Device and method for cleaning photomask
Disclosed herein is a device and a method of cleaning a photomask, which prevents haze from being generated on a surface of the photomask during a photolithography process. The photomask is heat treated to remove residual ions on a surface thereof and to induce curing and oxidation of Cr and MoSiON layers, thereby preventing diffusion of the ions. Etching of Cr and MoSiON layers due to a cleaning process is suppressed in order to significantly reduce a change in phase and transmissivity of optical properties of Cr and MoSiON.
1. A method of cleaning a photomask, comprising:
(a) conducting a first cleaning using an aqueous solution containing an acid in order to remove a polymer formed on the photomask, said acid selected from the group consisting of sulfuric acid, phosphoric acid, and nitric acid;
(b) conducting a second cleaning on the photomask using heated hydrogen peroxide and ozone water;
(c) conducting a first heat treatment by heating the photomask;
(d) conducting a third cleaning on the photomask with an aqueous solution of ammonia and hydrogen peroxide;
(e) conducting a fourth cleaning on the photomask using the heated hydrogen peroxide and ozone water; and (f) conducting a second heat treatment by heating the photomask.
2. The method as set forth in claim 1 , wherein a surface of the photomask is oxidized in step (c).
3. The method as set forth in claim 1 , wherein oxygen is applied on the surface of the photomask in steps (b) and (e).
4. The method as set forth in claim 1 , wherein a surface of the photomask is oxidized in step (f).
5. The method as set forth in claim 1 , further comprising conducting a rinsing process using ultrapure water after step (a).
6. The method as set forth in claim 1 , wherein the aqueous solution of step (a) further comprises hydrogen peroxide and ozone.
7. The method as set forth in claim 1 , wherein steps (b) and (e) are conducted at 40–100° Celsius.
8. The method as set forth in claim 1 wherein the heat treatment is conducted in a gas atmosphere which includes one or more gases selected from a group consisting of N 2 , Ar, O 2 , and He.
9. The method as set forth in claim 1 , wherein the heat treatment is conducted at 50–1000° Celsius for 5 min–5 hours.
10. The method as set forth in claim 1 , wherein the heat treatment is conducted at 50–400° Celsius.
11. The method as set forth in claim 4 , wherein ammonia (NH 4 ) is vaporized in step (f).