Sonnenschein, Nath & Rosenthal
Focal mechanism and method for controlling focal point position, and apparatus and method for inspecting semiconductor wafer
For effecting auto-focussing of an objective lens used for observing a semiconductor wafer, a semiconductor microscopic device includes an inspection stage for supporting a semiconductor wafer and an objective lens for observing the semiconductor wafer. For automatic focussing of the objective lens, a defocussing magnitude of a light spot is detected using a knife edge. A collimator lens is oscillated by a voice coil motor to oscillate the light spot on the wafer. A peak value of the defocussing quantity detected at this time is peak-held to generate a position detection signal. The inspection stage is vertically moved so that this position detection signal will be equal to a pre-set target value.
Sony Corporation Sony Precision Technology, Inc.
G
G02B
inventional
Asahiko Hiroki
Nogami Kikuchi