CN111892020A - A kind of synthetic method and device of high-purity electronic grade diborane - Google Patents

Abstract

The invention relates to the field of synthesis of diborane, in particular to a method and device for synthesizing high-purity electronic grade diborane. The synthesis method comprises the following steps: 1) dry reaction of alkali metal borohydride and boron trifluoride under solvent-free conditions to prepare crude diborane gas; 2) using potassium borohydride for crude diborane gas at 20 ‑40°C is purified to obtain the first treated gas; the first treated gas is purified by using sodium hydroxide at 15‑30 °C to obtain the second treated gas; Adsorption treatment is carried out at 20° C. to obtain the third treatment gas; the third treatment gas is subjected to gas-solid separation at a temperature lower than the freezing point of diborane to obtain solid diborane. The synthesis method can efficiently purify the crude diborane gas prepared by the dry process. After the treatment, the product has few impurities, the product purity reaches the high-purity electronic level, and the quality is comparable to that of foreign products.

Description

A kind of synthetic method and device of high-purity electronic grade diborane

technical field

The invention belongs to the field of synthesis of diborane, in particular to a method and device for synthesizing high-purity electronic grade diborane.

Background technique

Diborane, also known as diboron hexahydride and borane, has a molecular formula of B ₂ H ₆ and a relative molecular weight of 27.67. The molecular configuration of diborane is very special. Among the 6 hydrogen atoms in the molecule, 4 hydrogen atoms and two boron atoms are bonded by normal covalent bonds, and the other two hydrogen atoms each hydrogen atom and two boron atoms at the same time. Atoms are bonded to each other by two electrons, forming BHB bonds, which act as "bridges" connecting two boron atoms. According to the normal valence bond theory, diborane requires 14 valence electrons, and it has only 12 valence electrons, so it is a typical "electron-deficient" compound. In the electronics industry, diborane is used as a gaseous impurity source, a dopant for ion implantation and oxidative diffusion of boron doping, and is mainly used as a dopant in the production of P-type semiconductor chips.

Diborane is gaseous under normal conditions (15°C, 101.325kPa), and is a colorless, flammable, easily decomposed, highly toxic gas with a disgusting pyrotechnic odor and a slightly sweet taste. Diborane is a very active compound, which is not very stable at room temperature, and will slowly decompose to generate various high-level borohydride compounds with different contents, and at the same time, hydrogen will be released. The temperature increases, the decomposition accelerates, and the decomposition products vary with the temperature. Diborane is immediately hydrolyzed by water, and finally boric acid and a large amount of hydrogen are obtained.

The industrial production methods of diborane include the discharge method, the reaction of lithium aluminum hydride, lithium borohydride or other metal hydrides with the ether solution of boron trihalide, the reaction of trialkyl boron with hydrogen, and the like. Chinese Patent Application Publication No. CN1309619A discloses the use of inorganic hydroxide to remove boron trifluoride from dry-synthesized crude diborane gas.

In the above prior art, the synthesis and purification processes of crude diborane belong to the laboratory stage, the reactor capacity is small, the reaction conditions are easy to control, and the yield and purity of diborane are easily guaranteed. However, in industrial scale-up production, the factors affecting the purity and yield of diborane increase, and the purity of diborane is often difficult to reach high-purity electronic grade, which is also the reason why the dry process cannot achieve industrial scale-up production.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a method for synthesizing high-purity electronic grade diborane, the product of which can reach high-purity electronic grade and can meet the requirements of industrial scale-up production.

The second object of the present invention is to provide a device for synthesizing high-purity electronic grade diborane.

For achieving the above object, the technical scheme of the synthetic method of high-purity electronic grade diborane of the present invention is:

A synthetic method of high-purity electronic grade diborane, comprising the following steps:

1) dry reaction of alkali metal borohydride and boron trifluoride under solvent-free conditions to prepare crude diborane gas; the alkali metal borohydride at least includes potassium borohydride;

2) using potassium borohydride to purify crude diborane gas at 20-40 ° C to obtain the first treatment gas;

Purify the first treated gas with sodium hydroxide at 15-30°C to obtain the second treated gas;

The second treated gas is subjected to adsorption treatment at -40～-20°C using 13X molecular sieve to obtain the third treated gas;

The third treatment gas is subjected to gas-solid separation at a temperature lower than the freezing point of diborane to obtain solid diborane.

The method for synthesizing high-purity electronic-grade diborane of the present invention can efficiently purify the crude diborane gas prepared by the dry process. quite. The corresponding purification process, the process conditions are mild and not harsh, and can meet the requirements of industrial production.

The temperature below the freezing point of diborane is -90 to -186°C. At this temperature, diborane condenses in solid form, and impurity gases such as nitrogen are separated.

The alkali metal borohydride includes potassium borohydride and sodium borohydride, and the mass of sodium borohydride is not higher than 50% of the mass of potassium borohydride. In the form of a mixture of potassium borohydride and sodium borohydride, the reaction speed can be better regulated, and the decomposition of diborane caused by excessive reaction is avoided.

From the comprehensive consideration of reaction cost and product yield, preferably, in molar amount, the excess of alkali metal borohydride relative to boron trifluoride is 50-100%.

The lower the temperature of the dry reaction, the more conducive to inhibiting the decomposition of diborane; but the reaction temperature is too low will lead to slow reaction speed, long reaction time, incomplete reaction, long reaction time is beneficial to the decomposition of diborane, Incomplete reaction will result in a large residual amount of boron trifluoride in the reaction product. Taking into account the above factors and the economic benefits of industrial production, the temperature of the dry reaction is 0-20° C., and the reaction time is 4-12 hours. Under the technical scheme, it is more in line with the actual industrial production, and high-purity electronic-grade products that meet the requirements can be obtained in combination with the subsequent purification process.

The dry reaction is that the solid alkali metal borohydride reacts with boron trifluoride gas in a tumbling state, and hydrogen is used as a reaction medium to participate in the reaction process; the volume of hydrogen is 10-20% of the volume of boron trifluoride. By adopting this reaction method, the solid material and the gaseous material can be fully contacted and fully reacted. Moreover, since the synthesis reaction of diborane is relatively violent, the product is easy to decompose. In the production process of the industrialized method, even if a cold source is used to cool the system, due to the slow heat transfer, the actual reaction temperature will be much higher than that of the cold source. The temperature can also cause the reaction to run out of control and the product to decompose. Adding hydrogen as the reaction medium in the dry reaction, on the one hand, as a good heat transfer medium, hydrogen can enhance the heat transfer capacity of the device and make the reaction temperature closer to the temperature of the cold source. On the other hand, due to the decomposition products of hydrogen diborane There must be hydrogen in it, and hydrogen itself can inhibit the decomposition of diborane and effectively reduce the occurrence of side reactions.

The technical scheme of the synthesis device of high-purity electronic grade diborane of the present invention is:

A device for synthesizing high-purity electronic grade diborane, comprising:

Diborane synthesizer for synthesizing crude diborane gas; with crude diborane gas outlet;

The potassium borohydride chemical reaction purifier has a first feed gas inlet and a first feed gas outlet; the potassium borohydride chemical reaction purifier is filled with potassium borohydride for purifying the gas entering from the first feed gas inlet crude diborane gas, and the first processing gas is produced from the first raw material gas outlet;

The sodium hydroxide chemical reaction purifier has a second feed gas inlet and a second feed gas outlet; the sodium hydroxide chemical reaction purifier is filled with sodium hydroxide for purifying the gas entering from the second feed gas inlet the first treatment gas, and the second treatment gas is produced from the second raw material gas outlet;

The 13X molecular sieve adsorption purifier has a third feed gas inlet and a third feed gas outlet; the 13X molecular sieve adsorption purifier is filled with 13X molecular sieves for purifying the second treatment gas entered from the third feed gas inlet, and producing a third process gas from the third raw material gas outlet;

The ultra-low temperature gas-solid separator has an inlet pipeline and a gas outlet pipeline; the third process gas enters the ultra-low temperature gas-solid separator through the inlet pipeline, the diborane is solidified into a solid state, and the impurity gas is pumped from the gas outlet pipeline Vacuum device extraction;

A vacuum purification device, including a vacuum pumping device and a vacuum replacement gas filling device, used for vacuum purification of the synthesis device;

Between the crude diborane gas outlet and the first feed gas inlet, between the first feed gas outlet and the second feed gas inlet, between the second feed gas outlet and the third feed gas inlet, and between the third feed gas outlet and the Between the inlet pipelines of the ultra-low temperature gas-solid separator, as well as between the gas outlet pipeline and the vacuuming device, all are connected by connecting pipelines; the crude diborane gas is purified by potassium borohydride, sodium hydroxide purification, 13X molecular sieve in turn. After adsorption purification and ultra-low temperature gas-solid separation, solid diborane is obtained in the ultra-low temperature gas-solid separator.

The high-purity electronic-grade diborane synthesis device of the present invention can effectively purify the crude diborane gas produced by the dry process, so that the product reaches the high-purity electronic grade. The devices used are all industrialized mature equipment with industrialized production capacity.

In order to facilitate the vacuum purification, preferably, the vacuum replacement gas filling device includes a vacuum replacement gas storage tank, a diborane synthesizer, a potassium borohydride chemical reaction purifier, a sodium hydroxide chemical reaction purifier, and a 13X molecular sieve adsorption purifier. , The connecting pipeline between the ultra-low temperature gas-solid separators is connected with the vacuum replacement gas storage tank, so that the vacuum replacement gas is introduced into the connecting pipeline to assist the vacuum pumping device to carry out deep vacuum purification. The vacuum replacement gas can be selected from ultrapure hydrogen or ultrapure helium.

In order to better realize heat exchange and protect pipeline valves, preferably, both the inlet pipeline and the gas outlet pipeline of the ultra-low temperature gas-solid separator include a straight section and a spiral section for enhancing heat exchange.

In order to improve the purification speed and improve the processing capacity, preferably, the potassium borohydride chemical reaction purifier, the sodium hydroxide chemical reaction purifier, and the 13X molecular sieve adsorption purifier are all tubular purifiers, including an array type purifier for filling the purifying agent. The tube bundle and the shell, the array tube bundle is fixed in the shell, and the feed gas is purified after flowing through a purifying agent, and the purifying agent is potassium borohydride, sodium hydroxide, and 13X molecular sieve.

Description of drawings

Fig. 1 is the structural representation of the feeding system in the embodiment 1 of the present invention;

Fig. 2 is the sectional view of diborane synthesizer in the present invention;

Fig. 3 is the split view of diborane reaction tank in the present invention;

Fig. 4 is the structural representation of the diborane synthesis system in the embodiment of the present invention 1;

5 is a schematic structural diagram of a crude diborane gas purification system in Example 1 of the present invention;

Fig. 6 is the structural representation of the tubular purifier in the present invention;

Fig. 7 is the structural representation of ultra-low temperature gas-solid separation and purifier in the present invention;

Fig. 8 is the infrared detection figure of the diborane obtained by the method of the embodiment of the present invention 2;

Among them, 1-vacuum pump purification system, 2-diborane synthesizer, 20-flange feeding port, 21-diaphragm valve feeding port, 23-upper end cap, 24-lower end cap, 25-inner cylinder, 26-outer cylinder , 3-ice water bath bucket, 4-6N grade ultra-pure hydrogen cylinder, 5-3N electronic grade boron trifluoride cylinder, 6-roller, 7-cooling water machine, 8-cooling water sprayer, 80-first Rod cooling water sprayer, 81- The second rod cooling water sprayer, 9- Potassium borohydride chemical reaction purifier, 90- Crude diborane gas inlet valve, 91- The first process gas outlet valve, 92 -The first heat exchange medium inlet valve, 93-the first heat exchange medium outlet valve, 901-upper head, 902-lower head, 903-array tube bundle, 10-sodium hydroxide chemical reaction purifier, 100-stainless steel Diaphragm valve, 101-first treatment gas inlet valve, 102-second treatment gas outlet valve, 103-second heat exchange medium inlet valve, 104-second heat exchange medium outlet valve, 11-13X molecular sieve adsorption purifier, 110 -Second processing gas inlet valve, 111-Third processing gas outlet valve, 112-Third heat exchange medium inlet valve, 113-Third heat exchange medium outlet valve, 12-Ultra-low temperature gas-solid separation and purifier, 120-Inlet pipe Road valve, 121-outlet pipeline valve, 122-inlet pipeline, 123-outlet pipeline, 13-liquid argon cold trap, 200-cooling water flow control valve.

Detailed ways

The embodiments of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

One, the specific embodiment of the synthesis device of high-purity electronic grade diborane of the present invention

Example 1

The device for synthesizing high-purity electronic grade diborane in this embodiment includes a diborane synthesizer for producing crude diborane gas and a crude diborane gas purification system.

The generation of crude diborane gas in the diborane synthesizer needs to go through two processes of feeding and synthesis, which are realized by feeding system and synthesis system respectively.

(1) Feeding system

Due to its active chemical properties, diborane is easily decomposed. The addition system as shown in Figure 1 was used to suppress the violent reaction of the reaction raw materials during the addition. The feeding system includes a vacuum pump purification system 1, a diborane synthesizer 2, an ice-water bath 3 and a gas material filling system. The gas material filling system includes a 6N-grade ultra-pure hydrogen cylinder 4 and a 3N electronic-grade boron trifluoride cylinder 5.

The diborane synthesizer 2 is a hollow annular cylindrical container, the structure is shown in Figures 2 and 3, including an inner cylinder 25, an outer cylinder 26, an upper end cap 23, a lower end cap 24, and between the inner cylinder 25 and the outer cylinder 26. A ring-shaped space is formed, the upper end cap 23 and the lower end cap 24 are annular splits, and the upper and lower end caps are respectively sealed to replace the upper and lower ends of the cylindrical space to form a site for diborane synthesis reaction. The upper end cover is also welded with a flange type feeding port 20 and a diaphragm valve feeding port 21. The flange type feeding port 20 includes a section of round pipe at the lower end and a set of flange blind plates at the upper end connecting the lower end round pipe. The diaphragm valve feeding port 21 It includes a section of circular tube at the lower end and a stainless steel diaphragm valve at the upper end connecting the circular tube at the lower end. The diborane synthesizer 2 is all made of 316 stainless steel, and all the interfaces in contact with the diborane reaction material reach the level of electronic polishing; The diameter of the cylinder is 1 to 1.6 meters, and the diameter of the outer cylinder is 0.4 to 0.8 meters larger than the inner diameter.

The ice-water bath bucket 3 is used to hold ice water at 0°C, the diborane synthesizer 2 is placed in the ice-water bath bucket 3, and the diaphragm valve feeding port 21 of the diborane synthesizer 2 is connected to the vacuum pump purification system 1 and 6N level respectively through pipelines. The pure hydrogen cylinder 4 and the 3N electronic grade boron trifluoride cylinder 5 are connected, and a stainless steel diaphragm valve 100 is arranged on the pipeline.

The diborane synthesizer 2 is respectively connected with the vacuum pump purification system 1, the 6N grade ultrapure hydrogen cylinder 4 and the 3N electronic grade boron trifluoride cylinder 5 through the connecting pipeline.

The feeding operation is as follows: firstly, the solid reaction material alkali metal borohydride is injected into the diborane synthesizer through the flange-type feeding port of the diborane synthesizer, and then the flange-type feeding port is closed. Immerse the diborane synthesizer as a whole in an ice-water bath at 0°C, and the flange-type feeding port and the diaphragm valve feeding port for filling gas materials are exposed to the water surface as a whole; Boron trifluoride and 6N grade ultra-pure hydrogen) are filled with related pipelines for thorough purification. 6N grade ultra-pure hydrogen is used as vacuum displacement gas.

After purification, the pressure of the diborane synthesizer is -29inHg. Open the valve of the 3N electronic grade boron trifluoride cylinder and inject a certain amount of 3N electronic grade boron trifluoride into the diborane synthesizer through the diaphragm valve feeding port of the diborane synthesizer. Boron and boron trifluoride cylinders are placed on an electronic balance with an accuracy of 0.1g, which can control the injection amount of 3N electronic grade boron trifluoride, and the injection rate of 3N electronic grade boron trifluoride is 0.1-0.5 kg/min; Then open the valve of the 6N-grade ultra-pure hydrogen cylinder and inject 6N-grade ultra-pure hydrogen into the diborane synthesizer through the diaphragm valve feeding port of the diborane synthesizer. The volume of hydrogen added is 10%-20% of the volume of boron trifluoride. , hydrogen can speed up the heat transfer between the reaction material and the outside world, and can also effectively inhibit side reactions.

Finally, start the vacuum purification to purify and replace the vacuum purification system and gas material filling pipeline, inject 6N-grade ultra-pure hydrogen into the vacuum purification and gas material filling system to maintain pressure, and then connect the diborane synthesizer to the vacuum purification and gas material filling system. Note that the system is separated.

(2) Diborane synthesis system

A schematic diagram of the diborane synthesis system is shown in Figure 4. The diborane synthesis system includes a rolling machine 6 , a diborane synthesizer 2 , a cooling water machine 7 and a cooling water sprayer 8 .

The diborane synthesizer 2 is placed horizontally on the roller of the rolling machine 6, and the rotation of the roller drives the diborane synthesizer to roll. The cooling water machine 7 is connected to a cooling water sprayer 8 through a pipeline, and a cooling water flow regulating valve 200 is connected to the pipeline. The cooling water shower 8 includes a first rod-shaped cooling water shower 80 and a second rod-shaped cooling water shower 81 . The length of the rod-shaped cooling water sprayer extends along the horizontal direction of the diborane synthesizer, and the first rod-shaped cooling water sprayer 80 extends into the hollow structure of the diborane synthesizer from one side and extends to the other side. On the side of the diborane synthesizer, the hollow structure of the diborane synthesizer is spray-cooled, and the second rod-shaped cooler 81 is disposed outside the horizontally placed diborane synthesizer to spray-cool the outer peripheral surface of the diborane synthesizer.

On the rod-shaped cooling water sprayer, a spray head is installed at intervals of 10 cm along the length direction, and the cooling water at 4-20° C. produced by the cooling water machine 7 is sprayed inside and outside the diborane synthesizer.

The synthesis procedure is as follows:

Start the rolling machine, the rolling can make the solid material and the gas material fully contact and make it fully react, and the rolling time is 4-12 hours; during the rolling reaction of the diborane synthesizer, the cooling water continuously flows from the inside and the outside. Spray it to the diborane synthesizer to avoid the decomposition of diborane caused by the violent reaction in the diborane synthesizer.

(3) Crude diborane gas purification system

The schematic structural diagram of the crude diborane gas purification system is shown in Figure 5, including potassium borohydride chemical reaction purifier 9, sodium hydroxide chemical reaction purifier 10, 13X molecular sieve adsorption purifier 11, ultra-low temperature gas-solid separation purifier 12, A vacuum pump purification system 1 and a vacuum replacement gas filling device, the vacuum replacement gas filling device includes a 6N-grade ultra-pure hydrogen cylinder 4 .

The potassium borohydride chemical reaction purifier 9 is a tube-and-tube purifier. The schematic structural diagram is shown in Figure 6, including the middle main body, the upper head 901, and the lower head 902. The middle main body is a tube-and-shell structure, including a shell. , the array tube bundle 903 located in the shell and the tube sheet for fixing the array tube bundle. The lower end of the casing is connected with a heat exchange medium inlet pipe, which is connected to the first heat exchange medium inlet valve 92; the upper end of the casing is connected with a heat exchange medium outlet pipe, which is connected to the first heat exchange medium outlet valve 93. The upper and lower heads are flanged heads, and a section of round pipe is connected to the lower head, and a crude diborane gas inlet valve 90 is installed on the round pipe, and a section of round pipe is also connected to the upper head. A first process gas outlet valve 91 is mounted on the pipe.

The sodium hydroxide chemical reaction purifier 10 is also a tubular purifier, and its structure is the same as that of the potassium borohydride chemical reaction purifier 9, and correspondingly has a first treatment gas inlet valve 101, a second treatment gas outlet valve 102, and a first treatment gas inlet valve 102. Two heat exchange medium inlet valves 103 and second heat exchange medium outlet valves 104 .

The 13X molecular sieve adsorption purifier 11 is also a tubular purifier, and its structure is the same as that of the potassium borohydride chemical reaction purifier 9, corresponding to the second treatment gas inlet valve 110, the third treatment gas outlet valve 111, and the third heat treatment gas. The exchange medium inlet valve 112 and the third heat exchange medium outlet valve 113 .

The crude diborane gas inlet valve 90, the first processing gas outlet valve 91, the first processing gas inlet valve 101, the second processing gas outlet valve 102, the second processing gas inlet valve 110, and the third processing gas outlet valve 111 are all Stainless steel diaphragm valve.

The ultra-low temperature gas-solid separation and purifier 12 is a cylindrical bottle-shaped structure, as shown in FIG. 7 , including a bottle body, an air inlet pipeline 122, and an air outlet pipeline 123. The two sides of the top of the bottle body are welded with the air inlet pipeline 122 respectively. and the air outlet pipe 123, the air inlet end of the air inlet pipe is exposed to the bottle body, including a straight section and a spiral section, an inlet pipe valve 120 is installed on the straight section, and the air outlet end of the air inlet pipe extends into the bottle body and reaches the bottom of the bottle body; The air inlet end of the air outlet pipeline is located in the upper part of the bottle body, and the air outlet end is exposed from the bottle body, including a spiral section after the bottle body and a straight section connected to the spiral section, and an outlet pipeline valve 121 is installed on the straight section. The inlet pipeline valve 120 and the outlet pipeline valve 121 are both stainless steel diaphragm valves.

The spiral structure of the air inlet and outlet pipes is conducive to heat exchange and can effectively protect the stainless steel diaphragm valve. The ultra-low temperature gas-solid separation and purifier are all made of ultra-low temperature-resistant aluminum alloy materials except for the valve, and the interface in contact with diborane all reaches the level of electronic polishing; the inner diameter of the ultra-low temperature gas-solid separation and purifier is 20-40 cm, and the height is 1-2 cm. Meter. The ultra-low temperature gas-solid separation and purifier is placed in the liquid argon cold trap 13 to achieve ultra-low temperature.

Diborane synthesizer 2, potassium borohydride chemical reaction purifier 9, sodium hydroxide chemical reaction purifier 10, 13X molecular sieve adsorption purifier 11, ultra-low temperature gas-solid separation purifier 12 are connected in series in order for the production of diborane synthesizer. The crude diborane gas is passed through in sequence, and finally high-purity electronic grade diborane is obtained in the ultra-low temperature gas-solid separation and purifier 12 .

The connecting pipeline between the diborane synthesizer 2 and the potassium borohydride chemical reaction purifier 9, the connecting pipeline between the potassium borohydride chemical reaction purifier 9 and the sodium hydroxide chemical reaction purifier 10, the sodium hydroxide chemical The connection pipeline between the reaction purifier 10 and the 13X molecular sieve adsorption purifier 11, and the connection pipeline between the 13X molecular sieve adsorption purifier 11 and the ultra-low temperature gas-solid separation purifier 12 are respectively connected to the vacuum pump purification system 1.

The connecting pipeline between the diborane synthesizer 2 and the potassium borohydride chemical reaction purifier 9, the connecting pipeline between the potassium borohydride chemical reaction purifier 9 and the sodium hydroxide chemical reaction purifier 10, the sodium hydroxide chemical The connection pipeline between the reaction purifier 10 and the 13X molecular sieve adsorption purifier 11, and the connection pipeline between the 13X molecular sieve adsorption purifier 11 and the ultra-low temperature gas-solid separation purifier 12 are respectively connected to the 6N-grade ultrapure hydrogen cylinder 4.

The vacuum pump purification system 1 combined with the vacuum replacement gas filling system containing the 6N-grade ultra-pure hydrogen cylinder 4 can facilitate the deep vacuum and high purification of the connecting pipeline of the system.

The purification process is as follows:

1. Start vacuum purification to thoroughly purify the diborane purifier and related pipelines, and inject 6N-grade ultrapure hydrogen as a vacuum replacement gas in the vacuum purification; after purification, the pressure of the diborane purifier and related pipelines is - 29inHg.

2. Open the diaphragm valve feeding port of the diborane synthesizer, and the crude diborane gas of the diborane synthesizer enters the "potassium borohydride chemical reaction purifier → sodium hydroxide chemical reaction purifier → 13X molecular sieve adsorption purifier in sequence" →Ultra-low temperature gas-solid separation and purifier", the purification speed of diborane is controlled at 25-100 g/h:

①The crude diborane gas enters the potassium borohydride chemical reaction purifier from the bottom, and flows out from the top after contacting and reacting with potassium borohydride (chemically pure, 99.9%). The reaction temperature is controlled at 20-40°C, and the purifier can react a small amount of boron trifluoride in the crude diborane gas to convert it into diborane;

②The gas from the potassium borohydride chemical reaction purifier enters the sodium hydroxide chemical reaction purifier from the bottom, and flows out from the top after contacting and reacting with sodium hydroxide (chemically pure, 99.8%, anhydrous), and the sodium hydroxide chemical reaction purification The purifier controls the reaction temperature of the purifier to 15-30°C through circulating water heat exchange, and the purifier can react and absorb trace amounts of boron trifluoride and acid gas impurities;

③The gas from the sodium hydroxide chemical reaction purifier enters the 13X molecular sieve adsorption purifier from the bottom, and the 13X molecular sieve adsorption purifier controls the reaction temperature of the purifier to -40～-20 through the circulating heat exchange of the working fluid (water + ethylene glycol). ℃, the purifier can remove impurities and carbon dioxide with high boiling point (boiling point greater than -20℃);

④ The gas from the 13X molecular sieve adsorption and purifier enters the bottom of the ultra-low temperature gas-solid separation and purifier, and the ultra-low temperature gas-solid separation and purifier is immersed in liquid argon with a temperature of -186 ° C. Diborane condenses in the form of solid in the gas-solid separation On the inner wall of the purifier, impurities such as hydrogen and trace nitrogen can be discharged from the ultra-low temperature gas-solid separation and purifier through the vacuum system. After the separation and purification, the pressure of the ultra-low temperature gas-solid separation and purifier is -29inHg, and the solid diborane is sealed in the ultra-low temperature gas-solid separation purifier. In the purifier, it is removed by gasification of solid diborane when required.

In other embodiments of the high-purity electronic-grade diborane synthesis device of the present invention, other ultra-pure gases, such as nitrogen, argon, etc., can be used as the vacuum replacement gas. The inlet pipeline and outlet pipeline of the ultra-low temperature gas-solid separator can all be in the form of straight sections. Potassium borohydride chemical reaction purifier, sodium hydroxide chemical reaction purifier, and 13X molecular sieve adsorption purifier are all tubular purifiers, which can be in the form of fluidized beds.

Two, the specific embodiment of the synthetic method of high-purity electronic grade diborane of the present invention

Example 2

The synthesis method of the high-purity electronic grade diborane of the present embodiment adopts the synthesis device of the above embodiment, and specifically adopts the following steps:

(1) Feeding step

The diborane synthesizer is a batch reactor with a height of 1.5 meters, an inner cylinder diameter of 0.8 meters and an outer cylinder diameter of 1.2 meters. First, 3kg potassium borohydride and 1kg sodium borohydride are passed through the flange type of the diborane synthesizer. The feed port is injected into the diborane synthesizer, and then the flanged feed port is closed.

Immerse the diborane synthesizer as a whole in an ice-water bath at 0°C; start vacuum purification to thoroughly purify the diborane synthesizer and the pipelines related to gas material filling, first evacuate to -29inHg, and then flush into 6N level Ultrapure hydrogen to 50inHg, repeated 20 times; then the pressure of the diborane synthesizer was pumped to -29inHg, and the valve of the 3N electronic grade boron trifluoride cylinder was opened to the diborane synthesizer through the diaphragm valve feeding port of the diborane synthesizer Inject 2kg of 3N electronic grade boron trifluoride, and the injection rate of 3N electronic grade boron trifluoride is 0.2kg/min; after the injection of 3N electronic grade boron trifluoride is completed, inject 6N grade superoxide into the diborane synthesizer. Pure hydrogen, the volume of hydrogen added is 10% of the volume of boron trifluoride, close the feeding port of the diaphragm valve; finally start the vacuum purification to purify and replace the vacuum purification and gas material filling pipeline, and inject 6N into the vacuum purification and gas material filling system The pressure of ultra-pure hydrogen is kept to 50 inHg, and the diborane synthesizer is separated from the vacuum purification and gas material filling system.

(2) crude diborane gas synthesis step

Lift the filled diborane synthesizer out of the 0°C ice-water bath bucket, place it horizontally on the rolling machine, and install two rods on the hollow inner side of the diborane synthesizer and the outer side of the diborane synthesizer. Cooling water sprayer, the cooling water temperature is 10 ℃; start the rolling machine, the rolling time is 10 hours, and then the diborane synthesizer is lifted from the rolling machine and placed in the diborane purification station.

(3) Crude diborane gas purification step

Crude diborane gas purification system includes potassium borohydride chemical reaction purifier, sodium hydroxide chemical reaction purifier, 13X molecular sieve adsorption purifier, ultra-low temperature gas-solid separation purifier, vacuum pump purification system and vacuum displacement gas injection system.

Potassium borohydride chemical reaction purifier, sodium hydroxide chemical reaction purifier, and 13X molecular sieve adsorption purifier are all tubular purifiers, with a height of 1.5 meters, 25 array tube bundles, an array tube bundle inner diameter of 3 cm, and a shell inner diameter of 40 mm. centimeter. The inner diameter of the ultra-low temperature gas-solid separation purifier is 30 cm and the height is 1.2 meters.

After the diborane synthesis reaction is completed, connect the diborane synthesizer to the crude diborane gas purification system through the feeding port of the diaphragm valve of the diborane synthesizer, and start the vacuum purification to remove the diborane purifier and related pipelines. For thorough purification, first vacuum to -29inHg, then flush 6N grade ultrapure hydrogen to 50inHg, repeat 20 times; after purification, the pressure of the diborane purifier and related pipelines is -29inHg, open the diborane synthesizer. At the feeding port of the diaphragm valve, the crude diborane gas of the diborane synthesizer enters the "potassium borohydride chemical reaction purifier → sodium hydroxide chemical reaction purifier → 13X molecular sieve adsorption purifier → ultra-low temperature gas-solid separation purifier", The purification rate of diborane is controlled at 50 g/h:

①The crude diborane gas enters the potassium borohydride chemical reaction purifier from the bottom, and flows out from the top after contacting and reacting with potassium borohydride (chemically pure, 99.9%). The reaction temperature was controlled at 25°C;

②The gas from the potassium borohydride chemical reaction purifier (the first treatment gas) enters the sodium hydroxide chemical reaction purifier from the bottom, and flows out from the top after contacting and reacting with sodium hydroxide (chemically pure, 99.8%, anhydrous), The sodium hydroxide chemical reaction purifier controls the reaction temperature of the purifier at 20°C through circulating water heat exchange;

③ The gas (second treatment gas) from the sodium hydroxide chemical reaction purifier enters the 13X molecular sieve adsorption purifier from the bottom, and the 13X molecular sieve adsorption purifier changes the reaction temperature of the purifier by circulating heat exchange of the working fluid (water + ethylene glycol). Control -25℃;

④ The gas (the third treatment gas) from the 13X molecular sieve adsorption and purifier enters the bottom of the ultra-low temperature gas-solid separation and purifier, and the ultra-low temperature gas-solid separation and purifier is immersed in liquid argon with a temperature of -186 ° C. The form condenses on the inner wall of the low-temperature gas-solid separation and purifier. When the gas pressure in the ultra-low temperature gas-solid separation and purifier is basically equal to the gas pressure in the diborane synthesizer, equilibrate for 30 minutes, and then close the inlet pipeline of the ultra-low temperature gas-solid separation and purifier. Open the stainless steel diaphragm valve of the ultra-low temperature gas-solid separation and purifier outlet pipeline, start the vacuum system, and vacuum out the impurities such as hydrogen and trace nitrogen in the low-temperature gas-solid separation and purifier. Repeat this several times until the separation and purification is completed. When the pressure of the ultra-low temperature gas-solid separation and purifier is -29inHg, the solid diborane is sealed in the ultra-low temperature gas-solid separation and purifier, and it is taken out by gasification of solid diborane when needed. Grade diborane 301g.

Example 3

The synthetic method of the high-purity electronic grade diborane of the present embodiment is basically the same as the steps of Example 2, and the difference is only:

In step (1), the volume of hydrogen added is 15% of the volume of boron trifluoride.

In step (2), the temperature of the cooling water was 4°C, and the rolling time was 12 hours.

In step (3), the purification treatment temperature of potassium borohydride is 30°C, the purification treatment temperature of sodium hydroxide is 25°C, and the treatment temperature of 13X molecular sieve is -30°C.

Example 4

The synthetic method of the high-purity electronic grade diborane of the present embodiment is basically the same as the steps of Example 2, and the difference is only:

In step (1), the volume of hydrogen added is 20% of the volume of boron trifluoride.

In step (2), the temperature of the cooling water was 8°C, and the rolling time was 10 hours.

In step (3), the purification treatment temperature of potassium borohydride is 35°C, the purification treatment temperature of sodium hydroxide is 15°C, and the treatment temperature of 13X molecular sieve is -40°C.

3. Experimental example

The purity of the method for synthesizing diborane in Example 2 was tested, and the results were shown in FIG. 8 , and no infrared characteristic peaks other than diborane were found.

The following methods were used to further verify the purity of diborane:

An aluminum alloy steel cylinder with a volume of 20-60L is selected. The inner wall of the aluminum alloy steel cylinder should be polished. After polishing, the inner wall should be passivated with a hydrogen mixture containing 1-5% diborane. The valve should be a special angle valve for electronic gas. The aluminum alloy steel cylinder is protected with ultra-pure hydrogen when it is not in use, and the pressure is 2-3 kg.

The specific operations are:

1) Pump out the protective gas ultra-pure hydrogen in the aluminum alloy steel cylinder through the vacuum pump system, evacuate to -29inHg, close the valve of the aluminum alloy steel cylinder, and place the aluminum alloy steel cylinder on a high-precision balance with an accuracy of 0.1g and a range of 100Kg, Weigh its weight, denoted as G ₀ ;

2) After that, place the aluminum alloy steel cylinder in a water bath bucket with an ice-water mixture as the medium for 0.5-2 hours, so that the temperature of the aluminum alloy steel cylinder is kept constant at 0 °C;

3) import the obtained high-purity diborane into the aluminum alloy steel cylinder, when the pressure of the aluminum alloy steel cylinder reaches 0, close the valve of the aluminum alloy steel cylinder;

4) Take the aluminum alloy steel cylinder out of the water bath, and use high-purity nitrogen to purge the outer wall of the aluminum alloy steel cylinder to remove moisture;

5) Place the aluminum alloy steel cylinder on a high-precision balance with an accuracy of 0.1g and a range of 100Kg, and weigh its weight, denoted as G;

6) ΔG=GG ₀ , ΔG is the mass of diborane gas whose volume is the cylinder volume (V) at 0°C and whose pressure is 1 atmosphere. In this state, the state of diborane gas is close to the ideal gas, and the 22.4L/mol is the molar volume of diborane gas. Specifically, the molar mass M ₀ of diborane can be calculated. M ₀ =ΔG*22.4/V. The closer M ₀ is to the molecular weight of diborane, 27.67, it indicates that the prepared diborane The higher the alkane purity.

The diborane obtained in the above example was tested, and the aluminum alloy steel cylinder with a volume of 50 L was selected. According to the above-mentioned operation, the volume was the cylinder volume (50 L) at 0°C, and the pressure was 60.7 g of the mass of the diborane gas of 1 atmosphere. , the specific calculated molar mass of diborane is 27.19 g/mol.

According to the experience in the experimental process, the molar mass of diborane measured by this method is in the range of 26.90-27.67g/mol, and the diborane products can meet the needs of the electronics industry.

The yields of the diborane synthesis methods of Examples 2-4 were tested, and the results are shown in Table 1.

The yield of the diborane synthesis method of table 1 embodiment 2-4

Experiment number yield Example 2 76.7% Example 3 75.8% Example 4 76.2%

It can be seen from Table 1 that the yield of the industrial diborane synthesis method of Example 2-4 reaches more than 75%, which can meet the requirements of industrial production.

Claims (10)

1. a synthetic method of high-purity electronic grade diborane, is characterized in that, comprises the following steps: 1) dry reaction of alkali metal borohydride and boron trifluoride under solvent-free conditions to prepare crude diborane gas; the alkali metal borohydride at least includes potassium borohydride; 2) using potassium borohydride to purify crude diborane gas at 20-40 ° C to obtain the first treatment gas; Purify the first treated gas with sodium hydroxide at 15-30°C to obtain the second treated gas; The second treated gas is subjected to adsorption treatment at -40～-20°C using 13X molecular sieve to obtain the third treated gas; The third treatment gas is subjected to gas-solid separation at a temperature lower than the freezing point of diborane to obtain solid diborane. 2 . The method for synthesizing high-purity electronic grade diborane as claimed in claim 1 , wherein the temperature below the freezing point of diborane is -90 to -186° C. 3 . 3. the synthetic method of high-purity electronic grade diborane as claimed in claim 1, is characterized in that, described alkali metal borohydride comprises potassium borohydride and sodium borohydride, and the quality of sodium borohydride is not higher than borohydride 50% of potassium mass. 4. The method for synthesizing high-purity electronic grade diborane as claimed in claim 1 or 3, characterized in that, on a molar basis, the alkali metal borohydride is in excess of 50-100% relative to boron trifluoride. 5 . The method for synthesizing high-purity electronic grade diborane as claimed in claim 1 , wherein the temperature of the dry reaction is 0-20° C., and the reaction time is 4-12 h. 6 . 6. the synthetic method of high-purity electronic grade diborane as described in any one of claim 1-3,5, it is characterized in that, described dry process reaction is alkali metal borohydride solid under tumbling state, and The mixed gas of boron trifluoride and hydrogen is mixed and reacted; the volume of hydrogen is 10-20% of the volume of boron trifluoride. 7. a synthetic device of high-purity electronic grade diborane as described in any one of claim 1-6, is characterized in that, comprises: Diborane synthesizer for synthesizing crude diborane gas; with crude diborane gas outlet; Potassium borohydride chemical reaction purifier has a first raw material gas inlet and a first raw material gas outlet; the potassium borohydride chemical reaction purifier is filled with potassium borohydride for purifying the gas entering from the first raw material gas inlet crude diborane gas, and the first processing gas is produced from the first raw material gas outlet; The sodium hydroxide chemical reaction purifier has a second feed gas inlet and a second feed gas outlet; the sodium hydroxide chemical reaction purifier is filled with sodium hydroxide for purifying the gas entering from the second feed gas inlet the first treatment gas, and the second treatment gas is produced from the second raw material gas outlet; The 13X molecular sieve adsorption purifier has a third feed gas inlet and a third feed gas outlet; the 13X molecular sieve adsorption purifier is filled with 13X molecular sieves for purifying the second treatment gas entered from the third feed gas inlet, and producing a third process gas from the third raw material gas outlet; The ultra-low temperature gas-solid separator has an inlet pipeline and a gas outlet pipeline; the third process gas enters the ultra-low temperature gas-solid separator through the inlet pipeline, the diborane is solidified into a solid state, and the impurity gas is pumped from the gas outlet pipeline Vacuum device extraction; A vacuum purification device, including a vacuum pumping device and a vacuum replacement gas filling device, used for vacuum purification of the synthesis device; Between the crude diborane gas outlet and the first feed gas inlet, between the first feed gas outlet and the second feed gas inlet, between the second feed gas outlet and the third feed gas inlet, and between the third feed gas outlet and the Between the inlet pipelines of the ultra-low temperature gas-solid separator, as well as between the gas outlet pipeline and the vacuuming device, all are connected by connecting pipelines; the crude diborane gas is purified by potassium borohydride, sodium hydroxide purification, 13X molecular sieve in turn. After adsorption purification and ultra-low temperature gas-solid separation, solid diborane is obtained in the ultra-low temperature gas-solid separator. 8. The synthesis device of high-purity electronic grade diborane as claimed in claim 7, wherein the vacuum displacement gas filling device comprises a vacuum displacement gas storage tank, a diborane synthesizer, a potassium borohydride chemical reaction purifier , the connection pipeline between the sodium hydroxide chemical reaction purifier, the 13X molecular sieve adsorption purifier, and the ultra-low temperature gas-solid separator is connected with the vacuum replacement gas storage tank, so that the vacuum replacement gas is introduced into the connection pipeline, Auxiliary vacuum device for deep vacuum purification. 9. the synthetic device of high-purity electronic grade diborane as claimed in claim 7 or 8, is characterized in that, the inlet pipeline and the gas outlet pipeline of described ultra-low temperature gas-solid separator all comprise straight section and strengthen heat exchange Spiral segment. 10. The synthetic device of high-purity electronic grade diborane as claimed in claim 7 or 8, wherein the potassium borohydride chemical reaction purifier, the sodium hydroxide chemical reaction purifier and the 13X molecular sieve adsorption purifier are all columns The tubular purifier includes an arrayed tube bundle and a casing for filling the purifying agent, the arrayed tube bundle is fixed in the casing, and the feed gas is purified after flowing through the purifying agent, and the purifying agent is potassium borohydride, sodium hydroxide , 13X molecular sieve.

Images