| 摘要 |
PURPOSE:To contrive speed-up and high accuracy by a method wherein a rotary reflection mirror is provided in the light path of a detection optical system, and thus the photoelectric conversion of darkness and brightness of the light transmitting through a fixed slit accompanied with the rotation of the reflection mirror is performed according to the angles of rotation, and accordingly the position of pattern is detected. CONSTITUTION:The detection light of the pattern on a wafer is reflected by the poly surface mirror 13 provided in the light path, and projected onto the slit 8 fixed on the main body. The projection image on the slit 8 moves on the slit 8 with the rotation of the poly surface reflection mirror 13. Thereat, the poly surface reflection mirror 13 is rotated by a motor 15 via a gear head 14, and the angle of rotation of the rotary shaft of the motor 15 is measured by a rotary encoder 16. As the result, the photoelectric conversion of the light transmitting through the slit by a photomultiplier 9 based on the angle of rotation is performed. |
