# US 12,009,218 B2 · Pulsed etch process

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- Number: US 12,009,218 B2
- Document ID: US12009218B2
- Status: Granted
- Kind: B2
- Application number: 17/738,526
- Filed: 2022-05-06
- Published: 2023-11-09
- Granted: 2024-06-11
- Earliest claimed: 2022-05-06
- Assignees: Applied Materials, Inc.
- Applicants: Applied Materials, Inc.
- Inventors: Yifeng Zhou; Qian Fu
- Web page: https://patentgrep.com/patent/US12009218B2

## CPC

- H10P 50/242: {of Group IV materials}
- H01J 37/32146: {Amplitude modulation, includes pulsing}
- H01J 37/32706: {Polarising the substrate}
- 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

Described herein is a method for etching a sample. The method includes performing a plasma etch pulse. The plasma etch pulse is performed by directing a gas flow comprising silicon tetrachloride (SiCl4) and a diluent towards the sample. While directing the gas flow, a bias power is applied to achieve a bias state for a first time period. Then, a source power is applied to achieve a source state for a second time period, and then no bias power and no source power is applied to achieve a recovery state for a third time period. The plasma etch pulse is repeated until a target amount of the sample is etched.

## Claims

### Claim 1

A method of etching a sample comprising:
performing a plasma etch pulse, comprising:
directing a gas flow comprising silicon tetrachloride (SiCl4) and a diluent comprising Ar and He towards the sample;
applying a bias power to achieve a bias state for a first time period while directing the flow of the SiCl4 and the diluent towards the sample;
applying a source power to achieve a source state for a second time period; and
applying no bias power and no source power to achieve a recovery state for a third time period; and
repeating the plasma etch pulse until a target amount of the sample has been etched.

### Claim 2 (depends on 1)

The method of claim 1, wherein no source power is applied during the bias state and wherein no bias power is applied during the source state.

### Claim 3 (depends on 1)

The method of claim 1, wherein the bias power is from about 100 W to about 5000 W.

### Claim 4 (depends on 1)

The method of claim 1, wherein a bias frequency is from about 400 kHz to about 60 MHz.

### Claim 5 (depends on 1)

The method of claim 1, wherein the plasma etch pulse is performed at a pressure of about 0.1 mT to about 500 mT.

### Claim 6 (depends on 1)

The method of claim 1, wherein the plasma etch pulse is performed at a temperature of about −50° C. to about 300° C.

### Claim 7 (depends on 1)

The method of claim 1, wherein the source power is from about 100 W to about 5000 W.

### Claim 8 (depends on 1)

The method of claim 1, wherein the gas flow comprises SiCl4 in an amount of about 5 mol % to about 80 mol %.

### Claim 9 (depends on 1)

The method of claim 1, wherein the gas flow comprises Ar in an amount of about 5 mol % to about 15 mol % and He in an amount of about 5 mol % to about 90 mol %.

### Claim 10 (depends on 1)

The method of claim 1, wherein the first time period is about 10 μsec to about 1 msec, wherein the second time period is about 10 μsec to about 1 msec, and wherein the third time period is about 10 μsec to about 1 msec.

### Claim 11 (depends on 1)

The method of claim 1, where a ratio of the first time period to the second time period is about 1:10 to about 10:1.

### Claim 12 (depends on 1)

The method of claim 1, wherein a ratio of the third time period to an aggregate of the first time period and the second time period is about 1:1 to about 90:1.

### Claim 13 (depends on 1)

The method of claim 1, wherein the gas flow has a rate of about 50 sccm to about 2000 sccm.

### Claim 14 (depends on 1)

The method of claim 1, wherein a portion of the sample that is etched by the plasma etch pulse comprises a plurality of alternating layers of silicon and silicon germanium.

### Claim 15 (depends on 1)

The method of claim 1, wherein the plasma etch process causes a U-shaped profile in the sample.

### Claim 16

A method of etching a sample, comprising:
performing a plasma etch pulse, comprising:
applying a bias power to achieve a bias state for a first time period while directing a flow of a gas and a diluent towards the sample;
applying a source power to achieve a source state for a second time period; and
applying no bias power and no source power to achieve a recovery state for a third time period; and
repeating the plasma etch pulse until a target amount of the sample has been etched,
wherein no source power is applied during the bias state and wherein no bias power is applied during the source state and
wherein the gas comprises SiCl4 and the diluent comprises Ar and He.