J. Phys. IV France 05 (1995) C5-801-C5-807
TiN-TixSiy Codeposits A.P.C.V.D. Produced Using the TiCl4-N2-SiH2Cl2-H2 SystemG. Llauro, A. Bendeddouche, M. Nadal and R. Hillel
IMP-CNRS, 66860 Perpignan cedex, France
Mixtures of TiNx, TiSi2 and Ti5Si3(N) were chemically vapour codeposited at atmospheric pressure using the TiCl4 - N2 - SiH2C12 - H2 system. Compact materials with very intimately dispersed phases and with controlled composition were obtained between 825 - 875°C and using flow rate ranges : 0.5 ≤ DN2 ≤ 2.5, and 0.05 ≤ DSiH2Cl2 ≤ 0.2 (in l/h). DTiCl4 and DH2 were kept constant at 0.183 and 30 (in l/h) respectively. According to the Ti-Si-N ternary phase diagram, TiNx whith x = 0.95 +/- 0.05, TiSi2 and Ti5Si3(N), corresponding to some solubility of nitrogen into Ti5Si3, were in thermodynamical equilibrium. At 850°C, DTiC14 = 0.183 and DH2 = 30 (in l/h), the effect of N2 and SiH2Cl2 input concentrations were studied. At DSiH2Cl2 = 0.1 l/h, the deposition rate was found to increase linearly with the square root of the N2 molar fraction up to 5.10-2, then to decline at higher concentration. TiNx was 20 mol% at DN2 = 0.5 l/h, reached about 40 mol% at 1 l/h and remained almost constant while DN2 increased to 2 l/h. At DN2 = 2 l/h, about 70 mol% in TiNx was obtained with DSiH2Cl2 = 0.05 l/h. Then from DSiH2Cl2 ranging from 0,l to 0.2 l/h, TiNx concentration remains almost equal to 35 mol%. A linear dependence in the SiH2Cl2 concentration was observed for the growth rate. The relationship between the logarithmic plot of the growth rate versus the reciprocal of codeposition temperature (in Kelvin) was linear and an apparent activation energy of 105 kJ/mol was calculated. The effect of temperature on the TiNx preferred orientations was also evidenced.
© EDP Sciences 1995