Removal of contaminants from EUV masks
An aqueous cleaning composition containing sulfonic acids and a source of chloride ions is used to clean contaminants from EUV masks used in the manufacture of semiconductors. Optionally, the aqueous cleaning composition can include oxidizing agents and surfactants. The aqueous cleaning composition removes tin as well as other contaminants from the mask. Such other contaminants include, but are not limited to, aluminum oxide, etch and photoresist residues.
1. A method of removing contaminants from an extreme ultra-violet mask comprising:
a) inspecting the extreme ultra-violet mask for contaminants;
b) providing an aqueous cleaning composition consisting of water, a sulfonic acid or salt thereof, a source of chloride ions, optionally an oxidizing agent, and optionally a surfactant; and
c) contacting the extreme ultra-violet mask with the aqueous cleaning composition comprising sulfonic acid and a source of chloride ions to remove at least tin from the extreme ultra-violet mask.
2. The method of claim 1 , wherein the sulfonic acid has the formula:
R—S(═O) 2 —OH (I),
wherein R is an alkyl or aryl group.
3. The method of claim 2 , wherein R is C n H 2n+1 and the variable n is an integer of 1 and greater.
4. The method of claim 3 , wherein R is C n H 2n+1 and the variable n is an integer of 1-4.
5. The method of claim 1 , wherein the sulfonic acid is in amounts of at least 10 wt %.
6. The method of claim 5 , wherein the sulfonic acid is in amounts of 15-65 wt %.
7. The method of claim 1 , wherein the chloride ions are in amounts of at least 0.05 wt %.
8. The method of claim 7 , wherein the chloride ions are in amounts of at least 0.1-5 wt %.
9. The method of claim 1 , wherein the salt of the sulfonic acid has the formula:
R—S(═O) 2 —O − Y + (II),
wherein R is an alkyl or aryl group and Y + is a counter cation.
10. The method of claim 1 , wherein the aqueous cleaning composition is at a temperature of at least 30° C.
11. The method of claim 10 , wherein the aqueous cleaning composition is at 50-85° C.
12. A method of removing contaminants from an extreme ultra-violet mask comprising:
a) inspecting the extreme ultra-violet mask for contaminants;
b) providing an aqueous cleaning composition consisting of water, a source of chloride ions, a sulfonic acid or salt thereof having the formula:
R—S(═O) 2 —OH (I),
wherein R is an alkyl or aryl group, optionally an oxidizing agent and optionally a surfactant; and
c) contacting the extreme ultra-violet mask with the aqueous cleaning composition to remove at least tin from the extreme ultra-violet mask.