Slicing, cleaning, preparation of suede, peripheral etching, removal of PN + junction on the back, production of upper and lower electrodes, production of anti-reflection film, sintering, testing and grading, etc. 10 steps.
Specific Manufacturing Technology of Solar Cells
(1) Slice: The silicon rod is cut into square silicon wafers by multi-wire cutting.
(2) Cleaning: Clean the silicon wafer by conventional cleaning method, and then remove 30-50um of the cutting damage layer on the surface of the silicon wafer with acid (or alkali) solution.
(3) Fabrication of suede: Anisotropic etching of silicon wafer in alkali solution is used to fabricate suede on the surface of silicon wafer.
(4) Phosphorus diffusion: PN + junctions are formed by diffusion from coating source (liquid source or solid phosphorus nitride flake source), and the junction depth is generally 0.3-0.5um.
(5) Peripheral etching: The diffusion layer formed on the surface of the silicon wafer during diffusion will shorten the upper and lower electrodes of the battery and remove the diffusion layer by shielding wet etching or plasma dry etching.
(6) Remove the back PN + junction. The back PN + junction is usually removed by wet etching or grinding.
(7) Making upper and lower electrodes: using vacuum evaporation, electroless nickel plating or aluminium slurry printing and sintering process. First, the lower electrode is made, and then the upper electrode is made. Aluminum slurry printing is a widely used process.
(8) Making anti-reflection film: In order to reduce the input reflection loss, a layer of anti-reflection film should be coated on the surface of silicon wafer. The materials used to fabricate antireflective coatings are MgF2, SiO 2, Al2O3, SiO, Si3N4, TiO2, Ta2O5 and so on. The process methods can be vacuum coating, ion coating, sputtering, printing, PECVD or spraying.
(9) Sintering: Sintering battery chips on nickel or copper substrates.
(10) Test classification: according to the specified parameters and specifications, test classification.
