Stroboscopic scanning electron microscope to observe two-dimensional and dynamic potential distribution of semiconductor devices

The stroboscopic SEM is very usuful to observe the dynamic voltage contrast image of semiconductor devices at a certain phase of repeating cycles. It consists of the usual SEM and the pulse gate which is inserted between the electron gun and the first condenser lens. The effect which affects the pulse width in the picosecond region is avoided in the design of the pulse gate. The shortest half-width of pulse is 0.2 ps. The spot size at usual pulse operations (several ps - several ns) is smaller than 0.1 µm. Examples of the two-dimensional voltage contrast images are shown in cases of 1 GHz Gunn diode and of a Simple 8 MHz IC.