| 摘要 |
PROBLEM TO BE SOLVED: To provide a PTM (photoelectron multiplier) foreign matter detecting device and a PMT foreign matter detecting method in which a PMT voltage can be automatically regulated and in which foreign matter and depressions can be discriminated and detected. SOLUTION: The PTM foreign matter detecting device is provided with a stage 10 which is moved while holding a semiconductor wafer 1, comprises a generating means 14 to generate laser light, and is provided with irradiating means 13-1 and 13-2 to irradiate a wafer with the laser light generated by the generating means 14 from various angles, guiding mirrors 17a and 17b to guide the laser light to the irradiating means 13-1 and 13-2, mirrors 18-1 and 18-2 to refract the later light radiated from the irradiating means 13-1 and 13-2 and to irradiate the surface of a semiconductor wafer 1 with the laser light, a PMT 12 to detect scattered light that the laser light is irregularly reflected by foreign matter, and a control part 19 to regulate and control a PMT voltage automatically in the case that the scattered light detected by the PMT 12 exceeds a detection upper limit so as to be able to rescan.
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