# US 10,319,603 B2 · Selective SiN lateral recess

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- Number: US 10,319,603 B2
- Document ID: US10319603B2
- Status: Granted
- Kind: B2
- Application number: 15/792,328
- Filed: 2017-10-24
- Published: 2018-04-12
- Granted: 2019-06-11
- Earliest claimed: 2016-10-07
- Assignees: Applied Materials, Inc.
- Applicants: Applied Materials, Inc.
- Inventors: Zhijun Chen; Jiayin Huang; Anchuan Wang; Nitin Ingle
- Web page: https://patentgrep.com/patent/US10319603B2

## CPC

- H10P 50/283: {by chemical means}
- H01J 37/32357: {Generation remote from the workpiece, e.g. down-stream}
- H10P 14/6519: {the substance being oxygen}
- H10P 14/69433: {the material being a silicon nitride not containing oxygen, e.g. SixNy or SixByNz}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)

## Abstract

Exemplary methods for laterally etching silicon nitride may include flowing a fluorine-containing precursor and an oxygen-containing precursor into a remote plasma region of a semiconductor processing chamber. The methods may include forming a plasma within the remote plasma region to generate plasma effluents of the fluorine-containing precursor and the oxygen-containing precursor. The methods may also include flowing the plasma effluents into a processing region of the semiconductor processing chamber. A substrate may be positioned within the processing region, and the substrate may include a trench formed through stacked layers including alternating layers of silicon nitride and silicon oxide. The methods may also include laterally etching the layers of silicon nitride from sidewalls of the trench while substantially maintaining the layers of silicon oxide. The layers of silicon nitride may be laterally etched less than 10 nm from the sidewalls of the trench.

## Claims

### Claim 1

An etching method comprising:
flowing a fluorine-containing precursor and an oxygen-containing precursor into a processing region of the semiconductor processing chamber, wherein a substrate is positioned within the processing region, and wherein the substrate comprises a trench formed through stacked layers including alternating layers of silicon nitride and silicon oxide; and
laterally etching the layers of silicon nitride from sidewalls of the trench while substantially maintaining the layers of silicon oxide, wherein the layers of silicon nitride are laterally etched less than 10 nm from the sidewalls of the trench, and wherein a temperature within the processing region is maintained below about −20° C.

### Claim 2 (depends on 1)

The etching method of claim 1, wherein a flow-rate ratio of oxygen-containing precursor to fluorine-containing precursor is greater than or about 50:1.

### Claim 3 (depends on 1)

The etching method of claim 1, wherein the stacked layers comprise at least 50 layers of alternating layers of silicon nitride and silicon oxide, and wherein the trench is characterized by an aspect ratio of greater than or about 100:1.

### Claim 4 (depends on 1)

The etching method of claim 1, wherein the lateral etching is performed at a chamber operating pressure of less than or about 1 Torr.

### Claim 5 (depends on 1)

The etching method of claim 1, wherein the layers of silicon nitride are laterally etched less than or about 6 nm.

### Claim 6 (depends on 1)

The etching method of claim 1, wherein the lateral etching comprises oxidizing a portion of the silicon nitride to produce a fluorinated oxide.

### Claim 7 (depends on 6)

The etching method of claim 6, wherein fluorine within the fluorinated oxide diffuses through the oxidized portion of the silicon nitride to laterally etch the silicon nitride.

### Claim 8 (depends on 6)

The etching method of claim 6, wherein the method further comprises removing the fluorinated oxide from the silicon nitride.

### Claim 9 (depends on 8)

The etching method of claim 8, wherein removing the fluorinated oxide comprises etching the fluorinated oxide with plasma effluents produced from a fluorine-containing precursor and a hydrogen-containing precursor.

### Claim 10 (depends on 1)

The etching method of claim 1, wherein a layer of silicon nitride at an upper region of the trench and a layer of silicon nitride at a lower region of the trench differ in lateral etch amounts by less than about 30%.

### Claim 11

An etching method comprising:
flowing a fluorine-containing precursor and an oxygen-containing precursor into a remote plasma region of a semiconductor processing chamber;
forming a plasma within the remote plasma region to generate primary plasma effluents of the fluorine-containing and oxygen-containing precursors;
flowing the primary plasma effluents into a processing region of the semiconductor processing chamber, wherein a substrate is positioned within the processing region, and wherein the substrate comprises a trench formed through stacked layers including alternating layers of silicon nitride and silicon oxide;
oxidizing a portion of the silicon nitride from sidewalls of the trench to produce a fluorinated oxide region in each layer of silicon nitride;
flowing a fluorine-containing precursor into the remote plasma region of the semiconductor processing chamber while generating a plasma to produce secondary plasma effluents;
flowing the secondary plasma effluents into the processing region of the semiconductor processing chamber; and
laterally etching the fluorinated oxide region from each layer of silicon nitride, wherein a temperature within the semiconductor processing chamber during the etching method is less than or about −20° C.

### Claim 12 (depends on 11)

The etching method of claim 11, wherein a flow-rate ratio of oxygen-containing precursor to fluorine-containing precursor used to produce the primary plasma effluents is greater than or about 60:1.

### Claim 13 (depends on 11)

The etching method of claim 11, wherein the silicon nitride is oxidized to a depth of from about 1 nm to about 8 nm.

### Claim 14 (depends on 11)

The etching method of claim 11, wherein a bottom of the trench is at least partially oxidized along with the layers of silicon nitride, and wherein the bottom of the trench is etched less than or about 5 nm.

### Claim 15 (depends on 11)

The etching method of claim 11, wherein laterally etching the fluorinated oxide region from each layer of silicon nitride further comprises flowing a hydrogen-containing precursor into the semiconductor processing chamber.

### Claim 16 (depends on 11)

The etching method of claim 11, wherein the oxidized portion of silicon nitride comprises a lower quality oxide than the layers of silicon oxide.

### Claim 17 (depends on 11)

The etching method of claim 11, wherein a layer of silicon nitride at an upper region of the trench and a layer of silicon nitride at a lower region of the trench differ in lateral etch amounts by less than about 20%.