# US 2021/0242031 A1 · Method for using ultra-thin etch stop layers in selective atomic layer etching

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- Number: US 2021/0242031 A1
- Document ID: US20210242031A1
- Status: Published application
- Kind: A1
- Application number: 17/164,649
- Filed: 2021-02-01
- Published: 2021-08-05
- Earliest claimed: 2020-02-03
- Assignees: Tokyo Electron Limited; University of Colorado Boulder
- Applicants: Tokyo Electron Limited; University of Colorado Boulder
- Inventors: Omid Zandi; Paul Abel; Jacques Faguet; David Zywotko; Steven M. George
- Web page: https://patentgrep.com/patent/US20210242031A1

## CPC

- H10P 50/283: {by chemical means}
- H10P 50/285: {of materials not containing Si, e.g. PZT or Al2O3}
- H10P 14/6339: {deposition by cyclic CVD, e.g. ALD, ALE or pulsed CVD}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

Method for selective etching of materials using an ultrathin etch stop layer (ESL), where the ESL is effective at a thickness as small as approximately one monolayer using atomic layer etching (ALE). A substrate processing method includes depositing a first film on a substrate, depositing a second film on the first film, and selectively etching the second film relative to the first film using an ALE process, where the etching self-terminates at an interface of the second film and the first film.

## Claims

### Claim 1

A substrate processing method, comprising:
depositing a first film on a substrate;
depositing a second film on the first film; and
selectively etching the second film relative to the first film using an atomic layer etching (ALE) process, wherein the etching self-terminates at an interface of the second film and the first film.

### Claim 2 (depends on 1)

The method of claim 1, wherein the ALE process includes alternating gaseous exposures of a first reactant and a second reactant.

### Claim 3 (depends on 2)

The method of claim 2, wherein the ALE process includes a thermal ALE process that is performed without plasma excitation of the first reactant and the second reactant.

### Claim 4 (depends on 1)

The method of claim 1, wherein the first and second films are dielectric films.

### Claim 5 (depends on 1)

The method of claim 1, wherein the first and second films include different metal oxide films that are selected from the group consisting of Al2O3, ZrO2, and HfO2.

### Claim 6 (depends on 1)

The method of claim 1, wherein the second film includes an Al2O3 film.

### Claim 7 (depends on 6)

The method of claim 6, wherein the Al2O3 film is deposited using alternating gas exposures of Al(CH3)3 and H2O in an atomic layer deposition (ALD) process.

### Claim 8 (depends on 1)

The method of claim 1, wherein the ALE process includes alternating gaseous exposures of 1) HF and 2) Sn(acac)2, Al(CH3)3, Al(CH3)2Cl, SiCl4, or TiCl4.

### Claim 9 (depends on 1)

The method of claim 1, wherein the first film includes a ZrO2 film.

### Claim 10 (depends on 9)

The method of claim 9, wherein the ZrO2 film has a uniform thickness of approximately one monolayer.

### Claim 11 (depends on 9)

The method of claim 9, wherein the ZrO2 film is deposited using alternating gas exposures of ZrCl4 and H2O in an atomic layer deposition (ALD) process.

### Claim 12 (depends on 1)

The method of claim 1, further comprising:
following the removing, etching the first film using an additional ALE process.

### Claim 13 (depends on 12)

The method of claim 12, wherein the ALE process includes alternating gaseous exposures of a first reactant and a second reactant, and the additional ALE process includes alternating gaseous exposures of the first reactant and a third reactant that is different than the second reactant.

### Claim 14 (depends on 13)

The method of claim 13, wherein the ALE process and the additional ALE process are performed without plasma excitation of the first reactant, the second reactant, and the third reactant.

### Claim 15 (depends on 13)

The method of claim 13, wherein the first film includes a ZrO2 film, the second film includes an Al2O3 film, the first reactant includes HF, the second reactant includes Al(CH3)3, and the third reactant includes Al(CH3)2Cl.

### Claim 16

A substrate processing method, comprising:
providing a substrate containing a first film on a substrate and a second film on the first film;
initiating etching of the second film using a thermal atomic layer etching (ALE) process that selectively etches the second film relative to the first film;
removing the second film using the ALE process, wherein the etching self-terminates at an interface of the second film and the first film; and
following the removing, etching the first film using an additional ALE process, wherein the ALE process includes alternating gaseous exposures of a first reactant and a second reactant, and the additional ALE process includes alternating gaseous exposures of the first reactant and a third reactant that is different than the second reactant, and wherein the ALE process and the additional ALE process are performed without plasma excitation of the first reactant, the second reactant, and the third reactant.

### Claim 17

A substrate processing method, comprising:
depositing a ZrO2 film on a substrate;
depositing a Al2O3 film on the ZrO2 film;
initiating etching of the Al2O3 film using a thermal atomic layer etching (ALE) process that selectively etches the Al2O3 film relative to the ZrO2 film; and
removing the Al2O3 film using the thermal ALE process, wherein the etching self-terminates at an interface of the Al2O3 film and the ZrO2 film.

### Claim 18 (depends on 17)

The method of claim 17, wherein the thermal ALE process includes alternating gaseous exposures of HF and Al(CH3)3.

### Claim 19 (depends on 17)

The method of claim 17, wherein ZrO2 film has a uniform thickness of approximately one monolayer.

### Claim 20 (depends on 17)

The method of claim 17, further comprising:
following the removing, etching the ZrO2 film using an additional thermal ALE process that includes alternating gaseous exposures of HF and Al(CH3)2Cl.