Apparatus and method for detecting tilt angle of a wafer platform

摘要

An apparatus and a method for detecting the tilt angle of a wafer platform in a process machine, particularly in a medium density ion implanter. The apparatus and method can be used to accurately calibrate the zero-angle position of a wafer platform in the medium energy ion implanter. The apparatus includes a process chamber that has a cavity and a wafer platform therein, a window that is substantially transparent to laser energy mounted in a top wall of the chamber, and a laser emitter and receiver positioned outside the process chamber juxtaposed to the window for emitting a laser beam onto a wafer positioned on the wafer platform and receiving a reflected laser beam to determine a tilt angle of the wafer platform by the intensity of the reflected laser beam.