Abstract: In this work we have investigated the microwave plasma discharge assisted by electron cyclotron resonance for hydrogenation of thin film polycrystalline n+pp+ silicon solar cells in terms of defects passivation and surface etching. The polycrystalline silicon films were formed by high temperature chemical vapor deposition. Influence of various process parameters such as microwave plasma power (PMW), hydrogenation time (tH) and substrate temperature (TH) on the sheet resistance of the n+ emitter region and on the open-circuit voltage (Voc) of the n+pp+ structure were investigated. The n+ emitter region was obtained by phosphorus diffusion using a spin-on dopant P507 solution from filmtronics.