PROJECTION LENS UNIT FOR FOCUSING AND LEVELING APPLYING PROPERTY OF LENS, EXPOSURE APPARATUS HAVING THE SAME AND METHOD FOR CONTROLLING THEREOF

摘要

A projection lens unit, related exposure apparatus and control method are described in which measurement light irradiating a semiconductor substrate after passing through lenses in the projection lens unit and reference light irradiating the semiconductor substrate without passing through the lenses in the projection lens unit are used to derive a control signal adapted to adjust the position of the semiconductor substrate under the projection lens unit.