SEMICONDUCTOR MANUFACTURING APPARATUS

PURPOSE:To prevent any reaction product from adhering to a peep window by sticking a hot wire to the quartz glass peep window provided on the wall surface of a reaction chamber and heating the peep window. CONSTITUTION:A heating hot wire 109 is allowed to stick to a quartz glass peep window 108 provided through part of the wall surface 103 of a stainless reaction chamber, and the quartz glass peep window 108 is heated to 70-80 deg.C by supplying power to the hot wire 109. Hereby, any reaction product produced by etching in the reaction chamber is prevented from adhering to the quartz glass peep window 108, thereby assuring observation in the reaction chamber without reducing clearness over a long period of time.