SUBSTRATE BIAS EFFECT OF THE ACTIVATED REACTIVE EVAPORATION PROCESSEDBETA-SIC THIN-FILMS

beta-SiC him prepared by the activated reactive evaporation (ARE) proc ess, using Si as evaporation source and C2H2 as reactive gas, was prop osed as a thermoelement of potential beta-SiC/MoSi2 thin film thermoco uples [1]. In this paper, some of the important factors determining th e sensor performance, i.e., structural, electrical, and mechanical pro perties of the silicon carbide films, were studied as a function of on e of the important ARE process parameters, i.e., substrate bias, to im prove the him quality and obtain the optimum deposition conditions for the beta-SiC films with the properties suitable for thin film thermoc ouples. It was found that the film properties were very much dependent on substrate bias. The best quality beta-SIC films with a C/SI ratio of 1.17 were obtained under optimum deposition conditions, i.e., C2H2 pressure 3 mTorr, substrate temperature 700 degrees C, ARE electrode v oltage + 150 V, and substrate bias -50 V. Summarizing their electrical and mechanical properties: (i) conduction type, n-type; (ii) electric al resistivity, 4.8 Omega.cm; (iii) carrier density, 6.5 x 10(16) cm(- 3); (iv) Hall mobility, 19.4 cm(2)/Vs; (v) Vickers hardness, 3680 kg m m(-2) at 25 g load; and (vi) Knoop hardness, 2060 kg mm(-2) at 100 g l oad.