PURPOSE: To compensate focus variation due to environmental variation without a printing test by moving a reference surface for focusing in the optical axis direction on the basis of an output of a sensor means for detecting the environmental conditions of a pattern transfer device.
CONSTITUTION: An offset compensating function part of an automatic focusing means is constituted so that the outputs of an atmospheric pressure sensor 31, a temperature sensor 32, a humidity sensor 33, and a focus detector 34 are inputted to a microprocessor 35, and after executing operation, the miroprocessor 35 calculates a distance from the original point of the coordinates of an air sensor to a wafer surface and inputs the moving distance of a Z axis to a Z axis driver 36. An offset value for indicating the reference position of focusing is set up in an air sensor. The offset value is set up so that a best focusing position found by a printing test is the reference focusing position. When a fixed offset value is determined, an automatic focusing function part moves an wafer in the optical axis (Z axis) direction by the device 36 so that an offset reading value is set up to a required value on the basis of the output of the air sensor 34.
YABU SHUICHI
MURAKAMI JUNICHI
