CN103616369A

CN103616369A - Method for improving enrichment ratio of boron and phosphorus in ICP (inductively coupled plasma) impurity detection of trichlorosilane

Info

Publication number: CN103616369A
Application number: CN201310562562.0A
Authority: CN
Inventors: 贺珍俊; 李辉; 刘淑萍; 张耀平; 高云龙; 曹忠
Original assignee: INNER MONGOLIA SHENZHOU SILICON INDUSTRY Co Ltd
Current assignee: INNER MONGOLIA SHENZHOU SILICON INDUSTRY Co Ltd
Priority date: 2013-11-02
Filing date: 2013-11-02
Publication date: 2014-03-05

Abstract

The invention discloses a method for improving enrichment ratio of boron and phosphorus in ICP (inductively coupled plasma) impurity detection of trichlorosilane. According to the method, on the premise that no reagent causing secondary pollution is used, the enrichment effect of trace B and P in trichlorosilane is greatly improved. In general treatment process, the purposes of separating the matrix and enriching impurities are achieved mainly by volatilization of trichlorosilane, but the boiling points of the impurities B and P in trichlorosilane are low, so that the B and P are very easy to loss in the volatilization process. According to the invention, the adopted measures are usually as follows: adding reagents such as high-purity glycerinum, mannitol and acetonitrile are added into samples, but because the purities of the reagents cannot reach the electronic grade, new impurities are automatically added so as to affect the accuracy of the detection result. Through adopting the treatment method disclosed by the invention, the enrichment ratio of element B is improved by over 20% and enrichment ratio of element P even excesses 85%, and the method is verified by ICP-MS (inductively coupled plasma-mass spectrometry) detection.

Description

A kind of method that improves boron, phosphorus accumulation rate in trichlorosilane ICP impurity testing process

Technical field

This method relates to method for detecting impurities in production of polysilicon, refers in particular to a kind of method that improves boron, phosphorus accumulation rate in trichlorosilane ICP impurity testing process.

Background technology

Trichlorosilane purposes is very extensive, it is the critical materials of producing polycrystalline silicon semiconductor and monocrystalline silicon, its purity directly affects the quality of silicon, the strict purity of controlling trichlorosilane, especially reduce boron wherein, the content of phosphorus (B, P) impurity, just become one of key factor of producing high purity polycrystalline silicon and single crystal silicon product.

At present, how to make to use ICP to analyze accurately and become the emphasis that industry is paid close attention to the boron in trichlorosilane, phosphorus (B, P).In recent years, although more about the report of impurity in ICP detection trichlorosilane both at home and abroad, about the method for trichlorosilane sample preparation, also do not seek unity of standard.Especially in the volatilizing and enriching process of trichlorosilane, disposal route is varied, but main process is consistent, by trichlorosilane, volatilizees, and reaches the object of matrix separation, enrichment impurity.The self-control trichlorosilane matrix volatilizer that passes through having is processed; but DeGrain; this method has just been avoided the secondary pollution in volatilization process; in low, the low-boiling situation of content; volatilization causes that P, B loss causes that testing result is less than normal to be inevitable during matrix, and takes B, the protection of P volatile compound just important.At present, the safeguard measure of B element is had to the methods such as the glycerine of adding, sweet mellow wine, acetonitrile, but because these reagent do not reach the purity of electron level, virtually added again new impurity, affect result.Therefore,, in sample preparation process, how better enrichment boron, phosphorus (B, P) element become a difficult problem for domestic and international research.

Summary of the invention

The technical problem to be solved in the present invention is to provide a kind of method that improves boron, phosphorus accumulation rate in trichlorosilane ICP impurity testing process, uses this sample treatment, can improve trichlorosilane enrichment to B, P when volatilization matrix.This method, in the situation that not introducing novel substance element, reaches the object of enrichment, makes the result of detection more accurate.

Summary of the invention

The technical problem to be solved in the present invention is realized by following scheme: boron in a kind of raising trichlorosilane ICP impurity testing process, the method of phosphorus accumulation rate, it is characterized in that: in clean environment, first with transfer pipet, in clean crucible, add the ultrapure water that is divided into several, take a certain amount of trichlorosilane in crucible, the volume ratio of ultrapure water and trichlorosilane is 1:20, crucible is placed on to low temperature on electric hot plate to be evaporated into dry, cooling, successively slowly add nitric acid and hydrofluorite, after hydrolysate CL, with electric hot plate, in 60 ℃ of heating, after 3-5 minute, take off cooling again, solution is moved in volumetric flask, and rinse crucible inwall 3～5 times with ultrapure water, washing lotion is poured in volumetric flask in the lump, with ultrapure water constant volume, use national B, P standard solution configuration mixed standard solution, according to the measurement result of concentration of standard solution gradient, draw out B, the typical curve of P, finally use inductive coupling plasma emission spectrograph (ICP) or icp ms (ICP-MS) to measure the content of solution impurity.

The present invention also comprises following scheme: HNO ₃, HF must be electron level, through 2 sub-boiling distillations, purify afterwards, the HNO adding ₃, HF mol ratio is 3:1, the mol ratio of trichlorosilane sample and HF is more than 1:5, not introduce other impurity to guarantee complete reaction.Ultrapure water is secondary ion exchanged water, and resistivity reaches 18.2M Ω/cm.The national standard solution of B and P is: boron standard solution national standard material GSB G62008-901000 μ g/mL, phosphorus standard solution national standard material GSB G62008-90 1000 μ g/mL.The configuration of boron phosphorus mixed standard solution is to pipette respectively boron, phosphorus standard solution 1mL in 100mL volumetric flask, adds 10mL nitric acid, is diluted with water to scale mark, shakes up, and this standard solution boron, phosphorus are respectively 10mg/L, mixed standard solution matching while using.

Accompanying drawing explanation

Fig. 1 is process chart of the present invention.

Embodiment

The whole processing procedure of this method must be under thousand grades of laboratory environments, and while especially volatilizing in fuming cupboard, assurance is under thousand grades of laboratory environments, prevents secondary pollution.Inductive coupling plasma emission spectrograph (ICP), for being equipped with the spectrometer of hydrofluoric acid resistant system, needs the quarter bend of the configuration fluorine of resistance to hydrogen.The transfer pipet of the clean crucible of PFA material, the clean volumetric flask of 25 or 50ml of PFA material, infrared digital control-temperature electric heating plate and electronic balance used and PFA material etc. must be clean.Thermostatic electrothermal plate must be that number of the non-naked light of constant temperature is controlled electric hot plate.In this method, a crucial step is adding of ultrapure water, and the specific surface area of relevant water droplet is critical technical parameter.

Below for an embodiment:

As shown in Figure 1: flow process 1 first adds the ultrapure water that is divided into several in the PFA of wash clean crucible.Concrete operations are to extract a certain amount of ultrapure water with transfer pipet, rely on gravity that ultrapure water is dropped in to crucible bottom.

Flow process 2, has in the crucible of ultrapure water dripping, and takes a certain amount of trichlorosilane, and the volume ratio of trichlorosilane and ultrapure water is 20:1, will be placed on electric hot plate, and low temperature evaporates into dry, removes most of trichlorosilane matrix.

Flow process 3, take off crucible, in existing crucible, there is a large amount of hydrolysates, in crucible, slowly add a certain amount of electronic-stage hydrofluoric acid, after dissolving, add again a certain amount of electron level nitric acid, redissolve remaining silicon substrate and other impurity, wherein add the amount of electronic-stage hydrofluoric acid and nitric acid and the molar ratio of trichlorosilane to be greater than 5:1, with after emitting brown to the greatest extent oxynitrides, be again put on low temp. electric hot plate hot 5-10 minute a little.

Flow process 4, crucible is cooling from heating plate, by the volumetric flask of solution immigration 25,50mlPFA, and rinse crucible inwall 3～5 times with ultrapure water, wash water is poured in volumetric flask in the lump, with ultrapure water constant volume.

Flow process 5, the drafting of typical curve: in one group of 100mL volumetric flask, move into respectively 0 μ L, 100 μ L, 200 μ L, 500 μ L boron phosphorus standard mixed solutions (10mg/L), with 8%HF+4%HNO3, be diluted to scale, mix, the mass concentration of this solution boron phosphorus is respectively 0 μ g/L, 10 μ g/L, 20 μ g/L, 50 μ g/L.

Flow process 6, measures standard solution with inductive coupling plasma emission spectrograph (ICP), according to the concentration gradient difference drawing standard curve of B, P measurement result and standard solution.

Flow process 7, finally use inductive coupling plasma emission spectrograph (ICP) to detect unknown sample, according to typical curve, draw B, the P impurity content of unknown sample, and by icp ms (ICP-MS), measure the accuracy of the result.

1, method contrast test

Identical sample is taked respectively to the inventive method and common process method, and upper machine testing, reaches a conclusion: data are in Table 1 and table 2

The correlation data of table 1 this method and common process method

From above data, can find out, method of the present invention than common method by obvious effect

The comparative analysis of the different samples of table 2

Data show, the enrichment increase rate of B element all superelevation 20%, and P element is because radix is too little, accumulation rate has generally surpassed 85%, even higher.

2, the recovery test of sample

Pipette the standard solution containing 10 μ g/ml boron, phosphorus, add appropriate trichlorosilane, by disposal route of the present invention, condition, test, calculate the recovery of this method, in Table 3

Table 3 standard model adds recovery test result

Data draw by experiment, and recovery of standard addition meets real requirement, so disposal route of the present invention is feasible.

3, mass spectrum demonstration test

For the raising of data, first we consider may be due to the interference of silicon substrate.To this, we have passed through mass spectrometer check analysis, have got rid of the interference of silicon.Experimental data is in Table 4

Table 4ICP-MS analyzes the comparing result of same sample different disposal method

Above data reflect the interference that does not have silicon substrate, disturb in other words very little.

Claims

1. one kind is improved boron in trichlorosilane ICP impurity testing process, the method of phosphorus accumulation rate, it is characterized in that: first with transfer pipet, in crucible, add the ultrapure water that is divided into several, take a certain amount of trichlorosilane in crucible, the volume ratio of ultrapure water and trichlorosilane is 1:20, crucible is placed on to low temperature on electric hot plate to be evaporated into dry, cooling, successively slowly add nitric acid and hydrofluorite, after hydrolysate CL, with electric hot plate, in 60 ℃ of heating, after 3-5 minute, take off cooling again, solution is moved in volumetric flask, and rinse crucible inwall 3～5 times with ultrapure water, washing lotion is poured in volumetric flask in the lump, with ultrapure water constant volume, use national B, P standard solution configuration mixed standard solution, according to the measurement result of concentration of standard solution gradient, draw out B, the typical curve of P, finally use inductive coupling plasma emission spectrograph (ICP) or icp ms (ICP-MS) to measure the content of solution impurity.

2. a kind of method that improves boron, phosphorus accumulation rate in trichlorosilane ICP impurity testing process as claimed in claim 1, is characterized in that: HNO ₃, HF must be electron level, through 2 sub-boiling distillations, purify afterwards, the HNO adding ₃, HF mol ratio is 3:1, the mol ratio of trichlorosilane sample and HF is more than 1:5.

3. a kind of method that improves boron, phosphorus accumulation rate in trichlorosilane ICP impurity testing process as claimed in claim 1, is characterized in that: ultrapure water is secondary ion exchanged water, and resistivity reaches 18.2M Ω/cm.

4. a kind of method that improves boron, phosphorus accumulation rate in trichlorosilane ICP impurity testing process as claimed in claim 1, is characterized in that: the national standard solution of B and P is: boron standard solution national standard material GSB G62008-90 1000 μ g/mL, phosphorus standard solution national standard material GSB G62008-90 1000 μ g/mL.

5. a kind of method that improves boron, phosphorus accumulation rate in trichlorosilane ICP impurity testing process as claimed in claim 1, it is characterized in that: the configuration of boron phosphorus mixed standard solution is to pipette respectively boron, phosphorus standard solution 1mL in 100mL volumetric flask, add 10mL nitric acid, be diluted with water to scale mark, shake up, this standard solution boron, phosphorus are respectively 10mg/L.