Overlay keys unaffected by membrane quality asymmetry

摘要

In order to minimize device defects, an overlay key is disclosed that can measure actual misalignment values without being affected by the asymmetry of the underlayer.;In an overlay key used in a lithography process, an overlay key is used which is concave and convex in overlay measurement so as not to be affected by film quality asymmetry.;The overlay key can be used for asymmetric membranes on the mother.;When the overlay key is selected in the measurement, the right side of the left concave key and the left side of the right convex key allow accurate overlay measurement irrespective of the film quality asymmetry.;Therefore, according to the present invention, it is possible to minimize device defects by devising an overlay key capable of measuring actual misalignment values without being affected by the asymmetry of the underlayer.