Liquid-assisted cryogenic cleaning
View Patent ↗The present invention is directed to the use of a high vapor pressure liquid prior to or simultaneous with cryogenic cleaning to remove contaminants from the surface of substrates requiring precision cleaning such as semiconductors, metal films, or dielectric films. A liquid suitable for use in the present invention preferably has a vapor pressure above 5 kPa and a freezing point below −50° C.
1. A method for removing at least one contaminant from a surface, comprising:
applying at least one liquid of high vapor pressure to the surface, the at least one liquid sufficient for reacting with the at least one contaminant on the surface; and
applying cryogenic material to the surface.
2. A method for removing at least one contaminant from a surface, comprising:
applying at least one liquid of high vapor pressure to the surface, the at least one liquid sufficient for reacting with the at least one contaminant on the surface; and
applying cryogenic material to the surface at low humidity.
3. The method of any one of claims 1 and 2 wherein said applying at least one liquid and said applying cryogenic material occur simultaneously.
4. The method of any one of claims 1 and 2 , wherein said applying at least one liquid and said applying cryogenic material occur sequentially.
5. The method of any one of claims 1 and 2 , wherein said applying at least one liquid precedes said applying cryogenic material.
6. The method of any one of claims 1 and 2 , wherein the at least one liquid has a vapor pressure greater than or equal to 5 kPa at 25° C.
7. The method of any one of claims 1 and 2 , wherein the at least one liquid has a freezing point of less than or equal to about −50° C.
8. The method of any one of claims 1 and 2 , wherein the at least one liquid has a dipole moment of greater than about 1.5 D.
9. The method of any one of claims 1 and 2 , wherein the at least one liquid is selected from a group consisting of ethanol, acetone, ethanol-acetone mixtures, isopropyl alcohol, methanol, methyl formate, methyl iodide, ethyl bromide, acetonitrile, ethyl chloride, pyrrolidine, tetrahydrofuran, and any combination thereof.
10. The method of any one of claims 1 and 2 , wherein said applying the at least one liquid comprises applying the at least one liquid in a layer of at least 5 Å.
11. The method of any one of claims 1 and 2 , wherein said applying the at least one liquid comprises allowing the at least one liquid to contact the surface for at least one minute.
12. The method of any one of claims 1 and 2 , wherein during said applying the at least one liquid, the surface is rotated.
13. The method of any one of claims 1 and 2 , wherein said applying the at least one liquid comprises removing bulk water from the surface.
14. The method of any one of claims 1 and 2 , wherein said applying the at least one liquid comprises dissolving the at least one contaminant.
15. The method of any one of claims 1 and 2 , wherein said applying cryogenic material comprises directing a stream of gaseous and particulate cryogenic material at the surface.
16. The method of any one of claims 1 and 2 , wherein the cryogenic material comprises at least one gas.
17. The method of any one of claims 1 and 2 , wherein said applying cryogenic material comprises physically cleaning the surface at low humidity.
18. The method of any one of claims 1 and 2 , wherein said applying cryogenic material comprises physically cleaning the surface at a dew point temperature of less than −40° C.
19. The method of any one of claims 1 and 2 , wherein the surface is at a temperature of up to 100° C.
20. The method of any one of claims 1 and 2 , wherein the surface is at a temperature of 30° C. to 50° C.
21. The method of any one of claims 1 and 2 , wherein the at least one contaminant is a particulate and said applying the at least one liquid is sufficient to lower a force of adhesion between the particulate and the surface.