Method of producing a bonded wafer and the bonded wafer

Abstract

There is provided a method of producing a bonded wafer comprising bonding a bond wafer and a base wafer via an oxide film or directly and then reducing thickness of the bond wafer, characterized in that the base wafer is a wafer produced by processes comprising slicing a silicon single crystal ingot, and then subjected at least to chamfering, lapping, etching, mirror polishing and cleaning, and the etching process is conducted by subjecting the wafer to alkali etching, and then acid etching, and an etching amount in the alkali etching is larger than an etching amount in the acid etching, and a chamfered part of the base wafer is subjected to a mirror finishing process after the etching, and a bonded wafer produced by the method. There can be provided a base wafers for a bonded wafer having good flatness wherein generation of particles from a chamfered part or a back surface is reduced in high productivity, and a bonded wafer wherein very few particles are generated, having SOI layer or silicon active layer excellent in flatness and thickness uniformity and a method of producing it.

1 . A bonded wafer having a base wafer wherein a back surface of the base wafer is chemically etched, a chamfered part of the base wafer is subjected to chamfering and mirror finishing to form a mirror surface, and the chemically etched back surface is subjected to acid etching following to alkali etching.  
     
     
         2 . A bonded wafer having a base wafer wherein a back surface of it's the base wafer is chemically etched and a chamfered part of the base wafer is subjected to chamfering and mirror finishing to form a mirror surface, and on the chemically etched back surface, a maximal depth of pits is 6 μm or less and an average value of waviness is 0.04 μm or less.  
     
     
         3 . A bonded wafer having a base wafer wherein a power spectrum density on a back surface of the base wafer is 0.5 to 10 μm 3  as measured by waviness having a wavelength of 10 mm.  
     
     
         4 . A bonded wafer having a base wafer wherein at least a back surface and a chamfered part of the base wafer are mirror surface and the chamfered part of the base wafer is subjected to chamfering and mirror finishing.