| 摘要 |
PURPOSE:To make it possible obtain a wafer having a clean roughpolished surface, by jetting high pressure gas containing sprayed water drops from a nozzle into a middle pressure tank so that a gas stream containing ice particles obtained under adiabatic expansion is jetted from a jet port of the tank. CONSTITUTION:High pressure liquefied gas 2 such as liquefied oxygen, liquefied nitrogen or the like is evaporated by a carburetor 8 so as to form high pressure gas 9 at about 100 atm., and is jetted from a nozzle 3 into a middle pressure tank 4. Further, pure water is jetted from an injector 10 into the gas 9 upstream of the tank 4, and therefore, is turned into sprayed water drops 1. The sprayed water drops 1 reduces its pressure, abruptly in an adiabatic expansion section 11, and therefore, are turned into micro ice particles so as to obtain a gas stream 6 containing ice particles. The gas stream 5 from the jet port 6 in the tank 4 is jetted as ice blast 13 into a hood 12 at a pressure nearly equal to the atmospheric pressure. Then, when the ice blast 13 impinges upon a wafer 7 held to a wafer holding bed 14 under vacuum suction, the outer surface of the wafer 7 is polished by the energy owned by the micro ice particles at a high speed.
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