Apparatus and method for measuring thickness and temperature and substrate processing system

A method for measuring at least a thickness of a ceramic member provided in a chamber maintained in a vacuum atmosphere, the method comprising:

• making a terahertz wave incident on the ceramic member;
• obtaining an optical path difference between reflection waves of the terahertz wave reflected from a front surface and a rear surface of the ceramic member;
• and
• obtaining the thickness of the ceramic member based on the optical path difference.

A substrate processing system comprising:

• a substrate processing apparatus including:
• a chamber in which a mounting table configured to mount thereon a substrate is provided, the chamber configured to perform a predetermined process on the substrate mounted on the mounting table in a vacuum atmosphere;
• a ceramic member provided in the chamber;
• and a window made of a material that transmits a terahertz wave and provided at the chamber, to introduce the terahertz wave into the chamber;
• and
• a thickness/temperature measuring apparatus configure to measure at least a thickness of the ceramic member,
• wherein the thickness/temperature measuring apparatus includes:
• a terahertz wave generating unit configured to output a terahertz wave;
• a terahertz wave analysis unit configured to analyze a terahertz wave;
• and
• an optical system configured to guide the terahertz wave output from the terahertz wave generating unit to the ceramic member in the chamber through the window and guide reflection waves of the terahertz wave reflected from the ceramic member to the terahertz wave analysis unit through the window, and
• wherein the terahertz wave analysis unit obtains an optical path difference between a first reflection wave from a front surface of the ceramic member and a second reflection wave from a rear surface of the ceramic member and measures a thickness of the ceramic member based on the optical path difference.