Patent ID: 7795117

Claim:
A method of producing a semiconductor substrate, which comprises the steps of: forming an oxide film having a thickness of not more than 50 nm on a wafer for an active layer, wherein the wafer has a surface side on which a silicon layer is formed as the active layer; implanting hydrogen ions into the wafer for the active layer to form a hydrogen ion implanted layer to sputter a first quantity of oxygen (N HO ) from the oxide film; implanting ions other than hydrogen from the surface side to a depth shallower than the hydrogen ion implanted layer to sputter a second quantity of oxygen (N IO ) from the oxide film, wherein the first quantity of oxygen and the second quantity of oxygen are determined in consideration of total factor number producing an effect of suppressing hydrogen diffusion (N D ) expressed by formula (I) and N ID as follows: N D =N HO +N IO +N ID (I) wherein N D : total factor number producing an effect of suppressing hydrogen diffusion, N HO : oxygen introduced into the active layer through hydrogen ion implantation, N IO : oxygen introduced into active layer through ion implantation other than hydrogen, N ID : defects introduced into active layer through ion implantation other than hydrogen, N D >4.2*10 14 atoms/cm 2 , laminating the wafer for the active layer to a wafer for a support substrate through the oxide film on the wafer for the active layer; and then exfoliating the wafer for the active layer at the hydrogen ion implanted layer.