# US 9,520,433 B1 · Method of fabricating deep trench isolation structure in image sensor and device thereof

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- Number: US 9,520,433 B1
- Document ID: US9520433B1
- Status: Granted
- Kind: B1
- Application number: 14/839,617
- Filed: 2015-08-28
- Granted: 2016-12-13
- Earliest claimed: 2015-08-28
- Assignees: Taiwan Semiconductor Manufacturing Company, Ltd.
- Applicants: Taiwan Semiconductor Manufacturing Co., Ltd.
- Inventors: Hsin-Hung Chen; Dun-Nian Yaung; Jen-Cheng Liu; Alexander Kalnitsky; Wen-De Wang
- Web page: https://patentgrep.com/patent/US9520433B1

## CPC

- H10F 39/807: {Pixel isolation structures}
- H10F 39/011: {Manufacture or treatment of image sensors covered by group H10F39/12}
- H10F 39/199: {Back-illuminated image sensors}
- H10F 39/811: {Interconnections}
- H10W 10/0145: {of trenches having shapes other than rectangular or V-shape (H10W10/0143 takes precedence)}
- H10W 10/021: {of air gaps}
- H10W 10/17: formed using trench refilling with dielectric materials, e.g. shallow trench isolations
- H10W 10/20: Air gaps
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

A method includes forming a deep trench isolation structure on a substrate, the substrate having a back surface opposite to a front surface, the deep trench isolation structure opening toward the front surface. An oxide layer is formed on the front surface of the substrate and sidewalls and bottom of the deep trench isolation structure. The oxide layer on the front surface of the substrate is removed. A portion of the substrate at the opening of the deep trench isolation structure is removed and an epitaxial layer is formed on the substrate.

## Claims

### Claim 1

A method of fabricating image sensor device comprising:
forming a deep trench isolation structure on a substrate, the substrate having a back surface opposite to a front surface, the deep trench isolation structure opening toward the front surface;
forming an oxide layer on the front surface of the substrate and sidewalls and a bottom of the deep trench isolation structure;
removing the oxide layer on the front surface of the substrate;
removing a portion of the substrate at the opening of the deep trench isolation structure; and
forming an epitaxial layer on the substrate.

### Claim 2 (depends on 1)

The method of claim 1, wherein the deep trench isolation structure and the epitaxial layer collectively defines an air chamber.

### Claim 3 (depends on 2)

The method of claim 2, wherein the oxide layer is below a level of the front surface of the substrate.

### Claim 4 (depends on 1)

The method of claim 1, wherein removing the portion of the substrate at the opening of the deep trench isolation structure further comprises:
chamfering the oxide layer at the opening of the deep trench isolation structure to reveal the substrate.

### Claim 5 (depends on 1)

The method of claim 1, wherein forming the epitaxial layer further comprises:
forming the epitaxial layer from two opposite ends on the front surface of the substrate; and
merging the epitaxial layer atop the opening of the deep trench isolation structure.

### Claim 6 (depends on 5)

The method of claim 5, wherein forming the epitaxial layer on the substrate further comprises:
depositing a first upper epitaxial layer over the merged epitaxial layer.

### Claim 7 (depends on 1)

The method of claim 1, wherein forming the epitaxial layer on the substrate further comprises:
thinning the substrate from the back surface through to the deep trench isolation structure;
forming a front oxide layer on the epitaxial layer; and
disposing a conductive material in the deep trench isolation structure.

### Claim 8 (depends on 1)

The method of claim 1 further comprising:
treating the epitaxial layer with a temperature higher than 500° C.

### Claim 9 (depends on 1)

The method of claim 1, wherein the opening of the deep trench isolation structure is sealed by the epitaxial layer.

### Claim 10 (depends on 5)

The method of claim 5 further comprises:
forming a first upper epitaxial layer on the epitaxial layer.

### Claim 11 (depends on 5)

The method of claim 5, wherein merging the epitaxial layer atop the opening of the deep trench isolation structure further comprises:
effecting the epitaxial layer crossing the opening of the deep trench isolation structure.

### Claim 12 (depends on 5)

The method of claim 5, wherein forming the epitaxial layer from two opposite ends on the front surface of the substrate further comprises:
effecting the epitaxial layer going over the front surface and the deep trench isolation structure.

### Claim 13 (depends on 7)

The method of claim 7, wherein forming the front oxide layer on the epitaxial layer further comprises:
merging the oxide layer on the sidewalls of the deep trench isolation structure with the front oxide layer.

### Claim 14 (depends on 1)

The method of claim 1, wherein thinning the substrate from the back surface through to the deep trench isolation structure further comprises:
allowing access of the deep trench isolation structure from the back surface of the substrate.

### Claim 15 (depends on 1)

The method of claim 1, wherein the substrate and the oxide layer have different etching rates.

### Claim 16 (depends on 1)

The method of claim 1, wherein the oxide layer is a thermal oxide layer.

### Claim 17 (depends on 1)

The method of claim 1, wherein forming the deep trench isolation structure on the substrate comprises:
forming a hard mask material on the front surface; and
patterning the hard mask material.

### Claim 18 (depends on 1)

The method of claim 1, wherein the deep trench isolation structure has a depth of approximately 1 to 3 μm.

### Claim 19 (depends on 1)

The method of claim 1, wherein the substrate has a thickness ranging from 100 μm to 2000 μm.

### Claim 20 (depends on 1)

The method of claim 1, wherein the substrate is a device substrate.