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To enable lithography at low ki factors, OPC (optical proximity correction) on photo masks is a method of strong and growing importance. But CD (critical dimension) metrology ofOPC features is suffering from several drawbacks: -oPc structures often do not have two parallel edges, which are required for usual CD metrology methods. -There are no commonly agreed standard definitions how and where to measure some types of OPC structures. -The CDs are very small (often far below the lower limit ofCD standards). -There is no automated software for the measurement of OPC structures on operator level.A metrology method and a fully automated software for metrology of OPC structures based on LWM optical CD metrology tools is shown in this paper. It automatically distinguishes between hammerheads and serifs in various orientations. The method works analog to pitch measurements and requires only pitch calibration and no additional CD calibration. The results of light optical metrology tools with i-line and DUV wavelength is compared to CD SEM results.

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