Electrode materials polycrystalline silicon

One of the most widely used materials for the fabrication of modern VLSI circuits is polycrystalline silicon, commonly referred to as polysilicon. It is used for the gate electrode in metal oxide semiconductor (MOS) devices, for the fabrication of high value resistors, for diffusion sources to form shallow junctions, for conduction lines, and for ensuring ohmic contact between crystalline silicon substrates and overlying metallization structures. 

Improvements in the performance of integrated circuits and the trend towards VLSI-technology require the replacement of polycrystalline silicon by materials with a lower resistivity for use as gate electrodes. Transition metal silicides appear to be valuable possibilities for these applications. Timgsten-silicon compounds could be suitable precursors for the precipitation of tungsten-silicide thin films. Moreover tungsten-silicon compounds are nearly unknown and of scientific interest. 

Substrates, Films are usually prepared on platinum or gold electrodes which are inert, but semiconducting materials including indium tin oxide, n-type polycrystalline silicon, gallium arsenide, cadmium sulphide and cadmium selenide, graphite [38, 59], and oxide covered metals [60] have also been used. In the majority of cases, the films are produced readily and the only serious limitations are the potential and the nucleophilic nature of the solution. 

To avoid catalytic interaction of the analyte with a heater made of noble metal, the films are frequently coated with a thin, chemically inert layer of SiO. Such passivation very often serves as a support for further functional layers in top-down microelectronic technologies. It should be noted that the passivation of electrode materials allows a reduction in requirements relating to their thermodynamic stability. In particular, the indicated approach is used in micro-hotplate fabrication. As a result most micro-hotplate designers consider polycrystalline silicon doped with boron or phosphorus impurities to be a very appropriate material for making heaters and temperature sensors because, with capsulation covering, it is stable up to 1,000 °C (Panchapakesan et al. 2001 Hwang... 

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