Patterned mask having a transparent etching stopper layer

摘要

An optical exposure mask for patterning an optical beam comprises an etching stop layer (3) of a material that is substantially transparent with respect to the optical beam used for the exposure and selected from a group essentially consisted of Al2O3, MgO and a mixture thereof, a transparent pattern (6) provided on one of upper and lower major surfaces of the etching stop layer, and an opaque pattern (2) provided on one of the upper and lower major surfaces of the etching stop layer for patterning the optical beam, wherein the material forming the etching stop layer has an etching rate that is substantially smaller than an etching rate of a material that forms the transparent pattern for any of dry and wet etching processes. <IMAGE>