Method for analyzing trace chlorosilane in electronic-grade silane gas

Abstract

The invention provides a method for analyzing trace chlorosilane in electronic-grade silane gas, and relates to the technical field of gas analysis. The method comprises the following steps: pouring an absorption liquid into an absorption bottle, sealing a long tube end and a short tube end of the absorption bottle, and determining the blank content of chlorine element in the absorption liquid by using a mass spectrometer, the determined value being C1; the second pipe fitting is used for purging at the sampling opening; the long pipe end of the absorption bottle is sleeved with the second pipe fitting, the short pipe end of the absorption bottle is opened, and the absorption liquid absorbs silane gas; sealing the sampling bottle after sampling; measuring the chlorine content C2 in the sample solution; the chlorine content omega in the silane gas absorption liquid sample is calculated through a formula, and the chlorine ion content is calculated, so that the chlorine ion content in the silane gas is calculated, and the purpose of calculating the purity of the silane gas is achieved. The method can be used for analyzing the content of chlorosilane in the electronic-grade silane gas.

Description

Technical Field

[0001] The present invention relates to the technical field of gas analysis, and particularly relates to an analytical method for trace chlorosilanes in electronic-grade silane gas. Background Art

[0002] Electronic-grade silane gas is an important electronic special gas, mainly used in fields such as semiconductors, photovoltaics, and display panels. Silane gas is mainly produced by the disproportionation reaction of chlorosilanes, and then through multiple refining processes, high-purity silane gas is obtained. The refining of high-purity gases is limited by technology and cost. The higher the purity, the cost increases exponentially. Currently, the purity of silane gas can reach six nines.

[0003] Chlorosilanes in electronic-grade silane gas may cause the following harms to product quality:

[0004] Purity reduction: The presence of chlorosilanes will affect the purity of silane gas, resulting in its inability to meet the high-purity application requirements, and further affecting the performance and reliability of products such as semiconductor devices produced using this silane gas;

[0005] Impurity introduction: Chlorosilanes may cause some side reactions in subsequent process steps, introducing new impurities, which is a great threat to the quality stability of products and may lead to problems such as product defects and performance fluctuations;

[0006] Influence on deposition effect: In some applications such as thin film deposition, the presence of chlorosilanes may interfere with the normal deposition process, resulting in adverse effects on the uniformity and density of the thin film, thereby reducing the product quality;

[0007] Reduction of yield: The quality problems caused by chlorosilanes may lead to an increase in the scrap rate during the production process, resulting in waste of resources and an increase in costs.

[0008] Currently, impurity gases of different components in high-purity gases are separated and quantified by chromatography, but chromatography can only achieve the quantification ability at the ppm level. The quantification of lower concentrations has exceeded the theoretical and application scope of chromatography. Currently, there is no analytical technology for chlorosilanes in electronic-grade silane gas. Summary of the Invention

[0009] The purpose of the present invention is to develop an analytical method for trace chlorosilanes in electronic-grade silane gas to solve the problems mentioned in the above background art.

[0010] The present invention is achieved through the following technical solutions:

[0011] An analytical method for trace chlorosilanes in electronic-grade silane gas, comprising the following steps:

[0012] S1. After the absorption bottle is cleaned with ultrapure water, pour the absorption liquid into it, and seal the long tube end and the short tube end of the absorption bottle. Among them, the absorption liquid is used to measure the blank content of chlorine element by a mass spectrometer, and the measured value is C1;

[0013] S2. Put the second pipe fitting on the sampling port, open the valve to purge the second pipe fitting with the silane gas to be sampled, perform gas displacement on the second pipe fitting, fill the second pipe fitting with the silane gas to be measured and discharge the original air, and continuously maintain the purge to prevent air from entering;

[0014] S3. Open the long tube end and the short tube end of the absorption bottle, put the second pipe fitting on the long tube end of the absorption bottle, and the silane gas enters the absorption liquid in the absorption bottle through the second pipe fitting, and reacts fully in the absorption liquid, so that the chlorosilane in the silane gas dissolves in the absorption liquid, and the remaining gas is discharged through the short tube end of the absorption bottle;

[0015] S4. After sampling, remove the second pipe fitting sleeved on the long tube end of the absorption bottle, re-seal the long tube end and the short tube end of the absorption bottle, and close the valve at the sampling port to stop discharging the silane gas;

[0016] S5. Analyze the sample in the absorption bottle, and use a mass spectrometer to measure the chlorine content in the sample solution, and the measured value is C2;

[0017] S6. Calculate the chlorine content ω in the silane gas absorption liquid sample through the formula, calculate the chloride ion content, and thus calculate the chloride ion content in the silane gas to achieve the purpose of calculating its purity;

[0018] Among them, the formula is: ω = (C2 - C1) * m / ρ / f / t. In this formula, the difference between C2 and C1 is the actual content of chlorine in the sample solution, m is the mass of the absorption liquid, ρ is the gas density of the silane gas, f is the gas flow rate, and t is the sampling time.

[0019] Optionally, the capacity of the absorption bottle is 500 mL, the absorption bottle is made of FEP material, and the second pipe fitting is a latex tube with an inner diameter of 9 mm.

[0020] Optionally, the sealing and opening of the long tube end and the short tube end of the absorption bottle are implemented by the first pipe fitting. The two ends of the first pipe fitting are respectively sleeved on the long tube end and the short tube end of the absorption bottle to seal the inside of the absorption bottle, and remove the first pipe fitting sleeved on the long tube end of the absorption bottle to open the long tube end and the short tube end of the absorption bottle.

[0021] Optionally, in step S1, the absorption liquid is ultrapure water, and 300 ml of the absorption liquid is poured into the absorption bottle.

[0022] Optionally, in step S1, when C1 is less than 0.1 ng / L, the absorption liquid can be used for absorbing silane gas.

[0023] Optionally, before performing step S2, clean the sampling port with a clean dust-free cloth or dust-free paper to ensure that the sampling port is clean, dry, and free of liquid.

[0024] Optionally, in step S2, open the valve to purge the silane gas to be sampled through the second pipe fitting for not less than 1 min.

[0025] Optionally, in step S4, the sampling duration is 30 min and the gas flow rate is maintained at 2 L / min.

[0026] Optionally, in step S4, the sampling duration is determined by a timer, and the gas flow rate is determined by on-site process or a gas flow meter. When determined by the gas flow meter, the gas flow meter is connected to the first pipe fitting at the short tube end of the absorption bottle.

[0027] Optionally, in the formula, the unit of m is g, the unit of ρ is g / L, the unit of f is L / min, and the unit of t is min.

[0028] The beneficial effects of the present invention are as follows:

[0029] The present invention can establish a method for fixing chlorine elements in high-purity gases, measure the chlorine element content, form an analysis standard for chlorine elements in high-purity gases, and realize the analysis of chlorosilanes in electronic-grade silane gas. The present invention uses common equipment and instruments, has low cost, simple operation, and high analysis efficiency. Specific Embodiments

[0030] In the following, only some exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present invention. Therefore, the following description is considered to be exemplary in nature rather than restrictive.

[0031] The embodiments of the present invention will be described in detail below.

[0032] The present invention discloses an analysis method for trace chlorosilanes in electronic-grade silane gas. The equipment and instruments used include a mass spectrometer (ICP-MS), an absorption bottle, a first pipe fitting, and a second pipe fitting.

[0033] The chloride ion standard solution is measured by a mass spectrometer, so that the mass spectrometer obtains the functional relationship of the measured concentration value of chloride ions. After the mass spectrometer detects chlorine elements, an electrical signal will be generated. The mass spectrometer converts this electrical signal into the measured concentration value of chlorine elements. Since the actual concentration of the chlorine element standard solution is known, the measured concentration value is equal to the actual concentration value, and thus the conversion coefficient for converting the electrical signal into the measured concentration value of chlorine can be obtained, so that the chlorine content in the subsequent sample solution can be measured.

[0034] The absorption bottle has a capacity of 500 mL and is made of FEP (fluorinated ethylene propylene copolymer). Both the first pipe fitting and the second pipe fitting are latex tubes with an inner diameter of 9 mm.

[0035] The analysis method includes the following steps:

[0036] S1. After the absorption bottle is cleaned thoroughly with ultrapure water, pour 300 ml of the absorption liquid into it. Then, put the two ends of the first pipe fitting on the long tube end and the short tube end of the absorption bottle respectively to seal the inside of the absorption bottle. Among them, the absorption liquid is used to measure the blank content of chlorine element by a mass spectrometer, and the measured value is C1.

[0037] S2. Clean the sampling port with a clean dust-free cloth or dust-free paper to ensure that the sampling port is clean, dry and free of liquid.

[0038] S3. Put the cleaned second pipe fitting on the sampling port, open the valve and let the silane gas to be sampled purge the second pipe fitting for no less than 1 min to displace the gas in the second pipe fitting, fill the second pipe fitting with the silane gas to be measured and discharge the original air, and keep purging continuously to avoid air entry.

[0039] S4. Remove the first pipe fitting on the long tube end of the absorption bottle, put the second pipe fitting on the long tube end of the absorption bottle. The silane gas enters the absorption liquid in the absorption bottle through the second pipe fitting, and undergoes a full reaction in the absorption liquid, so that the chlorosilane in the silane gas dissolves in the absorption liquid, and the remaining gas is discharged through the short tube end of the absorption bottle.

[0040] S5. After sampling, remove the second pipe fitting on the long tube end of the absorption bottle, put one end of the first pipe fitting on the long tube end of the absorption bottle again to seal the inside of the absorption bottle, and close the valve of the sampling port to stop discharging the silane gas.

[0041] S6. Analyze the sample in the absorption bottle, and use a mass spectrometer to measure the chlorine content in the sample solution. The measured value is C2.

[0042] S7. Calculate the chlorine content ω in the silane gas absorption liquid sample through a formula, calculate the chloride ion content, and thus calculate the chloride ion content in the silane gas to achieve the purpose of calculating its purity.

[0043] Among them, the long tube of the absorption bottle is the pipeline extending into the absorption liquid, the gas enters the absorption bottle through the long tube, and the short tube is the pipeline connected to the absorption bottle, and the remaining gas after absorption is discharged from the absorption bottle through the short tube.

[0044] In step S1, the absorption liquid is ultrapure water, and the blank content C1 of chlorine element can be used as the silane gas absorption only when it is less than 0.1 ng / L.

[0045] In step S4, silane gas is introduced into ultrapure water used as the absorption liquid. During this process, the silane gas does not react with the ultrapure water. The chlorosilane gas contained in the silane gas reacts with the ultrapure water to generate hydrogen chloride. The chlorine element is fixed in the ultrapure water, and the silane gas that is insoluble in the absorption liquid is discharged through the short tube of the absorption bottle.

[0046] In step S5, the sampling duration is 30 min, and the gas flow rate is maintained at 2 L / min. The sampling duration is determined by a timer, and the gas flow rate is determined by the on-site process or a gas flow meter. When determined by the gas flow meter, the gas flow meter is connected to the first pipe fitting at the short tube end of the absorption bottle.

[0047] In step S7, the formula is:

[0048] ω = (C2 - C1) * m / ρ / f / t;

[0049] In this formula, the difference between C2 and C1 is the actual content of chlorine in the sample solution;

[0050] m is the mass of the absorption liquid, with the unit of g;

[0051] ρ is the gas density of the silane gas, with the unit of g / L;

[0052] f is the gas flow rate, fixed at 2 L / min;

[0053] t is the sampling time, fixed at 30 min.

[0054] The present invention can establish a method for fixing chlorine elements in high-purity gases, measure the content of chlorine elements, form an analysis standard for chlorine elements in high-purity gases, and realize the analysis of chlorosilanes in electronic-grade silane gas. The present invention uses common equipment and instruments, has low costs, is relatively simple to operate, and has high analysis efficiency.

[0055] The above embodiments are only preferred embodiments of the present invention and do not limit the technical solutions of the present invention. Any technical solution that can be achieved on the basis of the above embodiments without creative labor shall be regarded as falling within the scope of the patent rights of the present invention.

Claims

1. A method for analyzing trace amounts of chlorosilane in electronic grade silane gas, characterized in that: The steps include: S1. The absorption bottle is cleaned with ultrapure water and then poured into the absorption liquid, and the long tube end and the short tube end of the absorption bottle are sealed. The blank content of chlorine element in the absorption liquid is measured by mass spectrometer, and the measured value is C1; S2. Insert the second pipe into the sampling port, open the valve to allow the silane gas to be sampled to purge the second pipe, replace the gas in the second pipe, fill the second pipe with the silane gas to be tested and exhaust the original air, and continue to purge to prevent air from entering; S3. Open the long tube end and the short tube end of the absorption bottle, put the second pipe fitting on the long tube end of the absorption bottle, and the silane gas enters the absorption liquid in the absorption bottle through the second pipe fitting, and reacts fully in the absorption liquid, so that the chlorosilane in the silane gas is dissolved in the absorption liquid, and the remaining gas is discharged through the short tube end of the absorption bottle; S4. After sampling, remove the second pipe fitting on the long end of the absorption bottle, reseal the long and short ends of the absorption bottle, and close the valve of the sampling port to stop discharging silane gas; S5. Analyze the sample in the absorption bottle and determine the chlorine content in the sample solution by mass spectrometry, and the measured value is C2; S6. Calculate the chlorine content ω in the silane gas absorption liquid sample by the formula, calculate the chloride ion content, and thus calculate the chloride ion content in the silane gas to achieve the purpose of calculating its purity; The formula is: ω=(C2-C1)*m / ρ / f / t, in which the difference between C2 and C1 is the actual content of chlorine in the sample solution, m is the mass of the absorption liquid, ρ is the gas density of silane gas, f is the gas flow rate, and t is the sampling time.

2. The method for analyzing trace amounts of chlorosilane in electronic grade silane gas according to claim 1, characterized in that: The absorption bottle has a capacity of 500 mL and is made of FEP material. The second tube is a latex tube with an inner diameter of 9 mm.

3. The method for analyzing trace amounts of chlorosilane in electronic grade silane gas according to claim 1, characterized in that: The closing and opening of the long tube end and the short tube end of the absorption bottle are implemented by the first tube fitting. The two ends of the first tube fitting are respectively sleeved on the long tube end and the short tube end of the absorption bottle to seal the inside of the absorption bottle. Removing the first tube fitting sleeved on the long tube end of the absorption bottle opens the long tube end and the short tube end of the absorption bottle.

4. The method for analyzing trace amounts of chlorosilane in electronic grade silane gas according to claim 1, characterized in that: In the step S1, the absorption liquid is ultrapure water, and 300 ml of the absorption liquid is poured into the absorption bottle.

5. The method for analyzing trace amounts of chlorosilane in electronic grade silane gas according to claim 1, characterized in that: In the step S1, when C1 is less than 0.1 ng / L, the absorption liquid can be used for silane gas absorption.

6. The method for analyzing trace amounts of chlorosilane in electronic grade silane gas according to claim 1, characterized in that: Before performing step S2, clean the sampling port with a clean dust-free cloth or dust-free paper to ensure that the sampling port is clean, dry and free of liquid.

7. The method for analyzing trace amounts of chlorosilane in electronic grade silane gas according to claim 1, characterized in that: In step S2, the valve is opened to allow the silane gas to be sampled to purge the second pipe for no less than 1 minute.

8. The method for analyzing trace amounts of chlorosilane in electronic grade silane gas according to claim 1, characterized in that: In step S4, the sampling time is 30 minutes, and the gas flow rate is maintained at 2 L / min.

9. The method for analyzing trace amounts of chlorosilane in electronic grade silane gas according to claim 1, characterized in that: In step S4, the sampling duration is determined by a timer, and the gas flow rate is determined by an on-site process or a gas flow meter. When determined by a gas flow meter, the gas flow meter is connected to the first pipe fitting at the short pipe end of the absorption bottle.

10. The method for analyzing trace amounts of chlorosilane in electronic grade silane gas according to claim 1, characterized in that: In the formula, m is in g, ρ is in g / L, f is in L / min, and t is in min.