SELF LIMITING LATERAL ATOMIC LAYER ETCH

• US 20170178917A1
• Filed: 03/01/2017
• Published: 06/22/2017
• 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
• Granted Patent: US 10,714,354 B2
• Time in Patent Office: Days
• 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. An apparatus for processing a substrate, the apparatus comprising:

a process chamber;

one or more gas inlets fluidly connected with the process chamber;

a gas box for mixing process gases prior to flowing the process gases to the chamber, the gas box fluidly connected with the process chamber via the one or more gas inlets;

a mixing chamber for mixing ammonia with one or more of the process gases, the mixing chamber separate from the gas box and fluidly connected with the process chamber via the one or more gas inlets.

2. The apparatus of claim 1, wherein the mixing chamber is a mixing manifold.

3. The apparatus of claim 1, further comprising a set of parallel valves used to switch injection location to the process chamber of the process gases from the gas box and/or the mixing chamber.

4. The apparatus of claim 3, wherein the valves are configured such that ammonia mixed in the mixing manifold can be flowed to the process chamber via the one or more gas inlets, and one of the one or more gas inlets can introduce gas from the side of the process chamber.

5. The apparatus of claim 3, wherein the valves are configured such that ammonia mixed in the mixing manifold can be flowed to the process chamber via the one or more gas inlets, and one of the one or more gas inlets can introduce gas from the top of the process chamber.

6. The apparatus of claim 1, further comprising flow-control hardware associated with the one or more gas inlets and mixing chamber, and a controller having at least one processor and a memory, wherein,

the at least one processor and the memory are communicatively connected with one another,

the at least one processor is at least operatively connected with the flow-control hardware, and

the memory stores computer-executable instructions for controlling the at least one processor to at least control the flow-control hardware by:

(i) flowing a fluorine-containing etchant gas to the process chamber housing a substrate to selectively etch an oxidized layer on the substrate;

(ii) heating the substrate to remove non-volatile solid etch byproducts by sublimation.

7. The apparatus of claim 6, wherein the memory further includes instructions for flowing ammonia from the mixing chamber to the process chamber during the flowing of the fluorine-containing etchant.

8. The apparatus of claim 6, wherein the memory further includes instructions for repeating (i) and (ii).

9. The apparatus of claim 7, wherein the memory further includes instructions for repeating (i) and (ii).

10. The apparatus of claim 6, wherein the memory further includes instructions for (iii) flowing an oxidant to the process chamber to oxidize a semiconductor layer of the substrate.

11. The apparatus of claim 6, wherein the memory further includes instructions for purging the process chamber after exposing the substrate to the fluorine-containing gas.

12. The apparatus of claim 6, wherein the memory further includes instructions for flowing a hydrogen-containing gas to the process chamber during the flowing of the fluorine-containing etchant.

13. The apparatus of claim 10, further comprising a plasma generator, wherein the memory further includes igniting a plasma during (iii).

14. The apparatus of claim 1, wherein the process chamber is set at a chamber pressure less than about 10 Torr.

15. The apparatus of claim 14, wherein the process chamber is set at a chamber pressure between about 5 mTorr and about 400 mTorr.

16. The apparatus of claim 6, wherein the substrate has a feature in a semiconductor material defined by a patterned hard mask on the substrate surface, and the instructions further comprise:

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

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

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

17. The apparatus of claim 16, wherein according to the instructions the substrate is etched laterally.

18. The method of claim 16, wherein according to the instructions the oxidation, reaction and sublimation operations are cycled to remove semiconductor material in monolayer increments.

19. The method of claim 16, wherein according to the instructions the starting and ending profile of the etched portion of the feature has linear edges.

20. The method of claim 16, wherein the semiconductor material is laterally etched under the hard mask.