Method for Manufacturing Simox Wafer

A method for manufacturing a SIMOX wafer comprising the following sequential steps:

• forming a first ion-implanted layer at a first depth in a silicon wafer by heating the wafer at a temperature in the range from 200 to 600° C. and implanting oxygen ions from a surface of wafer at the rate of 5×1016 to 3×1017 atoms/cm2;
• cooling the wafer to a temperature in the range from room temperature to 200° C. and implanting oxygen ions from the surface of the wafer at the rate of 1×1014 to 1×1016 atoms/cm2 to form a second ion-implanted layer that is in an amorphous state at a second depth in the wafer such that the second ion-implanted layer becomes continuous with the first ion-implanted layer on a front surface side of the wafer;
• and
• wherein the wafer is elevated to a temperature that is not lower than 130° ° C. but less than the melting point of silicon while maintaining the wafer in an atmosphere containing oxygen and a gas containing chlorine that is not less than 1.0 volume % mixed therewith during elevation of the temperature and maintaining the temperature for 6 to 36 hours to change the first and the second ion-implanted layers into a BOX layer.