Solar cell boron diffusion method and boron diffusion device

Abstract

The invention discloses a solar cell boron diffusion method and a boron diffusion device, and belongs to the technical field of manufacturing of solar cells. The method comprises the following steps: putting a silicon wafer which needs to be subjected to boron diffusion into a diffusion furnace and carrying out warming; introducing a boron source, dichloroethylene, oxygen and nitrogen for boron diffusion; stopping introducing the boron source, the oxygen and the dichloroethylene and keeping the temperature at 900-960 DEG in a nitrogen atmosphere for 15-40min, wherein the nitrogen flow is 10-20L / min; and carrying out cooling, taking out the silicon wafer and finishing the diffusion process. The dichloroethylene is introduced in a high temperature diffusion process of a BBr3 liquid source, so that the on-chip uniformity and the inter-chip uniformity of the boron diffusion can be improved; corrosion of B2O3 to a quartz device in the furnace is retarded; the service lifetime of the quartz device is prolonged; and metal pollution of the silicon wafer in the high-temperature process is avoided.

Description

technical field [0001] The invention belongs to the technical field of solar cell production, and in particular relates to a solar cell boron diffusion method and a boron diffusion device. Background technique [0002] Solar energy is a clean, efficient and inexhaustible new energy source. In the new century, the governments of various countries regard the utilization of solar energy resources as an important content of the national sustainable development strategy. Photovoltaic power generation has the advantages of safety and reliability, no noise, no pollution, less constraints, low failure rate, and simple maintenance. At present, due to the extremely abundant reserves of silicon materials in the earth's crust, and the excellent electrical and mechanical properties of silicon solar cells compared with other types of solar cells, silicon solar cells occupy an important position in the field of photovoltaics. At the same time, Silicon solar cells are also the most widely...

AI Technical Summary

Problems solved by technology

For the silicon wafers placed in different positions of the diffusion furnace, due to the action of gravity during the conveying process of boron oxide, as the conveying distance increases, the content of boron oxide carried by the gas decreases, resulting in uneven doping between the wafers

[0013] (2) Boron oxide B formed during the diffusion process 2 o 3 Due to its high melting point, it is easy to deposit and solidify in the tail gas pipe at the furnace mouth, and block the exhaust pipe, which not only reduces the uniformity of the doping of the diffusion layer, but also easily leads to the rupture of the quartz device. leakage, resulting in a production accident

[0014] (3) The solidification and deposition of boron substances can easily cause the components of the diffusion furnace (such as diffusion air intake pipes, quartz furnace doors, paddles, etc.) to bond together. Solidified deposition will cause the quartz furnace door and the diffusion furnace to stick together. When the diffusion furnace tube is opened, it will easily cause damage to the quartz furnace door and increase production costs.

[0015] (4) The boron oxide generated during the operation of the process will condense on the inner wall of the diffusion furnace door when it is cold, and the boron oxide will react with the substances in the diffusion furnace door and corrode the diffusion furnace door, causing the inner wall of the furnace door to be uneven, and the furnace tube cannot be guaranteed. The airtightness, the external gas will enter the furnace tube and pollute the chip source

[0016] Boron diffusion doping is the key to achieve high conversion efficiency of n-type solar cells, but the current high-temperature boron diffusion uniformity is poor, which affects the performance of the cell

The essential problem of poor boron diffusion uniformity is that boron oxide has a high boiling point and is liquid at the diffusion temperature, so it is deposited unevenly on the silicon wafer. As the transmission distance increases, the gas-carried boron oxide content decreases, resulting in uneven doping between sheets

[0017] The existing technology is to connect an external pure water source bottle, carry water vapor into the pipeline through small nitrogen, and combine with boron oxide to form boric acid with a low boiling point, thereby improving the uniformity of boron diffusion and slowing down the B 2 o 3 Corrosion of quartz devices in the furnace tube, but water vapor cannot remove the metal impurities that may exist on the surface of the silicon wafer and in the furnace tube

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