Silicon oxynitride films with varying oxygen/nitrogen ratio were grown from SiH4, N2O, and NH3 by means of a plasma-enchanced chemical vapor deposition process. The elemental composition of the deposited films was measured by a variety of high-energy ion beam techniques. To determine the chemical structure we used Fourier transform infrared absorption spectroscopy and electron-spin resonance. Ellipsometric data and values for mechanical stress are also reported. We show that the entire range of compositions from silicon oxide to silicon nitride can be covered by applying two different processes and by adjusting the N2O/NH3 gas flow ratio of the respective processes. It is suggested that the N2O/SiH4 gas flow ratio is the major deposition characterization parameter, which also controls the chemical structure as far as the hydrogen bonding configuration is concerned. We found that the films contain significant amounts of excess silicon and that the mechanical stress in the oxynitrides is lower than in plasma nitride. The electron-spin density is low (∼1017/cm3) in all samples.

The anneal behavior of plasma-enhanced chemical vapor deposited silicon oxynitride films has been studied using Fourier transform infrared absorption spectroscopy, nuclear reaction analysis, and electron-spin resonance. The anneal temperature range was 500–1000 °C. It is observed that the oxynitrides which contain only N–H bonds are thermally stable in the temperature range under study. The layers which also contain Si–H bonds are considerably less thermally stable. Abundant hydrogen effusion from these layers is observed at temperatures as low as 600 °C, accompanied by cracking and shrinkage of the films. It is suggested that the coexistence of both Si–H and N–H bonds offers the possibility for cross linking and that consequently the decomposition temperature of both types of bonds is lowered. Evidence for the occurrence of cross linking is found in the infrared difference spectra. Consistently, the silicon unpaired electron density does not increase upon annealing. The Si–H and N–H bands effectively shift towards higher wave numbers upon annealing at higher temperatures. This is ascribed to the inhomogeneity in bond strength, which in turn is related to a variation in electronegativity of the surrounding groups.

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The Long Range Inlier, a steep-sided plateau underlain mainly by Grenvillian gneisses, is the most prominent topographic feature of western Newfoundland. Apatite fission-track analysis of 31 samples from the Long Range Inlier and its surroundings yielded measured apparent ages of 343–152 Ma. Age versus elevation plots, track-length distributions, and model thermal histories indicate that the region experienced slow cooling in the late Paleozoic, with apparent exhumation rates of 7–9 m∙Ma−1 and cooling rates of 0.08–0.28 °C∙Ma−1. Model thermal histories suggest that the present upper surface of the Long Range plateau cooled below ~120 °C in Ordovician times. The thermal histories are compatible with, but do not require, some exhumation of the Long Range Inlier along Acadian thrust faults. Results from Early Carboniferous sedimentary rocks of the Deer Lake Basin are similar to Long Range Inlier data from similar elevations, implying that at some time between ~350 and 300 Ma, the entire region was buried to depths sufficient to induce total annealing (T > 120 °C) in these samples. Closure ages determined from model thermal histories indicate that regional cooling to temperatures below ~120 °C began before 300 Ma. The Carboniferous sedimentary cover was largely removed by Jurassic time, perhaps in response to lowering of regional base level by rifting associated with the opening of the Atlantic Ocean.

The low pressure chemical vapor deposition of in situ phosphorus-doped polysilicon films from Sill4 and PH3 was investigated in a production-type hot wall horizontal tube reactor as a function of PHJSiH4 mole ratio and deposition temperature. With increasing PH3 partial pressure, a reduction in growth rate is observed because the dissociative chemisorption of Sill4 is inhibited. The reaction proceeds via homogeneous gas phase reactions which explains that, in our case where we operate at a relatively high pressure of about 1 torr, the reduction in growth rate is limited to a factor of 2 (87-45 A/min). By using caged cassettes and an injector, the uniformities were better than _+5% for a load of 100 wafers with a diameter of 125 mm, maintaining a flat temperature profile, within 0.5~ over the boat. The grain size and crystalline structure were studied with transmission electron microscopy. Films deposited at 580~ appeared to have the largest grain size and a perfectly smooth surface. Correspondingly, the resistivity of saturated doped films revealed a minimum value just above 500 ~cm for a deposition temperature of 580~ A linear relation between resistivity and inverse grain size was established. This relationship can be explained by a model that takes into account the resistance of grain boundaries.The low pressure chemical vapor deposition method is widely used in integrated circuit manufacturing for the deposition of polycrystalline silicon films (1-14). Some applications of the polysilicon films in integrated circuits are: gate electrode for MOS devices, interconnection conductor, resistor, and emitter contact. Other applications include photovoltaic conversion, thermal and mechanical sensors, and large-area LCDs. The deposition temperature appears to be an essential parameter with respect to film structure and morphology. A deposition temperature from 610 ~ to 630~ has been widely used in the industry. For lower temperatures, the as-deposited films are amorphous. Interestingly, it was found that films deposited in the amorphous state and annealed afterward showed an improved film structure (larger grains) and decreased surface roughness as compared to films deposited at higher temperatures (10-14).In order to obtain a conductive film, dopant atoms like phosphorus, boron, or arsenic need to be incorporated in the film. Originally, the dopant was introduced into the film after deposition by diffusion. Diffusion is still popular because it is a cost-effective method. However, diffusion has the disadvantages that several process steps at high temperatures with long process times are required, resulting in a high thermal load of the wafers. More recently, ion implantation as a doping method allowed very accurate dose control and profile definition at low process temperatures. However, ion implantation is an expensive approach and the dopant atoms do not reach the inside corner of polysilicon deposited over a sharp step as used in interconnections for VLSI applications (11).Lately, the possibility of introducing th...