Government of the United States of America, As Represented by the Secretary of Commerce

Jeremiah R Lowney

Michael W Cresswell

Santos Mayo

A method is provided for extracting overlay information from a target of an integrated circuit wafer wherein the first-level target has features wh are optically concealed by an overlying opaque planarized film. The target employed has an architecture including a resist feature on the planarized film and an embedded electron backscattering target feature disposed beneath the planarized film. This target is scanned with an electron bean of an energy sufficiently high (e.g., at least 11 keV) to penetrate the planarized film, be backscattered by the backscattered feature and return through the planarized film or through the planarized film and the resist feature. Electrons backscattered from the conductive first-level target feature through the resist feature are detected and a signal profile is generated based thereon. This signal profile is analyzed to extract overlay information.

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Leonardtown, MD, United States of America

Jeremiah R Lowney