Method for Manufacturing CMOS Image Sensor

Abstract

A method for manufacturing a CMOS image sensor capable of improving a low illumination characteristic is provided. The method includes: forming a photodiode and a gate poly of a transfer transistor on a semiconductor substrate; depositing a spacer material on the semiconductor substrate including the photodiode and the gate poly of the transfer transistor; and implanting p-type impurity ions in an upper portion of the photodiode through the spacer material deposited on the photodiode. Embodiments of the subject method can prevent ion damage of a surface of the photodiode caused by a dry etching process for forming spacers at sidewalls of the gate poly of a transfer transistor from occurring, which may improve a low illumination characteristic of the image sensor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings:

FIG. 1 is an equivalent circuit diagram of a 4T CMOS image sensor according to the related art;

FIGS. 2 through 4 are cross-sectional views of a CMOS image sensor for describing a method of manufacturing a CMOS image sensor according to the related art; and

FIGS. 5A through 5D are cross-sectional views of a CMOS image sensor for describing a method of manufacturing a CMOS image sensor according to an embodiment of the present invention.

Claims

1. A method for manufacturing a CMOS (complementary metal oxide silicon) image sensor comprising: forming a photodiode and a gate poly of a transfer transistor on a semiconductor substrate;depositing spacer material on the semiconductor substrate including the photodiode and the gate poly of the transfer transistor; andimplanting p-type impurity ions in an upper surface portion of the photodiode through the spacer material deposited on the photodiode.

2. The method according to claim 1, wherein the spacer material is a nitride layer or an oxide layer.

3. The method according to claim 1, wherein implanting the p-type impurity ions in an upper surface portion of the photodiode, comprises: forming a mask pattern on the semiconductor substrate exposing the spacer material on the photodiode; andimplanting p-type impurity ions through the spacer material into the upper surface portion of the photodiode using the mask pattern as a mask.

4. A method for manufacturing a CMOS (complementary metal oxide silicon) image sensor comprising: preparing a semiconductor substrate in which a device isolation region and an active region are defined;forming a gate poly at a predetermined part of the active region;implanting an n-type impurity ion in the active region at one side of the gate poly to form a photodiode having a predetermined depth;depositing spacer material on the semiconductor substrate including the photodiode and the gate poly; andimplanting a p-type impurity ions in an upper surface of the photodiode through the spacer material deposited on the photodiode.

5. The method according to claim 4, wherein the active region is made of a p-type semiconductor.

6. The method according to claim 4, wherein the spacer material is a nitride layer or an oxide layer.

7. The method according to claim 4, wherein the gate poly is a gate poly of a transfer transistor for a CMOS image sensor.

8. The method according to claim 4, wherein implanting the p-type impurity ions in an upper surface of the photodiode comprises: forming a mask pattern on the semiconductor substrate exposing the spacer material on the photodiode; andimplanting p-type impurity ions through the spacer material into the upper surface of the photodiode using the mask pattern as a mask.