TIME-RESOLVED INVESTIGATIONS OF N-MOS DEVICES BY CAPACITIVE COUPLING IN A LASER-SCANNING MICROSCOPE

A capacitive coupling method is used to study the stationary and switc hing properties of n-MOS inverters in a laser scanning microscope. The microscopic images contain information about the spatial distribution of the surface potential, a mapping of logical states can be performe d. The formation of the inversion channel of a n-MOS inverter with inc reasing gate voltage is observed with a voltage resolution better than 10 mV. The propagation of electrical pulses within the device under t est and the switching behaviour of the inverters are investigated with a time resolution of 100 ps. The capacitive coupling method is contac tless and no preparation of the device under test is necessary.