Characterisation of industrial-scale remote PECVD SiN depositions

Remote PECVD SiN deposition parameters have been optimised for a fired-through metallization process on multicrystalline silicon solar cells. The best pressure, gas ratio and deposition temperature resulted in cell efficiencies of up to 14.3% when used with a 30 Ohm/square emitter and above 15% for 40 Ohm/square diffusion. Fourier transform infrared spectroscopy revealed that, during firing, the films lost a significant proportion of their hydrogen content, providing good bulk and surface passivation. In all cases the refractive index was reduced by approximately 1% during firing. The parameter space that gives optimal conditions for the lighter emitter coincides with a region in which the refractive index can be varied, resulting in greater process flexibility.