摘要 |
<p>An apparatus for monitoring film deposition on a chamber wall in a process chamber. The apparatus includes a surface acoustic wave device provided on the chamber wall. The surface acoustic wave device is actuated to achieve a resonance frequency, and the resonance frequency produced is detected to determine whether a critical thickness of film on the wall of the chamber has been achieved, where an amount of decrease in the resonance frequency is proportional to a thickness of film on the chamber wall. The process chamber is cleaned when the resonance frequency detected falls within a first predetermined range.</p> |