Laser Scribing Thin Silicon Nitride Films

Silicon dioxide and titanium dioxide have been used as AR coatings in solar cells but SiO has a low refractive index whereas TiO does not contribute to surface passivation. Silicon nitride is an important exception to the general rule that carbide and silicide films are usually electrically conductive. Thin films of SiN refractory material are used to provide diffusion barriers, as a dielectric layer or for producing stable, electrically conductive metal contact layers. Many films are essential in both silicon based and thin film solar cell fabrication. In striving to reduce costs by simplifying cell structure, layers that perform multiple functions become attractive. SiN has been used for some years as an anti-reflective (AR) coating. Due to the recent acceptance of the passivation capability of silicon nitride films, it has become the highly favoured dielectric in silicon solar cell production.