Gate quality Si3N4 prepared by low temperature remote plasma enhanced chemical vapor deposition for III-V semiconductor-based metal-insulator-semiconductor devices

We report the properties of silicon nitride films deposited by the electron cyclotron resonance remote plasma enhanced chemical vapor deposition method on Si substrates using SiH4 and N2. The effects of nitrogen/silane gas ratio (R=N2/SiH4), electron cyclotron resonance power, substrate temperature, and H on growth, refractive index, chemical composition, and etch rate were investigated. Nominally stoichiometric Si3N4 films were obtained with a refractive index of 1.9∼2.0 at a wavelength of 632.8 nm. The etch rate of the films in a buffered HF solution (7:1) was low (∼0.7 nm/min) and increased with increasing H2 gas flow rate and decreasing substrate temperature during deposition. Fourier transform infrared spectroscopy and high temperature thermal evolution experiments showed very small amounts of H in the films. A leakage current less than 100 pA/cm2 at a field of 2 MV/cm, a resistivity of ≳4×1017 Ω cm, and breakdown strengths of 6-11 MV/cm at a current density of 1 μA/cm2 were observed. These properties are comparable to those of Si3N4 prepared by conventional high temperature (700 °C) chemical vapor deposition. The performance of GaAs-based field-effect-transistors in switching and power applications can be enhanced substantially by employing a metal-insulator-semiconductor structure. By taking advantage of an in situ process approach, insulator-GaAs structures were successfully gated with excellent interfacial properties.