| 摘要 |
PURPOSE: To highly accurately measure reflectance of a photosensitive substrate even to exposure light in an ultraviolet region by a method wherein a reflecting member having lower reflectance than that of the substrate is equipped with an optical member having at least one smooth face for reflecting the exposure light. CONSTITUTION: A high reflection member 20 and a low reflection member 100 are provided on a wafer stage WS. The low reflection member 100 has lower reflectance than that of a wafer W, and a surface of a glass plate 100 being the low reflection member is a non-coated smooth face ground with good plane accuracy. Only surface-reflected light on the non-coated smooth face is received via a projection optical system 14 or the like by a photoelectric detector 41. The photoelectric detector 41 sequentially outputs the photoelectric outputs of reflected light from respective exposure regions of the wafer W to exposure light onto a control system 42. The control system 42 calculates reflectance of the wafer W by a predetermined equation based on pre-measured photoelectric outputs, reflectance and the photoelectric outputs from the wafer W with respect to the reflection light which have been sequentially detected. |
