Patent ID: 7696057

Claim:
A method, comprising: forming an electron beam alignment target in a substrate, said electron beam alignment target comprising an electron back-scattering layer in a bottom of a trench and a capping layer on top of said electron back-scattering layer and filling said trench; forming an optical alignment target in said substrate after forming said electron beam alignment target, said optical alignment target positioned in a predetermined location in said substrate relative to a location of said electron beam alignment target in said substrate; forming a resist layer on said substrate; aligning a photomask to either said optical alignment target or to said electron beam alignment target, said photomask having a first pattern of clear and opaque regions representing a first set of features of a fabrication level of an integrated circuit; exposing said resist layer to actinic radiation through said photomask to form optically exposed regions in said resist layer, said opaque regions substantially blocking said actinic radiation and said clear regions substantially transmitting said actinic radiation; locating a home position of an electron beam relative to said location of said electron beam alignment target; exposing said resist to said electron beam in a second pattern to form electron beam exposed regions in said resist layer, said second pattern representing a second set of said features of said fabrication level of said integrated circuit; and developing said resist layer to transfer said first and second patterns to a resist pattern in said resist layer.