Substrate processing apparatus for performing plasma process

A substrate processing apparatus for performing a plasma process on a target substrate, the apparatus comprising:

• a process container configured to hold a vacuum therein and perform the plasma process on the target substrate accommodated therein, the process container including a container casing that defines a surrounding sidewall with a top opening and a dielectric transmission plate supported by the container casing and airtightly closing the top opening;
• a worktable configured to place the target substrate thereon inside the process container;
• a planar antenna disposed above the transmission plate and including a plurality of slots to supply microwaves from the slots through the transmission plate into the process container;
• a gas feed passage configured to supply a process gas, to be turned into plasma by the microwaves, into the process container;
• and
• an exhaust passage configured to exhaust gas from inside the process container,
• wherein the chamber casing includes an annular support portion extending inward from the surrounding sidewall, such that the transmission plate is supported on the annular support portion, and the annular support portion is made of a metal and coated with a silicon film that protects the annular support portion from sputtering of ions derived from the plasma.