Selective emitter structure, its preparation method and application

Abstract

The invention discloses a selective emitter structure, its preparation method and application. The selective emitter structure includes a first dielectric layer and a heavily doped silicide layer sequentially stacked on the surface of a crystalline silicon cell substrate, and a metal electrode as a first electrode is combined on the heavily doped silicide layer. In the present invention, by applying the aforementioned selective emitter structure to the front of the crystalline silicon solar cell, the contact between the metal electrode and the single crystal silicon substrate can be eliminated, the existence of a high recombination zone can be avoided, the recombination of carriers can be reduced, and a more excellent The passivation effect, and also improve the carrier collection efficiency, can obtain lower contact resistivity, thereby optimizing the battery performance, improving the battery efficiency, in addition to simplifying the manufacturing process of crystalline silicon solar cells, reducing the manufacturing cost.

Description

technical field [0001] The invention relates to a preparation process of a selective emitter structure, in particular to a selective emitter structure based on a silicon oxide / doped polycrystalline silicide laminated structure and its preparation method and application, belonging to the field of semiconductor technology. Background technique [0002] Tunnel Oxide Passivated-Contact Structures (TOPCon, Tunnel Oxide Passivated-Contact structures) is a new crystalline silicon solar cell structure proposed in 2014, aiming to improve the passivation of the back of the silicon cell. Specifically, this technology uses an n-type silicon wafer, first grows a layer of ultra-thin silicon oxide with a thickness of less than 3nm on the back of the silicon wafer, then deposits a layer of phosphorus-doped amorphous silicon or polysilicon layer, and finally prepares a full back metal electrodes. The main advantage of the TOPCon structure is that it realizes the comprehensive passivation of...

AI Technical Summary

Problems solved by technology

However, there are some defects in the existing preparation process of this type of solar cell, for example: when firing the front gate electrode, the silver paste will penetrate the anti-reflection layer and passivation layer, contact with single crystal silicon, and achieve a good electrode touch

However, despite the continuous optimization of the area and preparation method of the gate finger electrode, the direct contact between the metal and the single crystal silicon still exists, which will also introduce significant metal contact recombination damage, making it difficult to further improve the open circuit voltage and fill factor of the battery.

Specifically, the hazards of direct contact between metal electrodes and single crystal silicon are at least: ① resulting in a large number of interface states and serious carrier recombination. Generally speaking, the saturation current density of the metal-to-metal contact area is 2000fA / cm 2 above, thus seriously affecting the efficiency of the battery; ②The metal may diffuse into the single crystal silicon, resulting in serious recombination of carriers in the body

[0003] The current main method to reduce metal contact compound damage is to use selective emitter, that is, to use laser ablation of phosphosilicate glass or borosilicate glass to form local heavy doping during the ablation process, but the ablation process will bring surface damage layer, resulting in a large recombination current, J 0,met Probably at 1000fA / cm 2 about

In addition, there are many technical problems in the process and equipment of the commonly used boron-expanded emitters, mainly in the following aspects: 1) If BBr is used 3 As a diffusion source, it is easy to produce viscous by-products containing bromine in the furnace door area during the reaction process, resulting in sticking of the furnace door; 2) If BCl is used instead 3 To avoid sticking of the furnace door, HCl or Cl will be produced 2 Such strong corrosive by-products will seriously affect the life of equipment and pipelines

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