Fabrication method of P-type back-surface tunneling oxide passivation contact solar cell

Abstract

The invention provides a fabrication method of a P-type back-surface tunneling oxide passivation contact solar cell. The method comprises the steps of performing previous process processing on a frontsurface and a back surface of a P-type single-crystal silicon wafer; oxidizing the back surface to form an ultrathin tunneling oxide layer and fabricate a boron-doping silicon thin film layer; performing phosphorus diffusion on the front surface of the single-crystal silicon wafer, and fabricating a selective emitter; and printing metal electrodes on surfaces of a first passivation anti-reflection layer on the back surface and a second passivation anti-reflection layer on the front surface of the single-crystal silicon wafer, and forming favorable contact between the metal electrodes and thesingle-crystal silicon wafer, thereby obtaining P-type back-surface tunneling oxide passivation contact of the solar cell. The invention provides a complete and practical P-type tunneling oxide passivation contact solar fabrication process circuit, a process method of first back-surface boron-doping poly-silicon thin film and then front-surface phosphorus diffusion, secondary phosphorus diffusioncan be effectively prevented, so that a phenomenon that square resistance is not matched is generated, and the operability is high.

Description

technical field [0001] The invention relates to the field of solar cells, in particular to a method for preparing a P-type rear tunnel oxidation passivation contact solar cell. Background technique [0002] The recent rapid development of the photovoltaic market has accelerated the demand for high-efficiency cells. How to reduce costs and increase efficiency is still the most concerned by photovoltaic technicians. Conventional monocrystalline PERC cells are passivated by introducing an aluminum oxide / silicon nitride dielectric layer on the back, and adopt local metal contacts to effectively reduce electron recombination on the back surface and improve cell conversion efficiency. However, because the PERC cell limits the contact range on the back to the open area, the high recombination rate at the open area still exists. In order to further reduce the rear recombination rate to achieve the overall passivation of the rear, and to eliminate the back groove process, the full c...

AI Technical Summary

Problems solved by technology

This kind of diffusion method of phosphorus first and then boron, on the one hand, because the temperature of phosphorus expansion is lower than that of boron expansion, the process of boron expansion will cause secondary phosphorus expansion, resulting in poor square resistance matching, low contact resistance, and affected filling.

In addition, if the selective emitter made by existing laser doping is used, high-concentration doping cannot be achieved at the grid line and the advantage of efficiency improvement will be lost.