Atomic layer etching of GaN and other III-V materials

Patent metadata

Field	Value
Publication number	US-10056264-B2
Application number	US-201615173358-A
Country	US
Kind code	B2
Filing date	Jun 3, 2016
Priority date	Jun 5, 2015
Publication date	Aug 21, 2018
Grant date	Aug 21, 2018

Abstract

Provided herein are ALE methods of removing III-V materials such as gallium nitride (GaN) and related apparatus. In some embodiments, the methods involve exposing the III-V material to a chlorine-containing plasma without biasing the substrate to form a modified III-V surface layer; and applying a bias voltage to the substrate while exposing the modified III-V surface layer to a plasma to thereby remove the modified III-V surface layer. The disclosed methods are suitable for a wide range of applications, including etching processes for trenches and holes, fabrication of HEMTs, fabrication of LEDs, and improved selectivity in etching processes.

First claim

What is claimed is:

1. A method of etching a III-V material on a substrate, comprising:
a) exposing the III-V material to a chlorine-containing plasma without biasing the substrate to form a modified III-V surface layer, wherein the chlorine-containing plasma includes essentially no ionic species; and
b) applying a bias voltage to the substrate while exposing the modified III-V surface layer to an inert plasma to thereby remove the modified III-V surface layer.

2. The method of claim 1 , further comprising repeating (a) and (b) one or more times.

3. The method of claim 1 , wherein the bias voltage is at a level such that the removal is in a self-limiting regime.

4. The method of claim 1 , wherein the chlorine-containing plasma is generated from a process gas including a boron-containing compound, wherein about 0.5% to 10% (volumetric) of the process gas is the boron-containing compound.

5. The method of claim 1 , further comprising performing one or more additional cycles of (a) and (b), wherein the bias voltage is lowered during the one or more additional cycles.

6. The method of claim 1 , wherein the III-V material is GaN.

7. The method of claim 6 , wherein GaN is removed without removing an underlayer.

8. The method of claim 7 , wherein the underlayer is AlGaN.

9. The method of claim 1 , wherein the bias voltage is between about 20 V and 120 V.

10. The method of claim 1 , wherein the bias voltage is between about 50 V and 120 V.

11. The method of claim 1 , wherein the bias voltage is between about 50 V and 100 V.

12. The method of claim 1 , wherein the chlorine-containing plasma is generated from a mixture of a chlorine-containing gas and a boron-containing gas.

13. The method of claim 1 , wherein the chlorine-containing plasma is generated from a mixture of a Cl 2 and BCl 3 .

14. The method of claim 1 , wherein the inert plasma in (b) is an argon-containing plasma.

15. The method of claim 1 , wherein the bias voltage is at level such that the etch is selective to an underlying material.

16. A method of etching a III-V material on a substrate, comprising:
a) exposing the III-V material to a chlorine-containing plasma without biasing the substrate to form a modified III-V surface layer, wherein the chlorine-containing plasma is generated from a mixture of Cl 2 and BCl 3 , wherein about 0.5% to 10% (volumetric) of the mixture is BCl 3 and the remainder is Cl 2 ; and
b) applying a bias voltage to the substrate while exposing the modified III-V surface layer to an inert plasma to thereby remove the modified III-V surface layer.

17. The method of claim 16 , wherein about 5% of the mixture is BCl 3 .

18. A method of selectively etching a first III-V material relative to a second III-V material that underlies the first III-V on a substrate, comprising:
(a) exposing the first III-V material to a chlorine-containing plasma without biasing the substrate to form a first modified III-V surface layer,
(b) applying a first bias voltage to the substrate while exposing the first modified III-V surface layer to an inert plasma to thereby remove the first modified III-V surface layer,
(c) after (b), exposing the first III-V material to a chlorine-containing plasma without biasing the substrate to form a second modified III-V surface layer,
(d) applying a second bias voltage to the substrate while exposing the second modified III-V surface layer to an inert plasma to thereby remove the second modified III-V surface layer, wherein the second bias voltage is lower than the first bias voltage.

19. The method of claim 18 , wherein at the first bias voltage, the etch selectivity of the first III-V material relative to the second III-V material is less than infinity.

20. The method of claim 19 , wherein at the second bias voltage, the etch selectivity of the first III-V material relative to the second III-V material is infinity.

Assignees

• Lam Res Corp

Inventors

• Yang Wenbing
• Ohba Tomihito
• Tan Samantha
• Kanarik Keren Jacobs
• Marks Jeffrey
• Nojiri Kazuo

Classifications

• H10P72/0468

  comprising a chamber adapted to a particular process · CPC title

• H10P50/246 Primary

  of Group III-V materials · CPC title

• H10P50/20

  Dry etching; Plasma etching; Reactive-ion etching · CPC title

• H10P50/242 Primary

  of Group IV materials · CPC title

• H01J37/321

  the radio frequency energy being inductively coupled to the plasma · CPC title