Method for rapidly measuring trace boron impurities in polysilicon

Abstract

The invention relates to a method for rapidly measuring trace boron impurities in polysilicon. The method comprises the following steps: weighting a polysilicon sample; adding a mannitol solution into the sample; adding a potassium carbonate solution into the sample; adding hydrofluoric acid, then slowly dropping nitric acid in the sample and carrying out acidified dissolving; after the sample is dissolved, heating the obtained object, and stopping heating until white smoke is emitted completely; adding hydrochloric acid into the sample and soaking, diluting with a small amount of pure water, and cooling; adding methanol into the solution, uniformly shaking and making up to volume; rinsing ICP-MS (Inductively Coupled Plasma Mass Spectrometry) respectively by using ammonia water and pure water; and after the ICP-MS is rinsed completely, detecting the solution sample with metered volume by using ICP-MS, so that the boron content of the sample can be accurately measured. The method disclosed by the invention is simple in process, low in cost, can measure accurately, and rapidly measure the boron content of polysilicon.

Description

technical field [0001] The invention relates to the technical field of polysilicon purification, in particular to a method for rapidly measuring trace amounts of boron impurities in polysilicon. Background technique [0002] The energy crisis and the pollution of the environment by traditional energy have become the main restrictive factors for the development of society and national economy. In order to maintain sustainable development, countries all over the world are actively adjusting their energy structure and vigorously developing renewable energy. Polycrystalline silicon solar cells have become a hot spot of global concern. [0003] In recent years, solar cells have developed rapidly as a sustainable new energy source. As the basic raw material of the photovoltaic industry, polysilicon is in short supply, and domestic polysilicon production enterprises have been established one after another. Polycrystalline silicon is the basic material for photoelectric conversion...

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Problems solved by technology

[0004] At present, methods for determining boron impurity content in polysilicon mainly include spectrophotometry, inductively coupled plasma atomic emission spectrometry (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS), etc. The method of boron impurity content is complicated to operate, the detection period is long, the consumption of reagents is also large, and the accuracy of the measurement results is poor, which cannot meet the determination requirements of boron content in high-quality silicon; inductively coupled plasma atomic emission spectrometry (ICP-AES ) There is multispectral interference of matrix iron, which needs to be overcome by matrix matching, and cannot meet the requirements of accurate measurement of low-content boron impurities in polysilicon. Inductively coupled plasma mass spectrometry (ICP-MS) has low detection limit and less interference , wide dynamic linear range, high analytical precision, satisfying the characteristics of simultaneous determination of multiple elements

However, in the process of sample dissolution, due to the reaction of silicon with hydrofluoric acid and nitric acid, the temperature continues to rise, and the BF3 produced by the reaction continues to react with water and hydrofluoric acid to form boric acid and fluoboric acid, and then boric acid reacts with mannitol to form The complex acid reacts with hydrofluoric acid to generate fluoboric acid with a boiling point of 130°C, so the heating temperature must be controlled within 120°C, which will take about 4 hours to heat and dissolve the sample, which takes a long time to dissolve the sample, and the memory effect of the instrument measurement is relatively Large, affecting the accurate measurement of low-level boron impurities in polysilicon

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