Electrical resistivity, internal stress and surface corrosion of vacuum deposited Mo films on SiO2/Si substrate have been studied in relation to the film structure for the purpose of application to gates and interconnections of MOS LSIs. The resistivity is mainly dominated by grain boundary scattering of conduction electrons. The reflection coefficient of electrons at grain boundaries is determined by oxygen content in grain boundaries. The tensile stress in Mo films increases linearly with heat treatment temperature up to 1000°C. The increment of tensile stress can be explained by volume contraction of film due to increase in grain size. The surface corrosion of Mo films in deionized water and moisture has been investigated quantitatively using ellipsometry. The corrosion has also been found to be caused by grain boundaries. Studies of processing of Mo gates and interconnections have also been made, and we have succeeded in making a high speed MOS RAM.
Electrical conduction mechanism in thin film of amorphous semiconductor having the composition of Si12-Te48-As30-Ge10 (at%) is investigated. Sandwich-type samples with electronblocking Au electrode on both sides of the amorphous film are used in the present study. Current-voltage characteristic of this sample is quite different from the characteristic observed in the sample of Al-amorphous semiconductor-Au or Al-amorphous semiconductor-Al structure used in the previous work, and shows a marked dependence on ambient temperature. From the experimental results of the temperature dependence of potential barrier formed at the interface of Au and amorphous thin film, and from the evaluations of physical quantities which may' be relevant for the conduction, it is concluded that there exist three different mechanisms of carrier transport and the predominance of each mechanism depends on the ambient temperature range. That is, at relatively low temperature about 259K, bulk limited current flow due to the Poole-Frenkel effect dominates the conduction mechanism. At room temperature (295K), contact limited current becomes dominant for the conduction; whilst at temperatures about 357K, space charge limited-current due to injected hole is dominant.
The electrooptic characteristics of cholesteric-nematic mixtures were studied in relation to surface alignment, layer thickness (d) and helical pitch (p). It was made clear that their characteristics could be consistently understood by taking the ratio (d/p) of layer thickness to helical pitch into consideration, and the optimum value of d/p for display devices was about 0.7 for the parallel-aligned cell (parallel cell) and about 0.5 for the vertical-aligned cell (vertical cell).