抄録
This paper proposes a thickness measurement method of silicon-oxide and poly-silicon film deposited on 12" silicon wafer for spin etcher. Halogen lamp is used as a light source for generating a wide-band spectrum, which is guided and focused on the wafer surface through a optical fiber cable. Interference signal from the film is detected by optical sensor to determine the thickness of the film using spectrum analysis and several signal processing techniques including curve-fitting and adaptive filtering. Test wafers with three kinds of priori-known films, poly-silicon and silicon-oxide, are measured while the wafer is spinning at 20Hz and DI water flowing on the wafer surface. From experimental results the algorithm presented in the paper is proved to be effective with accuracy of maximum 1.8% error.
