Diffusion method for polycrystalline silicon solar photovoltaic cell silicon chip

Abstract

The invention relates to a diffusion method for a polycrystalline silicon solar photovoltaic cell silicon chip. The method comprises the following steps of: 1, putting the silicon chip into a furnace; 2, oxidizing; 3, diffusing a phosphorus source for the first time; 4, performing impurity distribution for the first time; 5, diffusing the phosphorus source for the second time; 6, performing impurity distribution for the second time; 7, gettering; and 8, taking the chip out of the furnace. The diffusion method for the polycrystalline silicon solar photovoltaic cell silicon chip has the advantages that: the phosphorus impurity doping concentration distribution is good, the diffusion rate has high controllability, the first pass yield of diffusion of the silicon chip is improved, the minority carrier lifetime of a polycrystalline silicon chip is prolonged, and the utilization rate of the phosphorus source in the diffusion process is high.

Description

technical field [0001] The invention relates to a solar photovoltaic cell, in particular to a method for diffusing a silicon chip of a polycrystalline silicon solar photovoltaic cell, and belongs to the field of solar cell manufacturing. Background technique [0002] Polycrystalline silicon solar cell technology, which emerged in the 1980s, has been successfully applied to large-scale polycrystalline silicon solar cell production after 30 years of accumulation and improvement. The breakthrough in the total installed capacity of photovoltaic power generation in the world has benefited from the excellent tubular diffusion solutions provided by companies such as Centrotherm Photovoltaics in Germany and Tempress Systems in the Netherlands. These are suitable for polysilicon piece The tubular diffusion furnace has a unique design from the temperature control method, exhaust air treatment, soft landing and other systems to meet the up polysilicon PV The need for mass producti...

AI Technical Summary

Problems solved by technology

This process method has a narrow adjustment window, and it is difficult to obtain an excellent phosphorus impurity doping concentration distribution. The obtained silicon wafer usually has a higher surface doping concentration, which also brings a higher loading The rate of carrier recombination reduces the photoelectric conversion efficiency of photovoltaic cells;

[0006]2. The controllability of the diffusion rate of phosphorus atoms in the silicon wafer by the traditional diffusion method is poor;

[0007]3. In the traditional diffusion method, when the furnace is out of the furnace, there is often a small amount of residual phosphorus pentoxide and other substances in the furnace tube of the tubular diffusion furnace. When the furnace door is opened, the pentoxide Phosphorus encounters cold water vapor to form metaphosphoric acid, which will drip and contaminate silicon wafers, reducing the first-time yield of silicon wafer diffusion;

[0008]4. After the traditional diffusion method is completed, there will inevitably be dislocation defects at the grain boundaries of polycrystalline silicon wafers, where more dangling bonds can be formed. These dangling bonds and Iron and other metal ions form the recombination center of photogenerated minority carriers, which reduces the minority carrier lifetime of polycrystalline silicon wafers and reduces the photoelectric conversion efficiency of polycrystalline silicon cells.

[0009]5, such as As shown in Figure 2, the large nitrogen intake pipeline of the traditional diffusion method is set at the front end of the phosphorus source pipeline. Due to the interference of the gas flow of the large flow nitrogen gas for saturation (hereinafter referred to as large nitrogen), it is not conducive to the phosphorus source. The rapid derivation of , this design makes the phosphorus source utilization rate low in the diffusion process

Images