A method and apparatus for inspecting a reticle measures line widths using an inspection tool that images the reticle and compares the image with a design database to detect errors in real time. The differences between the line widths of patterns on the reticle and the design database are stored during the inspection procedure. The difference (or "bias") information is then processed off-line to create a map of all the local line-width deviation values (i.e., bias) of every feature on the reticle. The resultant local bias map can be used as a feedback mechanism to improve the reticle manufacturing process, as a "go/no go" criteria for the validity of the reticle, and as a standard report shipped together with the mask to the wafer fabrication facility, where it can be used as a yield-enhancing tool.
RELATED APPLICATIONS
This application a continuation of application Ser. No. 10/322,708, filed on Dec. 19, 2002 now U.S. Pat. No. 7,133,549, which is a continuation of application Ser. No. 09/286,498, filed on Apr. 5, 1999 now abandoned, the disclosures of which Applications are incorporated by reference herein.
