Investigation of rapid thermal oxide/ silicon nitride passivation stack of n+ emitter

• RTO process induces active phosphorus profile change.
• SiN/SiO2 process-induced changes.
• SiN/SiO2 is an efficient stack for emitter surface passivation.
• Anticipation on starting emitter process parameters.

To anticipate the initial phosphorus diffusion parameters of silicon solar cells process fabrication, we report in this paper an overview of our experiments on silicon n+-emitters passivation by means of rapid thermal silicon oxide/silicon nitride stack. The process-induced changes have been evaluated and explained. We found that 900 °C and 80 s were the appropriate process parameters to grow 10 nm silicon oxide. Investigation of the effect of this oxidation on n+ multicrystalline silicon emitters revealed a large decrease (more than 25%) of the sheet resistance and around 12% increase of the junction depth. The experiments also revealed that the passivation effect of the optimal silicon oxide/silicon nitride stack is efficient only for higher emitter quality. In addition, we found that this stack reduces the surface reflection more than the optimal single silicon nitride layer.