Process for fabricating semiconductor integrated circuit device, and exposing system and mask inspecting method to be used in the process

Claim 1

An integrated circuit device fabrication method comprising: (a) transferring a first pattern on a first phase shift optical mask substrate onto a positive photosensitive resist film on a wafer with a reduction projection exposure apparatus by illuminating the first pattern and projecting a reduced real image of the first pattern onto the positive photosensitive resist film; (b) patterning a first underlying film on the wafer using the patterned positive photosensitive resist film as an etching mask, thereby forming a first film pattern; (c) transferring a second pattern on a second phase shift optical mask substrate onto a negative photosensitive resist film on the wafer with the reduction projection exposure apparatus by illuminating the second pattern and projecting a reduced real image of the second pattern onto the negative photosensitive resist film; and (d) patterning a second underlying film on the wafer using the patterned negative photosensitive resist film as an etching mask, thereby forming a second film pattern.