Focussing method and system of exposure apparatus

摘要

A focussing method and system transmits a light for measuring a focus to a semiconductor wafer at a fixed incident angle having high reflectance and detects a light reflected at a surface of a photoresist layer on the semiconductor wafer. The light is transmitted at an incident angle such that the amount of light reflected from the surface of the photoresist layer is larger than the amount of light which penetrates the surface thereof. The reflected light is detected, and the position of the semiconductor wafer is controlled in response to the amount of light detected. The focussing system has a source part, a detection part, and a control part. The source part creates the light and then transmits the light to the surface of the photoresist layer. The detection part detects the amount of reflected light and generates a detection signal corresponding thereto. The control part controls the position of the semiconductor wafer in response to the detection signal generated at the detection part.