WO2024087340A1

WO2024087340A1 - Silicon-based precursor purification method and purification system

Info

Publication number: WO2024087340A1
Application number: PCT/CN2022/138262
Authority: WO
Inventors: 刘颖; 裴凯; 赵毅; 孙良礼; 李晓婷
Original assignee: 大连科利德光电子材料有限公司
Priority date: 2022-10-27
Filing date: 2022-12-11
Publication date: 2024-05-02
Also published as: KR20240060518A; CN115591272A; CN115591272B

Abstract

A silicon-based precursor purification method and purification system, relating to the field of electronic precursor purification. The method comprises the following steps: (S.1) dispersing an adsorbent in an ionic liquid to obtain adsorption slurry; (S.2) dissolving an industrial-grade silicon-based precursor in the adsorption slurry, so that the industrial-grade silicon-based precursor is in contact with the adsorbent, and metal ion impurities in the industrial-grade silicon-based precursor are adsorbed by the adsorbent; and (S.3) after the adsorption is finished, rectifying a crude silicon-based precursor to remove a light component and a heavy component in the silicon-based precursor to obtain an electronic-grade silicon-based precursor. By changing the environment of the silicon-based precursor in the purification process, the silicon-based precursor can be effectively separated from metal ion impurities mixed in the silicon-based precursor, so that adsorption of the metal ion impurities is facilitated; in addition, by using various means in combination, the physical or chemical adsorption effect on the metal ion impurities is improved.

Description

Purification method and purification system of silicon-based precursor

Technical Field

The present invention relates to the field of electronic precursor purification, and in particular to a purification method and a purification system for silicon-based precursors.

Background technique

Advanced integrated circuit manufacturing technology has promoted the continuous development of new materials. With the reduction of integrated circuit line width and the increase of transistor density, the application of advanced precursor materials in ultra-large-scale integrated circuit technology has become more and more the focus of attention. Precursor materials are mainly used in key processes for the manufacture of semiconductor integrated circuit memory and logic chips, such as epitaxy, lithography, chemical vapor deposition (CVD) and atomic layer deposition (ALD). Through chemical reactions and other methods, thin films with specific electrical properties are formed on the surface of integrated circuit silicon wafers, which is crucial to the quality of the film. As an important branch of this, silicon-based precursors have been one of the hot spots in the field of advanced integrated circuit core materials in recent years. Its main uses include: selective epitaxial growth of SiGe films, CVD and ALD growth of silicon nitride, silicon oxide, low dielectric constant and high dielectric constant thin film materials for different purposes, etc.

With the continuous development of semiconductor technology, silicon-based precursor materials have become the key to the development of integrated circuit technology. Technical indicators such as material purity and metal impurity content will directly affect the quality and performance of the chip. In advanced IC preparation processes, the purity of silicon-based precursor materials needs to reach more than 99.99%, and the mass fraction of metal impurities is less than 1x10 ^9. At present, reactive distillation, complex distillation and adsorption distillation are mainly used to separate, refine and purify materials to meet the needs of the development of the semiconductor industry.

The patent with application number 202010256194.7 discloses a purification process of octamethylcyclotetrasiloxane, comprising the steps of: using high-purity argon as a carrier gas, removing metal impurities in octamethylcyclotetrasiloxane by adsorption reaction under a slightly boiling state; performing distillation purification to separate octamethylcyclotetrasiloxane from an adsorbent, and removing organic impurities as well as water and oxygen to obtain an octamethylcyclotetrasiloxane intermediate; further purifying the octamethylcyclotetrasiloxane intermediate by secondary distillation to obtain a pure octamethylcyclotetrasiloxane with a purity greater than 99.999%, which meets the requirements for deposition of the cladding of optical fiber preforms.

Patent No. 202010256194.7 discloses a method for purifying electronic-grade octamethylcyclotetrasiloxane, which is purified by distillation. The process includes the following steps: 1) 99% octamethylcyclotetrasiloxane is put into a distillation tower, and at a pressure of 0.02-0.03MPa, the tower top temperature is 90-96°C, and a small amount of residual hexamethylcyclotrisiloxane (abbreviated as D3) is removed from the top of the tower. 2) The octamethylcyclotetrasiloxane from which D3 has been removed flows out from the bottom of the tower and enters the reactor of the de-heavy distillation tower, and a special high-efficiency metal complex ligand with a material weight ratio of 0.01-0.1% is added, heated to 90-100°C, reacted for 1-10 hours, and vacuum distilled to obtain electronic-grade octamethylcyclotetrasiloxane.

technical problem

The silicon-based precursor materials in the prior art contain a large amount of metal impurities, which makes it difficult to meet the needs of the development of the semiconductor industry. The present invention provides a method for purifying the silicon-based precursor to overcome the above-mentioned defect.

Technical Solutions

To achieve the above-mentioned purpose, the present invention is implemented by the following technical solutions:

In a first aspect, the present invention first provides a method for purifying a silicon-based precursor, comprising the following steps:

(S.1) dispersing the adsorbent in the ionic liquid to obtain an adsorption slurry;

(S.2) dissolving an industrial-grade silicon-based precursor in an adsorption slurry so that the industrial-grade silicon-based precursor contacts the adsorbent, thereby allowing metal ion impurities in the industrial-grade silicon-based precursor to be adsorbed by the adsorbent;

(S.3) After the adsorption is completed, the silicon-based precursor is distilled to remove light components and heavy components in the silicon-based precursor to obtain an electronic grade silicon-based precursor.

In the prior art, silicon-based precursors are usually applied with metal or organometallic catalysts during the synthesis process. For example, in the process of synthesizing chlorosilanes, ternary copper catalysts (Cu, Cu ₂ O, Cu ₂ O) and Cu powder reduced by CuCl are usually used as catalysts. It has also been proven that zinc, aluminum, selenium, antimony, phosphorus, manganese, etc. can also be used as co-catalysts for the copper-catalyzed production of chlorosilanes. At the same time, there are often certain impurities such as iron, calcium and lead in the upstream raw silicon powder. These impurities often participate in the reaction during the synthesis of silicon-based precursors and eventually enter the finished silicon-based precursors. Since these metal impurities are volatile, it is difficult to separate them from silicon-based precursors by conventional distillation methods. These metal impurities will not have a significant impact on conventional organosilicon synthesis and conventional material applications, but for silicon-containing films formed by chemical vapor deposition (CVD) and atomic layer deposition (ALD), these impurities will have a great impact on the electrical properties of silicon-containing films.

In order to remove metal ion impurities in silicon-based precursors, an adsorption step is usually added to the purification process in the prior art. Usually, the adsorption step is to adsorb the metal ion impurities in the silicon-based precursor by an adsorbent in a physical or chemical way. However, since the impurity metal ions need to be in contact with the adsorbent in the adsorption process to achieve adsorption, it is often necessary to increase the adsorption time to improve the adsorption effect on the impurity metal ions. However, there are still some metal ion impurities that are covered by the silicon-based precursor and are difficult to contact with the adsorbent. Therefore, the conventional adsorbent has limited improvement in the adsorption effect on metal ion impurities.

In order to improve the adsorption effect of metal ions in silicon-based precursors, the applicant deliberately changed the environment in which the silicon-based precursors were located during the purification process. It was unexpectedly found that when the silicon-based precursors were dissolved in the adsorption slurry composed of ionic liquids and adsorbents, the adsorption effect of metal ions in the silicon-based precursors was greatly improved. The reasons are: (1) Ionic liquids are liquids composed entirely of ions, and they have good solubility for both organic and inorganic substances. The applicant found that due to the principle of like dissolves like, the solubility of metal ions in ionic liquids is much higher than the solubility of metal ions in silicon-based precursors. (2) Since the present invention purifies the silicon-based precursors under solution conditions, the contact area between the silicon-based precursors and the adsorption slurry is increased. Therefore, the present invention innovatively realizes the extraction of metal ions in the silicon-based precursor through this method, thereby transferring the metal impurities originally dissolved in the silicon-based precursor to the ionic liquid, thereby eliminating the interaction between the silicon-based precursor and the metal impurity ions, which is beneficial to the physical or chemical adsorption of the metal ion impurities by the adsorbent in the adsorption slurry, thereby being able to quickly adsorb the metal ion impurities in the silicon-based precursor and prevent the metal ion impurities from evaporating into the purified silicon-based precursor during the subsequent distillation process of the silicon-based precursor.

In addition, since the ionic liquid is non-volatile, the ionic liquid will not be brought into the ionic liquid after distillation during the distillation process of the silicon-based precursor.

Preferably, the ionic liquid includes one or more combinations of imidazole ionic liquids, quaternary ammonium ionic liquids, quaternary phosphonium ionic liquids, pyrrolidine ionic liquids, and piperidine ionic liquids.

Preferably, the cation of the ionic liquid is N-hexylpyridine, N-butylpyridine, N-octylpyridine, N-butyl-N-methylpyrrolidine, 1-butyl-3-methylimidazole, 1-propyl-3-methylimidazole, 1-ethyl-3-methylimidazole, 1-hexyl-3-methylimidazole, 1-octyl-3-methylimidazole, 1-allyl-3-methylimidazole, 1-butyl-2,3-dimethylimidazole, 1-butyl-3-methylimidazole, tributylmethylphosphine, tributylethylphosphine, Any one of tetrabutylphosphine, tributylhexylphosphine, tributyloctylphosphine, tributyldecylphosphine, tributyldodecylphosphine, tributyltetradecylphosphine, triphenylethylphosphine, triphenylbutylphosphine, triphenylmethylphosphine, triphenylpropylphosphine, triphenylpentylphosphine, triphenylacetonylphosphine, triphenylbenzylphosphine, triphenyl(3-bromopropyl)phosphine, triphenylbromomethylphosphine, triphenylmethoxyphosphine, triphenylethoxycarbonylmethylphosphine, triphenyl(3-bromopropyl)phosphine, triphenylvinylphosphine, and tetraphenylphosphine.

Preferably, the anion of the ionic liquid is ^any one of _BF4- ^, _PF6- ^, _CF3SO3- ^, ₍ _CF3SO2 ₎ _2N- _, _C3F7COO- _, _C4F9SO3 ^, _CF3COO- _, ⁽ _CF3SO2 ₎ _3C- ^, ₍ _C2F5SO2 ₎ ^3C- ^, ₍ _C2F5SO2 ⁾ _2N- _, _and _SbF6- .

Preferably, the ionic liquid includes 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium dicyanamide, 1-ethyl-3-methylimidazolium trifluoroacetate, 1-ethyl-3-methylimidazolium chloroaluminate, 1-ethyl-2,3-dimethylimidazolium tetrafluoroborate, 1-hexyl-3-methylimidazolium bis-trifluoromethanesulfonyl imide, 1-allyl-3-methylimidazolium bis-trifluoromethanesulfonyl imide, 1-ethyl-3-methylimidazolium chloride, 1-ethyl -3-Methylimidazolium bistrifluoromethanesulfonyl imide salt, 1-sulfonic acid butyl-2-methyl-3-hexadecyl imidazolium hydrogen sulfate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium carbonate, 1-ethyl-3-methylimidazolium L-lactate, 1,3-dimethylimidazolium hexafluorophosphate, 1-ethyl-3-methylimidazolium hexafluorophosphate, 1-propyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-hexyl- 3-Methylimidazolium hexafluorophosphate, 1-octyl-3-methylimidazolium hexafluorophosphate, 1-decyl-3-methylimidazolium hexafluorophosphate, 1-tetradecyl-3-methylimidazolium hexafluorophosphate, 1-benzyl-3-methylimidazolium hexafluorophosphate, 1-allyl-3-methylimidazolium hexafluorophosphate, 1-vinyl-3-ethylimidazolium hexafluorophosphate, 1-vinyl-3-butylimidazolium hexafluorophosphate, 1-hexadecyl-2,3-dimethylimidazolium hexafluorophosphate, 1-octyl -2,3-dimethylimidazolium hexafluorophosphate, 1,3-dimethylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-decyl-3-methylimidazolium tetrafluoroborate, 1-benzyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-2,3-dimethylimidazolium tetrafluoroborate, 1-propyl-2,3-dimethylimidazolium tetrafluoroborate, 1-octyl-2,3-dimethylimidazolium tetrafluoroborate, 1-octyl-2,3-dimethylimidazolium tetrafluoroborate.

Preferably, the silicon-based precursor comprises any one of octamethylcyclotetrasiloxane, trimethylsilane, tetramethylsilane, trisilylamine, tetraethoxysilane and diethoxymethylsilane.

Preferably, the adsorbent in step (S.1) comprises any one of activated carbon, porous alumina, silica gel powder, zeolite or molecular sieve.

Preferably, the outer surface of the adsorbent in step (S.1) is also coated with a polymer coating;

The polymer coating comprises a nitrogen-doped matrix layer coated on the outer surface of the adsorbent;

The nitrogen-doped base layer is chemically bonded to the sodium polyacrylate chain segment on the outside.

In a preferred technical solution of the present invention, the outer surface of the adsorbent is also coated with a layer of polymer coating, which includes a nitrogen-doped matrix layer and a sodium polyacrylate segment. The nitrogen-doped matrix layer can coordinate and complex with metal ions due to the doping of nitrogen elements, thereby having a good adsorption effect on metal ions. The sodium polyacrylate segment can react with divalent and higher-valent metal ions to produce a cross-linking reaction, thereby coating and fixing the metal ions to prevent the metal ions from escaping from the adsorption slurry.

Preferably, the preparation method of the adsorbent is as follows:

(1) Coating a layer of resin containing nitrogen atoms on the surface of the adsorbent;

(2) reacting the adsorbent coated with the nitrogen atom resin with acrylic acid chloride, thereby grafting acrylic acid groups on the surface of the adsorbent coated with the nitrogen atom resin, thereby forming a nitrogen-doped matrix layer, i.e., an intermediate, on the adsorbent;

(3) The intermediate is copolymerized with sodium acrylate to obtain an adsorbent coated with a polymer coating.

Preferably, the mass ratio of the intermediate in step (3) to sodium acrylate is 1:(0.5-2).

The applicant of the present invention has found that the mass ratio of the intermediate to sodium acrylate has an important influence on the final adsorption and purification effect. When the amount of sodium acrylate added is too much, sodium polyacrylate will completely cover the adsorbent, thereby reducing the porosity of the final adsorbent and reducing the adsorption effect on metal ions.

Preferably, in step (2), the contact temperature between the industrial-grade silicon-based precursor and the adsorbent is 0-20°C.

The adsorption temperature of silicon-based precursors in the adsorption purification process in the prior art is usually under boiling conditions, but under high temperature conditions, the irregular diffusion movement (i.e., Brownian motion) of metal ions will be accelerated, which is not conducive to the capture of metal ions by the adsorbent. The present invention chooses to adsorb metal ion impurities in the silicon-based precursor under lower temperature conditions, which is conducive to improving the adsorption effect. At the same time, it saves energy consumption in the adsorption process.

In a second aspect, the present invention further provides a purification system for purifying a silicon-based precursor, which at least comprises:

A purification unit, comprising a purification tank for containing materials, a stirring device for stirring the materials inside the purification tank, and a heating device for heating the purification tank;

A distillation unit is arranged at the top of the purification tank, so as to distill the tantalum-silicon-based precursor evaporated in the cavity;

A collecting unit, comprising a collector connected to a pipeline of the distillation unit, so as to collect the silicon-based precursor flowing out of the distillation unit;

The pressure control unit is connected to the collector pipeline and is used to control the internal pressure of the entire purification system.

Preferably, it further comprises a gas supply unit, which comprises a gas tank for introducing inert gas into the interior of the purification tank, and a pressure control valve for controlling the flow rate of the inert gas flow being delivered.

Preferably, the outer casing of the collector is provided with a cold well.

Beneficial Effects

Therefore, the present invention has the following beneficial effects:

(1) The present invention effectively separates the silicon-based precursor from the metal ion impurities mixed therein by changing the environment of the silicon-based precursor during the purification process, thereby facilitating the adsorption of the metal ion impurities;

(2) The present invention improves the physical or chemical adsorption effect of metal ion impurities by combining multiple means;

(3) At the same time, the present invention also saves energy consumption during the adsorption process.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 SEM photo of adsorbent A.

FIG. 2 is a gas phase detection diagram of industrial grade octamethylcyclotetrasiloxane.

FIG3 is a mass spectrum of hexamethylcyclotrisiloxane (D3).

FIG4 is a mass spectrum of octamethylcyclotetrasiloxane (D4).

FIG5 is a mass spectrum of decamethylcyclopentasiloxane (D5).

FIG. 6 is a gas phase detection diagram of electronic grade octamethylcyclotetrasiloxane obtained after purification.

FIG. 7 is a schematic diagram of the structure of a purification system for purifying a silicon-based precursor according to the present invention.

Among them: purification unit 100, purification tank 110, stirring device 120, driving motor 121, transmission rod 122, stirring paddle 123, heating device 130, distillation unit 200, distillation column 210, distillation filler 220, collection unit 300, collector 310, cold well 320, low boiling collector 330, pressure control unit 400, gas supply unit 500, gas tank 510, pressure control valve 520.

Embodiments of the present invention

The present invention is further described below in conjunction with the accompanying drawings and specific embodiments of the specification. Those of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are generally only embodiments of a part of the present invention, rather than all embodiments. Therefore, based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work should fall within the scope of protection of the present invention.

[Preparation of adsorbent coated with polymer coating]

Adsorbent A:

(1) 100 g of porous alumina was dispersed in 100 ml of deionized water, and then 50 ml of 37% formaldehyde aqueous solution and 0.1 g of hexamethylenetetramine were added to the water, mixed evenly, and then 30 g of melamine was added. After stirring evenly, the temperature was raised to 80°C and reacted for 30 minutes, and then filtered and dried to obtain porous alumina coated with melamine formaldehyde resin;

(2) 100 g of porous alumina coated with melamine formaldehyde resin was dispersed in 200 ml of dichloromethane, and then 4.5 g (50 mmol) of acryloyl chloride was added dropwise at 0°C. After reacting for 1 h, the intermediate (A) was obtained by filtration.

(3) In a 500 mL four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a dropping funnel, a certain amount of deionized water and 10% of the intermediate (A) by weight of the total system were added, and then 4.5% of the chain transfer agent sodium bisulfite by weight of the system was added, and the mixture was stirred and dispersed. The mixture was heated to 65°C, and then 15% of the monomer acrylic acid by weight of the system and 0.06% of the initiator ammonium persulfate by weight of the system were added dropwise. After the addition was completed, the mixture was kept warm for 3 h, and the mixture was neutralized with a 30% sodium hydroxide aqueous solution to a pH value of 7 to 7.5. The adsorbent A was filtered, washed, and dried to obtain an electron microscope photograph of the adsorbent A, as shown in FIG1 .

Adsorbent B:

(1) Disperse 100 g of silica gel powder in 200 ml of deionized water, then add 5 g of dopamine to the solution, stir at room temperature for 8 h, filter and dry to obtain silica gel powder coated with polydopamine;

(2) Disperse 100 g of silica gel powder coated with polydopamine in 200 ml of dichloromethane, then add 4.5 g (50 mmol) of acryloyl chloride dropwise at 0 °C, react for 1 h, and filter to obtain the intermediate (B);

(3) In a 500 mL four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a dropping funnel, add a certain amount of deionized water and 10% of the intermediate (B) by weight of the total system, then add 4.5% of the chain transfer agent sodium bisulfite by weight of the system, stir and disperse, heat to 65°C, then dropwise add 15% of the monomer acrylic acid by weight of the system and 0.06% of the initiator ammonium persulfate by weight of the system. After the dropwise addition is completed, keep warm for 3 h, neutralize with 30% sodium hydroxide aqueous solution to a pH value of 7-7.5, filter, wash, and dry to obtain adsorbent B.

Adsorbent C:

(1) Disperse 100 g of porous alumina in 100 ml of deionized water, then add 20 g of polyvinyl alcohol to the water, stir evenly, let stand for 3 hours, filter and dry to obtain porous alumina coated with polyvinyl alcohol;

(2) 100 g of porous alumina coated with polyvinyl alcohol was dispersed in 200 ml of dichloromethane, and then 4.5 g (50 mmol) of acryloyl chloride was added dropwise at 0°C. After reacting for 1 h, the intermediate (C) was obtained by filtration.

(3) In a 500 mL four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a dropping funnel, add a certain amount of deionized water and 10% of the intermediate (C) by weight of the total system, then add 4.5% of the chain transfer agent sodium bisulfite by weight of the system, stir and disperse, heat to 65°C, then dropwise add 15% of the monomer acrylic acid by weight of the system and 0.06% of the initiator ammonium persulfate by weight of the system. After the dropwise addition is completed, keep warm for 3 h, neutralize with 30% sodium hydroxide aqueous solution to a pH value of 7-7.5, filter, wash, and dry to obtain adsorbent C.

Adsorbent D:

(3) In a 500 mL four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a dropping funnel, add a certain amount of deionized water and 10% of the intermediate (A) by weight of the total system, then add 4.5% of the chain transfer agent sodium bisulfite by weight of the system, stir and disperse, heat to 65°C, then dropwise add 25% of the monomer acrylic acid by weight of the system and 0.06% of the initiator ammonium persulfate by weight of the system. After the dropwise addition is completed, keep warm for 3 h, neutralize with 30% sodium hydroxide aqueous solution to a pH value of 7-7.5, filter, wash, and dry to obtain adsorbent D.

【Purification system】

As shown in FIG. 2 , the present invention further discloses a purification system for purifying a silicon-based precursor, the system comprising at least the following steps:

The purification unit 100 includes a purification tank 110 for containing materials, wherein the materials include industrial-grade silicon-based precursors, adsorbents, and ionic liquids, etc. Therefore, the silicon-based precursor can be in contact with the adsorbent dispersed in the ionic liquid medium inside the purification tank 110, so that the metal ion impurities in the silicon-based precursor can be dissolved in the ionic liquid and adsorbed and purified by the adsorbent.

In order to improve the contact effect between the silicon-based precursor and the adsorbent, the present invention deliberately arranges a stirring device 120 on the purification tank 110 for stirring the material inside the purification tank 110. The stirring device 120 includes a driving motor 121 arranged on the top of the purification tank 110 and a transmission rod 122 connected thereto and extending into the purification tank 110. The transmission rod 122 is provided with a stirring paddle 123 for stirring the material. When the driving motor 121 is started, the driving motor 121 can drive the transmission rod 122 to rotate, so that the stirring paddle 123 shears the material, thereby increasing the stirring effect on the material.

In order to facilitate the temperature control of the material inside the purification tank 110 , the present invention further provides a heating device 130 on the periphery of the purification tank 110 , thereby facilitating the heating of the material inside the purification tank 110 .

A group of distillation units 200 in communication with the purification tank 110 is disposed on the top thereof. The distillation units 200 include a distillation column 210 , and the interior of the distillation column 210 is filled with a distillation filler 220 .

The collecting unit 300 includes a collector 310 connected to the pipeline of the distillation unit 200. A cold well 320 is provided on the outside of the collector 310. A cooling medium such as liquid nitrogen can be poured into the cold well 320. When the silicon-based precursor comes out of the distillation column 210, the cold well 320 is used to receive and collect the silicon-based precursor flowing out. The collecting unit 300 also includes a low-boiling collector 330 for receiving the low-boiling substances obtained by distillation.

The pressure control unit 400 is connected to the collector 310 through a pipeline and is used to control the internal pressure of the entire purification system.

The gas supply unit 500 includes a gas tank 510 for supplying inert gas into the purification tank 110 , and a pressure control valve 520 for controlling the flow rate of the inert gas flow being supplied.

【Purification of Octamethylcyclotetrasiloxane (D4)】

Example 1

The purification method of octamethylcyclotetrasiloxane comprises the following steps:

(S.1) 10 kg of silica gel powder and 100 kg of ionic liquid (1-ethyl-3-methylimidazolium tetrafluoroborate) are added to the purification tank 110, and the stirring device 120 is started to completely disperse the silica gel powder in the ionic liquid to obtain an adsorption slurry. The gas supply unit 500 is started to introduce nitrogen into the adsorption slurry at a rate of 10 L/h, thereby removing the air inside the purification tank;

(S.2) The internal temperature of the purification tank 110 is controlled at 20° C., and then 50 kg of industrial-grade octamethylcyclotetrasiloxane (D4) is added into the purification tank 110 and stirred so that the octamethylcyclotetrasiloxane is dissolved in the adsorption slurry and contacts with the adsorbent. After stirring and adsorbing for 3 hours, the metal ion impurities in the industrial-grade octamethylcyclotetrasiloxane are adsorbed by the adsorbent;

(S.3) After the adsorption is completed, the gas supply of the gas supply unit 500 is stopped, and then the internal pressure of the purification tank 110 is controlled at 0.05 MPa through the pressure control unit 400, and the temperature is raised and heated by a program, and the fraction with a receiving temperature of 98°C at the top of the distillation unit 200 is collected to remove the light components in the industrial-grade octamethylcyclotetrasiloxane. Then, the internal pressure of the purification tank 110 is controlled at 0.02 MPa, and the fraction with a receiving temperature of 113°C at the top of the distillation unit 200 is collected to obtain electronic-grade octamethylcyclotetrasiloxane, and high-boiling-point substances flow out from the bottom of the purification tank 110.

In order to compare the purity changes of octamethylcyclotetrasiloxane obtained before and after purification, GC-MS detection was performed on industrial-grade octamethylcyclotetrasiloxane and electronic-grade octamethylcyclotetrasiloxane obtained after purification.

Among them, Figure 3 is the gas phase detection spectrum of industrial grade octamethylcyclotetrasiloxane, wherein the peak at 6.209min is hexamethylcyclotrisiloxane (D3), and its mass spectrum is shown in Figure 4; the peak at 7.550min is octamethylcyclotetrasiloxane (D4), and its mass spectrum is shown in Figure 5; the peak at 10.401min is decamethylcyclopentasiloxane (D5), and its mass spectrum is shown in Figure 6; the remaining peaks are high boiling point substances.

The gas phase detection spectrum of the electronic grade octamethylcyclotetrasiloxane obtained after purification is shown in FIG7 . It can be seen that after purification, it only contains octamethylcyclotetrasiloxane (D4).

Example 2

(S.1) 10 kg of adsorbent A and 100 kg of ionic liquid (1-ethyl-3-methylimidazolium tetrafluoroborate) are added to the purification tank 110, and the stirring device 120 is started to completely disperse the silica gel powder in the ionic liquid to obtain an adsorption slurry. The gas supply unit 500 is started to pass nitrogen into the adsorption slurry at a rate of 10 L/h, thereby removing the air inside the purification tank;

(S.3) After the adsorption is completed, the gas supply of the gas supply unit 500 is stopped, and then the internal pressure of the purification tank 110 is controlled at 0.05 MPa through the pressure control unit 400, and the temperature is raised by programming to collect the fraction with a receiving temperature of 98°C at the top of the distillation unit 200 to remove the light components (D3) in the industrial-grade octamethylcyclotetrasiloxane. Then, the internal pressure of the purification tank 110 is controlled at 0.02 MPa, and the fraction with a receiving temperature of 113°C at the top of the distillation unit 200 is collected to obtain electronic-grade octamethylcyclotetrasiloxane, and high-boiling-point substances flow out from the bottom of the purification tank 110.

Example 3

(S.1) 10 kg of adsorbent B and 100 kg of ionic liquid (1-ethyl-3-methylimidazolium tetrafluoroborate) are added to the purification tank 110, and the stirring device 120 is started to completely disperse the silica gel powder in the ionic liquid to obtain an adsorption slurry. The gas supply unit 500 is started to pass nitrogen into the adsorption slurry at a rate of 10 L/h to remove the air inside the purification tank;

Example 4

(S.1) 20 kg of adsorbent B and 100 kg of ionic liquid (1-ethyl-3-methylimidazolium tetrafluoroborate) are added to the purification tank 110, and the stirring device 120 is started to completely disperse the silica gel powder in the ionic liquid to obtain an adsorption slurry. The gas supply unit 500 is started to introduce nitrogen into the adsorption slurry at a rate of 10 L/h to remove the air inside the purification tank;

Comparative Example 1

(S.1) 10 kg of porous alumina coated with melamine formaldehyde resin and 100 kg of ionic liquid (1-ethyl-3-methylimidazolium tetrafluoroborate) are put into the purification tank 110, and the stirring device 120 is started to completely disperse the silica gel powder in the ionic liquid to obtain an adsorption slurry. The gas supply unit 500 is started to pass nitrogen into the adsorption slurry at a rate of 10 L/h, thereby removing the air inside the purification tank;

Comparative Example 2

(S.1) 10 kg of adsorbent C and 100 kg of ionic liquid (1-ethyl-3-methylimidazolium tetrafluoroborate) are added to the purification tank 110, and the stirring device 120 is started to completely disperse the silica gel powder in the ionic liquid to obtain an adsorption slurry. The gas supply unit 500 is started to introduce nitrogen into the adsorption slurry at a rate of 10 L/h, thereby removing the air inside the purification tank;

Comparative Example 3

(S.1) 10 kg of adsorbent D and 100 kg of ionic liquid (1-ethyl-3-methylimidazolium tetrafluoroborate) are added to the purification tank 110, and the stirring device 120 is started to completely disperse the silica gel powder in the ionic liquid to obtain an adsorption slurry. The gas supply unit 500 is started to introduce nitrogen into the adsorption slurry at a rate of 10 L/h to remove the air inside the purification tank;

【Purification of Tetraethoxysilane】

Example 5

The method for purifying tetraethoxysilane comprises the following steps:

(S.1) 10 kg of adsorbent A and 100 kg of ionic liquid (1,3-dimethylimidazolium tetrafluoroborate) are added to the purification tank 110, and the stirring device 120 is started to completely disperse the silica gel powder in the ionic liquid to obtain an adsorption slurry. The gas supply unit 500 is started to introduce nitrogen into the adsorption slurry at a rate of 10 L/h to remove the air inside the purification tank;

(S.2) The internal temperature of the purification tank 110 is controlled at 10° C., and then 50 kg of industrial-grade tetraethoxysilane is added into the purification tank 110 and stirred so that the tetraethoxysilane is dissolved in the adsorption slurry and contacts with the adsorbent. After stirring and adsorbing for 5 hours, the metal ion impurities in the industrial-grade tetraethoxysilane are adsorbed by the adsorbent;

(S.3) After the adsorption is completed, the gas supply of the gas supply unit 500 is stopped, and then the internal pressure of the purification tank 110 is controlled at 0.05 MPa through the pressure control unit 400, and the temperature is raised by programming to collect the fraction with a receiving temperature of 93~95°C at the top of the distillation unit 200 to remove the light components in the industrial-grade octamethylcyclotetrasiloxane. Then, the internal pressure of the purification tank 110 is controlled at 0.02 MPa, and the fraction with a receiving temperature of 108~110°C at the top of the distillation unit 200 is collected to obtain electronic-grade tetraethoxysilane, and high-boiling-point substances flow out from the bottom of the purification tank 110.

【Purification of Tetramethylsilane】

Example 6

The method for purifying tetramethylsilane comprises the following steps:

(S.2) The temperature inside the purification tank 110 is controlled at 0°C, and then 50 kg of industrial-grade tetramethylsilane is added into the purification tank 110, and stirred so that the tetramethylsilane is dissolved in the adsorption slurry and contacts the adsorbent. After stirring and adsorbing for 5 hours, the metal ion impurities in the industrial-grade tetramethylsilane are adsorbed by the adsorbent;

(S.3) After the adsorption is completed, the gas supply of the gas supply unit 500 is stopped, and then the internal pressure of the purification tank 110 is controlled at one atmosphere through the pressure control unit 400, and the temperature is programmed to be increased and the fraction at 26-28°C is received at the top of the distillation unit 200 to obtain electronic grade tetramethylsilane, and high-boiling point substances flow out from the bottom of the purification tank 110.

【Purification of trimethylsilane】

Example 7

The method for purifying trimethylsilane comprises the following steps:

(S.2) The temperature inside the purification tank 110 is lowered to -10°C, and then 50 kg of industrial-grade trimethylsilane is added into the purification tank 110, and the trimethylsilane is stirred to dissolve in the adsorption slurry and contact with the adsorbent A. After stirring and adsorbing for 5 hours, the metal ion impurities in the industrial-grade trimethylsilane are adsorbed by the adsorbent A;

(S.3) After the adsorption is completed, the gas supply of the gas supply unit 500 is stopped, and then the internal pressure of the purification tank 110 is controlled at one atmosphere through the pressure control unit 400, and the temperature is programmed to be increased and the fraction at 6-7°C received at the top of the distillation unit 200 is collected to obtain electronic grade trimethylsilane, and high-boiling point substances flow out from the bottom of the purification tank 110.

【Performance test results】

The metal ion impurity contents in the purified octamethylcyclotetrasiloxane in Examples 1 to 4 and Comparative Examples 1 to 3, the tetraethoxysilane obtained in Example 5, the tetramethylsilane prepared in Example 6, and the trimethylsilane prepared in Example 7 are shown in Table 1 below.

Table 1

It can be seen from the data in the above table that the preparation method of the present invention can achieve a good purification effect on the silicon-based precursor and can effectively remove metal ion impurities and high and low boiling point substances in the silicon-based precursor.

By comparing Example 1 with Examples 1 to 4, it is found that after the polymer coating is coated on the outside of the adsorbent, the adsorption effect of metal ion impurities inside the silicon-based precursor can be effectively improved.

By comparing Example 2 with Comparative Examples 1 and 2, it is found that after the nitrogen-doped matrix layer is coated on the outside of the adsorbent, the adsorption effect of metal ion impurities inside the silicon-based precursor can be improved to a certain extent, but after the sodium polyacrylate segment is chemically bonded to the outside of the nitrogen-doped matrix layer, the adsorption effect of metal ion impurities can be greatly improved. This shows that a synergistic effect can be formed between the nitrogen-doped matrix layer and the sodium polyacrylate segment.

By comparing Example 2 with Comparative Example 3, it was found that the adsorbent D in Comparative Example 3 had an excessive amount of sodium acrylate added during the synthesis process, which closed the pores of the adsorbent, resulting in a decrease in porosity, thereby affecting the adsorption effect on metal ion impurities.

Claims

The method for purifying a silicon-based precursor comprises the following steps:

(S.1) dispersing the adsorbent in the ionic liquid to obtain an adsorption slurry;

(S.2) dissolving an industrial-grade silicon-based precursor in an adsorption slurry so that the industrial-grade silicon-based precursor contacts the adsorbent, thereby allowing metal ion impurities in the industrial-grade silicon-based precursor to be adsorbed by the adsorbent;

(S.3) After the adsorption is completed, the crude silicon-based precursor is distilled to remove light components and heavy components in the silicon-based precursor to obtain an electronic grade silicon-based precursor.
The method for purifying a silicon-based precursor according to claim 1, characterized in that:

The silicon-based precursor comprises any one of octamethylcyclotetrasiloxane, trimethylsilane, tetramethylsilane, trisilylamine, tetraethoxysilane and diethoxymethylsilane.
The method for purifying a silicon-based precursor according to claim 1, characterized in that:

The adsorbent in the step (S.1) includes any one of activated carbon, porous alumina, silica gel powder, zeolite or molecular sieve.
The method for purifying a silicon-based precursor according to claim 1 or 3, characterized in that:

The outer surface of the adsorbent in the step (S.1) is also coated with a polymer coating;

The polymer coating comprises a nitrogen-doped matrix layer coated on the outer surface of the adsorbent;

The nitrogen-doped base layer is chemically bonded to the sodium polyacrylate chain segment on the outside.
The method for purifying a silicon-based precursor according to claim 4, characterized in that:

The preparation method of the adsorbent is as follows:

(1) Coating a layer of resin containing nitrogen atoms on the surface of the adsorbent;

(2) reacting the adsorbent coated with the nitrogen atom resin with acryloyl chloride, thereby grafting acrylic acid groups on the surface of the adsorbent coated with the nitrogen atom resin, thereby forming a nitrogen-doped matrix layer, i.e., an intermediate, on the adsorbent;

(3) The intermediate is copolymerized with sodium acrylate to obtain an adsorbent coated with a polymer coating.
The method for purifying a silicon-based precursor according to claim 4, characterized in that:

The mass ratio of the intermediate in step (3) to sodium acrylate is less than 1:2.
The method for purifying a silicon-based precursor according to claim 1, characterized in that:

In the step (2), the contact temperature between the industrial-grade silicon-based precursor and the adsorbent is 0-20°C.
A purification system for purifying a silicon-based precursor, characterized in that it at least comprises:

A purification unit (100), comprising a purification tank (110) for containing materials, a stirring device (120) for stirring the materials inside the purification tank (110), and a heating device (130) for heating the purification tank (110);

A distillation unit (200) is arranged on the top of the purification tank (110) to distill the silicon-based precursor evaporated in the cavity (110);

A collecting unit (300), comprising a collector (310) connected to a pipeline of the distillation unit (200), so as to collect the silicon-based precursor flowing out of the distillation unit (200);

The pressure control unit (400) is connected to the collector (310) pipeline and is used to control the internal pressure of the entire purification system.
The purification system for purifying a silicon-based precursor according to claim 8, characterized in that:

The system also includes a gas supply unit (500), wherein the gas supply unit (500) includes a gas tank (510) for introducing an inert gas into the interior of the purification tank (110), and a pressure control valve (520) for controlling the flow rate of the inert gas flow being delivered.
The purification system for purifying a silicon-based precursor according to claim 8, characterized in that:

The collector (310) is provided with a cold well (320) on its outer casing.