A doping gas path for doping single crystal with zone melting gas

Abstract

The invention provides a novel doping gas path for a zone-melting gas-doped single crystal. The pipeline structure of the doping gas path is shaped like a Greek letter Pi, the middle part of the Pi-shaped doping gas path is an L-shaped section pipeline with an enough length, one end of the L-shaped section pipeline is communicated with a protective gas inlet and a doping gas inlet, the other end of the L-shaped section pipeline is communicated with a gas outlet and a gas exhaust outlet, the gas outlet enters a hearth, a flow meter is arranged at each of the protective gas inlet, the doping gas inlet and the gas outlet, and a pressure valve is arranged at the gas exhaust outlet. By the novel doping gas path provided by the invention, the doping gas can be fully and uniformly mixed with the protective gas in a limited space inside a zone-melting furnace before entering the furnace and thus the uniformity of the gas-doped single crystal is improved and the doping efficiency is increased.

Description

technical field [0001] The invention creates the technical field of zone melting single crystal silicon growth, and specifically relates to a doping gas path in a zone melting furnace of single crystal silicon. Background technique [0002] In the process of zone melting silicon single crystal preparation, high-purity polycrystalline silicon raw materials can be made into doped silicon single crystal with certain electrical properties by doping a certain amount of electrically active impurities. At present, the doping methods of zone melting silicon single crystal are polycrystalline deposition method, silicon core doping method, solution coating doping method, rod hole doping method, neutron transmutation doping method (NTD) and gas phase doping method. Wait. Among them, the neutron transmutation doping method, that is, the axial and radial uniformity of resistivity of NTD single crystal is the best, and at the same time, the processing cycle is long and the price is very ...

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Problems solved by technology

However, the above studies did not involve the research on the influence of the doping gas path on the doping process

[0004] The dopant gas path is used to transport the protective gas and dopant gas with a certain flow rate into the zone furnace after mixing. The common gas path pipeline structure is as follows: figure 1 As shown, similar to the "I" shape, the mixing part of the doping gas path is generally located in a fixed space in the zone furnace, and the size of the space is limited, generally within 80cm×95cm, so the gas is often directly transported without mixing evenly In the zone furnace, the distribution of dopant gas in the zone furnace is uneven, the axial uniformity of the produced gas-doped single crystal silicon is not good, and the repeatability of the gas-doped single crystal uniformity is not ideal.

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