Methods of laser processing photoresist in a gaseous environment

• US 8,986,562 B2
• Filed: 08/07/2013
• Issued: 03/24/2015
• Est. Priority Date: 08/07/2013
• Status: Active Grant

• Current Assignee: Veeco Instruments Incorporated
• Original Assignee: Ultratech Incorporated (Veeco Instruments Incorporated)
• Inventors: Zafiropoulo, Arthur W., Hawryluk, Andrew M.
• Primary Examiner(s): CULBERT, ROBERTS P
• Application Number:
  US13/961,655
• Publication Number:
  US 20150041431A1
• Time in Patent Office: 594 Days
• Field of Search: 216/48, 216/49, 216/67
• US Class Current: 216/48
• CPC Class Codes: G03F 7/168 Finishing the coated layer, e.g. drying, baking, soaking
• CPC Class Codes: G03F 7/26 Processing photosensitive materials; Apparatus therefor G03F7/12 - G03F7/24 take precedence
• CPC Class Codes: G03F 7/38 Treatment before imagewise removal, e.g. prebaking G03F7/265 takes precedence
• CPC Class Codes: G03F 7/40 Treatment after imagewise removal, e.g. baking
• CPC Class Codes: G03F 7/405 Treatment with inorganic or organometallic reagents after imagewise removal
• CPC Class Codes: H01L 21/0273 characterised by the treatment of photoresist layers
• CPC Class Codes: H01L 21/67069 for drying etching

Abstract

Methods of laser processing photoresist in a gaseous environment to improve at least one of etch resistance and line-edge roughness are disclosed. The methods include sequentially introducing first and second molecular gases to the photoresist surface and performing respective first and second laser scanning of the surface for each molecular gas. The first molecular gas can be trimethyl aluminum, titanium tetrachloride or diethyl zinc, and the second molecular gas comprises water vapor. Short dwell times prevent the photoresist from flowing while serving to speed up the photoresist enhancement process.

Claims

1. A method of improving on a patterned product wafer at least one of an etch resistance and a line-edge roughness of a photoresist layer having a surface, comprising:

a) exposing the photoresist layer to a first process gas comprising either trimethyl aluminum (Al₂(CH3)₆) gas, titanium tetrachloride (TiCL₄) gas or diethyl zinc ((C₂H₅)₂Zn) gas;

b) laser irradiating the photoresist layer and the first process gas to cause the first process gas to infuse into the photoresist layer, wherein the photoresist surface is raised to a temperature of between 300°

C. and 500°

C. with a temperature uniformity of +/−

5°

C.;

c) removing remaining first process gas from a vicinity of the photoresist layer;

d) exposing the photoresist layer to a second process gas comprising H₂O; and

e) laser irradiating the photoresist layer and second process gas to cause the H₂O to infuse into the photoresist layer, wherein the photoresist surface is raised to a temperature of between 300°

C. and 500°

C. with a temperature uniformity of +/−

5°

C.

2. The method according to claim 1, wherein the laser irradiating includes scanning a laser beam over the surface of the photoresist layer.

3. The method according to claim 1, wherein the scanning includes either moving the laser beam, moving the patterned product wafer or moving both the laser beam and the patterned product wafer.

4. The method according to claim 2, wherein the laser beam forms a line image at the photoresist surface.

5. The method according to claim 4, wherein the line image has a dwell time τ

in the range 1 ms≦

τ

≦

100 ms.

6. The method according to claim 4, wherein the line image has a width W in the range 0.2 mm≦

W≦

2 mm and a length L in the range 10 mm≦

L≦

100 mm.

7. The method according to claim 4, wherein the line image has a scan speed v_s in the range 20 mm/s≦

v_s≦

5,000 mm/s.

8. The method according to claim 4, wherein the laser beam has a power density P in the range 50 watts/cm²≦

P≦

150 watts/cm².

9. The method according to claim 1, wherein the patterned product wafer is maintained in an interior of a process chamber.

10. The method according to claim 1, further comprising etching the processed patterned product wafer.

11. The method according to claim 1, wherein steps a) through e) are carried out over the entire wafer in a wafer process time of between 30 seconds and 120 seconds.

12. The method according to claim 1, wherein steps a) through e) are repeated one or more times, with an additional step of removing the second process gas from the vicinity of the photoresist layer after each step e).

13. The method according to claim 1, wherein the product wafer resides within a process chamber interior, and wherein removing the first process gas from the vicinity of the photoresist layer includes at least one of evacuating the first process gas from the chamber interior and purging the chamber interior with an inert gas.

14. A method of processing a product wafer residing in an interior of a process chamber and having a patterned photoresist layer with a surface to improve at least one of an etch resistance and a line-edge roughness, comprising:

a) exposing the surface of the photoresist layer to a first molecular process gas;

b) scanning a laser beam over the surface of the photoresist layer to cause infusion of molecules of the first molecular process gas into the photoresist layer, wherein the photoresist surface is raised to a temperature of between 300°

C. and 500°

C. with a temperature uniformity of +/−

5°

C.;

c) removing remaining first molecular process gas from the chamber interior;

d) exposing the photoresist layer to a second molecular process gas and repeating step b) for the second molecular process gas; and

wherein the first molecular process gas is one of trimethyl aluminum (Al₂(CH3)₆) gas, titanium tetrachloride (TiCL₄) gas or diethyl zinc ((C₂H₅)₂Zn) gas, and the second molecular process gas comprises H₂O.

15. The method according to claim 14, wherein the laser beam forms a line image at the photoresist surface, and wherein the line image has a dwell time τ

in the range 1 ms≦

τ

≦

100 ms.

16. The method according to claim 15, wherein the line image has a width W in the range 0.2 mm≦

W≦

2 mm and a length L in the range 10 mm≦

L≦

100 mm.

17. The method according to claim 15, wherein the line image has a scan speed v_s in the range 20 mm/s≦

v_s≦

5,000 mm/s.

18. The method according to claim 14, wherein the laser beam has a power density P in the range 50 watts/cm²≦

P≦

150 watts/cm².

19. The method according to claim 14, further comprising etching the processed patterned product wafer.

20. The method according to claim 14, wherein steps a) through d) are carried out over the entire wafer in a wafer process time of between 30 seconds and 120 seconds.

21. The method according to claim 14, wherein removing the first molecular process gas from the chamber interior includes at least one of evacuation of the first molecular process gas from the chamber interior and purging the chamber interior with an inert gas.

22. A method of processing a product wafer residing in an interior of a process chamber and having a patterned photoresist layer having a surface to improve at least one of an etch resistance and a line-edge roughness, comprising:

a) sequentially introducing first and second molecular process gases to the process chamber interior, including removing the first or second molecular process gas from the process chamber interior prior to introducing the other of the first or second molecular process gas;

b) laser scanning the photoresist surface for each of the first and second molecular gases to cause the sequential infusion of the first and second molecular gases into the photoresist layer; and

c) repeating steps a) and b) multiple times, wherein the first molecular gas is either trimethyl aluminum (Al₂(CH3)₆), titanium tetrachloride (TiCL₄) or diethyl zinc (C₂H₅)₂Zn), and the second molecular gas comprises water vapor.

23. The method according to claim 22, wherein the laser scans are performed using a laser beam that forms a line image, and wherein the line image has a dwell time τ

in the range 1 ms≦

τ

≦

100 ms.

24. The method according to claim 23, wherein the line image has a width W in the range 0.2 mm≦

W≦

2 mm and a length L in the range 10 mm≦

L≦

100 mm.

25. The method according to claim 23, wherein the line image has a scan speed v_s in the range 20 mm/s≦

v_s≦

5,000 mm/s.

26. The method according to claim 23, wherein the laser beam has a power density P in the range 50 watts/cm²≦

P≦

150 watts/cm².

27. The method according to claim 22, wherein removing the first or second molecular process gas from the chamber interior includes at least one of:

i) evacuation of the first or second molecular process gas from the chamber interior and ii) purging the chamber interior with an inert gas.

28. A method of processing a product wafer residing in an interior of a process chamber and having a patterned photoresist layer having a surface to improve at least one of an etch resistance and a line-edge roughness, comprising:

a) exposing the surface of the photoresist layer to a first process gas comprising molecules, wherein the first process gas molecules are selected from the group of molecules comprising;

trimethyl aluminum (Al₂(CH3)₆) gas, titanium tetrachloride (TiCL₄) gas or diethyl zinc ((C₂H₅)₂Zn) gas; and

b) scanning a laser beam over the surface of the photoresist layer to cause infusion of the molecules of the first process gas into the photoresist layer, wherein the photoresist surface is raised to a temperature of between 300°

C. and 500°

C. with a temperature uniformity of +/−

5°

C.

29. The method according to claim 28, further comprising after step b):

c) removing the first process gas from the chamber interior;

d) exposing the photoresist layer to a second process gas containing H₂O molecules; and

e) scanning the laser beam over the surface of the photoresist layer to cause infusion of the H₂O molecules into the photoresist layer.

30. The method according to claim 28, wherein removing the first process gas from the chamber interior includes at least one of:

i) evacuating the first or second molecular process gas from the chamber interior and ii) purging the chamber interior with an inert gas.

31. The method according to claim 28, wherein scanning laser beam forms a line image having a dwell time τ

in the range 1 ms≦

τ

≦

100 ms.

32. The method according to claim 31, wherein the line image has a width W in the range 0.2 mm≦

W≦

2 mm, a length L in the range 10 mm≦

L≦

100 mm, a scan speed v_s in the range 20 mm/s≦

v_s≦

5,000 mm/s, and a power density P in the range 50 watts/cm²≦

P≦

150 watts/cm².

33. The method according to claim 28, wherein steps a) and b) are carried out over the entire product wafer in a wafer process time of between 30 seconds and 120 seconds.