PHOTOREPEATER

摘要

PURPOSE:To facilitate the detection of the accuracy of a stage movement by a method wherein a system of lenses and a source of a detection light which has a wavelength which can be transmitted through a mask substrate are provided and the light from the source is projected to the direction opposite to the exposure direction and a reference mark is detected. CONSTITUTION:A detection light source 11 has a wavelength which can be transmitted through a mask substrate 4. A reference mark M is formed on a light transmissible plate 13 provided to a stage. A detective light L2 from the backside of the light transmissible plate 13 has a wavelength such that the light L2 is not transmitted through the mark M and detects it but is transmitted through a semitransparent film 42 and a resist film 43 and the resist film 43 is not sensitive to the light L2. The light L2 transmitted through the substrate 4 is reflected by a half-mirror 14 through a contraction lens 3 and detected by an image detector of a detection system 16 through a contraction lens 15. The half-mirror 14 transmits a light L1 from its backside and reflects the light L2 inciding from the front side totally. A method such as indicating the detected result in comparison to a standard pattern signal is applied to the detection system 16.