| 摘要 |
An apparatus for transferring images of a pattern of a reticle onto a semiconductor wafer, by projection exposure through a projection lens system having a plurality of lens components. In the apparatus, environmental conditions such as temperature, pressure, humidity, etc. are sensed and a focus error and a magnification error of the projection lens system related to the changes in the environmental conditions are calculated. On the basis of the thus calculated focus error, the interval between the projection lens system and the semiconductor wafer in the direction of an optical axis of the projection lens system is adjusted, while, on the basis of the calculated magnification error, at least one of the lens components of the projection lens system is displaced in the direction of the optical axis of the projection lens system. By this, a satisfactory imaging performance of the projection lens system is stably assured, regardless of the changes in the environmental conditions.
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