| 摘要 |
PURPOSE:To prevent any deterioration in revolving power and printing precision due to defocussing from occurring by a method wherein positions of negative and exposed body in a mirror projection type optical system are detected to shift the negative and/or exposed body to the optimum position of exposed body in view of the characteristics of projection optical system on the basis of the results of detection. CONSTITUTION:A processing circuit 16 provided with a reference voltage setting up circuit 21, an adding circuit 22 and a power amplifier 23 etc. controls a valve 18 so that the sum (l0) of gap (l1) between a mask 1 and a projection optical system 5 and another gap (l2) between the projection optical system 5 and a negative 3 may become constant. To meet such a requirement, the reference voltage setting up circuit 21 outputs an analog voltage (l0) corresponding to gap commanding value; the adding circuit 22 outputs error voltage epsilon corresponding to l1+l2-l0 on the basis of detection output voltage l1, l2 from gap sensers 15, 12 and output voltage l0 from the reference voltage setting up circuit 21; and the power amplifier 23 controls the valve 18 corresponding to the error voltage epsilon. Through these procedures, the position of substrate 3 in Z direction can be controlled in the mode of negative feedback to be the position making l1+l2=l0 i.e. the optimum image forming position in a mirror projection type exposing apparatus. |
