Passivated emitter and rear cells (PERC) on p-type Cz Si wafers are currently being migrated to mainstream production, applying the ongoing improvements in recent years. For PERC solar cells, the emitter recombination loss becomes the main loss of the entire cell. Currently, two-step diffusion consisting of low temperature phosphosilicate glass (PSG) deposition and high-temperature drive-in has been widely applied in production and can reduce saturation current density (J(0)) of the emitter in the passivated area. However, a low contact resistance under metal area cannot be guaranteed. Meanwhile, the determination of the saturation current density J(0) in the passivated area is dependent on the injection density during the measurement, and exact calculation of J(0,metal) is not as convenient as J(0,diffusion) which could lead to a wrong assessment in cell analysis. In this study, a three-step diffusion (low-temperature PSG deposition-high-temperature drive-in-low temperature PSG deposition) with low J(0) and low Ag-Si contact resistance is investigated and combined with a selective emitter by an etch-back process. The results are compared with a conventional two-step POCl3 diffusion. The accuracy of J(0) measurement and J(0,metal) test method is also discussed. With these improvements, the champion cell efficiency of our PERC solar cells fabricated on 156 x 156 mm(2) wafers using screen printing technology and industrial-type process has reached 22.61% with Voc of 684.4 mV and a fill factor of 81.49%, as confirmed by Fraunhofer ISE CalLab PV cells. By implementing the diffusion process to mass production, the average cell-efficiency gain is approximately 0.2% with a median efficiency of 21.7%.