# US 7,611,921 B2 · Method for manufacturing CMOS image sensor which improves sensitivity by removing a passivation membrane in a pixel region of the CMOS image sensor

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- Number: US 7,611,921 B2
- Document ID: US7611921B2
- Status: Granted
- Kind: B2
- Application number: 11/644,221
- Filed: 2006-12-21
- Published: 2007-06-28
- Granted: 2009-11-03
- Earliest claimed: 2005-12-28
- Assignees: Dongbu Electronics Co., Ltd.
- Inventors: Jin Han Kim
- Web page: https://patentgrep.com/patent/US7611921B2

## CPC

- H10F 39/028: {performed after manufacture of the image sensors, e.g. annealing, gettering of impurities, short-circuit elimination or recrystallisation}
- H10F 39/026: {Wafer-level processing}
- H10F 39/8063: {Microlenses}
- H10F 39/024: {of coatings or optical elements}
- H10F 39/18: Complementary metal-oxide-semiconductor [CMOS] image sensors; Photodiode array image sensors
- 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 manufacturing a CMOS image sensor is disclosed. The method includes the steps of: forming a passivation oxide and a passivation nitride after forming a pad; performing a hydrogen anneal; selectively removing the passivation nitride and cleaning the passivation oxide; opening and cleaning the pad by removing the passivation oxide from the pad region; forming a pad protection membrane; forming color filter array, planarization layer and a plurality of microlenses; and removing the pad protection membrane from the pad region. A circle defect in a pixel region may be removed according to the disclosed method for manufacturing the CMOS image sensor. Accordingly, the sensitivity of the CMOS image sensor may be increased by raising the quality of the CMOS image sensor and reducing reflectance of the light.

## Claims

### Claim 1

A method for manufacturing a CMOS image sensor, comprising:
forming a passivation oxide and a passivation nitride after forming a pad;
performing a hydrogen anneal;
selectively removing the passivation nitride directly over a pixel region of the CMOS image sensor and cleaning the passivation oxide by ashing, then cleaning with a solvent;
opening and cleaning the pad by removing the passivation oxide over the pad, wherein the step of cleaning the pad further includes the steps of ashing, solvent cleaning and secondary ashing;
forming a pad protection membrane;
forming a color filter array, a planarization layer and a plurality of microlenses; and
removing the pad protection membrane.

### Claim 2 (depends on 1)

The method as recited in claim 1, wherein the pad protection membrane comprises a plasma enhanced tetraethyl orthosilicate (PE TEOS) membrane or a thermosetting resin membrane.

### Claim 3 (depends on 2)

The method as recited in claim 2, wherein the pad protection membrane has a thickness of 200 to 600 Å.

### Claim 4 (depends on 2)

The method as recited in claim 2, wherein the pad protection membrane comprises the PE TEOS membrane, and removing the PE TEOS membrane comprises dry etching.

### Claim 5 (depends on 2)

The method as recited in claim 2, wherein the pad protection membrane comprises the thermosetting resin membrane, and removing the thermosetting resin comprises oxygen ashing.

### Claim 6 (depends on 1)

The method of claim 1, wherein the step of performing the hydrogen anneal comprises a thermal reflow using a gas mixture including hydrogen gas and nitrogen gas.

### Claim 7 (depends on 1)

The method of claim 1, wherein the step of performing the hydrogen anneal comprises a thermal reflow using a reducing gas selected from a group comprising silane and ammonia and/or a noble gas selected from a group comprising helium, neon, argon and kypton gas.

### Claim 8 (depends on 6)

The method of claim 6, wherein the step of performing the hydrogen anneal comprises a thermal reflow using a gas mixture including hydrogen and nitrogen.

### Claim 9 (depends on 6)

The method of claim 6, wherein the step of performing the hydrogen anneal comprises a thermal reflow using a reducing gas selected from a group comprising silane and ammonia and/or a noble gas selected from a group comprising helium, neon, argon and kypton.

### Claim 10 (depends on 1)

The method as recited in claim 1, wherein the color filter array, the planarization layer and the plurality of microlenses are sequentially formed on a surface of the pad protection membrane over the pixel region of the CMOS image sensor before the pad protection membrane is removed to expose the pad.

### Claim 11

A method for manufacturing a CMOS image sensor, comprising:
forming a passivation oxide and a passivation nitride over a pad in the CMOS image sensor;
selectively removing the passivation nitride directly over a pixel region of the CMOS image sensor and the pad and cleaning the passivation nitride and the passivation oxide by ashing, then cleaning with a solvent;
opening the pad by removing the passivation oxide over the pad; cleaning the pad by ashing, solvent cleaning and secondary ashing;
forming a pad protection membrane over an entire surface of the CMOS image sensor;
forming a color filter array, a planarization layer and a plurality of microlenses on the CMOS image sensor; and
removing an exposed portion the pad protection membrane.

### Claim 12 (depends on 11)

The method of claim 11, further comprising performing a hydrogen anneal.

### Claim 13 (depends on 11)

The method as recited in claim 11, wherein the pad protection membrane comprises a plasma enhanced tetraethyl orthosilicate (PE TEOS) membrane or a thermosetting resin membrane.

### Claim 14 (depends on 13)

The method as recited in claim 13, wherein the pad protection membrane has a thickness of 200 to 600 Å.

### Claim 15 (depends on 13)

The method as recited in claim 13, wherein the pad protection membrane comprises the PE TEOS membrane, and removing the PE TEOS membrane comprises dry etching.

### Claim 16 (depends on 13)

The method as recited in claim 13, wherein the pad protection membrane comprises the thermosetting resin membrane, and removing the thermosetting resin comprises oxygen ashing.

### Claim 17 (depends on 11)

The method as recited in claim 11, wherein the color filter array, the planarization layer and the plurality of microlenses are sequentially formed on a surface of the pad protection membrane over the pixel region of the CMOS image sensor before the exposed portion of the pad protection membrane is removed.

### Claim 18 (depends on 11)

The method as recited in claim 11, further comprising cleaning the pad after the removal of the passivation oxide over the pad by a second ashing.