PURPOSE: To attain a high accuracy control of mirror cutting remains, by cutting deep multiple grooves on a large thickness Si single crystal wafer, on the other hand, by laminating a small thickness and a high specific resistance Si single crystal wafer as its bottom surface.
CONSTITUTION: A lozenge focusing mirror made of an Si single crystal 21 consists of a groove part 22 made of a low specific resistance Si single crystal and a bottom surface 23 made of a high specific resistance Si single crystal, and also parallel deep grooves 10-1W10-N are formed along its shorter rectangular secant. And for the deep grooves 10, only Si single crystals in a groove section 22 are processed with an electrical wire discharging process, and for a bottom section 23, an Si single crystal having a highly accurate thickness and being cut out from a high specific resistance Si single crystal being processed with a non-distortion mirror surface processing is used. Therewith, not only the cutting remains can be formed constantly and highly accurately but also a surface with almost no residual processing distortion can be obtained.
HAMAGUCHI TSUNEO
OKUBO TOSHIO
