To provide a wafer detector which can detect accurately a position of wafer even if the wafer as detected matter absorbs lights of specific wavelength.
Even if a film applied on a wafer 1, for example, a nitride film, has properties of absorbing lights of specific wavelength (for example, lights near 660 nm in Fig. 3), as a light emitting spectrum of the white light is in the strong intensity in a wavelength band of a wide band as shown in Fig. 3, lights of the other wavelength band (a wavelength band except for 660 nm) are certainly reflected on an end surface of the wafer 1, and the light is received by both light receiving elements 12, 12 to output a light receiving signal. The light receiving signal is determined to exceed a specific level in a comparing circuit (not shown), and it is detected that the wafer 1 is present in a frontward position of light transmitting and receiving elements 11, 12.
NODA NAOAKI
SHIMAZAKI MASAO
| JP2002170799A | 2002-06-14 | |||
| JPH1116822A | 1999-01-22 | |||
| JP2000082845A | 2000-03-21 | |||
| JP2000294839A | 2000-10-20 | |||
| JP2000183408A | 2000-06-30 |