Atomic layer removal process with higher etch amount

• US 8,058,179 B1
• Filed: 12/23/2008
• Issued: 11/15/2011
• Est. Priority Date: 12/23/2008
• Status: Expired due to Fees

• Current Assignee: Novellus Systems Incorporated (LAM Research Corporation)
• Original Assignee: Novellus Systems Incorporated (LAM Research Corporation)
• Inventors: Nittala, Lakshmi, Meinhold, Henner, van Schravendijk, Bart, Draeger, Nerissa, te Nijenhuis, Harald
• Primary Examiner(s): Tran; Binh X
• Assistant Examiner(s): Cathey, Jr.; David
• Application Number:
  US12/343,102
• Time in Patent Office: 1,057 Days
• Field of Search: None
• US Class Current: 438/714
• CPC Class Codes: H01L 21/02164 the material being a silicon oxide, e.g. SiO2
• CPC Class Codes: H01L 21/02271 deposition by decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition H01L21/02266 takes precedence
• CPC Class Codes: H01L 21/02274 in the presence of a plasma [PECVD]
• CPC Class Codes: H01L 21/02337 treatment by exposure to a gas or vapour
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/76837 Filling up the space between adjacent conductive structures; Gap-filling properties of dielectrics

Abstract

Higher overall etch rate and throughput for atomic layer removal (ALR) is achieved. The reaction is a self-limiting process, thus limiting the total amount of material that may be etched per cycle. By pumping down the process station between reacting operations, the reaction is partially “reset.” A higher overall etch rate is achieved by a multiple exposure with pump down ALR process.

Claims

1. A method comprising:

(a) providing a substrate in a first processing station;

(b) reacting a film on the substrate with one or more reactants to form a solid reaction product, the solid reaction product having a greater specific volume than the film consumed to form the solid reaction product;

(c) reducing a pressure in the first processing station;

(d) reacting the film with the one or more reactants to form additional solid reaction product while substantially all the solid reaction product of operation (b) remains on the substrate; and

(e) removing the solid reaction product, wherein a reduced pressure in operation (c) is maintained for a period less than or equal to a duration of operation (e).

2. The method of claim 1, further comprising transferring the substrate to a second processing station after operation (d).

3. The method of claim 1, further comprising repeating operations (c) and (d).

4. The method claim 1, further comprising repeating operations (b) though (e).

5. The method of claim 1, wherein removing the solid reaction product comprises sublimating the solid reaction product at an elevated substrate temperature.

6. The method of claim 1, wherein the one or more reactants comprise a fluorine source and a nitrogen source.

7. The method of claim 6, wherein the nitrogen source comprises one or more of ammonia (NH₃) and atomic nitrogen (N*).

8. The method of claim 6, wherein the fluorine source comprises at least one of hydrogen fluoride (HF), fluorine (F₂), nitrogen trifluoride (NF₃), atomic fluorine (F*), ammonium fluoride (NH₄F), and ammonium bifluoride (NH₄F:

HF).

9. The method of claim 6, wherein the fluorine source is hydrogen fluoride and the nitrogen source is ammonia, and wherein a flow rate ratio of hydrogen fluoride to ammonia is about 1 to 1 to about 3 to 1.

10. The method of claim 1, wherein during operation (b), a reactant partial pressure is about 1 mTorr to about 100 mTorr.

11. The method of claim 1, wherein operation (b) is performed at a first processing station pressure and operation (d) is performed at a second processing station pressure.

12. The method of claim 1, wherein operation (b) is performed at a first processing station pressure and operation (d) is performed at the first processing station pressure.

13. The method of claim 1, further comprising flowing an inert gas during at least one of operations (b), (c), (d), or (e).

14. The method of claim 13, wherein the inert gas is heated to a temperature above 25°

C.

15. The method of claim 1, wherein the pressure in operation (c) is reduced to between about 0.01 mTorr and about 50 mTorr.

16. The method of claim 1, wherein the pressure in operation (c) is reduced to less than about 10 mTorr.

17. The method of claim 1, wherein a reduced pressure in operation (c) is maintained for a period of between about 1 second and 60 seconds.