Self limiting lateral atomic layer etch

• US 9,620,376 B2
• Filed: 08/19/2015
• Issued: 04/11/2017
• Est. Priority Date: 08/19/2015
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Kamp, Tom, Rastgar, Neema, Drymon, Michael Carl
• Primary Examiner(s): Ahmed, Shamim
• Application Number:
  US14/830,661
• Publication Number:
  US 20170053808A1
• Time in Patent Office: 601 Days
• Field of Search: 438690, 438739
• CPC Class Codes: H01J 2237/334 Etching
• CPC Class Codes: H01J 37/32091 the radio frequency energy being capacitively coupled to the plasma
• CPC Class Codes: H01J 37/321 the radio frequency energy being inductively coupled to the plasma
• CPC Class Codes: H01J 37/3211 Antennas, e.g. particular shapes of coils
• CPC Class Codes: H01J 37/32449 Gas control, e.g. control of the gas flow
• CPC Class Codes: H01L 21/0223 formation by oxidation, e.g. oxidation of the substrate
• CPC Class Codes: H01L 21/02238 silicon in uncombined form, i.e. pure silicon
• CPC Class Codes: H01L 21/3065 Plasma etching; Reactive-ion etching
• CPC Class Codes: H01L 21/3081 characterised by their composition, e.g. multilayer masks, materials
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/67069 for drying etching

Abstract

Methods of and apparatuses for laterally etching semiconductor substrates using an atomic layer etch process involving exposing an oxidized surface of a semiconductor substrate to a fluorine-containing etch gas and heating the substrate to remove non-volatile etch byproducts by a sublimation mechanism are provided herein. Methods also including additionally pulsing a hydrogen-containing gas when pulsing the fluorine-containing etch gas. Apparatuses also include an ammonia mixing manifold suitable for separately preparing and mixing ammonia for use in various tools.

Claims

1. A method of etching a substrate comprising a semiconductor material, the method comprising:

providing a patterned semiconductor substrate having a feature in a semiconductor material defined by a patterned hard mask of the substrate surface;

exposing the substrate to an oxidant to conformally oxidize a surface of the feature in the semiconductor material to form an oxidized surface;

exposing the substrate to a fluorine-containing gas to isotropically etch the oxidized surface of the substrate in a self-limiting reaction selective to non-oxidized semiconductor material; and

heating the substrate to remove non-volatile solid etch byproducts by sublimation;

such that the profile of the etched portion of the feature is maintained.

2. The method of claim 1, wherein the substrate is etched laterally.

3. The method of claim 1, wherein the substrate is heated to a temperature between about 60°

C. and about 300°

C. to remove the non-volatile solid etch byproducts.

4. The method of claim 1, wherein the starting and ending profile of the etched portion of the feature has linear edges.

5. The method of claim 4, wherein the oxidation, reaction and sublimation operations are cycled to remove semiconductor material in monolayer increments.

6. The method of claim 1, wherein the oxidant is a gas selected from the group consisting of oxygen, ozone, silicon oxide, carbon monoxide, carbon dioxide, and nitrous oxide.

7. The method of claim 1, wherein the oxidant is a plasma generated from a gas selected from the group consisting of oxygen, ozone, silicon oxide, carbon monoxide, carbon dioxide, and nitrous oxide.

8. The method of claim 1, further comprising exposing the oxidized layer to a hydrogen-containing gas during the exposing of the substrate to a fluorine-containing gas.

9. The method of claim 1, wherein the semiconductor layer is exposed to the oxidant at a temperature between about −

60°

C. and about 250°

C.

10. The method of claim 5, wherein the semiconductor material is laterally etched under the hard mask.

11. The method of claim 1, wherein the semiconductor layer is exposed to the oxidant at a chamber pressure between about 5 mTorr and about 400 mTorr.

12. The method of claim 1, wherein the fluorine-containing gas is selected from the group consisting of nitrogen trifluoride and sulfur trifluoride.

13. The method of claim 1, wherein the oxidized layer is selectively etched when a chuck holding the substrate is set at a temperature between about −

60°

C. and about 100°

C.

14. The method of claim 8, wherein the flow rate ratio of the fluorine-containing gas to the hydrogen-containing gas is between about 1:

1 and 10;

1.

15. The method of claim 5, wherein the substrate is processed without breaking vacuum.

16. The method of claim 4, wherein the hard mask comprises nitride.