A SEM Surface Voltage Measurement Technique

A plug in module has been developed for the measurement of surface voltages of semiconductor devices in a standard S.E.M. The secondary electrons produced by the S.E.M. electron beam are removed by a normal field and collected in a modified Everhart-Thornley detector. The design of the apparatus allows complete top access to the device. The detector output vs. surface voltage is essentially linear over a -10 to +10 volt range.