Tubular furnace structure for gas diffusion

Abstract

The invention provides a tubular furnace structure for gas diffusion. The tubular furnace structure comprises a furnace body, a furnace mouth and a furnace tail of the furnace body are provided with an air inlet structure and an air exhaust structure respectively, the air inlet structure and the air exhaust structure enable the whole furnace body to form a one-way channel where air enters from thefurnace mouth and exits from the furnace tail, and the problem caused by uneven flow of air entering and exiting in the same direction is avoided. The problem that the square resistance uniformity ofa furnace mouth of a traditional air inlet tubular furnace is poor can be solved by changing the air inlet mode.

Description

technical field [0001] The invention relates to the field of solar cell manufacturing, in particular to the furnace body design technology for diffusion in the field of solar cell manufacturing. Background technique [0002] Of all solar cells, silicon solar cells are the most commercially available. Photoelectric conversion solar cells can directly convert solar energy into electrical energy, and its power generation principle is based on the photovoltaic effect of semiconductor PN junctions. P-type silicon wafers need to diffuse phosphorus elements to obtain PN junctions, and N-type silicon wafers need to diffuse boron elements to obtain PN junctions. During the production of solar cells, part of the process needs to diffuse or deposit some elements on the silicon wafer to form a thin layer structure. Such as boron diffusion process, phosphorus diffusion process, low pressure boron diffusion process, low pressure phosphorus diffusion process, etc. The diffusion process ...

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Problems solved by technology

[0003] At present, the diffusion equipment on the market adopts the gas in and out of the furnace tail, and the structure of the gas in and out is one way of air intake and one way of exhaustion, such as figure 1 As shown (the arrow is the air flow direction), and the gas outlet needs to go through the exhaust pipeline with the same length as the furnace body, so due to the single limitation of the inlet and outlet positions, the gas flow in the furnace tube will be uneven, and the The doping concentration gas is larger in the place where the gas is pumped, and the less it goes to the place where the gas is pumped, resulting in poor uniformity of the square resistance at the furnace mouth and a large difference in the square resistance inside the tube, resulting in uneven final diffusion; and for phosphorus diffusion. In other words, the exhaust gas intake at the furnace tail will lead to the accumulation of metaphosphoric acid at the furnace mouth, which will cause corrosion of the metal parts at the furnace mouth and increase the maintenance cost of the furnace mouth.

[0004] The conventional diffusion furnace body adopts a single air intake structure with a single air intake direction. Due to the large size of the furnace tube, the atmosphere of the gas in the furnace tube will not be uniform

Moreover, this kind of air intake pipe adopts a single air inlet, which is easy to cause the doped gas flow rate in the place where the air intake will be high, while the furnace mouth is used to extract air, and the air extraction port is at the bottom of the furnace tube, so that the position of the air intake will be high. As a result, the air flow presents an obvious arc shape, which has a great influence on the uniformity of the square resistance at the pumping position. The gas flow rate doped in the pumping place is small, resulting in a large difference between the furnace mouth and the furnace tail, and the pumping along the way In the case of air and one way of air intake, there will be obvious deflection of air flow, resulting in uneven air flow in the furnace tube

In the phosphorus diffusion, the exhaust gas of the furnace tail gas inlet and the furnace mouth will cause the P that does not participate in the reaction at the furnace mouth 2 o 5 All of them gather at the air inlet and the furnace door. After the furnace door is opened, the temperature drops and reacts with water vapor in the air to form metaphosphoric acid, which causes corrosion of metal devices.

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