# US 2010/0167459 A1 · Method for fabricating cmos image sensor

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- Number: US 2010/0167459 A1
- Document ID: US20100167459A1
- Status: Published application
- Kind: A1
- Application number: 12/648,829
- Filed: 2009-12-29
- Published: 2010-07-01
- Earliest claimed: 2008-12-29
- Inventors: Chung-Kyoung Jung
- Web page: https://patentgrep.com/patent/US20100167459A1

## CPC

- H10F 39/024: {of coatings or optical elements}
- H10F 39/026: {Wafer-level processing}
- H10F 39/8053: {Colour filters}
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION

## Abstract

A method for fabricating a CMOS image sensor which reduces occurrence of a dark current. The method includes forming a photodiode in a semiconductor substrate, forming an insulating film over and contacting the semiconductor substrate and the photodiode, respectively, forming a hard mask film over and contacting the insulating film, exposing an area of the insulating film corresponding spatially to the photodiode by performing a first etching process on the hard mask film, and then forming a trench in the insulating film by performing a second etching process using the etched hard mask film as a mask.

## Claims

### Claim 1

A method comprising:
forming a plurality of photodiodes in a semiconductor substrate at fixed intervals;
forming an interlayer insulating film over an entire surface of the semiconductor substrate including the photodiodes;
forming a hard mask film over an entire surface of the interlayer insulating film;
forming a photoresist pattern over the hard mask film for exposing a hard mask film region corresponding to a photodiode region;
etching the hard mask film by performing a first etching process using the photoresist pattern as a mask; and then
selectively etching the interlayer insulating film by performing a second etching process using the etched hard mask film as a mask.

### Claim 2 (depends on 1)

The method of claim 1, wherein the first etching process comprises a dry etching process.

### Claim 3 (depends on 1)

The method of claim 1, wherein the second etching process comprises a wet etching process.

### Claim 4 (depends on 3)

The method of claim 3, wherein the wet etching process is performed using DHF.

### Claim 5 (depends on 4)

The method of claim 4, wherein the DHF has a ratio of H2O:HF of 1 to 5:1.

### Claim 6 (depends on 1)

The method of claim 1, wherein the hard mask film comprises PE-Nitride.

### Claim 7 (depends on 1)

The method of claim 1, wherein selectively etching the interlayer insulating film comprises forming a trench in the interlayer insulating film.

### Claim 8

A method comprising:
forming a photodiode in a semiconductor substrate;
forming an insulating film over and contacting the semiconductor substrate and the photodiode, respectively;
forming a hard mask film over and contacting the insulating film;
exposing an area of the insulating film corresponding spatially to the photodiode by performing a first etching process on the hard mask film; and then
forming a trench in the insulating film by performing a second etching process using the etched hard mask film as a mask.

### Claim 9 (depends on 8)

The method of claim 8, wherein the photodiode has an uppermost surface that is substantially coplanar to the uppermost surface of the semiconductor substrate.

### Claim 10 (depends on 8)

The method of claim 8, wherein the semiconductor substrate comprises a p++ type semiconductor substrate.

### Claim 11 (depends on 8)

The method of claim 8, wherein the insulating film comprises an oxide film.

### Claim 12 (depends on 11)

The method of claim 11, wherein the oxide film comprises undoped silicate glass.

### Claim 13 (depends on 8)

The method of claim 8, wherein the hard mask film comprises PE-Nitride.

### Claim 14 (depends on 8)

The method of claim 8, wherein the trench corresponds spatially to the photodiode.

### Claim 15 (depends on 8)

The method of claim 8, wherein the first etching process comprises a dry etching process.

### Claim 16 (depends on 8)

The method of claim 8, wherein the second etching process comprises a wet etching process.

### Claim 17 (depends on 16)

The method of claim 16, wherein the wet etching process is performed using DHF

### Claim 18 (depends on 17)

The method of claim 17, wherein the DHF has a ratio of H2O:HF of 1 to 5:1.

### Claim 19

A method comprising:
forming a photodiode in a semiconductor substrate;
forming an oxide film over the semiconductor substrate and the photodiode, respectively;
forming a hard mask film over the oxide film;
exposing an area of the oxide film corresponding spatially to the photodiode by performing a dry etching process on the hard mask film; and then forming a trench by performing a wet etching process on the oxide film.

### Claim 20 (depends on 19)

The method of claim 19, wherein the oxide film comprises undoped silicate glass and the hard mask film comprises PE-Nitride.