Shaped etch profile with oxidation

• US 10,403,507 B2
• Filed: 02/03/2017
• Issued: 09/03/2019
• Est. Priority Date: 02/03/2017
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Choi, Tom, Ko, Jungmin, Ingle, Nitin
• Primary Examiner(s): Spalla, David C
• Application Number:
  US15/424,181
• Publication Number:
  US 20180226259A1
• Time in Patent Office: 942 Days
• CPC Class Codes: H01J 37/32091 the radio frequency energy being capacitively coupled to the plasma
• CPC Class Codes: H01J 37/32357 Generation remote from the workpiece, e.g. down-stream
• CPC Class Codes: H01J 37/3244 Gas supply means
• CPC Class Codes: H01J 37/32568 Relative arrangement or disposition of electrodes; moving means
• CPC Class Codes: H01L 21/02238 silicon in uncombined form, i.e. pure silicon
• CPC Class Codes: H01L 21/02252 formation by plasma treatment, e.g. plasma oxidation of the substrate after treatment of an insulating film by plasma H01L21/3105 and subgroups
• CPC Class Codes: H01L 21/3065 Plasma etching; Reactive-ion etching
• CPC Class Codes: H01L 21/3086 characterised by the process involved to create the mask, e.g. lift-off masks, sidewalls, or to modify the mask, e.g. pre-treatment, post-treatment
• CPC Class Codes: H01L 21/31116 by dry-etching

Abstract

Processing methods may be performed to form recesses in a semiconductor substrate. The methods may include oxidizing an exposed silicon surface on a semiconductor substrate within a processing region of a semiconductor processing chamber. The methods may include forming an inert plasma within the processing region of the processing chamber. Effluents of the inert plasma may be utilized to modify the oxidized silicon. A remote plasma may be formed from a fluorine-containing precursor to produce plasma effluents. The methods may include flowing the plasma effluents to the processing region of the semiconductor processing chamber. The methods may also include removing the modified oxidized silicon from the semiconductor substrate. The methods may include isotropically etching a silicon-containing material from the semiconductor substrate.

Claims

1. An etching method comprising:

oxidizing an exposed silicon surface on a semiconductor substrate within a processing region of a semiconductor processing chamber;

forming an inert plasma within the processing region of the semiconductor processing chamber;

damaging at least part of the oxidized silicon with effluents of the inert plasma;

forming a remote plasma from a fluorine-containing precursor to produce plasma effluents;

flowing the plasma effluents to the processing region of the semiconductor processing chamber;

removing the damaged oxidized silicon from the semiconductor substrate; and

isotropically etching a silicon-containing material from the semiconductor substrate.

2. The etching method of claim 1, wherein the inert plasma comprises a helium plasma.

3. The etching method of claim 1, wherein the inert plasma is formed from a bias power below about 100 W.

4. The etching method of claim 1, wherein the surface of the oxidized silicon on the semiconductor substrate is damaged to a depth from the surface within the semiconductor substrate of greater than about 5 nm.

5. The etching method of claim 1, wherein a pressure within the semiconductor processing chamber while forming the inert plasma and during the damaging is maintained below about 3 Torr.

6. The etching method of claim 1, wherein the remote plasma is formed in a region of the semiconductor processing chamber fluidly isolated from the processing region of the semiconductor processing chamber or is formed in a remote plasma unit fluidly coupled with the semiconductor processing chamber.

7. The etching method of claim 1, wherein the semiconductor substrate is maintained at a temperature above or about 80°

C. during the removal of the damaged oxidized silicon.

8. The etching method of claim 7, wherein removing the damaged oxidized silicon exposes an undamaged portion of oxidized silicon, and wherein an etching selectivity of a damaged portion of the oxidized silicon to the undamaged portion of the oxidized silicon is greater than or about 100:

1.

9. The etching method of claim 1, wherein the oxidizing comprises:

forming an oxygen-based plasma within the processing region of the semiconductor processing chamber; and

contacting the exposed silicon surface with plasma effluents of the oxygen-based plasma.

10. The etching method of claim 1, wherein the remote plasma is additionally formed from a hydrogen-containing precursor.

11. The etching method of claim 1, wherein isotropically etching the silicon-containing material comprises contacting the silicon-containing material with radical effluents of a fluorine-containing precursor.

12. An etching method comprising:

oxidizing an exposed silicon surface on a semiconductor substrate within a processing region of a semiconductor processing chamber to produce a region of silicon oxide;

forming an inert plasma within a processing region of a semiconductor processing chamber;

damaging at least a portion of the region of silicon oxide with effluents of the inert plasma;

contacting the damaged silicon oxide with plasma effluents of a first fluorine-containing precursor to remove silicon oxide;

exposing silicon beneath the silicon oxide; and

etching the silicon with plasma effluents of a second fluorine-containing precursor, wherein the oxidizing, damaging, contacting, and etching are all performed in the semiconductor processing chamber.

13. The etching method of claim 12, wherein the etching is performed at a temperature of about 100°

C.

14. The etching method of claim 12, wherein the plasma effluents of the first fluorine-containing precursor and second fluorine-containing precursor are formed in a remote region of the semiconductor processing chamber fluidly coupled with, and physically separated from, the processing region of the semiconductor processing chamber, or in a remote plasma unit.

15. The etching method of claim 12, wherein plasma effluents of the second fluorine-containing precursor further include plasma effluents of a hydrogen-containing precursor.

16. The etching method of claim 12, wherein the damaged silicon oxide is additionally contacted with a hydrogen-containing precursor.

17. The etching method of claim 16, wherein the hydrogen-containing precursor bypasses the remote region of the semiconductor processing chamber, and wherein the hydrogen-containing precursor interacts with the plasma effluents of the fluorine-containing precursor subsequent to the plasma effluents of the fluorine-containing precursor exiting the remote region of the semiconductor processing chamber.