We performed three experiments using the spray of steam-water mixture. The first one is the experiment of removing dry-etch residue from a wafer. We found that the spray can remove the dry-etch residue in via holes with the help of a small amount of chemicals. This result is in sharp contrast with the result with the use of air-water mixed spray, and suggests that the removal of dry-etch residue is essentially due to physical actions of the spray, rather than the actions of chemicals. The second and third experiments are resist lift-off and metal erosion, respectively. We found that the performances of both depend on the water flow rate in the same manner; a certain amount of water is helpful, but excessive amount of water is of no effect. Based on these experimental results, we propose that in cleaning or eroding surfaces using the steam-water mixed spray, the condensation effect of steam plays an important role and the performances can be controlled by tuning the amount of water.
