Effect of hydrogen on passivation quality of SiNx/Si-rich SiNx stacked layers deposited by catalytic chemical vapor deposition on c-Si wafers

• Passivation mechanism of Si-rich SiNx/SiNx stacked layers is investigated.
• H atoms play important role in passivation quality of the stacked layer.
• Addition of H2 gas during Si-rich SiNx film deposition greatly enhances effective minority carrier lifetime (τeff).
• For a Si-rich SiNx film with refractive index of 2.92, τeff improves from 3.3 to 5.1 ms by H2 addition.

We investigate the role of hydrogen content and fixed charges of catalytic chemical vapor deposited (Cat-CVD) SiNx/Si-rich SiNx stacked layers on the quality of crystalline silicon (c-Si) surface passivation. Calculated density of fixed charges is on the order of 1012 cm− 2, which is high enough for effective field effect passivation. Hydrogen content in the films is also found to contribute significantly to improvement in passivation quality of the stacked layers. Furthermore, Si-rich SiNx films deposited with H2 dilution show better passivation quality of SiNx/Si-rich SiNx stacked layers than those prepared without H2 dilution. Effective minority carrier lifetime (τeff) in c-Si passivated by SiNx/Si-rich SiNx stacked layers is as high as 5.1 ms when H2 is added during Si-rich SiNx deposition, which is much higher than the case of using Si-rich SiNx films prepared without H2 dilution showing τeff of 3.3 ms.