We have studied the influence of different process parameters on the composition and mechanical properties of silicon-nitride layers deposited in a SiH4-NH3-N~ plasma. The layers were deposited at temperatures between 300 ~ and 600~ at total pressures between 65 and 195 Pa and RF frequencies between 0.1 and 20 MHz. The Si/N ratio and the density of the as-deposited layers were determined by means of RBS. IR spectroscopy was used to measure the hydrogen content and Si-H/N-H ratio of the plasma nitride layers. It is shown that hydrogen content, density, and mechanical stress of plasma silicon-nitride layers strongly depend on deposition conditions. To explain the experimental data, a simplified reaction model is given. With this model, differences in densities, hydrogen content, and stress can be related to cross-linking reactions and to the extent of ion bombardment which takes place at different excitation frequencies.Plasma silicon-nitride layers are widely used in the IC technology for passivation of devices. The layers act as barriers against the diffusion of impurity ions such as sodium, and they are also used for scratch protection during mounting operations. The electrical and mechanical properties of plasma silicon-nitride layers depend strongly on composition, density, and mechanical stress and, therefore, on the deposition conditions. Composition and stress measurements of plasma silicon-nitride layers have been reported (1-4), but attempts to make a more systematic study and quantitative evaluation of the results are relatively, scarce. Therefore, a systematic experimental approach was applied to study composition, density, and stress of plasma silicon-nitride layers prepared under various deposition conditions.In this paper, we report on the influence of deposition temperature, gas pressure, gas phase composition, and RF frequency on the composition, density, and stress of plasma silicon-nitride layers. The experimental data will be described by a simplified reaction model.

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Stability of hydrogen in silicon nitride films deposited by lowpressure and plasma enhanced chemical vapor deposition techniques J. Vac. Sci. Technol. B 7, 150 (1989); 10.1116/1.584707 Characterization of hydrogenation and dehydrogenation of postplasma treated lowpressure chemicalvapor deposited amorphous silicon films Silicon (oxy) nitride films ( SiO x Ny ) have been deposited onto silicon by low-pressure chemical vapor deposition using SiHzCl z , NzO and NH3 or ND 3 • Nuclear reaction analysis, elastic recoil detection, and Rutherford backscattering spectrometry have been used to determine the elemental composition of the films with emphasis on the hydrogen and deuterium content. In the as-deposited, NH 3 -grown films the bulk hydrogen concentration is about 3 at. % for an oxygen! nitrogen atomic ratio (OIN) smaller than 0.4, for OIN> 0.4 it is lower. In 900 and 1000·C vacuum annealed films the bulk hydrogen concentration as a function of OIN goes through a maximum at O/N ::::0.4. By comparing this observation with the D content in ND 3 -grown films as a function ofOIN, a model is deduced which explains this behavior. This model involves an oxygen induced increase of the electronegativity of the atoms to which hydrogen/deuterium is bound. Annealing at 1000 ·C in a Hz/N 2 gas mixture ofNH 3 -grown films results in bulk hydrogen concentrations ranging between those measured after the 1000 ·C vacuum anneal and the values for the as-deposited state. The chlorine concentration increases with increasing oxygen content in the oxynitride films from 0.04 at. % at OIN = 0 to 0.65 at. % at OIN = 00. Implications of the data and the proposed model for the electrical performance of the silicon (oxy ) nitrides are briefly discussed.