NOUFERROUS METALLURGICAL EQUIPMENT

Low-pressure boron diffusion device with BC_l3 as doping source is one of the important manufacturing equipment of N-type TOPCon solar cells. Its process features uneasy control of gas transportation， strong corrosiveness of process gas， high requirement in reaction cleanliness and high-temperature tail gas. In view of such characteristics， this paper optimizes the gas path system and adds the gas path heat tracing to ensure the accuracy and stability of BC_l3 At the same time， the full-quartz furnace door adopted and the water-cooled flange and air-cooled flange added can effectively eliminate metal ion contamination and improve the minority carrier life as well as the efficiency of solar cells. Moreover， the full-wrapped water cooling， filter element filtration and wash function doubles the filter element replacement cycle and the service life of the vacuum pump. This paper also studies the diffusion square resistance and defect rate under different insertion methods. Compared with the downstream vertical insertion method， the horizontal insertion method has the advantages of large diffusion square resistance range of the upper， middle and lower silicon wafers in the same quartz boat， and low black-edge defect rate after they are made into battery.