Patent ID: 7226864
Filing Date: 2007-06-05
Classification: B24B,C30B,H01L

Abstract:
1. A method for producing a silicon wafer comprising: a slicing step of slicing a single-crystal ingot into thin disc-like wafers; a chamfering step of chamfering the wafer obtained from the slicing step; a lapping step for flattening the chamfered wafer; an etching step for eliminating processing distortions on the surfaces of the wafer introduced during the chamfering and lapping steps; a mirror-polishing step for mirror-polishing the surface of the etched wafer; and a cleaning step for cleaning the mirror-polished wafer, wherein: the etching step consists of a first etching phase for acid-etching the wafer followed by a rear-surface mild polishing step for abrading part of roughness formed on the rear surface of the wafer as a result of the first etching phase followed by a second etching phase for alkali-etching the wafer after the first etching phase; and wherein: the total thickness of superficial layers on the front and rear surfaces of a wafer removed during the first and second etching phases constituting the etching step is 25-30 μm with the summed thickness of superficial layers on the front and rear surfaces of the wafer removed by acid etching during the first etching phase being 20-25 μm, and the summed thickness of superficial layers on the front and rear surfaces of the wafer removed by alkali etching during the second etching phase being 5-10 μm, wherein the time for abrading the rear surface of a wafer during the rear surface mild polishing step is 30-45 sec, or the rear surface mild polishing is performed such that the rear surface of the wafer has a luster of 120-140% after polishing.