Microwave plasma CVD apparatus provided with a microwave transmissive window made of specific ceramics for the formation of a functional deposited film

摘要

An improved microwave plasma CVD apparatus for forming a functional deposited film which is provided with a microwave transmissive window composed of a sintered alpha-alumina ceramics body containing alpha- alumina as a matrix comprised of fine particles with a mean particle size d satisfying the equation 0.5 &mgr;m≦d≦50 &mgr;m and with a ratio of &rgr;.sub.2 /&rgr;.sub.1 between the theoretical density &rgr;. sub.1 and the bulk density &rgr;.sub.2 satisfying the equation 0. 800. ltoreq.&rgr;.sub.2 /&rgr;.sub.1 ≦0.995.