2000 年 66 巻 7 号 p. 1093-1097
In this study, the optical technology to detect small particles adhering to a wafer and crystal originated particles(COPs)existing in the wafer, whose diameters are approximately 0.1μm, is theoretically developed. The technology to separate COPs from detected particles is also developed. The intensity distribution of light scattered by particles and COPs is calculated using the Maxwell equation under the assumption that they are illuminated by laser light. The finite difference-time domain(FD-TD)method is used to solve the Maxwell equation. The following results were obtained by these calculations. Both particles and COPs are detected when an Ar-ion laser(λ=488 nm)with P-polarization is illuminated perpendicularly downward onto the wafer. and the obliquely scattered light is detected. Only particles are detected when a YAG laser(λ=532 nm)with S-polarization is illuminated obliquely and the light scattered perpendicularly upward is detected. On the basis of the abovementioned results. it is theoretically verified that both particles and COPs Larger than 0.1μm in diameter are detected and recognized independently.