Patent ID: 8070910

Claim:
A shower head structure comprising: a shower head section provided to face a top surface of a mounting table in an evacuatable treating vessel; a multiplicity of gas injection holes, opened in a lower surface of the shower head section, that inject a processing gas into the treating vessel; a temperature observation through hole opened in the lower surface of the shower head section to face the top surface of the mounting table; a transparent observation window that airtightly seals an upper portion of the temperature observation through hole; a radiant thermometer provided at a top surface side of the transparent observation window; and an adhesion preventive gas supply path, communicating with the temperature observation through hole, that supplies thereinto an adhesion preventive gas, which prevents a film from being deposited on the transparent observation window, wherein a gas flow prevention plate, made of a transparent material and that prevents a back flow of a gas, is installed below a gas outlet, in which the adhesion preventive gas supply path communicates with the temperature observation through hole, wherein a diffusion area is provided at an upper portion of the temperature observation through hole, wherein the gas outlet, in which the adhesion preventive gas supply path communicates with the temperature observation through hole, is provided at a sidewall of the diffusion area, and wherein the gas flow prevention plate is installed at a bottom portion of the diffusion area; wherein the adhesion preventive gas supplied into the temperature observation through hole prevents the processing gas from reaching a lower surface of the transparent observation window, wherein the gas flow prevention plate is provided in the temperature observation through hole between an opening of the temperature observation through hole in the lower surface of the shower head section and the gas outlet, in which the adhesion preventive gas supply path communicates with the temperature observation through hole, wherein, in the gas flow prevention plate, plural fine gas injection holes are formed, and wherein the adhesion preventive gas is a nonreactive gas.