CN-121974298-A - Electronic grade anhydrous hydrogen fluoride purification method and system

CN121974298ACN 121974298 ACN121974298 ACN 121974298ACN-121974298-A

Abstract

The invention relates to the technical field of chemical purification, and discloses an electronic grade anhydrous hydrogen fluoride purification method and system, wherein the method comprises the steps of dehydration through molecular sieve low-temperature adsorption at-80 ℃ to-110 ℃; and (3) accurately analyzing the water concentration by adopting dual-wavelength differential infrared detection and combining a dynamic background subtraction algorithm, and if the water content is more than or equal to 5 ppb, performing cyclic treatment, and entering a rectifying tower for deep purification after reaching the standard. The system comprises a low-temperature adsorption unit, a multi-channel infrared moisture detection unit, a circulation control valve group and a rectifying tower, and is provided with double adsorption columns which alternately operate, temperature and pressure compensation and a full-high-purity corrosion-resistant material design. According to the invention, by constructing a dual-wavelength differential infrared detection architecture, the infrared absorption and moisture absorption signals of the electronic-grade anhydrous hydrogen fluoride gas are effectively separated, the problem of misjudgment of moisture detection caused by band overlapping is solved, and the accurate online monitoring of the moisture content of 5/1000000000 magnitude is realized.

Inventors

FU WEIXING
LIAO YUNENG
DENG JIAJUN
Que Xiangjian
WANG SUFANG

Assignees

福建省龙氟新材料有限公司

Dates

Publication Date: 20260505
Application Date: 20260211

Claims (10)

1. A method for purifying electronic grade anhydrous hydrogen fluoride, comprising: Obtaining an electronic grade anhydrous hydrogen fluoride gas stream to be purified; introducing the gas flow into a low-temperature adsorption unit, and selectively adsorbing moisture in the gas by using a molecular sieve adsorbent in a temperature range of-80 ℃ to-110 ℃ to form primarily dehydrated gas; introducing the primarily dehydrated gas into an infrared moisture detection unit, wherein the infrared moisture detection unit is provided with a dual-wavelength differential detection channel, the central wavelength of a first detection channel is set to be 2.7 mu m and is used for simultaneously responding to a composite absorption signal of moisture and hydrogen fluoride, and the central wavelength of a second detection channel is set to be 3.3 mu m and is only used for responding to a characteristic absorption signal of hydrogen fluoride; Based on the output signals of the first detection channel and the second detection channel, performing dynamic background subtraction operation to eliminate interference of self infrared absorption of hydrogen fluoride gas on moisture detection and obtain a corrected moisture concentration value; Judging whether the corrected water concentration value is lower than a preset threshold value of 5/1000000000, if not, reintroducing the gas flow into a low-temperature adsorption unit for cyclic treatment, and if so, introducing the gas flow into a rectifying tower for deep separation to obtain an electronic-grade anhydrous hydrogen fluoride finished product.
2. The method of claim 1, wherein the gas stream is introduced into a cryogenic adsorption unit and the molecular sieve adsorbent is used to selectively adsorb moisture in the gas at a temperature in the range of-80 ℃ to-110 ℃ to form a primarily dehydrated gas, comprising: Introducing the gas flow into any one of a first adsorption column and a second adsorption column which are arranged in parallel, wherein sodium molecular sieve particles with the aperture of 3.8 angstroms are filled in the adsorption columns, the particle size is 0.5mm to 1.2mm, and the stacking density is 0.6g/cm 3 to 0.8g/cm 3 ; Controlling the temperature of the adsorption column shell to be maintained at-80 ℃ to-110 ℃ so that moisture is selectively adsorbed and hydrogen fluoride passes through; when the current adsorption column finishes the 4-hour adsorption period, switching to another adsorption column for continuous adsorption, enabling the current adsorption column to enter a regeneration working condition, and finishing regeneration by introducing high-purity nitrogen and heating for 2 hours at 150 ℃.
3. The method of purifying electronic grade anhydrous hydrogen fluoride of claim 2, wherein the primarily dehydrated gas is directed to an infrared moisture detection unit configured with dual wavelength differential detection channels, wherein a first detection channel has a center wavelength set to 2.7 μm for simultaneous response to a composite absorption signal of moisture and hydrogen fluoride, and a second detection channel has a center wavelength set to 3.3 μm for only response to a characteristic absorption signal of hydrogen fluoride, comprising: the pulse type middle infrared light-emitting diode is adopted as a light source, the emission spectrum of the light-emitting diode covers the wave band of 2.5 mu m to 4.0 mu m, and the modulation frequency is 1000Hz; a narrow-band interference filter with a center wavelength of 2.7 mu m and a half-width of 20nm is arranged in the first detection channel, and a narrow-band interference filter with a center wavelength of 3.3 mu m and a half-width of 20nm is arranged in the second detection channel; The thermopile type infrared sensor is used for respectively receiving the transmitted light intensity signals of the two channels, the response time is 50ms, and the noise equivalent power is less than 5 multiplied by 10 -10 W/. V.Hz.
4. The method for purifying electronic grade anhydrous hydrogen fluoride of claim 3, wherein performing a dynamic background subtraction operation based on the output signals of the first and second detection channels to eliminate interference of the hydrogen fluoride gas's own infrared absorption with moisture detection, and obtaining a corrected moisture concentration value, comprises: Collecting the original absorbance of the first detection channel Original absorbance with the second detection channel ; Based on the molar absorption coefficient ratio of the pre-calibrated hydrogen fluoride at 2.7 μm to 3.3 μm Calculating the equivalent absorbance of the hydrogen fluoride caused in the first detection channel ; From the slave Is subtracted by Obtaining the net absorbance contributed by only moisture ; According to lambert-beer law, will Conversion to moisture concentration value The formula is Wherein The molar absorptivity of the water at 2.7 μm was 180L/(mol cm), The optical path length was 10cm.
5. The method of electronic grade anhydrous hydrogen fluoride purification of claim 4, wherein performing a dynamic background subtraction operation further comprises: monitoring the temperature and the pressure in the detection cavity of the infrared moisture detection unit in real time; For original absorbance according to ideal gas state equation And (3) with Temperature and pressure correction is carried out, and the correction formula is that Wherein And (3) with Respectively standard reference temperature 298 Kelvin and standard atmospheric pressure 100KPa, And (3) with Is the measured temperature and pressure; and performing the dynamic background subtraction operation by using the absorbance data after the temperature and pressure correction.
6. The method for purifying electronic grade anhydrous hydrogen fluoride according to claim 5, wherein determining whether the corrected moisture concentration value is lower than a preset threshold value of 5/1000000000, if not, reintroducing the gas stream into a low temperature adsorption unit for cyclic treatment, and if so, introducing the gas stream into a rectifying tower for deep separation to obtain an electronic grade anhydrous hydrogen fluoride finished product, comprises: Acquiring a corrected water concentration value every 30 seconds; When the water concentration value is greater than or equal to 5/1000000000, the bypass valve is closed, and the two pneumatic cut-off valves are opened, so that the gas flows through the circulating pipeline and returns to the inlet of the low-temperature adsorption unit; When the water concentration value is less than 5/1000000000, two pneumatic cut-off valves are closed and the bypass valve is opened, so that the gas flows to the rectifying tower.
7. The method for purifying electronic grade anhydrous hydrogen fluoride of claim 6, wherein the step of introducing the gas stream into a rectifying tower for deep separation to obtain an electronic grade anhydrous hydrogen fluoride finished product comprises: Controlling the operation pressure of the rectifying tower to be between 0.8MPa and 1.2MPa, the temperature of the tower top to be between 19 ℃ and 21 ℃, and the temperature of the tower bottom to be between 23 ℃ and 25 ℃; Polytetrafluoroethylene Raschig ring packing is filled in the rectifying tower, the specific surface area is 200m 2 /m 3 , and the height of the packing layer is 3m; High-purity hydrogen fluoride steam is evaporated from the top of the tower and condensed into a finished product, and water and high-boiling impurities are enriched in the tower bottom and discharged to a tail gas treatment unit.
8. The method for purifying electronic grade anhydrous hydrogen fluoride according to claim 7, wherein the adsorption column shell of the low temperature adsorption unit is made of monel alloy, the inner wall is subjected to electrolytic polishing treatment, the surface roughness is less than 0.4 μm, all wet parts of the system are made of high-purity monel 400 alloy or polyvinylidene fluoride material, the sealing element is made of perfluoroether rubber, and the system is subjected to ultra-pure water flushing, high-purity nitrogen purging and high-temperature baking water removal treatment at 150 ℃ for 12 hours before being put into use.
9. An electronic grade anhydrous hydrogen fluoride purification system comprising: a gas input interface for receiving an electronic grade anhydrous hydrogen fluoride gas stream to be purified; The inlet of the low-temperature adsorption unit is communicated with the gas input interface and is used for selectively adsorbing moisture in gas at-80 ℃ to-110 ℃; The gas inlet of the infrared moisture detection unit is communicated with the outlet of the low-temperature adsorption unit and is used for detecting the moisture concentration in dehydrated gas with high precision; The circulating control valve group is arranged between the outlet of the infrared moisture detection unit and the inlet of the low-temperature adsorption unit and is used for controlling whether the gas returns to the low-temperature adsorption unit for reprocessing according to the detection result; the inlet of the rectifying tower is communicated with the outlet of the infrared moisture detection unit and is used for carrying out final rectification and purification on the gas reaching the standard; and the finished product output interface is communicated with the top outlet of the rectifying tower and is used for outputting an electronic-grade anhydrous hydrogen fluoride finished product.
10. The electronic grade anhydrous hydrogen fluoride purification system of claim 9, wherein the low temperature adsorption unit comprises a first adsorption column and a second adsorption column which are connected with a gas pipeline through a three-way switching valve, wherein when the first adsorption column is in an adsorption working condition, the second adsorption column is in a regeneration working condition, the regeneration process is completed by introducing high-purity nitrogen and heating for 2h at 150 ℃, and the switching period of the adsorption working condition and the regeneration working condition is 4h.

Description

Electronic grade anhydrous hydrogen fluoride purification method and system Technical Field The invention belongs to the technical field of chemical purification, and particularly relates to an electronic grade anhydrous hydrogen fluoride purification method and system. Background As semiconductor fabrication processes continue to evolve toward the nanometer scale, the purity requirements for electronics chemicals have risen to the ppt level. The purity of the electronic grade anhydrous hydrogen fluoride is directly determined by the yield and reliability of the device as a key reagent in the wafer cleaning and etching process. In the field, moisture is one of the most harmful impurities, and metal ion dissolution, oxide layer defects and particle pollution are extremely easy to cause, so that accurate online monitoring of moisture content becomes a core link of purification process control. At present, the infrared spectrometry is widely applied to detection of trace moisture in gas due to the advantages of non-contact, quick response and the like. The moisture analysis technology based on the infrared absorption principle relies on the characteristic absorption peak of water molecules in a specific wave band for quantification. However, in an electronic grade anhydrous hydrogen fluoride gas environment, the hydrogen fluoride molecules themselves have strong, broad band intrinsic absorption in the near infrared region, with significant overlap of absorption lines with characteristic peaks of water molecules. The spectrum interference causes that the traditional single-wavelength or fixed reference wavelength infrared detection system is difficult to effectively distinguish the water signal from the hydrogen fluoride background noise, so that the water concentration is misjudged, and particularly under the detection requirement of low ppb or even ppt level, the signal-to-noise ratio is rapidly deteriorated, and the measurement result is severely distorted. The prior art generally adopts physical drying pretreatment, off-line sampling analysis or introduces complex calibration procedures to relieve interference, but the methods either sacrifice real-time performance or introduce secondary pollution risks or cannot adapt to dynamic fluctuation of continuous high-purity production scenes. More importantly, the existing optical detection module lacks dynamic modeling and real-time compensation capability for hydrogen fluoride background absorption, and background noise drift further amplifies detection errors when gas components, pressure or temperature change. Disclosure of Invention The invention provides a method and a system for purifying electronic grade anhydrous hydrogen fluoride, which aim to solve the technical problem that in the purification process of electronic grade anhydrous hydrogen fluoride, trace moisture detection is interfered by an infrared absorption band of the electronic grade anhydrous hydrogen fluoride, so that the existing infrared spectrometer misjudges the moisture concentration and cannot meet the requirement of semiconductor grade purity. According to the invention, by constructing a multichannel infrared detection architecture based on differential spectrum analysis and dynamic background subtraction and combining a low-temperature adsorption-desorption cyclic purification process, high-precision on-line monitoring and high-selectivity removal of the moisture content are realized, so that the moisture content in a final product is ensured to be stably controlled below 5/1000000000. The invention provides a method for purifying electronic grade anhydrous hydrogen fluoride, which comprises the following steps: Obtaining an electronic grade anhydrous hydrogen fluoride gas stream to be purified; introducing the gas flow into a low-temperature adsorption unit, and selectively adsorbing moisture in the gas by using a molecular sieve adsorbent in a temperature range of-80 ℃ to-110 ℃ to form primarily dehydrated gas; introducing the primarily dehydrated gas into an infrared moisture detection unit, wherein the infrared moisture detection unit is provided with a dual-wavelength differential detection channel, the central wavelength of a first detection channel is set to be 2.7 mu m and is used for simultaneously responding to a composite absorption signal of moisture and hydrogen fluoride, and the central wavelength of a second detection channel is set to be 3.3 mu m and is only used for responding to a characteristic absorption signal of hydrogen fluoride; Based on the output signals of the first detection channel and the second detection channel, performing dynamic background subtraction operation to eliminate interference of self infrared absorption of hydrogen fluoride gas on moisture detection and obtain a corrected moisture concentration value; Judging whether the corrected water concentration value is lower than a preset threshold value of 5/1000000000, if not, reintroducing the ga