Fully silicided metallization

At the same time, the fully doped polysilicon resistivity (LPCVD or PECVD) is proving inadequate for future generation IC devices, and interest is shifting to refractory metal silicides and/or refractory metals as replacements. Therefore, it is not clear how significant the development of such a new process will be for integrated circuit manufacture. There are other applications, however, where it may be better suited. 

As an instance, the partial Ti-Si-B phase diagram is presented in Fig. 1. Silicon is not practically dissolved in TiB, and is fully concentrated in the metal matrix and in a ternary boro-silicide when it forms. This ternary boro-silicide phase of unknown structure (designated here as the T-phase) was found to be present as a very fine dispersoid around 200 nm in diameter in the three-phase eutectic (Ti) + T + TiB (Fig. 2). The ternary eutectic alloy hardness vv temperature plot shows a great potential for strengthening up to 600°C in comparison with the binary (Ti) + TiB (Fig. 3). 

The parent carbon hydride, on the other hand, is the fully covalent methane, CH4, the simplest of thousands of alkanes of general formula C 2n+2- Although others had prepared the corresponding silanes before, Alfred Stock, in 1916, was the first to carry out a systematic investigation of them with the aid of his vacuum hne and its mercury-activated stopcocks and valves. In the absence of air and water, he found that the metal silicides (as he had the borides, see p. 400) reacted with various acids, as represented in Equation (15.3) ... 

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