Patent ID: 7393615

Claim:
A method of identifying a flare-affected region on a wafer comprising: mounting a mask in an exposure apparatus of a photolithography system that includes a light source for emitting an exposure light and a projection lens for focusing the exposure light onto a wafer, the mask comprising a mask substrate having a light shielding region and a light transmission region, and each of the regions including at least one group of light transmission patterns transparent to the exposure light; projecting light emitted by the light source through the mask and projection lens and onto a photoresist layer on a wafer to expose the photoresist layer, and forming photoresist patterns by developing the exposed photoresist layer; measuring the line widths of photoresist patterns formed by exposure light from the light shielding region of the mask, and the line widths of photoresist patterns formed by exposure light from the light transmission region of the mask; comparing the line widths of the photoresist patterns formed by exposure light from the light shielding region of the mask to the line widths of the photoresist patterns formed by exposure light from the light transmission region of the mask, and based on said comparing, determining an amount of flare produced by the projection lens; when the exposed area of the wafer has been determined to have been affected by the flare, discerning an interval on the exposed area of the wafer over which the line widths of the photoresist patterns formed by exposure light from the light transmission region of the mask vary substantially; and identifying a circular region of the wafer, having a radius equal to said interval and a center located at a position corresponding to the boundary between the light transmission region and the sight shielding region, as having been affected by flare produced by the lens during the exposure of the photoresist layer.