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 N-2. The effects of nitrogen/silane gas ratio (R=N-2/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 similar to 2.0 at a wavelength of 632.8 nm. The etch rate of the films in a buffered HF solution (7:1) was low (similar to 0.7 nm/min) and increased with increasing H-2 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/cm(2) at a field of 2 MV/cm, a resistivity of >4x10(17) Omega cm, and breakdown strengths of 6-11 MV/cm at a current density of 1 mu A/cm(2) were observed. These properties are comparable to those of Si3N4 prepared by conventional high temperature (700 degrees 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. (C) 1996 American Vacuum Society.