Controllable-etching laminated passivation structure and preparation method and application thereof

The invention provides a controllable etching laminated passivation structure and a preparation method and application thereof, the laminated passivation structure comprises a plurality of layers of double-layer passivation structures stacked on a crystalline silicon substrate, each double-layer passivation structure is composed of a layer of nano silicon oxide film and a layer of doped polycrystalline silicon film, and the number of the double-layer passivation structures is 3-10. According to the invention, a plurality of layers of nano silicon oxide films and doped polycrystalline silicon films are repeatedly arranged on the surface of the crystalline silicon substrate, when the polycrystalline silicon is etched and thinned in an alkaline solution, because the etching selection ratio of silicon oxide and polycrystalline silicon is large, the alkaline solution is relatively slow to etch silicon oxide, the nano silicon oxide films play an etching buffer role, and the polycrystalline silicon is etched and thi