Verfahren und Vorrichtung zum Erzielen eines rechten Einfallswinkels zwischen einen Laserstrahl und eine reflektierende Oberfläche.

摘要

The disclosure relates to an etch monitor system, the angle of incidence to normal between a laser beam (13) and a reflective surface (18), such as a silicon wafer, is adjusted by a rotatable mirror (20) having a pinhole (22) formed therethrough, the rotatable mirror being moveably mounted to be positioned in a first location within a light path and a second location out of said light path. When the rotatable mirror is located in the light path, the pinhole allows a beam of the laser beam to pass from a laser source to the reflective surface. If the beam is normal to the reflective surface, the beam is directed back toward the laser source through the pinhole. If the beam is not normal to the reflective surface, the beam is reflected by the rotatable mirror to a target (26), allowing observation of a lit spot of the target to enable normalization by making appropriate adjustments.