To easily and freely adjust dislocation density in a non-diffusion layer to a required level, in manufacturing of a diffusion wafer having a double structure of a heavily-doped impurity diffusion layer and the non-diffusion layer.
The method of manufacturing the diffusion wafer includes: a step of forming a material wafer 11 having a prescribed thickness by slicing a silicon ingot; a step of forming a working strain layer 12 on both sides the material wafer 11 by applying a lapping process to the material wafer 11; a step of removing an etching removal layer 13 on the surface of the working strain layer 12 by controlling it by chemicals; a step of forming the heavily-doped impurity diffusion layer 14 and the non-diffusion layer 15 by diffusing dopants on both sides of the material wafer 11 in a prescribed depth; and a step of making the diffusion wafer 16 having the double structure by dividing the material wafer 11 into two along the center part of its width in the thickness direction. An amount of etching on the surface of the working strain layer 12 is controlled in the step of etching removal to adjust dislocation density in the non-diffusion layer 15.
Tetsuma Ikegami
Akira Sudo