International Business Machines Corporation

Thomas P Donohue

George A Sai-Halasz

Fritz J Hohn

A system for the detection of features in a semiconductor wafer for registration. An E-beam scans across an insulator covered with a metallic layer. The high energy electrons penetrate and cause the generation of electron/holes pairs. The drift or migration can be sensed as a current, the intensity of which is a function of the applied field strength. The field strength is in turn varied by the topology of the feature or the presence of a junction in the device. Since the E-beam position is known, registration occurs by correlation with the underlying feature as it is mapped out by sensing variations in current. The feature may be an alignment mark or a device under construction on the wafer.

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Katonah, NY, United States of America

Thomas P Donohue