Automatic positioning of device electrodes using the scanning electron microscope

In current technology, the edge definition that can be achieved by the photoresist process is approximately ten times sharper than the registration accuracy that can be maintained over a workpiece of any reasonable size. A description is presented of an attempt to improve registration through feedback from the workpiece itself; the servo signal is generated by the photoresist-exposing radiation, a submicron-diameter electron beam. Using this technique, the gate electrode of a field-effect transistor (FET) has been automatically positioned relative to the channel.