Industrial large scale silicon nitride deposition on photovoltaic cells with linear microwave plasma sources

Microwave plasmas have some outstanding features like high charge carrier concentrations at ion- and electron energies below 10 eV, which predestine these plasmas for thin film deposition technologies requiring a non-remarkable ion impact. The plasma deposition of the passivating Si3N4-layers on multi-crystalline solar cells without formation of ion impact induced surface recombination centres is an example for such kind of process. By using the process gases SiH4, NH3 and H2 a hydrogen rich plasma is generated resulting in excellent passivation properties of the silicon nitride layers on photovoltaic cells. In order to achieve stable plasma conditions on large-scale industrial deposition dimensions (150 nm/min at an area of 20×100 cm2) over long times, magnetic field enhanced linear microwave plasma sources based on the plasmaline® principle were applied. Following, some results for this remote microwave PECVD of Si3N4 on multi-crystalline silicon solar cells are presented.