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This paper presents the approach to reduce the deterioration of poly-Si based passivating contacts through screen- printed silver pastes by modifying the SiNx capping layer thickness and firing temperature. Its impact is investigated by fabricating p-type back junction solar cells featuring the passivating contacts at the cell rear side. We demonstrate that the improved contact formation without compromising of the quality of passivating contacts is possible if the firing temperature is optimized for the chosen SiNx layer thickness. On the full area of M2-sized industrial p−type Cz wafers, we achieve an open-circuit voltage of 716 mV and an efficiency of 22.6%, both independently. A median contact resistivity of 2 mΩcm2 is measured with transfer length method for the optimized SiNx layer thickness and firing temperature. The investigation with scanning electron microcopy shows that certain amount of small etch pits are necessary to form the contact between screen-printed silver and phosphorus-doped poly-Si properly. The best efficiency that we achieved so far with this cell concept is 22.9 %, independently confirmed. [ABSTRACT FROM AUTHOR]