NONDESTRUCTIVE INTERNAL OBSERVATION IN ELECTRON-ACOUSTIC MICROSCOPY USING METAL-OXIDE-SEMICONDUCTOR LSI CHIP

A metal-oxide-semiconductor (MOS)-LSI was observed by electron-acousti c microscopy (EAM) under various operating conditions of acceleration voltage (HV). The results are as follows. (1) When HV=20 kV, arrays of contact holes which were covered with both an Al (thickness: 0.5 mu m ) and an SiO2 (0.6 mu m) layer could be observed. (2) However they cou ld not be observed when HV=15 kV. (3) The observable depth of EAM is c ontrollable using HV as a parameter. (4) The adjustment of the irradia tion power of the electron beam should make it possible to achieve non destructive internal observation of MOS-LSI specimens.