Microwave plasma CVD in the system Si-C-H-Ar: effect of process parameters

Si-C films were prepared on steel by the microwave (2.45 GHz) decomposition of tetramethylsilane (TMS) diluted in argon. The device used decouples the plasma power and the substrate temperature. The effects of various parameters (substrate position, temperature, gas flow rate, power, pressure) on composition and deposition rate were investigated. They are discussed in relation to electrostatic probe measurements. For all conditions, deposition rates are high (3-60 μm h-1). By using only TMS, the Si/C ratio in the films is restricted to values between 0.3 and 0.7. The variations in the process parameters do not induce significant changes in film compositions, however, they significantly change the deposition rates and the film hardness. In this field, the TMS dissociation process seems quite invariant with the conditions. With the introduction of SiH4 to the input gas phase (i.e., mixture SiH4 + TMS + Ar), silicon-rich films were obtained. The composition range was extended to Si/C = 1.7 but the mechanical properties are strongly changed.