Among all solar cell technologies,silicon-based heterojunction (HJT) solar cell has been attracted the most attention because of its high conversion efficiency,few process steps and low temperature coefficient.Furthermore,HJT also provides best energy yield and lowest levelized cost of electricity (LCOE) due to its better performance at elevated working temperature on the surface of solar panels.According to accumulated data and simulation results,HJT delivers 6~10% more electricity depending on locations and consequently leads to lowest LCOE.From the electricity cost point of view,HJT is no doubt the most important next generation PV technology.In manufacturing of HJT solar cells,plasma enhanced chemical vapor deposition (PECVD),the equipment used to deposit multiple amorphous silicon (a-Si) layers to passivate wafer surface,plays the most critical role in device performance.A good PECVD system should operate stably at very low power density to avoid plasma damage.For 20% cell efficiency,very low surface recombination velocity is necessary to ensure over 730mV implied Voc after a-Si passivation.A good uniformity over large area is also necessary for high volume production purpose.