| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent the deterioration in measurement accuracy of the flatness of a wafer by a method wherein a photodetector, to be used to measure the quantity of light which passed through a reference mark, is provided on the lower surface of the stage where the wafer is placed. SOLUTION: The light 10 sent from an exposure light source is focused by a condensing lens, etc., it is passed through an inspection reticle 1 on which a slit-like long and narrow light-shielding pattern 4 is formed, the light is introduced into a projection lens 2, a reference mark 5, consisting of a light- transmitting pattern, is formed and the light is incident on a wafer stage 3. A light detector 6, which measures the quantity of light passing through the reference mark 5, is provided on the lower surface of the wafer stage 3, and the stepping accuracy of the wafer stage 3 is measured. As a result, the deterioration of measurement accuracy due to the flatness of the wafer can be prevented, and the time required for maintenance can also be cut down.</p> |
