Vapor-assisted cryogenic cleaning
View Patent ↗The present invention is directed towards the use of a reactive gas or vapor of a reactive liquid prior to or in combination with cryogenic cleaning to remove contaminants from the semiconductor surfaces or other substrate surfaces requiring precision cleaning. The reactive gas or vapor is selected according to the contaminants to be removed and the reactivity of the gas or vapor with the contaminants. Preferably, this reaction forms a gaseous byproduct which is removed from the substrate surface by the flow of nitrogen across the surface.
1. A method for removing at least one contaminant from a surface, comprising:
applying at least one reactant to the surface, the at least one reactant selected from a group consisting of ozone, hydrogen, nitrogen, nitrogen oxides, nitrogen triflouride, helium, argon, neon, sulfur trioxide, oxygen, fluorine, fluorocarbon gases, ethanol, acetone, ethanol-acetone mixtures, isopropyl alcohol, methanol, methyl formate, methyl iodide, and ethyl bromide, the at least one reactant in a form selected from a group consisting of a gas and a vapor, the at least one reactant sufficient for reacting with the at least one contaminant on the surface, wherein the at least one contaminant is other than a metal contaminant;
allowing the at least one reactant to condense on the surface; and
applying cryogenic material to the surface.
2. The method of claim 1 , wherein said applying at least one reactant and said applying cryogenic material occur simultaneously.
3. The method of claim 1 , wherein said applying at least one reactant and said applying cryogenic material occur sequentially.
4. The method of claim 1 , wherein said applying at least one reactant precedes said applying cryogenic material.
5. The method of claim 1 , wherein the at least one contaminant comprises a material selected from a group consisting of organic material, inorganic material, metal-organic material, polymeric material, and particulate material.
6. The method of claim 1 , wherein the at least one contaminant comprises a material of a type selected from a group consisting of residue material, photoresist material, film material, homogeneous material, and inhomogeneous material.
7. The method of claim 1 , wherein the at least one contaminant material comprises particulate material that is less than or equal to about 0.13 μm in size.
8. The method of claim 1 , wherein said applying the at least on reactant comprises allowing the at least one reactant to contact the surface for up to 20 minutes.
9. The method of claim 1 , wherein during said applying the at least one reactant, the surface and the at least one reactant are at the same temperature.
10. The method of claim 1 , wherein said applying the at least one reactant occurs at a pressure not to exceed atmospheric pressure.
11. The method of claim 1 , wherein said applying the at least one reactant occurs at a temperature of up to 200° C.
12. The method of claim 1 , further comprising generating reactive chemical species during said applying the at least one reactant.
13. The method of claim 1 , wherein said applying the at least one reactant is in the presence of a free radical initiator.
14. The method of claim 13 , wherein the free radical initiator is selected from a group consisting of ultraviolet light, x-ray, laser, corona discharge, and plasma.
15. The method of claim 1 , wherein during said allowing the at least one reactant to condense, the surface is at a temperature that is less than that of the at least one reactant.
16. The method of claim 1 , wherein the at least one contaminant is a particulate and said allowing the at least one reactant to condense is sufficient to lower a force of adhesion between the particulate and the surface.
17. The method of claim 1 , wherein said applying cryogenic material comprises directing a stream of the cryogenic material at the surface.
18. The method of claim 1 , wherein the cryogenic material comprises CO 2 gas and CO 2 particulates.
19. The method of claim 1 , wherein said applying cryogenic material comprises physically cleaning the surface at low humidity.
20. The method of claim 1 , wherein said applying cryogenic material comprises physically cleaning the surface at a dew point temperature of less than −40° C.
21. The method of claim 1 , further comprising removing a byproduct of a reaction between the at least one reactant and the at least one contaminant from the surface.
22. The method of claim 21 , wherein said removing comprises passing a flow of material selected from a group consisting of nitrogen and air across the surface.