Substrate bias effect of the activated reactive evaporation processed β-SiC thin films

Abstract

β-SiC film prepared by the activated reactive evaporation (ARE) process, using Si as evaporation source and C 2H 2 as reactive gas, was proposed as a thermoelement of potential β-SiC/MoSi 2 thin film thermocouples [1]. In this paper, some of the important factors determining the sensor performance, i.e., structural, electrical, and mechanical properties of the silicon carbide films, were studied as a function of one of the important ARE process parameters, i.e., substrate bias, to improve the film quality and obtain the optimum deposition conditions for the β-SiC films with the properties suitable for thin film thermocouples. It was found that the film properties were very much dependent on substrate bias. The best quality β-SiC films with a C/Si ratio of 1.17 were obtained under optimum deposition conditions, i.e., C 2H 2 pressure 3 mTorr, substrate temperature 700 °C, ARE electrode voltage +150 V, and substrate bias −50V. Summarizing their electrical and mechanical properties: (i) conduction type, n-type; (ii) electrical resistivity, 4.8Ω·cm; (iii) carrier density, 6.5 × 10 16cm −3; (iv) Hall mobility, 19.4cm 2/Vs; (v) Vickers hardness, 3680 kg mm −2 at 25 g load; and (vi) Knoop hardness, 2060 kg mm −2 at 100 g load.