# US 10,374,057 B2 · Method of forming metal contacts in the barrier layer of a group III-N HEMT

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- Number: US 10,374,057 B2
- Document ID: US10374057B2
- Status: Granted
- Kind: B2
- Application number: 15/730,853
- Filed: 2017-10-12
- Published: 2018-02-01
- Granted: 2019-08-06
- Earliest claimed: 2013-04-03
- Assignees: Texas Instruments Incorporated
- Applicants: Texas Instruments Incorporated
- Inventors: Yoshikazu Kondo; Shoji Wada; Hiroshi Yamasaki; Masahiro Iwamoto
- Web page: https://patentgrep.com/patent/US10374057B2

## CPC

- H10D 30/015: {of FETs having heterojunction interface channels or heterojunction gate electrodes, e.g. HEMT}
- H10D 62/85: being Group III-V materials, e.g. GaAs
- H10D 62/8503: {Nitride Group III-V materials, e.g. AlN or GaN}
- H10D 64/0116: {to Group III-V semiconductors}
- H10D 64/256: {for lateral devices wherein the source or drain electrodes are recessed in semiconductor bodies (source or drain electrodes of TFTs H10D30/673)}
- H10D 64/62: Electrodes ohmically coupled to a semiconductor
- H10P 14/40: of conductive or resistive materials
- H10P 50/246: {of Group III-V materials}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

Metal contact openings are etched in the barrier layer of a group III-N HEMT with a first gas combination that etches down into the barrier layer, and a second gas combination that etches further down into the barrier layer to a depth that lies above the top surface of a channel layer that touches and lies below the barrier layer.

## Claims

### Claim 1

A method of forming a high electron mobility transistor comprising:
forming a channel layer over a substrate;
forming a barrier layer over the channel layer, the barrier layer including a GaN material;
etching the GaN material of the barrier layer with a gas combination that includes boron trichloride (BCl3) and sulfur hexafluoride (SF6) to form a number of metal contact openings, each of the metal contact openings having a bottom surface that lies above and spaced apart from a top surface of the channel layer; and
etching the GaN material of the barrier layer exposed by the metal contact openings with a gas combination that includes boron trichloride (BCl3) and chlorine (Cl2) to deepen each metal contact opening to a second bottom surface, the second bottom surface lying above and spaced apart from the top surface of the channel layer.

### Claim 2 (depends on 1)

The method of claim 1, further comprising depositing a metal contact layer that contacts each second bottom surface and fills the metal contact openings.

### Claim 3 (depends on 2)

The method of claim 2, further comprising planarizing the metal contact layer to form a number of spaced-apart metal contacts that lie in the number of metal contact openings.

### Claim 4 (depends on 1)

The method of claim 1, wherein the gas combination that includes BCl3 and SF6 also etches through a cap layer over the barrier layer, and through a passivation layer over the cap layer.

### Claim 5 (depends on 4)

The method of claim 4, wherein the cap layer includes GaN and the passivation layer includes silicon nitride.

### Claim 6 (depends on 1)

The method of claim 1, wherein the gas combination that includes BCl3 and SF6 also etches through a passivation layer over the barrier layer.

### Claim 7 (depends on 6)

The method of claim 6, wherein the passivation layer includes silicon nitride.

### Claim 8 (depends on 1)

The method of claim 1, wherein the channel layer includes GaN.

### Claim 9 (depends on 1)

The method of claim 1, wherein the GaN material of the barrier layer is AlGaN.