Method for producing polycrystalline silicon rod, polycrystalline silicon rod, and polycrystalline silicon mass

Abstract

A polycrystalline silicon rod is synthesized by the Siemens process (S101). A plastic bag the inside of which has been cleaned is covered over the polycrystalline silicon rod from the inside a reactor so that the polycrystalline silicon rod is contained in the plastic bag (S103), after which the polycrystalline silicon rod is taken out of the reactor (S104), and thermally sealed to be stored in a sealed state (S105). According to the present invention, processes such as cleaning, etching, and washing that are conventionally considered essential are no longer always necessary, so fluorine ions, nitrate ions, and nitrogen dioxide ions remaining on the surface can all be kept at less than 0.2 ppbw. Further, by covering with a plastic bag, the level of metal contamination is significantly reduced. Moreover, handling the polycrystalline silicon rod according to the present invention prevents surface contamination from proceeding even when stored for long periods of time.

Description

technical field [0001] The invention relates to surface cleaning technology of polycrystalline silicon rods. Background technique [0002] Single crystal silicon, which is indispensable in the manufacture of semiconductor devices and the like, is often grown by the FZ method or the CZ method using polycrystalline silicon rods produced by the Siemens method or polycrystalline silicon ingots obtained by pulverizing them as raw materials. The Siemens method refers to a method in which a silane raw material gas such as trichlorosilane or monosilane is brought into contact with a heated silicon core wire, thereby depositing polysilicon on the silicon core wire by CVD (Chemical Vapor Deposition, Chemical Vapor Deposition) method. Vapor phase growth (precipitation) on the surface. [0003] For polycrystalline silicon ingots, the polycrystalline silicon rods synthesized by the Siemens method are taken out of the reactor and crushed. In order to remove the pollutants adhering to the...

AI Technical Summary

Problems solved by technology

[0005] Components of the acid mixed solution remain on the surface of the silicon material after etching, and water rinsing is required to remove the residue. However, if the residual component is high in concentration, it is difficult to completely remove it by rinsing with water.

Furthermore, when single crystal silicon is grown by the CZ method using a polycrystalline silicon block with residues on its surface as a raw material, crystallization lines disappear or become disordered, which is evidence of single crystallization, and there is a problem that the completeness of crystallization cannot be guaranteed.

[0006] The reason for this is not necessarily clear, but it may be caused by nitrogen (N) components and fluorine (F) components in the above-mentioned acid mixed solution remaining on the surface of the polycrystalline silicon block.

[0007] In particular, there are numerous cracks or fissures in the polysilicon block, so when the components of the acid mixture solution enter these gaps, it is almost impossible to remove them completely.

These residual components are mainly three types of nitrate ion components, nitrite ion components, and fluoride ion components. However, according to the measurement of the inventors, the following results were obtained: 24-hour ultrasonic cleaning can not completely remove these residual components

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