NONDESTRUCTIVE INTERNAL OBSERVATION OF METAL-OXIDE-SEMICONDUCTOR LSI DESIGNED BY 0.8 mu m RULE

A metal-oxide-semiconductor (MOS)-LSI chip was designed by the 0.8 mu m rule, and a passivated film on the chip was etched off while keeping the chip mounted on a ceramic package. The acoustic signal generated by irradiation of a chopped electron beam was picked up by a piezoelectric detector (PZT element) attached to the back of the package. The results of observation by electron-acoustic microscopy (EAM) are as follows: (a) the observable depth (tx) was proportional to the electron range (Re); (b) tx shifted to a shallower side (about 50% of Re) compared to the case of bipolar transistors; (c) contact holes (0.8 mu m2) were distinctly observed at HV=19 kV; and (d) the resolution of our EAM was estimated to be about 0.4 mu m at a chopping frequency of the electron beam of 1 MHz and an acceleration voltage of 18-19 kV. 10 refs.