Patent ID: 6191858
Filing Date: 2001-02-20
Classification: G03F

Abstract:
A position detecting apparatus comprising:an illumination optical system for applying illumination light to a wafer mark and a mask mark both for scattering incidence light for position alignment, the wafer mark being formed on an exposure surface of a wafer, the mask mark being formed on a mask surface of an exposure mask, and the illumination light being applied along an optical axis which is oblique relative to the exposure surface;an observation optical system having a light reception surface on which scattered light from the wafer mark and the mask mark is focussed, an optical axis of said observation optical system being slanted in a direction opposite to a direction of an optical axis of said illumination optical system, relative to a normal direction to the exposure surface of the wafer, and regular reflection light of the illumination light applied to the wafer and the mask from said illumination optical system being set so as not to become incident upon the light reception surface; andcontrol means for controlling to detect a positional relation between the wafer and the mask in accordance with images formed by said observation optical system by using the scattered light from the wafer mark and the mask mark.