Tablet for wafers - with specified surface roughness parameters for the seating surfaces

摘要

Rest plates for wafers during a CVD treatment are usually made of SiC-coated carbon material and polished. To prevent the wafers from sticking to the surface, the seating surfaces for the wafers are recessed and given a surface roughness of at least 1 micron, max. roughness depth of 10 micron and flatness of +- 50 micron or less. Pref. the tablet (10) is a polished SiC plate, impregnated with Si. The surfaces (11) for seating the wafers have a surface roughness with an arithmetical mean of Ra = 2.5 micron and a max. roughness depth Rmax of 15.5 micron. The flatness index is +/- 50 micron or less. Tests have shown that no wafers were damaged out of 72, but 10 out of 72 were damaged in parallel tests, when the Patent method was not applied. ADVANTAGE - This prevents damage to the wafers, when attempts are made to tear them off the seat by force.