Czochralski zone melting gas doping method for preparing zone-melted silicon single crystal

Abstract

The invention relates to a Czochralski zone melting gas doping method for preparing a zone-melted silicon single crystal. The method is characterized by comprising the following steps of: doping, pulling polycrystalline silicon by a Czochralski method, machining and annealing the polycrystalline silicon, putting into a zone melting furnace, pulling the single crystal by a zone melting method, and introducing a certain amount of dopant gas in the process of pulling the crystal by the zone melting method, wherein the introduction amount of the dopant gas is gradually reduced or increased; and if the target concentration of a dopant of the zone-melted silicon single crystal is c0, controlling the concentration of the dopant at the tail of the polycrystalline silicon to be c0, wherein k is the segregation coefficient of the dopant. The concentration of the dopant of the polycrystalline rod is uniform, and gas doping is not required to be performed at a retention stage, so the concentration uniformity of a silicon melt is extremely high. Therefore, compared with a neutron transmutation doping (NTD) method, the method is low in cost and short in production period; and compared with a zone melting gas doping method and a Czochralski zone melting method, the method has the advantage that: the radial resistivity uniformity of the zone-melted single crystal is effectively improved.

Description

technical field [0001] The invention relates to a method for producing zone-melting silicon single crystals, in particular to a Czochralski zone-melting gas doping method for producing zone-melting silicon single crystals. Background technique [0002] At present, the existing technologies for producing extrinsic zone melting silicon single crystal in the semiconductor industry mainly include: NTD method (neutron transmutation doping), zone melting gas doping method and Czochralski zone melting method. [0003] The resistivity uniformity of zone-melted silicon single crystal produced by NTD (neutron transmutation doping) method is the highest, but the cost is high and the production cycle is long. [0004] In the production process of the zone melting gas doping method, the zone melting silicon single crystal is doped by feeding doping gas. The dopant gas (phosphine or borane) is a solid dopant phosphorus or boron hydride, which is decomposed into hydrogen gas and the corre...

AI Technical Summary

Problems solved by technology

The large axial resistivity gradient leads to a large difference between the center resistivity and the edge resistivity of the silicon wafer, thus greatly reducing the radial resistivity uniformity of the zone melting silicon single crystal

[0008] In the drawing stage of the zone melting method, if the head of the polycrystalline silicon rod is upward, due to the influence of the axial resistivity distribution of the polycrystalline silicon itself and the influence of segregation, although the axial resistivity distribution of the drawn zone melting silicon single crystal is higher than that of the head Improved when going down, but still not well controlled

Secondly, the silicon melt melted at the melting interface of the polycrystalline silicon rod has a large difference in resistivity. Under the inability to obtain effective melt convection, the melt resistivity is relatively uneven, and finally reduces the radial resistance of the zone-melted silicon single crystal. rate uniformity

[0009] There are certain defects in the above three methods of producing molten silicon single crystal in the production area. Therefore, it is necessary to design a new method that can not only retain its advantages, but also make up for its shortcomings. The application of three new methods for the process of manufacturing zone-melted silicon single crystals has not yet been reported in the literature

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