Patent ID: 7601644
Filing Date: 2009-10-13
Classification: B24B,H01L

Abstract:
1. A method for manufacturing silicon wafers, the method comprising, in the order indicated: a planarization step of grinding or lapping a front surface and a rear surface of a silicon wafer which is in a form of a thin disk and is obtained by slicing a silicon single crystal ingot; a single-wafer acid etching step of supplying an acid etching liquid to the surface of the planarized single silicon wafer while spinning the single silicon wafer, thereby spreading the supplied acid etching liquid over the entire wafer surface due to centrifugal force generated by spinning, and etching the entire wafer surface so as to control the surface roughness Ra of the wafer surface to 0.05 μm or less; and a double-sided simultaneous polishing step of polishing both of the front surface and the rear surface of the acid-etched single silicon wafer simultaneously, wherein the acid etching liquid is an aqueous solution containing hydrofluoric acid, nitric acid and phosphoric acid respectively, the mixing ratio as percents by weight of the hydrofluoric acid, nitric acid, phosphoric acid and water in the aqueous solution is such that hydrofluoric acid:nitric acid:phosphoric acid=4.5% to 10.5%:25.5 to 40.0%:30.0 to 45.5%, the spinning speed at which the wafer is spun in the single-wafer acid etching step is 500 to 2000 rpm, and the viscosity of the acid etching liquid is 10 to 35 mPa·sec.