The high cost of crystalline silicon solar cells has been considered as one of the major obstacles to their terrestrial applications. Spin on doping (SOD) is presented as a useful process for the manufacturing of low cost solar cells. Phosphorus (P509) was used as an n-type emitters of solar cells. N-type emitters were formed on p-type EFG ribbon Si wafers by using a SOD at different spin speed (1,000∼4,000 rpm), diffusion temperatures (800℃∼950℃), and diffusion time (5∼30 min) in N2+O2 atmosphere. With optimum condition, we were able to achieve cell efficiency of 14.1%.