Study On Preparation Of Silicon Nitride Thin Films By Pulsed Laser Deposition

Silicon nitride thin films were widely used in the semiconductor devices,microelectronic industry, optoelectronics industry and solar cells for their excellent chemical stability, isolation and optics property.Silicon nitride thin films can be prepared by low pressure chemical vapor deposition (LPCVD), pulsed laser deposition (PLD), magnetron sputtering, plasma-enhanced chemical vapor deposition (PECVD) and so on. Pulsed laser deposition is a newly developed film-growth technique which can easily fabricate high-quality films compared to other techniques, because of its advantages of lower temperature during deposition, simple hardware, lower contamination during depositon, higher deposition rate, and the ability of preparing thin films with complicated composition. In addition, the technique allows the deposition of silicon nitride thin films at low temperature with high quality.In this paper, silicon nitride films were prepared on Si (100) substrates at various nitrogen pressures, different substrate temperatures and laser energy, and then annealing was conducted in 15Pa N2 at the temperature of 600℃. The films were examined by X-ray diffraction (XRD), scan electron microscopy (SEM) and ellipsometry. Through the research of the structural and optical properties of silicon nitride films, effects of deposition parameters for growing silicon nitride films were obtained.The experimental results indicate that the increasing nitrogen pressure can improve the morphology of silicon nitride thin films significantly, the differences in substrate temperature crucially influence the chemical composition of the films, to some extent, pulse energy affects the properties of silicon nitride films, and the properties of silicon nitride thin films can not be improved apparently after 30 minutes annealing at 600℃in 15Pa nitrogen pressure.Through the research of the structure,composition and morphology of silicon nitride thin films, effects of deposition parameters and optimized parameters for growing silicon nitride thin films were obtained. The results suggested that high quality silicon nitride thin films can be prepared by PLD.