Patent ID: 8050488

Claim:
A method of analyzing a wafer sample comprising: detecting first defects of a photoresist pattern on the wafer sample having a plurality of shot regions exposed by an exposure process with related exposure conditions, respectively, each of the shot region including a first portion exposed within a tolerance error range of a reference exposure condition and a second portion exposed out of the reference exposure condition; setting up the first defects detected from the second portion of at least two shot regions as second defects of the photoresist pattern; obtaining a first reference image displaying the second defects; setting up at least one of the first defects positioned at the first portion of the shot region and corresponding to the second defects of the first reference image as a third defect of the photoresist pattern; setting up a position of the third defect as a weak point of the photoresist pattern on the first portion of the shot region; determining the exposure conditions relative to the shot region having no weak point at the first portion thereof as an exposure margin of the exposure process; and obtaining a second reference image displaying the weak point of the photoresist pattern on the first portion of the shot region when the reference exposure condition belongs to the exposure margin of the exposure process.