Patent ID: 7077901

Claim:
A process for producing a single crystal silicon wafer comprising a silicon enriched in silicon isotope whose mass number is 28 to an average concentration of more than 98%, said process comprising: a step (i) wherein a porous layer is formed on a single crystal silicon substrate comprising a silicon whose concentration of mass number 28 silicon isotope is less than 92.5% on an average; a step (ii) wherein a starting silicon whose concentration of mass number 28 silicon isotope is more than 98% on an average is dissolved in a melt for liquid-phase epitaxy by supplying a gas containing said starting silicon to said melt until said starting silicon is in a supersaturated state in said melt under reductive atmosphere maintained at high temperature; a step (iii) wherein said single crystal silicon substrate is immersed in said melt to grow a single crystal silicon layer on the surface of said porous layer of said single crystal silicon substrate; and a step (iv) wherein said single crystal silicon layer grown on said porous layer of said single crystal silicon substrate in said step (iii) is made to be as a wafer and said wafer is peeled from a portion of said porous layer.