Industrial PVD metallization for high efficiency crystalline silicon solar cells

In this paper we present first results concerning different thermal evaporation processes for thin aluminum layers, which are carried out on a pilot system with a throughput of up to 540 wafers/h (156 × 156 mm²). To qualify the processes the deposited aluminum layers were evaluated with respect to homogeneity and conductivity. Additionally the effect of the different processes on the passivation quality of a thermally grown 100 nm thick SiO₂ was analyzed by means of lifetime measurements, indicating a negligible effect of the conducted process variations on the passivation quality. Finally high-efficiency silicon solar cells were prepared to determine the overall potential and to compare it with an electron beam (e-gun) evaporation process, which is used as a standard process in our laboratory. An efficiency of up to 21% was achieved by the high deposition rate technique performing at least as well as our standard high efficiency process.