Trimethylaluminum high-efficiency purification process and equipment

Abstract

The present application relates to the technical field of metal organic source purification, and specifically discloses a high-efficiency purification process for trimethylaluminum.The high-efficiency purification process for trimethylaluminum provided by the present application comprises the following steps: S1, applying a subsonic wave to pretreat crude trimethylaluminum and simultaneously performing low-temperature cooling; S2, performing vacuum distillation, continuously extracting low-boiling-point impurities under dynamic vacuum conditions, and simultaneously collecting distillates by using a cryogenic receiving tank; and S3, obtaining ultrapure trimethylaluminum by performing gradient condensation and vacuum extraction on the remaining mother liquor.A high-efficiency purification process for trimethylaluminum precisely destroys the chemical adsorption state of trace impurities (such as dimethylaluminum chloride and organosilicon) through the subsonic wave-low-temperature coupling effect, and significantly improves the removal efficiency of ppm-level impurities in combination with vacuum gradient separation.The advantage of the process is that it avoids the pollution of aluminum oxide particles caused by high temperature, and also greatly reduces energy consumption, and is particularly suitable for the large-scale continuous production of semiconductor-grade purity trimethylaluminum.

Description

Technical Field

[0001] This invention relates to the field of metal-organic source purification technology, specifically to a high-efficiency purification process and equipment for trimethylaluminum. Background Technology

[0002] High-purity trimethylaluminum (TMA), as a core metal-organic source material in the semiconductor industry, occupies an irreplaceable strategic position in advanced thin-film deposition processes. Its unique molecular structure makes it a key precursor for chemical vapor deposition (MOCVD) technology, especially in metal-organic chemical vapor deposition (MOCVD) and atomic layer deposition (ALD) processes, enabling the atomic-level growth of high-performance dielectric / piezoelectric thin films such as aluminum nitride (AlN) and aluminum oxide (Al2O3) through precise control of reaction kinetics. In optoelectronics, TMA is a core raw material for fabricating high-efficiency LED chip epitaxial structures, and its purity directly determines the crystal quality and luminous efficiency of the p-type doped layer. In the photovoltaic industry, ultrathin Al2O3 passivation layers deposited using TMA-based ALD processes can significantly improve the quantum efficiency of PERC cells. Furthermore, in the manufacturing of 5G RF chips, AlN piezoelectric thin films grown with TMA, due to their high electromechanical coupling coefficient, have become a key functional layer in thin-film bulk acoustic resonators.

[0003] Traditional trimethylaluminum purification processes suffer from significant technical bottlenecks: reliance on polar solvents such as diethyl ether and tetrahydrofuran easily leads to the formation of stable complexes, making separation difficult and resulting in a purity of only 99.5%, which fails to meet the requirements of semiconductor applications. Simultaneously, high-temperature distillation has low separation efficiency for impurities with similar boiling points (such as dimethylaluminum chloride), affecting thin film performance. Currently, the industry's common method for trimethylaluminum purification is distillation column purification, with some upgrades and improvements, such as pressure swing distillation and vacuum distillation. However, conventional distillation methods can only purify trimethylaluminum to 99.9999% (6N purity), making it difficult to purify it to 99.99999% (7N purity). Summary of the Invention

[0004] The purpose of this invention is to provide a highly efficient purification process for trimethylaluminum to overcome the aforementioned shortcomings in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A highly efficient purification process for trimethylaluminum includes the following steps:

[0007] S1, the crude trimethylaluminum is subjected to infrasonic pretreatment and simultaneously cooled at low temperature;

[0008] S2, vacuum distillation, continuously extracts low-boiling-point impurities under dynamic vacuum conditions, while collecting the distillate in a cryogenic receiving tank.

[0009] S3, the remaining mother liquor was subjected to gradient condensation and vacuuming to obtain ultrapure trimethylaluminum.

[0010] Furthermore, the infrasound frequency in S1 is 10~20Hz and the power is 200W.

[0011] Furthermore, the low-temperature cooling in S1 involves maintaining the system temperature at 5°C for 3 hours.

[0012] Furthermore, the vacuum distillation in S2 is gradient vacuum distillation.

[0013] Furthermore, the vacuum distillation in S2 involves reducing the system vacuum from 10 kPa to 1 kPa in stages and maintaining it at 1 kPa vacuum for 6 hours.

[0014] The gradient condensation in S3 reduces the system temperature to -5 to 0°C in a gradient cooling manner, while simultaneously reducing the vacuum level to 0.1 kPa and maintaining it for 6 hours.

[0015] Furthermore, after the vacuuming process in step S3 is completed, the distillation vessel is heated to 20-30°C and maintained for 12 hours before sampling and testing.

[0016] Furthermore, in S2, the vacuum degree of the system starts from 10 kPa and is adjusted in stages at a gradient rate of 1 kPa / 15 min until the vacuum degree reaches 1 kPa.

[0017] Furthermore, in S3, the system temperature starts at 5°C and is adjusted in stages at a gradient cooling rate of 2°C / 0.5h until the temperature reaches the range of -5°C to 0°C.

[0018] A trimethylaluminum high-efficiency purification device, employing the aforementioned trimethylaluminum high-efficiency purification process, includes a crystallization tank and a water bath tank surrounding the crystallization tank. The crystallization tank is equipped with a condensation component inside, which includes a ring-shaped condensation assembly. The condensation assembly has two states: initially, it is in a superimposed state, and during condensation, it is in an expanded state.

[0019] Furthermore, the condensing component is provided with a guiding component, which includes an annular guide rail and a spiral guide rail connected end to end. The condensing assembly is provided with a guiding block, which slides on the annular guide rail and the spiral guide rail and is responsible for moving the condensing assembly up and down.

[0020] The trimethylaluminum high-efficiency purification process provided by the present invention has the following advantages in the above technical solutions:

[0021] This process precisely disrupts the chemisorbed state of trace impurities (such as dimethylaluminum chloride and organosilicon) through infrasound-low temperature coupling, and significantly improves the removal efficiency of ppm-level impurities by combining it with vacuum gradient separation. Its advantages include avoiding alumina particle contamination caused by high temperatures, while also greatly reducing energy consumption, making it particularly suitable for the large-scale continuous production of semiconductor-grade pure trimethylaluminum.

[0022] It should be understood that the foregoing general description and the following detailed description are exemplary and illustrative only, and are not intended to limit this disclosure.

[0023] This application provides an overview of various implementations or examples of the technology described in this disclosure, and is not a full disclosure of the entire scope or all features of the disclosed technology. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0025] Figure 1 A process flow diagram provided for an embodiment of the present invention;

[0026] Figure 2 This is an overall external structure diagram provided for an embodiment of the present invention;

[0027] Figure 3 This is an overall front view structural diagram provided for an embodiment of the present invention;

[0028] Figure 4 This is an overall cross-sectional structural diagram provided for an embodiment of the present invention;

[0029] Figure 5 This is an unfolded structural diagram of the first condenser plate and the second condenser plate provided in an embodiment of the present invention;

[0030] Figure 6 This is a top view of the fully unfolded first condenser plate and multiple second condenser plates provided in an embodiment of the present invention.

[0031] Figure 7 This is a top view of the first limiting block and the second limiting block separated according to an embodiment of the present invention;

[0032] Figure 8 This is a top-view structural diagram showing the first limiting block and the second limiting block separated, as provided in an embodiment of the present invention.

[0033] Figure 9 This is a structural diagram of the guide component provided in an embodiment of the present invention;

[0034] Figure 10 This is another structural view of the guide component provided in an embodiment of the present invention;

[0035] Figure 11 Provided for embodiments of the present invention Figure 10 Enlarged structural diagram at point A.

[0036] Explanation of reference numerals in the attached figures:

[0037] 1. Crystallization tank; 2. Water bath tank; 3. Condensation component; 31. First condensing plate; 32. Second condensing plate; 33. Vacuum pipe; 331. Outer pipe; 332. Inner pipe; 333. Slide groove; 334. Drive bar; 34. Gear motor; 35. Pulley; 36. Transmission belt; 37. Fixed ring; 38. Rotary ring; 39. First limiting block; 310. Second limiting block; 311. Locking block; 312. Limiting groove; 313. Sliding column; 314. Arc groove; 4. Guide component; 41. Annular guide rail; 42. Spiral guide rail; 43. Guide block. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0039] Please see the appendix Figure 1 This invention provides a highly efficient purification process for trimethylaluminum, comprising the following steps:

[0040] The crude trimethylaluminum product was subjected to infrasonic pretreatment and simultaneous low-temperature cooling to precisely destroy the chemically adsorbed state of trace impurities (such as dimethylaluminum chloride, organosilicon, etc.).

[0041] Reduced pressure distillation is used to continuously extract low-boiling-point impurities under dynamic vacuum conditions, while a cryogenic receiving tank is used to collect the distillate.

[0042] The remaining mother liquor is subjected to gradient condensation and the vacuum level is reduced;

[0043] After the vacuuming process was completed, the distillation vessel was heated to 20-30°C and maintained for 12 hours before sampling and testing were performed, and ultrapure trimethylaluminum was obtained.

[0044] Example 1:

[0045] 1. Place 1000g of crude trimethylaluminum in a distillation apparatus. Under the action of infrasound with a frequency of 10Hz and a power of 200W, the system temperature is controlled at 5℃ by low-temperature freezing and maintained for 3 hours. Then start vacuum distillation, use a cryogenic receiving tank to receive low-boiling-point products, control the system vacuum at 10kPa, and then perform gradient depressurization at a rate of 1kPa / 15min until the vacuum reaches 1kPa. Then continue vacuuming for 6 hours.

[0046] 2. Then, the system is cooled down to 0℃ using a gradient cooling method, while the vacuum degree is reduced to 0.1kPa and maintained for 6 hours. The system temperature starts from 5℃ and is adjusted in stages at a gradient cooling rate of 2℃ / 0.5h until the temperature reaches 0℃.

[0047] 3. After vacuuming, the distillation vessel was heated to 25°C and maintained for 12 hours, yielding a total of 825g of high-purity trimethylaluminum, which was then sampled and tested.

[0048] In this case, the trimethylaluminum was purified to a yield of 82.5%. The product was analyzed by a JNM-ECZ400S nuclear magnetic resonance spectrometer: 1H NMR (400 MHz, C6D6) δ: -0.35 (s, 9H). Inductively coupled plasma atomic emission spectrometry (Optima8000) detected all inorganic elements <0.1ppm, achieving a purity of 7N.

[0049] The results of the main impurity element detection are as follows:

[0050] Element Before purification (ppm) After purification (ppm) Chlorine content 1.2 0.02 Silicon content 6.1 0.05

[0051] Example 2:

[0052] 1. Place 1500g of crude trimethylaluminum in a distillation apparatus. Under the action of infrasound with a frequency of 15Hz and a power of 200W, the system temperature is controlled at 5℃ by low-temperature freezing and maintained for 3 hours. Then start vacuum distillation, use a cryogenic receiving tank to receive low-boiling-point products, control the system vacuum at 10kPa, and then perform gradient depressurization at a rate of 1kPa / 15min until the vacuum reaches 1kPa. Then continue vacuuming for 6 hours.

[0053] 2. Then, the system is cooled down to -2℃ using a gradient cooling method, while the vacuum degree is reduced to 0.1kPa and maintained for 6 hours. The system temperature starts from 5℃ and is adjusted in stages at a gradient cooling rate of 2℃ / 0.5h until the temperature reaches the -2℃ range.

[0054] 3. After the vacuuming was completed, the distillation vessel was heated to 25°C and maintained for 12 hours, yielding a total of 1252g of high-purity trimethylaluminum.

[0055] In this case, the trimethylaluminum was purified to a yield of 83.5%. The product was analyzed by a JNM-ECZ400S nuclear magnetic resonance spectrometer: 1H NMR (400 MHz, C6D6) δ: -0.35 (s, 9H). Inductively coupled plasma atomic emission spectrometry (Optima8000) detected all inorganic elements <0.1ppm, achieving a purity of 7N.

[0056] The results of the main impurity element detection are as follows:

[0057] Element Before purification (ppm) After purification (ppm) Chlorine content 2.3 0.03 Silicon content 7.3 0.04

[0058] Example 3:

[0059] 1. Place 1800g of crude trimethylaluminum in a distillation apparatus. Under the action of infrasound with a frequency of 20Hz and a power of 200W, the system temperature is controlled at 5℃ by low-temperature freezing and maintained for 3 hours. Then start vacuum distillation, use a cryogenic receiving tank to receive low boiling points, control the system vacuum at 10kPa, and then perform gradient depressurization at a rate of 1kPa / 15min until the vacuum reaches 1kPa. Then continue vacuuming for 6 hours.

[0060] 2. Then, the system is cooled down to -5℃ using a gradient cooling method, while the vacuum degree is reduced to 0.1kPa and maintained for 6 hours. The system temperature is adjusted in stages from 5℃ with a gradient cooling rate of 2℃ / 0.5h until the temperature reaches the -5℃ range.

[0061] 3. After the vacuuming was completed, the distillation vessel was heated to 30°C and maintained for 12 hours, yielding a total of 1476g of high-purity trimethylaluminum.

[0062] In this case, the trimethylaluminum was purified to a yield of 82%. The product was analyzed by a JNM-ECZ400S nuclear magnetic resonance spectrometer: 1H NMR (400 MHz, C6D6) δ: -0.35 (s, 9H). Inductively coupled plasma atomic emission spectrometry (Optima8000) detected all inorganic elements <0.1ppm, achieving a purity of 7N.

[0063] The results of the main impurity element detection are as follows:

[0064] Element Before purification (ppm) After purification (ppm) Chlorine content 5.8 0.03 Silicon content 9.8 0.03

[0065] This process precisely disrupts the chemisorbed state of trace impurities (such as dimethylaluminum chloride and organosilicon) through infrasound-low temperature coupling, and significantly improves the removal efficiency of ppm-level impurities by combining it with vacuum gradient separation. Its advantages include avoiding alumina particle contamination caused by high temperatures, while also greatly reducing energy consumption, making it particularly suitable for the large-scale continuous production of semiconductor-grade pure trimethylaluminum.

[0066] Please see the appendix Figure 2-11 The present invention provides a trimethylaluminum high-efficiency purification device, which applies the above-mentioned trimethylaluminum high-efficiency purification process, including a crystallization tank 1 and a water bath tank 2 wrapped around the crystallization tank 1. The crystallization tank 1 is provided with a condensation component 3 inside. The condensation component 3 includes a ring-shaped condensation assembly. The condensation assembly has two states: initially in a superimposed state and during condensation in an expanded state.

[0067] A vacuum pipe 33 is rotatably connected to the crystallizer 1, which is responsible for extracting low-boiling-point impurities. The vacuum pipe 33 is connected to a negative pressure pipe, which is connected to a vacuum pump. The vacuum pump is connected to a cryogenic receiving tank through a pipeline to achieve the purpose of collecting distillate.

[0068] The condensation assembly includes a first condensation plate 31 and multiple second condensation plates 32. The first condensation plate 31 is fixedly connected to a fixing ring 37, and each of the second condensation plates 32 is fixedly connected to a rotating ring 38. The suction pipe 33 includes an outer pipe 331 and an inner pipe 332 that slides inside the outer pipe 331. Specifically, the outer wall of the inner pipe 332 is provided with a sliding groove 333, and the inner wall of the outer pipe 331 is fixedly connected to a driving bar 334. The driving bar 334 can slowly rotate the inner pipe 332 through the sliding groove 333.

[0069] Specifically, the fixed ring 37 is fixedly sleeved on the outer wall of the inner tube 332, and the rotating ring 38 is rotatably sleeved on the outer wall of the inner tube 332 through the annular groove. The bottom of the first condensing plate 31 and the multiple second condensing plates 32 are fixedly connected with sliding columns 313. The multiple second condensing plates 32 are provided with arc-shaped grooves 314, and the sliding columns 313 slide on the inner wall of the arc-shaped grooves 314.

[0070] When the inner tube 332 rotates, it rotates the first condensing plate 31 and the sliding column 313. When the sliding column 313 rotates to the end of the arc groove 314, it drives the second condensing plate 32 that is closely attached below. In this way, the upper second condensing plate 32 drives the lower second condensing plate 32. Finally, it unfolds into a circular condensation area.

[0071] Preferably, a geared motor 34 is provided on the outside of the crystallization tank 1. The outer wall of the output end of the geared motor 34 and the outer wall of the outer tube 331 are both fixedly sleeved with pulleys 35. A transmission belt 36 is sleeved on the outside of a pair of pulleys 35. When the geared motor 34 is turned on, the outer tube 331 can be slowly rotated in the forward direction, and the inner tube 332 will also start to rotate.

[0072] Specifically, a sealed bearing is provided at the contact position between the outer tube 331 and the crystallizer 1, so that the outer tube 331 can easily rotate on the inner wall of the crystallizer 1 without affecting the sealing effect of the crystallizer 1.

[0073] At the end of the above process, the crystallized trimethylaluminum is heated and melted into a liquid state. A small portion will be overheated and rise into a gaseous or misty state. Subsequently, it will automatically evaporate after becoming liquid. Therefore, by setting up a circular condensation area, the misty or gaseous trimethylaluminum can be condensed into liquid and collected, thereby accelerating the collection rate of trimethylaluminum and further improving the collection efficiency.

[0074] Preferably, a first limiting block 39 is fixedly connected to the inner wall of the crystallization tank 1. A limiting groove 312 is opened at the bottom of the first limiting block 39. A second limiting block 310 is fixedly connected to the outer end of the second limiting block 310 located at the bottom. A locking block 311 is fixedly connected to the top of the second limiting block 310. Initially, the locking block 311 is located inside the limiting groove 312. The locking block 311 is made of elastic material, and the elastic force is greater than the friction force between the sliding column 313 and the arc groove 314 and the driving force of the multiple second condensing plates 32. It can be between 5-15 Newtons and can be adjusted adaptively according to actual needs.

[0075] Initially, the second condensing plate 32 at the bottom is limited by the elastic force between the locking block 311 and the limiting groove 312. When the last second condensing plate 32 is about to move, the pulling force breaks through the elastic force, the last second condensing plate 32 begins to rotate, and finally the entire condensing area begins to move.

[0076] The condensing component 3 is provided with a guide component 4, which includes an annular guide rail 41 and a spiral guide rail 42. A guide block 43 is fixedly connected to the uppermost condensing plate. The guide block 43 slides on the annular guide rail 41 and the spiral guide rail 42 respectively, and is responsible for moving multiple condensing plates up and down.

[0077] Initially, the guide block 43 is located at the end of the annular guide rail 41. After it starts moving, the guide block 43 rotates about 330 degrees (taking the 11 second condensing plates 32 in the figure as an example). The entire condensing assembly is expanded to its maximum size and then moves to the spiral guide rail 42. It moves down along the spiral guide rail 42 while rotating until it reaches the set height (the height is set according to actual needs). At this time, the condensing assembly is closer to the crystallization. The generated mist and water vapor will quickly come into contact with the condensing assembly and condense into liquid and fall down, thereby further improving the condensation rate and collection rate.

[0078] Preferably, a first limiting block 39 is also provided on the inner wall of the crystallization tank 1. The first limiting block 39 is slidably connected to the inner wall of the crystallization tank 1. When the second limiting block 310 approaches the first limiting block 39, the locking block 311 enters the limiting groove 312 of the first limiting block 39 to complete the limitation. When the inner tube 332 is driven in reverse, the first condensing plate 31 climbs up along the spiral guide rail 42 and begins to gather multiple second condensing plates 32. Since the locking block 311 is in the limiting groove 312 at this time, the last second condensing plate 32 does not rotate but only moves up and down until all the second condensing plates 32 are gathered. When the pulling force is greater than the elastic force of the locking block 311, the first condensing plate 31 and multiple second condensing plates 32 rise spirally together in a gathered state until the locking block 311 enters the limiting groove 312 of the first limiting block 39 above, that is, returns to the initial position and waits for the next use.

[0079] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A highly efficient purification process for trimethylaluminum, characterized in that: Includes the following steps, S1, the crude trimethylaluminum is subjected to infrasonic pretreatment and simultaneously cooled at low temperature; S2, vacuum distillation, continuously extracts low-boiling-point impurities under dynamic vacuum conditions, while collecting the distillate in a cryogenic receiving tank. S3, the remaining mother liquor was subjected to gradient condensation and vacuuming to obtain ultrapure trimethylaluminum; The infrasound frequency in S1 is 10~20Hz and the power is 200W; The low-temperature cooling in S1 involves maintaining the system temperature at 5°C for 3 hours. The vacuum distillation in S2 is a gradient vacuum distillation, in which the vacuum degree of the system is reduced from 10 kPa to 1 kPa in stages and maintained at 1 kPa vacuum degree for 6 hours. The gradient condensation in S3 involves cooling the system to a temperature range of -5 to 0°C using a gradient cooling method, while simultaneously reducing the vacuum level to 0.1 kPa and maintaining it for 6 hours. The vacuum level of the system in S2 starts from 10 kPa and is adjusted in stages at a gradient rate of 1 kPa / 15 min until the vacuum level reaches 1 kPa.

2. The high-efficiency purification process for trimethylaluminum according to claim 1, characterized in that, After the vacuuming process in step S3 is completed, the distillation vessel is heated to 20-30°C and maintained for 12 hours before sampling and testing.

3. The high-efficiency purification process for trimethylaluminum according to claim 1, characterized in that, In S3, the system temperature starts at 5°C and is adjusted in stages at a gradient cooling rate of 2°C / 0.5h until the temperature reaches the range of -5°C to 0°C.

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