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In this thesis the passivation and diffusion of hydrogen of sputtered silicon nitride layers in multicristalline silicon solar cells was investigated. Firstly the dependence of the volume passivation from different deposition and layer parameters such as temperature, pressure, and layer thickness was examined. The focus of this investigation was the influence of these parameters on the diffusion respectively the passivation of the solar cell. Based on a literature research and the experimental results a qualitative model which describes the diffusion mechanisms of hydrogen in a solar cell could be found. By optimizing the hydrogen concentration and by using an ammonium pretreatment before coating the cell efficiency could be improved significantly. Based on the investigation of the working mechanisms of the ammonium pretreatment, alternative ammonium prepreatment methods were tested such as a DC-plasma pretreatment and a RF cathode.