Patent ID: 7645702

Claim:
A manufacturing method of a silicon wafer, including: an etching process ( 14 ) storing acid etching solution and alkali etching solution in plural etching tanks, respectively, and immersing a silicon wafer gone through a lapping process and having degraded superficial layers in the acid etching solution and the alkali etching solution in order so as to remove the degraded superficial layers; a double surface polishing process ( 16 ) to simultaneously polish the front and rear surfaces of said wafer after said etching process; wherein the acid etching solution includes hydrofluoric acid, nitric acid, acetic acid, and water, respectively, wherein, when the resistivity of the silicon wafer is below 1 Ω·cm, the mixing ratio of hydrofluoric acid, nitric acid, acetic acid, and water is hydrofluoric acid: nitric acid: and water=1:1 to 5:3 to 8:3 to 7 by percent by weight, wherein, when the resistivity of the silicon wafer is above 1 Ω·cm, the mixing ratio of hydrofluoric acid, nitric acid, acetic acid, and water is hydrofluoric acid: nitric acid: and water=1:5 to 9:1 to 6:1 to 5 by percent by weight, wherein a total removal depth in the acid etching is 5 to 7 μm, wherein sodium hydroxide aqueous solution of 40 to 60 percent by weight is used in the alkali etching solution of said etching process ( 14 ), wherein a total removal depth in the alkali etching is 13 to 15 μm, wherein, in said double surface simultaneous polishing process ( 16 ), a flow rate of abrasive supplied to the wafer is made 1 to 20 L/min, a loading capacity of an upper lapping plate is made 50 to 500 g/cm2, and a ratio of a lower lapping plate number of rotations to the upper lapping plate number of rotations is taken as the upper lapping plate: the lower lapping plate=1:2 to 20, thereby making a polishing removal depth A in said wafer front surface is 5 to 10 μm , and making a polishing removal depth B in said rear surface is 2 to 6 μm , and making a difference (A−B) between said polishing removal depth A and said polishing removal depth B is 3 to 4 μm.