| 摘要 |
PURPOSE:To obtain a silicon substrate having intrinsic gettering effect by heat treating a Czochralski single crystal containing specific amount of tin from a low temperature in multiple stages, thereby reducing the plastic deformation of a silicon substrate. CONSTITUTION:A Czochralski single crystal containing tin of 0.1atm% or less and 0.001atm% or higher is heat treated at low temperatures is oxygen atmosphere, and heat treated at the temperature higher than this. For example, it is first heat treated as an IG heat treatment at the temperature of 1,200 deg.C or higher in nonacidic atmosphere, solid solution oxygen near the surface of a wafer is diffused externally, thereby forming a low oxygen concentration layer. Then, it is started from 500 deg.C in the oxygen atmosphere, sequentially raised at the temperature in a range of 10-100 deg.C so that the final temperature is to 850 deg.C in multiple stage low temperature heat treatment. In this stage, the growth of the precipitating nucleus of oxygen is advanced. Then, a heat treatment of 950- 1,200 deg.C for 2hr or longer is performed to form the internal defects of high density in the interior of the wafer, thereby causing the effect of the IG. |
