Production process:
Slicing, cleaning, preparing suede, peripheral etching, removing the back PN+ junction, making the upper and lower electrodes, making an anti-reflection film, sintering, testing the split, etc. 10 steps.
Solar cell specific manufacturing process description
(1) Slicing: Using a multi-wire cut, the silicon rod is cut into square wafers.
(2) Cleaning: It is cleaned by a conventional wafer cleaning method, and then the surface of the silicon wafer is cut with a acid (or alkali) solution to remove the damaged layer by 30-50 um.
(3) Preparation of suede: Anisotropic etching of the silicon wafer with an alkali solution The suede was prepared on the surface of the silicon wafer.
(4) Phosphorus diffusion: The coating source (or liquid source, or solid phosphorus nitride sheet source) is used for diffusion to form a PN+ junction, and the junction depth is generally 0.3-0.5 um.
(5) Peripheral etching: A diffusion layer formed on the peripheral surface of the silicon wafer during diffusion causes short-circuiting of 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 back PN+ junction. The back side PN+ junction is removed by conventional wet etching or grinding.
(7) Making upper and lower electrodes: using vacuum evaporation, electroless nickel plating or aluminum paste printing and sintering. Make the lower electrode first, then make the upper electrode. Aluminum paste printing is a widely used process.
(8) Making an anti-reflection film: In order to reduce the reflection loss, an anti-reflection film is coated on the surface of the silicon wafer. The materials for making the anti-reflection film are MgF2, SiO2, Al2O3, SiO, Si3N4, TiO2, Ta2O5 and the like. The method may be a vacuum coating method, an ion plating method, a sputtering method, a printing method, a PECVD method, or a spray method.
(9) Sintering: The battery chip is sintered on a base plate of nickel or copper.
(10) Test binning: Test classification according to the specified parameter specifications. The process of producing cell sheets is complicated, and generally involves major steps such as wafer inspection, surface texturing, diffusion bonding, dephosphorization, plasma etching, anti-reflection coating, screen printing, rapid sintering, and inspection and packaging. .
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