTD. (DB HiTek Co., Ltd.)
• Original Assignee: Dongbuanam Semiconductor, Inc. (DB HiTek Co., Ltd.)
• Inventors: Shim, Hee Sung
• Application Number:
  US11/172,169
• Publication Number:
  US 20060001043A1
• Time in Patent Office: Days
• US Class Current: 257/183
• CPC Class Codes: H01L 27/14609 Pixel-elements with integrated switching, control, storage or amplification elements scanning details of imagers (circuitry of solid-state image sensors H04N25/00); circuitry of imagers H04N25/70
• CPC Class Codes: H01L 27/1463 Pixel isolation structures
• CPC Class Codes: H01L 27/14632 Wafer-level processed structures
• CPC Class Codes: H01L 27/14643 Photodiode arrays; MOS imagers
• CPC Class Codes: H01L 27/14687 Wafer level processing
• CPC Class Codes: H01L 27/14689 MOS based technologies

Abstract

A CMOS image sensor and fabricating method thereof are disclosed, by which a dark current can be reduced. The present invention includes a first conductive type semiconductor substrate divided into an active area and a field area, an STI layer formed in the field area to divide the first conductive type semiconductor substrate into active area and the field area, a second conductive type photodiode region formed in the active area of the first conductive type semiconductor substrate, a readout circuit formed in the active area of the first conductive type semiconductor substrate to read out data of the photodiode regions, and a first conductive type well formed between the second conductive type photodiode region and the STI layer.

Claims

1. A CMOS image sensor comprising:

a first conductive type semiconductor substrate divided into an active area and a field area;

an STI layer formed in the field area to divide the first conductive type semiconductor substrate into active area and the field area;

a second conductive type photodiode region formed in the active area of the first conductive type semiconductor substrate;

a readout circuit formed in the active area of the first conductive type semiconductor substrate to read out data of the photodiode regions; and

a first conductive type well formed between the second conductive type photodiode region and the STI layer.

2. The CMOS image sensor of claim 1, wherein the first conductive type semiconductor substrate comprises an epitaxial wafer having either a 0°

or 4°

tilt.

3. The CMOS image sensor of claim 1, further comprising a first conductive type heavily doped layer on a surface of the second conductive type photodiode regions.

4. A CMOS image sensor comprising:

a first conductive type semiconductor substrate divided into an active area and a field area;

an STI layer formed in the field area to divide the first conductive type semiconductor substrate into active area and the field area;

a second conductive type photodiode region formed in the active area of the first conductive type semiconductor substrate;

a readout circuit formed in the active area of the first conductive type semiconductor substrate to read out data of the photodiode regions; and

a first conductive type well formed between the STI layer and the active area of the first conductive semiconductor substrate.

5. The CMOS image sensor of claim 4, wherein the first conductive type semiconductor substrate comprises an epitaxial wafer having either a 0°

or 4°

tilt.

6. The CMOS image sensor of claim 4, further comprising a first conductive type heavily doped layer on a surface of the second conductive type photodiode regions.

7. A method of fabricating a CMOS image sensor, comprising the steps of:

forming a trench in a field area of a first conductive type semiconductor substrate wherein an active area and the field area are defined on the first conductive type semiconductor substrate and wherein a photodiode region and a readout circuit region to read out data of the photodiode region are defined in the active area;

forming a first conductive type well by implanting a first conductive type impurity into the trench neighboring the photodiode region; and

forming an STI layer by filling the trench with an insulating layer.

8. A method of fabricating a CMOS image sensor, comprising the steps of:

forming a trench in a field area of a first conductive type semiconductor substrate wherein an active area and the field area are defined on the first conductive type semiconductor substrate and wherein a photodiode region and a readout circuit region to read out data of the photodiode region are defined in the active area;

forming a first conductive type well by implanting a first conductive type impurity into the trench in the vicinity of the active area; and

forming an STI layer by filling the trench with an insulating layer.

9. A method of fabricating a CMOS image sensor, comprising the steps of:

preparing a first conductive type semiconductor substrate wherein an active area and a field area are defined on the first conductive type semiconductor substrate and wherein a photodiode region and a readout circuit region to read out data of the photodiode region are defined in the active area;

forming a trench in the field area;

forming a first conductive type well by implanting a first conductive type impurity into the trench in the vicinity of the active area;

forming an STI layer by filling the trench with an insulating layer;

implanting a second conductive type impurity into the photodiode region; and

heavily implanting the first conductive type impurity into a surface of the photodiode region implanted with the second conductive type impurity.