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Silicon nitride films prepared by the Plasma Enhanced Chemical VaporDeposition technique (PECVD) are widely used in microelectronics. The intrinsic stress value of the silicon nitride films is a key factor which determines their reliability. A low frequency (50 kHz) RF discharge and a N 2 /NH 3 /SiH 4 gas mixture were used to deposit silicon nitride films on 4-inch silicon wafers in a horizontal hot-wall reactor at a temperature of 350 °C. The compressive stresses in the deposited films were found to increase linearly with the nitrogen ionization created in the glow discharge. The nitrogen ion bombardment at the film surface induces ion implantation into the deposited film which results in film expansion. The stresses were deduced by the interference fringes technique and from surface profiler measurements. Optical Emission Spectroscopy of the N 2 /NH 3 /SiH 4 discharge was used for measuring the N+ peak intensity variation with the 2 pak ntesit vaiaton ithth partial pressure of the nitrogen gas. When the nitrogen ionization was increased, a shift of the main infrared transmission peak corresponding to the Si-N bond in the silicon nitride films was observed using Fourier Transform Infrared Spectroscopy (FTIR). The Si-H and N-H infrared peaks in the films were not affected by the ion bombardment. A linear relationship was found between the wavenumber of the main infrared Si-N peak vM ( 835-875 cm" 1 ) and the intrinsic stress ai of the deposited nitride films with the slope dvM/doi -4.85x10" 8 cm' 1 /Pa.

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The fabrication process of a two-dimensional position sensitive radiation detector (2-D PSD) with a 4 cm 2 active area is presented. Critical steps in the fabrication are emphasised . Edge effects represent critical problems in producing large area ion implanted silicon radiation detectors with low leakage currents and a high breakdown voltage (BV) . Two methods have been used to increase the breakdown voltage of the junction : the use of i) floating held limiting rings (FFLR) and ii) field plates (FP) . Several situations have been simulated analytically and numerically. A comparison of the theoretical results with the measurements realised using the detectors is presented. It is shown that a substantial improvement in the BV of the detector can be achieved by these methods.

Plasma enhanced chemical vapor deposited ( PECVD ) silicon oxynitride films with refractive indices varying from 1.65 to 1.85 have been deposited in a hot-wall reactor using a SiH4/NH3/N2O gas mixture. A systematic investigation of the variation of the intrinsic stress of the deposited films with the parameters of deposition and the properties of the films, has been carried out. Our results show that silicon oxynitride films deposited in optimal conditions can support annealing temperatures of 900°C without cracking. The mechanical stresses in the films were determined by the Newton's fringes technique and a surface profiler. The film thickness was measured by ellipsometry at a wavelength of 632.8 nm. Fourier transform infrared spectroscopy ( FTIR ) was used to measure the hydrogen content of the films. The composition of the silicon oxynitride films was determined by Auger electron spectroscopy ( AES ) and Rutherford backscattering spectrometry ( RBS ).