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High Productive Solar Cell Passivation on Roth&Rau MAiA® MW-PECVD Inline Machine – A Comparison of Al2O3 , SiO2 and SiNx-H Process Conditions and Performance
H.-P. Sperlich, D. Decker, P. Saint-Cast, E. Erben, L. Peters
Lifetime, Passivation, PECVD, Al2O3, ALD
Wafer-Based Silicon Solar Cells and Materials Technology
Subtopic: Manufacturing Issues and Processing
Event: 25th European Photovoltaic Solar Energy Conference and Exhibition / 5th World Conference on Photovoltaic Energy Conversion, 6-10 September 2010, Valencia, Spain
Session: 2CO.3.6
1352 - 1357
ISBN: 3-936338-26-4
Paper DOI: 10.4229/25thEUPVSEC2010-2CO.3.6
0,00 EUR
Document(s): paper


High rate Al2O3 PECVD deposition process has been established and optimized on industrial proven MAiA PECVD system from Roth&Rau AG with plasma generation by a 2.45 GHz linear microwave plasma sources and gas mixture comprising of nitrous oxide (N2O), trimethylaluminium (TMAl) and argon (Ar) by using a “plug & play” approach based on existing SiO2 process (0.1mBar pressure and 350°C Heater Temp). Compared to the existing Silicon Oxide or Nitride process the TMAl-chemistry was found much more reactive to result in significant higher deposition rate and very localized deposition traces. By optimizing the design of the TMAl gas inlet we achieved same excellent uniformity for thickness (<3%) and RI (<1%) like for SiO2 and SiNx-H films on the same reactor, whereas the precursor utilization is much better providing reasonable low chemical costs per wafer and cleaner chamber with higher uptime and less maintenance interaction. Process window experiments were done for PECVD Al2O3 with respect to carrier lifetime. Effective lifetime (4 ms) and high negative fix charge density (13E12 cm-2) were achieved, which is comparable to PAALD films reported in the literature. Firing stability of passivation properties appear is still an issue. Nevertheless first p-type PERC cell passivation experiment were done using our process on industrial solar cells from an early customer. PECVD-Al2O3 perform comparable (Isc) or even better (Voc, FF, ETA +0.4%) than the inhouse ALD-type film.