Advanced diffusion system for low contamination in-line rapid thermal processing of silicon solar cells

A novel diffusion system for in-line rapid thermal diffusion is presented. The lamp-heated furnace has a low thermal mass and a metal free transport system based on the walking beam principle. The furnace has been used to process first solar cells with lightly and highly doped emitters respectively. Solar cells with shallow lightly doped emitters show that the emitters processed in the new device can be well passivated. Shallow emitters with sheet resistances of up to 40 /sq. have been contacted successfully by means of screen printing and firing through a SiNx antireflection coating.