# US 2014/0154875 A1 · Method of epitaxial germanium tin alloy surface preparation

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- Number: US 2014/0154875 A1
- Document ID: US20140154875A1
- Status: Published application
- Kind: A1
- Application number: 14/175,527
- Filed: 2014-02-07
- Published: 2014-06-05
- Earliest claimed: 2012-04-26
- Assignees: Applied Materials, Inc.
- Applicants: Applied Materials, Inc.
- Inventors: Errol Antonio C. SANCHEZ; Yi-Chiau HUANG
- Web page: https://patentgrep.com/patent/US20140154875A1

## CPC

- H10P 14/3602: {In-situ cleaning}
- H10P 14/24: using chemical vapour deposition [CVD]
- H10P 14/3211: {Silicon, silicon germanium or germanium}
- H10P 14/3212: {including tin}
- H10P 14/3411: {Silicon, silicon germanium or germanium}
- H10P 14/3412: {including tin}
- H10P 14/3442: {N-type}
- H10P 14/3444: {P-type}
- H10P 50/242: {of Group IV materials}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

Methods of preparing a clean surface of germanium tin or silicon germanium tin layers for subsequent deposition are provided. An overlayer of Ge, doped Ge, another GeSn or SiGeSn layer, a doped GeSn or SiGeSn layer, an insulator, or a metal can be deposited on a prepared GeSn or SiGeSn layer by positioning a substrate with an exposed germanium tin or silicon germanium tin layer in a processing chamber, heating the processing chamber and flowing a halide gas into the processing chamber to etch the surface of the substrate using either thermal or plasma assisted etching followed by depositing an overlayer on the substantially oxide free and contaminant free surface. Methods can also include the placement and etching of a sacrificial layer, a thermal clean using rapid thermal annealing, or a process in a plasma of nitrogen trifluoride and ammonia gas.

## Claims

### Claim 1

A method of preparing a surface, comprising:
heating a substrate in a processing chamber to a first temperature, the substrate comprising a layer comprising Ge and Sn;
removing contaminants from a surface of the layer comprising Ge and Sn; and
depositing a second layer on the surface of the layer comprising Ge and Sn.

### Claim 2 (depends on 1)

The method of claim 1, wherein removing the contaminants comprises using an etching gas.

### Claim 3 (depends on 2)

The method of claim 2, wherein the etching gas is delivered to the layer comprising Ge and Sn at a temperature greater than 300° C.

### Claim 4 (depends on 2)

The method of claim 2, wherein the etching gas comprises a halide gas.

### Claim 5 (depends on 1)

The method of claim 1, wherein the first temperature is from 300° C. to 400° C.

### Claim 6 (depends on 1)

The method of claim 1, wherein the layer comprising Ge and Sn further comprises a dopant.

### Claim 7 (depends on 6)

The method of claim 6, wherein the dopant comprises phosphorus (P), boron (B), or arsenic (As).

### Claim 8 (depends on 1)

The method of claim 1, wherein the second layer comprises Ge, doped Ge, GeSn, SiGeSn, doped GeSn, or doped SiGeSn.

### Claim 9

A method of preparing a surface, comprising:
heating a substrate in a processing chamber to a first temperature, the substrate comprising a layer comprising Ge and Sn;
forming a sacrificial layer on the surface of the layer comprising Ge and Sn;
transferring the substrate to a second processing chamber; and
removing the sacrificial layer.

### Claim 10 (depends on 9)

The method of claim 9, wherein the sacrificial layer is from 20 Å to 40 Å thick.

### Claim 11 (depends on 9)

The method of claim 9, wherein the sacrificial layer is removed using an etching gas comprising a halide gas.

### Claim 12 (depends on 9)

The method of claim 9, wherein the first temperature is from 300° C. to 400° C.

### Claim 13 (depends on 9)

The method of claim 9, wherein the sacrificial layer is formed at a temperature between about 150° C. and about 500° C.

### Claim 14 (depends on 9)

The method of claim 9, wherein the layer comprising Ge and Sn comprises a dopant.

### Claim 15 (depends on 9)

The method of claim 9, wherein the dopant comprises phosphorus (P), boron (B), or arsenic (As).

### Claim 16

A method of preparing a surface, comprising:
heating a substrate in a processing chamber to a first temperature, the substrate comprising a layer comprising Ge and Sn;
delivering an activated gas comprising ammonia and nitrogen trifluoride gas to the surface of the substrate, the nitrogen-containing gas forming one or more salts on a surface of the layer comprising Ge and Sn;
heating the substrate to a second temperature to sublimate the one or more salts, creating a cleaned surface; and
depositing a second layer on top of the cleaned surface, wherein the second layer comprises Ge, doped Ge, a GeSn layer, a SiGeSn layer, a doped GeSn layer, a doped SiGeSn layer, an insulator, or a metal.

### Claim 17 (depends on 16)

The method of claim 16, wherein the activated reactive gas is delivered at a temperature from 20° C. to 60 ° C.

### Claim 18 (depends on 16)

The method of claim 16, wherein the one or more salts are sublimated at a temperature from 80° C. to 150 ° C.

### Claim 19 (depends on 16)

The method of claim 16, wherein the activated reactive gas is introduced under vacuum.

### Claim 20 (depends on 16)

The method of claim 16, wherein the ammonia to nitrogen trifluoride are introduced in the processing chamber at a molar ratio of from 5:1 (ammonia to nitrogen trifluoride) to 30:1.