PERC cell back surface passive film layer and PERC cell preparation method based on ALD process

Abstract

The invention discloses a PERC cell back surface passive film layer and further discloses a PERC cell preparation method based on the ALD process. The PERC cell back surface passive film layer comprises a back surface alumina layer, a back surface SiONx layer and a back surface SiNx layer which are sequentially deposited on a PERC cell silicon substrate surface outwardly. The PERC cell preparation method comprises steps of texturing; expansion; back surface polishing, etching and dephosphorization glass; back surface ALD alumina preparation; front surface PECVD deposition of a SiNx anti-reflection film; back surface PECVD deposition of a back surface passive film layer; local back surface laser opening; screen printing; sintering. In a back surface PECVD deposition process of the back surface passive film layer, after a silicon chip enters a furnace tube, furnace tube temperature rises to 400-600 DEG C, the SiONx film is firstly deposited, and the SiNx is then deposited. The PERC cell back surface passive film layer and the PERC cell preparation method are advantaged in that cell conversion efficiency is high, an independent annealing process after ALD alumina preparation is omitted, cost is reduced, and cell conversion efficiency is improved; when front surface plating is carried out after back surface plating, a surface color of the monocrystalline silicon chip is uniform, and cell appearance is effectively improved.

Description

technical field [0001] The invention relates to a film layer and a battery preparation method, in particular to a passivation film layer and a PERC battery preparation method. Background technique [0002] Conventional fossil fuels are increasingly depleted. Among the existing sustainable energy sources, solar energy is undoubtedly the cleanest, most common and most potential alternative energy source. Solar power generation devices are also called solar cells or photovoltaic cells. Solar energy is directly converted into electrical energy. The principle of power generation is based on the photovoltaic effect of the semiconductor PN junction. With the development of technology, PERC solar cells with partial contact back passivation have appeared. The core is to use aluminum oxide and nitride on the back of the silicon wafer. Silicon covering, in order to passivate the surface and improve the long-wave response, so as to improve the conversion efficiency of the battery. There...

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Problems solved by technology

[0002] Conventional fossil fuels are increasingly depleted. Among the existing sustainable energy sources, solar energy is undoubtedly the cleanest, most common and most potential alternative energy source. Solar power generation devices are also called solar cells or photovoltaic cells. Solar energy is directly converted into electrical energy. The principle of power generation is based on the photovoltaic effect of the semiconductor PN junction. With the development of technology, PERC solar cells with partial contact back passivation have appeared. The core is to use aluminum oxide and nitride on the back of the silicon wafer. Silicon covering, in order to passivate the surface and improve the long-wave response, so as to improve the conversion efficiency of the battery. There are two main methods of aluminum oxide deposition: PECVD method and ALD method, and ALD must have Annealing process, so if ALD method is used to prepare alumina on the back side of PERC, annealing step is required. The purpose of annealing is to activate hydrogen in alumina and remove -CH 3 and -OH groups, without annealing, the large amount of hydrogen present in the SiNx film on the backside and the -CH in alumina during sintering after printing 3 Combine with -OH to form CH 4 or H 2 O, destroys the aluminum oxide and SiNx films when gathering and escaping at high temperature, which makes the passivation effect worse and reduces the electrical performance of the cell, and has a greater impact on the light decay of the cell. After the ALD method, PECVD is used for integrated annealing and back coating , when the front coating is done after the back coating, there will be obvious chromatic aberration on the surface of the silicon wafer due to the winding plating, and it also prolongs the overall process time of the back film

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