In silicon solar cells, the doping process is performed to form a Back Surface Field (BSF) layer and is followed by many other processes. In this study, phosphorus doped a-Si:H doped at a high concentration in the tunnel oxide layer was crystallized through furnace annealing and Excimer Laser Annealing (ELA), in order to apply it to the Polycrystalline (Poly) - BSF layer in the Tunnel Oxide Passivated Contact (TOPCon) structure. In the excimer laser annealing fabrication process, an XeCl excimer laser with a wavelength of 308 nm was used, and the thickness of the a-Si layer and energy density of the laser were varied from 20 to 40 nm and from 390 to 450 mJ/㎠, respectively. The highest carrier lifetime and implied VOC were found to be 588 ㎲ and 697 mV, respectively, at an a-Si thickness of 20 nm and energy density of the laser of 450 mJ/㎠. The TOPCon cell was fabricated using wet oxidation and plasma oxidation. Its efficiency and FF were found to be higher when fabricated using the wet process, with values of 19.41% and 74.8%, respectively, while its VOC and JSC values were higher when it was fabricated using plasma oxidation, with values of 41.04 mJ/㎠ and 644 mV, respectively. Therefore, if the conditions providing for a high implied VOC and carrier lifetime and sufficient crystallization were found, the efficiency of n-type TOPCon solar cells could be increased.