Plasma process device

A plasma process device comprising:

• a processing chamber having an electrically conductive top wall for performing a processing using a plasma;
• microwave guiding means for guiding a microwave into said processing chamber;
• a dielectric shower plate having at least one gas inlet hole for supplying to said processing chamber a reaction gas attaining a plasma state by said microwave, said shower plate having a lower surface facing said processing chamber and an upper surface positioned on a side opposite to said lower surface;
• and
• a reaction gas supply passage to supply said reaction gas to said gas inlet hole,
• said reaction gas supply passage having a first wall portion including said upper surface of said shower plate, and a second wall portion including an electrically conductive surface of said top wall of said chamber arranged facing said upper surface,
• said reaction gas supply passage being formed at a region other than the transmission path of microwaves guided to said processing chamber by said microwave guiding means.