INFLUENCE OF THE DEPOSITION PARAMETERS ON THE BONDING AND OPTICAL-PROPERTIES OF SINX ECR FILMS

SiNx films are deposited at room temperature using an electron cyclotron resonance plasma system for different N-2/SiH4 gases flow ratios (1.6-9) and microwave powers (50-200 W). The optical and bonding properties of the films and their N/Si ratio are studied as a function of the deposition parameters. Two operation modes of the ECR source, that we call mode A and mode B, resulting in films with similar properties are found. In fact, the films deposited at low powers (50-100 W) and high N-2/SiH4 ratios (7.5-9) (mode A) have similar characteristics to those deposited at high powers (150-200 W) and low N-2/SiH4 ratios (1.6-3). Near stoichiometric SiNx films are obtained in both modes, at 50 W and N-2/SiH4 ratio = 9 or at 150 W and N-2/SiH4 ratio = 1.6. A threshold in the microwave power (15 W) for the effective formation of the SiNx films is found. The two operation modes and the threshold are explained as a function of the strong dependence of the ion current density on the microwave power.