| 摘要 |
PURPOSE: To make it possible to adjust an incident angle of a laser beam in a vertical state to a reflective face of a silicon wafer in an etching monitor system. CONSTITUTION: A rotatable mirror 20 having a through pin hole is provided. The rotatable mirror 20 is set at a first position in an optical path or a second position out of the optical path. Through the pin hole of the rotatable mirror 20 in the optical path, a laser beam 13 can pass from the laser beam source to a reflective face 16. If the beam is vertical to the reflective face 16, the beam is turned backward to the laser beam source. If the beam is not vertical to the reflective face, the beam is reflected to a target through the rotatable mirror 20, and thereby a light spot at the target can be observed. In this way the beam is directed vertically by adequate adjustment operation. |
