Apparatus for detecting positions of wafer and mask and deformation error detecting method

Abstract

A wafer has first and second wafer marks formed thereon, and a mask has first and second mask marks formed thereon. The first and second mask marks are in correspondence with the first and second wafer marks, the first and second mask marks and the first and second wafer marks constituting first and second alignment mark groups. First and second illumination optical system apply illumination light to the first and second alignment mark groups. First and second observation optical systems obtains images formed by scattered light from the first and second alignment mark groups. Optical axes of the first and second observation optical systems are oblique relative to an exposure surface, and the optical axes vertically projected upon the exposure surface cross at a right angle a straight line interconnecting the first and second wafer marks. A controller detects a size of the wafer and mask in accordance with images obtained by the first and second observation optical systems. High precision position alignment is possible even during exposure without lowering throughput.

Claims aren’t available for this document.