Atomic layer clean for removal of photoresist patterning scum

• US 10,494,715 B2
• Filed: 07/19/2017
• Issued: 12/03/2019
• Est. Priority Date: 04/28/2017
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Agarwal, Pulkit, Kumar, Purushottam, LaVoie, Adrien
• Primary Examiner(s): Choudhry, Mohammad M
• Application Number:
  US15/654,612
• Publication Number:
  US 20180312973A1
• Time in Patent Office: 867 Days
• CPC Class Codes: C23C 16/45527 characterized by the ALD cycle, e.g. different flows or temperatures during half-reactions, unusual pulsing sequence, use of precursor mixtures or auxiliary reactants or activations
• CPC Class Codes: C23C 16/45544 characterized by the apparatus
• CPC Class Codes: H01J 2237/334 Etching
• CPC Class Codes: H01J 37/32009 Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources plasma generation in general H05H1/24
• CPC Class Codes: H01J 37/32449 Gas control, e.g. control of the gas flow
• CPC Class Codes: H01L 21/02164 the material being a silicon oxide, e.g. SiO2
• CPC Class Codes: H01L 21/02263 deposition from the gas or vapour phase
• CPC Class Codes: H01L 21/0332 characterised by their composition, e.g. multilayer masks, materials
• CPC Class Codes: H01L 21/31138 by dry-etching
• CPC Class Codes: H10N 50/01 Manufacture or treatment

Abstract

Methods and apparatuses for removing photoresist patterning scum from patterning mandrel structures without damaging other features or structures on a semiconductor substrate are desirable for patterning precision. Methods involve cleaning carbon-containing features on a semiconductor substrate by an atomic layer cleaning (ALC) process to descum the carbon-containing features without substantially modifying feature critical dimensions. The ALC process involves exposing the carbon-containing features to an oxidant or reductant in absence of a plasma, or other energetic activation, to modify scum on the surface of the carbon-containing features. The modified scum on the surface of the carbon-containing features is then exposed to an inert gas along with a plasma ignited at a pressure between 0.1 Torr and 10 Torr and a power of less than 200 W to remove the modified scum from the surface of the carbon-containing features.

Claims

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

(a) providing to a chamber the semiconductor substrate comprising a carbon-containing material having a pattern of carbon-containing features, the carbon-containing features having on a surface a non-desirable carbon-containing residue resulting from incomplete ashing of material following lithographic processing of photoresist during prior patterning operations conducted on the carbon-containing material; and

(b) cleaning the carbon-containing features by an atomic layer cleaning (ALC) process to remove the non-desirable carbon-containing residue (scum) from the carbon-containing features without substantially modifying critical dimensions of the carbon-containing features, the ALC process comprising;

(i) exposing the carbon-containing features to an oxidant or reductant in absence of a plasma or other energetic activation to modify the scum on the surface of the carbon-containing features; and

(ii) exposing the modified scum on the surface of the carbon-containing features to an inert gas and igniting a plasma at a pressure greater than 0.1 Torr and less than 6 Torr and a power of less than 125 W to remove the modified scum from the surface of the carbon-containing features.

2. The method of claim 1, wherein the oxidant is selected from a group consisting of:

oxygen (O₂), nitrous oxide (N₂O), diols, water, ozone (O₃), alcohols, esters, ketones, carboxylic acids.

3. The method of claim 2, wherein dosing of the semiconductor substrate with the oxidant oxidatively saturates the semiconductor substrate to generate a saturated monolayer.

4. The method of claim 1 wherein (b)(i), exposure of the carbon-containing features to a reductant converts carbon in the carbon-containing features to a hydrocarbon having a chemical formula of C_XH_Y where x and y are integers greater than or equal to 1.

5. The method of claim 1, wherein the inert gas is selected from the group consisting of:

helium, nitrogen, argon, neon and combinations thereof.

6. The method of claim 1, wherein the carbon-containing features comprise mandrel structures comprising a material selected from the group consisting of spin-on carbon, photoresist, and amorphous carbon.

7. The method of claim 1, wherein the chamber is set to a chamber pressure between about 0.1 Torr and about 0.5 Torr.

8. The method of claim 1, wherein the plasma is ignited using a plasma power between about 10 W and 50 W.

9. The method of claim 1, wherein the chamber is purged with the inert gas or a vacuum after (b)(i).

10. The method of claim 9, wherein purging the chamber removes any one or more selected from a group consisting of:

oxidants, reducing agents, or liberated byproducts.

11. The method of claim 3, wherein exposing the carbon-containing features to the ignited plasma energetically activates the saturated monolayer to liberate volatile byproducts.

12. The method of claim 11, wherein the volatile byproducts are selected from a group consisting of:

carbon monoxide (CO), carbon dioxide (CO₂), and hydrocarbons having a chemical formula of C_XH_Y.

13. The method of claim 11, wherein methods of energetic plasma activation include that provided by a capacitively coupled reactor (CCP), inductively coupled reactor (ICP) or are thermal-based, ultraviolet-based, or photon-based.

14. The method of claim 11, wherein the chamber is purged with the inert gas or a vacuum after the energetic activation of the saturated monolayer by the ignited plasma to remove oxidants, reducing agents, or liberated byproducts.

15. The method of claim 1, wherein the scum on the surface of the carbon-containing features is less than 3 Å

thick.

16. The method of claim 1, wherein completing claim 1 (b)(i) and claim 1 (b)(ii) comprises an etch cycle which removes 0.5 Å

to 2 Å

of the modified scum per cycle.

18. The method of claim 1, wherein the scum comprises undesirable surface roughness remaining on the surface of the carbon-containing features after lithography.

19. The method of claim 18, wherein the scum comprises footings or stringers.

20. The method of claim 19, wherein the footings or stringers have a higher surface area to volume ratio than the carbon-containing features.

17. An apparatus for processing a semiconductor substrate, comprising:

one or more process chambers, each process chamber having a chuck;

one or more gas inlets into the process chambers and associated flow-control hardware; and

a controller having a processor and a memory, wherein

the processor and the memory are communicatively connected with one another, the processor is at least operatively connected with the flow-control hardware, and the memory stores computer-executable instructions for controlling the processor to at least control the flow-control hardware by;

cleaning a semiconductor substrate comprising a carbon-containing material having a pattern of carbon-containing features housed within at least one of the process chambers

by an atomic layer cleaning (ALC) process to remove non-desirable carbon material (scum) from the carbon-containing features without substantially modifying feature critical dimensions, the ALC process comprising;

exposing the carbon-containing features to an oxidant or reductant in absence of a plasma or other energetic activation to modify scum on a surface of the carbon-containing features; and

exposing the modified scum on the surface of the carbon-containing features to an inert gas and igniting a plasma at a pressure greater than 0.1 Torr and less than 6 Torr and a power of less than 125 W to remove the modified scum from the surface of the carbon-containing features.