Process sequence for photoresist stripping and cleaning of photomasks for integrated circuit manufacturing
A method and system for cleaning and/or stripping photoresist from photomasks used in integrated circuit manufacturing comprising a process and means of introducing a mixture of sulfuric acid and ozone (or a mixture of sulfuric acid and hydrogen peroxide) to the surface of a photomask while applying megasonic energy. The invention also comprises method and system comprising a process and means of introducing ozonated deionized water and/or a low temperature dilute aqueous solution (dAPM) to the surface of photomasks while applying megasonic energy. The process and apparatus also remove post plasma ashed residues and other contaminants from photomask surfaces.
1 . A method of photoresist stripping and/or cleaning photomasks comprising:
(a) supporting a photomask in a process chamber; and
(b) applying a mixture comprising sulfuric acid and ozone (SOM) to the photomask while applying acoustical energy to the photomask.
2 . The method of claim 1 wherein the SOM applied to the photomask is at a temperature less than 90° C.
3 . The method of claim 1 wherein the SOM is preferably free of bubbles.
4 . The method of claim 1 further comprising rinsing the photomask with deionized water while applying megasonic energy to the photomask after application of the SOM.
5 . The method of claim 1 further comprising applying a mixture of deionized water and ozone (DIO 3 ) to the photomask after application of the SOM.
6 . The method of claim 5 wherein the DIO 3 has a concentration of ozone less than 100 parts per billion deionized water.
7 . The method of claim 1 further comprising applying a dilute aqueous solution of ammonium hydroxide and hydrogen peroxide (dAPM) to the photomask while applying acoustical energy to the photomask, wherein the dAPM is applied at a temperature less than 30° C. and after the application of the SOM.
8 . The method of claim 7 wherein the weight ratio of ammonium hydroxide to hydrogen peroxide to water in the dAPM is about 1:y:x where 2<y<10 and 200<x<1000.
9 . The method of claim 7 further comprising rinsing the photomask with deionized water while applying acoustical energy to the photomask after the application of the dAPM.
10 . The method of claim 1 further comprising:
(c) rinsing the photomask with deionized water while applying megasonic energy to the photomask;
(d) applying a ozonated deionized water (DIO 3 ) to the photomask;
(e) applying a dilute aqueous solution of ammonium hydroxide and hydrogen peroxide (dAPM) to the photomask while applying acoustical energy to the photomask, wherein the dAPM is applied at a temperature less than 30° C.; and
(f) rinsing the photomask with deionized water while applying acoustical energy to the photomask;
wherein steps (b) through (f) are performed sequentially.
11 . The method of claim 1 wherein the SOM further comprises hydrogen peroxide.
12 . A method of cleaning photomasks comprising:
supporting a photomask in a process chamber; and
applying a dilute aqueous solution of ammonium hydroxide hydrogen peroxide (dAPM) to the photomask while applying megasonic energy.
13 . The method of claim 12 wherein the dAPM is applied at a temperature less than 30° C.
14 . The method of claim 12 wherein the weight ratio of ammonium hydroxide to hydrogen peroxide to water in the dAPM is about 1:y:x where 2<y<10 and 200<x<1000.
15 . The method of claim 12 further comprising applying a mixture of deionized water and ozone (DIO 3 ) to the photomask prior to the application of the dAPM.
16 . The method of claim 12 further comprising rinsing the photomask with deionized water while applying acoustical energy to the photomask after the application of the dAPM.
17 . A method of photoresist stripping and/or cleaning photomasks comprising:
(a) supporting a photomask in a process chamber; and
(b) applying a mixture comprising sulfuric acid and ozone (SOM) to the photomask while applying acoustical energy to the photomask.
18 . The method of claim 17 wherein the SPM further includes dissolved ozone gas.