In order to study the passivation characteristics of the carrier selective contact structure in N-type crystalline silicon cells, a special material structure was designed. The change of implied open circuit voltage after annealing, deposition of SiNx∶H film and sintering of the materials structure with different doping concentration distribution were compared and the passivation mechanism was analyzed. The results show that the implied open circuit voltage is very sensitive to the doping concentration distribution of structure. The ‘penetrating diffusion’ increase across poly-Si/SiOx into the c-Si base, the corresponding implied open circuit voltage increases firstly and decreases later after annealing, SiNx∶H film deposition and sintering. After the samples were deposited with SiNx∶H thin film, the increase of the implied open circuit voltage gradually decreases; and the value of implied open circuit voltage samples show a tends to decline after sintering, and the declining trend of the implied open circuit voltage gradually decreases. When a suitable doping process is selected, the average value of the implied open circuit voltage can reach 738 mV after firing.