JPS6471125A - Exposure of semiconductor - Google Patents

Abstract

PURPOSE:To align a mask and a wafer with high accuracy by exposing the wafer only when the quantities of positional displacement in each fixed direction from respective alignment marks put to the mask and the wafer respectively are kept within a tolerance. CONSTITUTION:Alignment beams 34, 35 are passed through alignment marks 30, 31, and applied to each alignment mark 22, 23 put onto a wafer 21, and the reflected beams of the marks 22, 23 are reflected by mirrors 36, 37 and projected to alignment photo-detectors 32, 33. The detectors 32, 33 output these incident beams to a servo control section 40 and an exposure timing generating section 41 as alignment detecting signals a1, a2. The control section 40 moves a wafer stage so that the quantities of the X and Y directions of the marks 22 and 30, 23 and 31 are brought to zero by the signals a1, a2. Even when vibrations are applied from the outside, on the other hand, the generating section 41 transmits an exposure signal S over a pulse laser oscillator 24. when the signals a1, a2 are kept within the tolerance of a positional displacement allowance setting section 43 simultaneously.