Microwave plasma processing apparatus

The present invention relates to a microwave plasma processing apparatus described in the microwave plasma processing apparatus, an improved quartz glass top plate used as the microwave transmission window. The surface of the top plate surface facing the substrate W roughness arithmetic average surface roughness Ra of 0.2μm or less. Thus, in the microwave plasma processing, even when the top plate is exposed to harsh conditions over a high electron density and high electron temperature, may be configured by the top plate of the quartz glass material occurs causing particles to be suppressed minimum.