The specific production of solar cells includes 10 steps such as slicing, cleaning, preparation of textured surface, phosphorus diffusion, remove the rear PN+ junction, making upper and lower electrodes,fabrication of anti-reflection film, sintering, and test classification.
1. Slicing: use multi-wire cutting to cut silicon rods into square silicon wafers.
2. Cleaning: Use conventional silicon wafer cleaning methods to clean, and then use acid (or alkali) solution to remove 30-50um of the cut damage layer on the surface of the silicon wafer.
3. Preparation of textured surface: anisotropic etching of silicon wafers with alkaline solution to prepare textured surfaces on the surface of silicon wafers.
4. Phosphorus diffusion: use coating source (or liquid source, or solid phosphorus nitride flake source) for diffusion to form PN+ junction, the junction depth is generally 0.3-0.5um.
5. Peripheral etching: The diffusion layer formed on the peripheral surface of the silicon wafer during diffusion will short-circuit the upper and lower electrodes of the battery, and the peripheral diffusion layer is removed by masking wet etching or plasma dry etching.
6. Remove the rear PN+ junction. The back PN+ junction is usually removed by wet etching or grinding.
7. Make the upper and lower electrodes: use vacuum evaporation, electroless nickel plating or aluminum paste printing and sintering. Make the lower electrode first, and then make the upper electrode. Aluminum paste printing is a widely used process method.
8. Fabrication of anti-reflection film: In order to reduce the loss of incident reflection, a layer of anti-reflection film should be covered on the surface of the silicon wafer. Materials for making anti-reflection coatings include MgF2, SiO2, Al2O3, SiO, Si3N4, TiO2, Ta2O5, etc. The process method can be vacuum coating method, ion coating method, sputtering method, printing method, PECVD method or spraying method, etc.
9. Sintering: The battery chip is sintered on a nickel or copper base plate.
10. Test classification: According to the specified parameter specification, test classification.
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