The material and electrical properties of SiNx:H films deposited using a 2% SiH4/N2 mixture with additional N2 in an electron cyclotron resonance reactor have been evaluated. Deposition rate, refractive index, and stoichiometry have been determined using ellipsometry, Rutherford backscattering spectrometry, and infrared spectroscopy. Current-voltage and dielectric breakdown characteristics have been measured on metal-insulator-silicon structures. Stoichiometric material with a hydrogen content of 1.5 at. % is created using a ratio of SiH4/N2=0.003, P=2 mTorr, T=250 °C, and power=650 W. Hydrogen levels are reduced by using lower ratios of SiH4/N2, lower total pressure, or higher microwave power. Higher total pressure results in significantly enhanced deposition rates, but with greatly increased H and O content. The low-field resistivity of these films is largely independent of the process parameters over the range investigated. The dielectric breakdown strength is significantly greater in films deposited at higher temperature, but is somewhat degraded in films deposited at lower ratios of SiH4/N2, despite the higher density and lower hydrogen content of these films.

No abstract

The profiles and surface morphologies of etched SiC can be effectively controlled using electron cyclotron resonant plasmas. When high bias (100 V) is applied to the substrate, etching is anisotropic and smooth surfaces result, with the exception of trenches which form at the base of the sidewall features. In contrast, etching at low bias (8 V) is more isotropic with no apparent trenching, but results in textured etched surfaces and jagged sidewall features. However, the etched surfaces and sidewall features can be smoothed by subjecting the samples to a high bias pretreatment prior to etching at lower bias. Etching isotropy is strongly dependent on both the applied bias and the proximity of the sample to the ECR source. A combination of high and low bias etching has been employed for micromachining cantilever structures from single‐crystal SiC.

The wet chemical etching of GaInP, GaAs, and InP in solutions of HCl:CH3COOH:H20= has been evaluated. In the absence of the oxidant, H202, the solutions etch tnP and GaInP with high selectively over GaAs but rough surfaces are formed. When H202 is added, smoother surfaces are obtained and depending on the H202 concentration, the etchant can be made highly selective for GaAs. The etch rate of these mixtures varies strongly with the age of the solution, initially increasing and then gradually declining. The increase in etch rate is attributed to the formation of C12 in solution from the reaction of HC1 with H202, and the eventual decrease in etch rate to the gradual evaporation of C12 from solution. The CH3COOH in these mixtures functions as a nonaqueous solvent. In dilute solutions (1 HCI: y CH3COOH: 1 H202, with y -> 20) slow etch rates and smooth surfaces can be obtained for all three materials, suggesting that this etchant may be useful for recessing layers for heterostructure electronic and optoelectronic device applications.