▪ Removing surface contaminations and saw damage layers
▪ Reducing light reflection and increasing light absorption
▪ Anisotropic etching occurs in a hot alkaline solution to form micron pyramid texture
▪ Preparing uniform PN junctions to from a built-in electric field, which separates photo-generated carriers
▪ The BCl3 source is introduced into the high temperature diffusion furnace for a period of time, and P + doping layer is formed on the surface of n-type silicon wafer
BSG Removal and Back Side Polish
▪ Removing BSG layer on the back
▪ Back Side Polish
▪ BSG Removal：Using a certain concentration of acid solutions to chemically react with the back of the silicon wafer, so as to etch the BSG on the back side.
▪ Alkali etching: using the etching effect of alkali to polish the back of the silicon waferetching.
Low Pressure Chemical Vapor Deposition
▪ Providing a tunneling oxide layer to selectively pass electrons.
▪ The amorphous silicon layer is formed, and the passivation film layer is constructed together with the oxide layer.
▪ SiO2 is formed through the reaction of oxygen and silicon under low pressure and high temperature process condition.
▪ SiH4 is thermally decomposed into Si and H2 under low pressure and high temperature， and the amorphous silicon layer is formed.
▪ Polysilicon formation through high temperation crystallization process of amorphous silicon.
▪ At the same time, the polysilicon is doped with phosphorus to form N+ layer，Phosphorus doping in Poly to form good ohmic contact with back electrode.
▪ POCl3 source is diffused at high temperature for a period of time to conduct phosphorus doping on Poly-Si.
▪ PSG， Removing wrapped-around PSG layer on the front side of silicon wafer.
▪ Poly-Si，Removing the Poly-Si on the front side of the silicon wafer.
▪ PSG， Removing the BSG on the front side and the PSG on the back side.
▪ PSG Removal : Using a certain concentration of acid solutions to chemically react with the back of the silicon wafer, so as to etch off the edge junction.
▪ Alkali etching: Using the etching effect of alkali to remove polycrystalline silicon film on the front surface
▪ The field effect passivation of AlOx film is used to reduce the minority carrier recombination on silicon wafer surface
▪ TMA and ozone are fed into the furnace tube, and AIOx film is grown by the method of ALD(atomic layer deposition)
Front side / Back side SiNx coating
▪ Depositing SiNx anti- reflective thin film to reduce light reflection.
▪ SiNx thin film is deposited using PECVD method through ionized decomposition of SiH4 and NH3 gas.
Screen Printing & Firing
▪ Ag paste is printed on the surface of the silicon wafer and fired to form a conductive electrode, in order to collecting and exporting current
▪ Printing back busbar and drying
▪ Printing back finger and drying
▪ Printing front busbar and drying
▪ Printing front finger
▪ Light injection
▪ According to the test sorting standards, the solar cells are classified by appearance, EL and electrical performance.
▪ Automatic Optical Inspection
▪ Electroluminescent test
▪ IV test