Plasma reactor with non-power-absorbing dielectric gas shower plate assembly

A plasma reactor comprising:

• a process chamber comprising a side wall and a workpiece support in said process chamber;
• a gas distribution plate overlying said process chamber and comprising:
• a first dielectric front plate and a dielectric back plate joined to one another along facing surfaces, one of said facing surfaces comprising a first top surface of said first dielectric front plate;
• an array of plural gas supply channels formed in said first top surface and an array of gas injection orifices extending axially through said first dielectric front plate, said gas injection orifices intersecting said gas supply channels;
• a peripheral gas supply channel in said first top surface intersecting said gas supply channels, and a gas supply coupled to said peripheral gas supply channel;
• wherein said first dielectric front plate is formed of a first dielectric material and said back plate is formed of a second dielectric material;
• and
• a power applicator overlying said gas distribution plate, and a power source coupled to said power applicator, each of said first and second dielectric materials being generally transparent to radiation from said power source.