Patent ID: 7116815

Claim:
A method for inspecting a chrome-less mask, wherein the chrome-less mask at least includes a transparent region and a phase shift region, the method comprising the steps of: providing a database holding: a mask database that corresponds to the chrome-less mask, wherein the mask database includes a frame line pattern and that area and pattern enclosed by the frame line pattern corresponds with area and pattern enclosed by the phase shift region of the chrome-less mask; and a first inspection signal pattern, wherein the first inspection signal pattern is generated by the mask database; providing an inspection instrument for inspecting the chrome-less mask and a second inspection signal pattern for inspecting the chrome-less mask, wherein scanning location of the second inspection signal pattern corresponds to scanning location of the first inspection signal pattern; and comparing the first inspection signal with the second inspection signal to find any difference, wherein no discrepancies between the first inspection signal pattern and the second inspection signal pattern indicates the chrome-less mask is defect-free.