Patent ID: 7002663

Claim:
A projection exposure apparatus having a light emitting unit, an exposure stage on which a work piece is placed, a first mask for exposing a first pattern on a first surface of the work piece, a second mask for exposing a second pattern on a second surface of the work piece, a projection lens for projecting the first pattern formed on the first mask and the second pattern formed on the second mask on the work piece placed on the exposure stage, an alignment microscope for detecting a first alignment mark formed the first mask or a second alignment mark formed the second mask and the work piece, a reversal stage for turning over the work piece whose first surface is exposed, and a controlling unit for controlling emission of exposure light from the light emitting unit, replacement of the first and second masks, transportation of the exposure stage, an alignment process by the alignment microscope, a work piece reversal process by the reversal stage, and transportation of the work piece, wherein a first reflecting material and a second reflecting material provided on a surface of the exposure stage, and the controlling unit controls so that when the exposure stage is moved from an exposure position where an exposure process is carried out on the work piece to a work piece feeding and discharging position where the work piece which is exposed is replaced with a work piece to be exposed, exposure light is emitted from the light emitting unit to the first alignment mark on the first mask and an image of the first alignment mark of the first mark is projected on the first reflecting material, and a reflected image of the first alignment mark image which is projected is detected by the alignment microscope thereby detecting position of the first mask, when the exposure stage is moved to a reversal handing over position where the work piece whose first surface of the work piece is exposed is replaced with a reversed work piece to be exposed, exposure light is emitted to the alignment mark of the second mask from the light emitting unit, an image of the second alignment mark of the second mark is projected on the second reflecting material, and a reflected image of the projected second alignment mark image is detected by the alignment microscope thereby detecting position of the second mask.