JP4795153B2 - Method for treating borazine compounds - Google Patents

Description

  The present invention relates to a method for treating a borazine compound. Specifically, the present invention relates to a method for treating a borazine compound using an organic solvent.

  As the performance of information equipment increases, LSI design rules become finer year by year. In the manufacture of LSIs with fine design rules, the materials that make up LSIs must also have high performance and function on fine LSIs.

  For example, regarding materials used for interlayer insulating films in LSIs, a high dielectric constant causes signal delay. In a fine LSI, the influence of this signal delay is particularly great. For this reason, development of a new low dielectric constant material that can be used as an interlayer insulating film has been desired. Further, in order to be used as an interlayer insulating film, it is necessary not only to have a low dielectric constant but also to be excellent in characteristics such as moisture resistance, heat resistance and mechanical strength.

  As a response to such a demand, a borazine compound having a borazine ring skeleton in the molecule has been proposed (see, for example, Patent Document 1). Since the borazine compound has a low molecular polarizability, the formed film has a low dielectric constant. In addition, the formed film is excellent in heat resistance.

  Conventionally, borazine compounds have only been synthesized in a small amount at a laboratory level using a flask or the like as a reaction vessel. On the other hand, in view of the usefulness of the borazine compound, it is clear that it is necessary to synthesize in a large amount in a larger scaled-up reaction vessel in view of mass production in the future.

Here, considering the case of synthesizing a large amount of a borazine compound in a large-scale plant such as a factory, an apparatus that can come into contact with the borazine compound (for example, a pipe connecting a reaction apparatus and a purification apparatus, or a borazine compound from a purification apparatus) It is expected that the borazine compound adheres to a pipe for taking out the gas; hereinafter, also simply referred to as “borazine compound device”). If the synthesis of the borazine compound is continued while leaving such a deposit, the impurities may be mixed into the borazine compound that is the product, leading to a decrease in quality such as a decrease in purity. In the semiconductor field such as an interlayer insulating film in an LSI, the presence of impurities and fine particles in the material adversely affects the characteristics of the semiconductor element and the like, and therefore extremely high quality is required. Therefore, when synthesizing a large amount of a borazine compound in a large-scale plant or the like, it is considered that it is necessary to periodically stop the operation of the plant, open the apparatus, and wash the adhered borazine compound.
JP 2000-340689 A

As a method for cleaning the borazine compound adhering to the borazine compound apparatus, for example, a method of cleaning with water or alcohol (for example, methanol) can be considered.
However, when a borazine compound is washed using a compound having an OH group such as water or alcohol, hydrogen is generated by a reaction between the compound and the borazine compound. The hydrogen generated in this manner is not preferable in the chemical industry because it is extremely dangerous because it may react explosively with oxygen in the air in the presence of fire. On the other hand, in order to avoid the explosion of hydrogen generated in this way, it is necessary to separately install a device for collecting hydrogen, which may increase the manufacturing cost.

  Accordingly, an object of the present invention is to provide means for safely washing a borazine compound adhering to a borazine compound apparatus without generating hydrogen.

  The present inventors have intensively studied to solve the above problems. And in the process, it discovered that a borazine compound showed reducibility. Specifically, it has been found that a borazine compound in which a hydrogen atom is bonded to at least one of boron atoms forming a borazine skeleton exhibits reducibility. And based on the said knowledge, it discovers that the said borazine compound can be wash-processed by using the organic solvent which can carry out the oxidative cleavage of the BH bond in the borazine compound which has the above structures, and completes this invention. It came to.

  That is, the present invention has the following chemical formula 1:

In the formula, each R ₁ is independently a hydrogen atom or an alkyl group, each R ₂ is independently a hydrogen atom, an alkyl group or an alkoxy group, and at least one R ₂ is a hydrogen atom.
A borazine compound treatment method comprising a contacting step of contacting a borazine compound represented by the formula (1) with an organic solvent capable of oxidative cleavage of the BH bond in the borazine compound.

  According to the present invention, the borazine compound adhering to the borazine compound apparatus can be safely washed without accompanying the generation of hydrogen.

  The present invention has the following chemical formula 1:

A borazine compound treatment method comprising a contacting step of contacting a borazine compound represented by the formula (1) with an organic solvent capable of oxidative cleavage of the BH bond in the borazine compound.

The present invention has been completed by finding that the borazine compound represented by the chemical formula 1 exhibits reducibility, but the mechanism by which the borazine compound represented by the chemical formula 1 exhibits reducibility is completely described. Is not clear. However, the following mechanism has been estimated. That is, as will be described later, in the borazine compound represented by Chemical Formula 1, at least one of R ₂ bonded to boron is a hydrogen atom, and the hydrogen atom in this B—H bond is hydride (H ⁻ ). Therefore, it is considered that it exhibits reducibility. In addition, the said mechanism is based on estimation to the last, Comprising: Even if the reducibility of a borazine compound is exhibited by the other mechanism, the technical scope of this invention is not influenced at all.

In Chemical Formula 1, R ₁ is a hydrogen atom or an alkyl group. Such an alkyl group is not particularly limited and may be linear, branched or cyclic, but the alkyl group preferably has 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms. The number is more preferably 1-2. Specific examples of the alkyl group include, for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, s-butyl group, t-butyl group, pentyl group, isopentyl group, neopentyl group, hexyl group, Examples include heptyl group, octyl group, nonyl group, decyl group, cyclopropyl group, cyclopentyl group, and cyclohexyl group.
Alkyl groups other than these may be used. Among these, from the viewpoint of easy synthesis and handling, R ₁ is particularly preferably a methyl group or an ethyl group, and most preferably a methyl group. R ₁ may be the same or different from each other, but from the viewpoint of easy synthesis and handling, all R ₁ are preferably the same.

In Chemical Formula 1, R ₂ is a hydrogen atom, an alkyl group or an alkoxy group, and at least one R ₂ is a hydrogen atom. Since the form of such an alkyl group and the number of carbon atoms of the alkoxy group are the same as those of R ₁ described above, the description thereof is omitted here. Specific examples of the alkoxy group include, for example, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, an s-butoxy group, a t-butoxy group, a pentoxy group, an isopentoxy group, a neopentoxy group, and a hexoxy group. , Heptoxy group, octoxy group, nonyloxy group, decyloxy group and the like. Alkoxy groups other than these may be used. Among them, from the viewpoint of efficiency of reaction during processing, it is preferred that R ₂ is a hydrogen atom. R ₂ may be the same or different from each other, but from the viewpoint of easy synthesis and handling, all R ₂ are the same (that is, all R ₂ are hydrogen atoms). It is preferable.

  The present invention is characterized in that the borazine compound is treated by bringing a predetermined organic solvent into contact with the borazine compound. Here, specific examples of borazine compounds that can be used include, for example, borazine, N, N ′, N ″ -trimethylborazine, N, N ′, N ″ -triethylborazine, N, N ′, N ″ -tri ( n-propyl) borazine, N, N ′, N ″ -tri (isopropyl) borazine, N, N ′, N ″ -tri (n-butyl) borazine, N, N ′, N ″ -tri (s-butyl) Borazine, N, N ′, N ″ -tri (isobutyl) borazine, N, N ′, N ″ -tri (t-butyl) borazine, N, N ′, N ″ -tri (1-methylbutyl) borazine, N, N ′, N ″ -tri (2-methylbutyl) borazine, N, N ′, N ″ -tri (neopentyl) borazine, N, N ′, N ″ -tri (1,2-dimethylpropyl) borazine, N, N ', N "-tri (1-ethylpropyl) borazine, , N ′, N ″ -tri (n-hexyl) borazine, N, N ′, N ″ -tricyclohexylborazine, N, N′-dimethyl-N ″ -ethylborazine, N, N′-diethyl-N ″- Examples include methyl borazine, N, N′-dimethyl-N ″ -propyl borazine and the like. In the present invention, only one borazine compound may be treated alone, or may be treated in the form of a mixture of two or more. Usually, only one type is treated alone.

  The borazine compound treatment method of the present invention is used, for example, for the purpose of washing the borazine compound adhering to the borazine compound apparatus during the synthesis of the borazine compound.

There is no restriction | limiting in particular about the method of synthesize | combining a borazine compound, A conventionally well-known knowledge can be referred suitably. An example of a method for preparing an N-alkylborazine in which R ₂ is all hydrogen atoms among the borazine compounds represented by Chemical Formula 1 above is ABH ₄ (A is a lithium atom, a sodium atom or a potassium atom. ) And an alkali boron hydride represented by (RNH ₃ ) _n X (R is a hydrogen atom or an alkyl group, X is a sulfuric acid group or a halogen atom, and n is 1 or 2) An example is a method in which an amine salt is reacted in a solvent.

In alkali borohydride (ABH ₄ ), A is a lithium atom, a sodium atom or a potassium atom. Examples of alkali borohydrides include sodium borohydride and lithium borohydride.

In the amine salt ((RNH ₃ ) _n X), R is a hydrogen atom or an alkyl group, and X is a sulfate group or a halogen atom. And when X is a sulfate group, n is 2, and when X is a halogen atom, n is 1. When n is 2, R may be the same or different from each other. In consideration of the yield of the synthesis reaction and the ease of handling, R is preferably the same alkyl group. R, since corresponding to R ₁ in Formula 1, specific form of the R in the amine salt is the same as R ₁ in Formula 1 can be selected depending on the structure of the desired borazine compound. Therefore, detailed description is omitted here. Examples of amine salts include, for example, ammonium chloride (NH ₄ Cl), monomethylamine hydrochloride (CH ₃ NH ₃ Cl), monoethylamine hydrochloride (CH ₃ CH ₂ NH ₃ Cl), monomethylamine hydrobromide (CH ₃ NH ₃ Br), monoethylamine hydrofluorate (CH ₃ CH ₂ NH ₃ F), ammonium sulfate ((NH ₄ ) ₂ SO ₄ ), monomethylamine sulfate ((CH ₃ NH ₃ ) ₂ SO ₄ ) And the like. However, it is not limited to these.

  What is necessary is just to select the alkali borohydride and amine salt to be used according to the structure of the borazine compound to synthesize | combine. For example, when producing N-methylborazine in which a methyl group is bonded to the nitrogen atom constituting the borazine ring, an amine salt such as monomethylamine hydrochloride, where R is a methyl group, is used as the amine salt. Good.

  The mixing ratio of alkali borohydride and amine salt is not particularly limited, but when the amount of amine salt used is 1 mol, the amount of alkali borohydride used is preferably 1 to 1.5 mol. .

  The solvent for synthesis is not particularly limited, and examples thereof include tetrahydrofuran, monoethylene glycol dimethyl ether (monoglyme), diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl ether (triglyme), and tetraethylene glycol dimethyl ether (tetraglyme). .

  The reaction conditions between the alkali borohydride and the amine salt are not particularly limited. Reaction temperature becomes like this. Preferably it is 20-250 degreeC, More preferably, it is 50-240 degreeC, More preferably, it is 100-220 degreeC. When the reaction is performed within the above range, the amount of hydrogen generation can be easily controlled. The reaction temperature can be measured using a temperature sensor such as a K thermocouple.

On the other hand, a borazine compound in which an alkyl group or an alkoxy group is bonded to one or two boron atoms forming a borazine skeleton is an alkene with respect to the B—H bond of N-alkylborazine in which R ₂ is all hydrogen atoms. Can be synthesized by a technique such as a hydroboration reaction in which is inserted, or a substitution reaction with an alkyl metal compound or alcohol.

  The synthesized borazine compound can be purified as necessary. As a purification method of the borazine compound, for example, distillation purification is used.

  The size and type of the distillation purification apparatus may be determined according to the environment and scale. For example, if a large amount of borazine compound is to be processed, an industrial scale distillation column can be used. If a small amount of borazine compound is to be treated, distillation purification using a distillation tube can be used. For example, as a specific example of a distillation apparatus for treating a small amount of a borazine compound, a distillation apparatus in which a Liebig cooling pipe is attached to a three-necked flask with a Claisen type connecting pipe can be used. However, the technical scope of the present invention is not limited to the embodiment using such a distillation apparatus.

  The temperature at the time of distillation purification is not particularly limited, and can be appropriately set according to the type of borazine compound synthesized. For example, the temperature is usually about 100 to 150 ° C.

  Furthermore, additional treatments such as filtration treatment may be performed on a daily basis to improve the purity of the obtained borazine compound.

  As described above, the treatment method of the present invention is used for the purpose of treating a borazine compound adhering to a borazine compound apparatus, for example. By the treatment of the adhering borazine compound, it is possible to suppress the occurrence of the problem that the apparatus for borazine compound is cleaned cleanly and the purity of the borazine compound newly synthesized thereafter is lowered. Hereinafter, the treatment method of the present invention will be described in detail by taking as an example a form for treating the borazine compound adhering to the apparatus for borazine compounds, but the technical scope of the present invention is determined based on the description of the claims. Should be done and should not be limited to only the following forms.

  “Apparatus for borazine compounds” means all apparatuses that can come into contact with borazine compounds in all industrial series of processes such as synthesis and storage of borazine compounds. For example, in the method for synthesizing a borazine compound exemplified in the above description, the borazine compound can come into contact with a synthesizer or a distillation purification apparatus. Moreover, when a filtration process is performed, a borazine compound can also contact a filtration apparatus. Further, the borazine compound can also come into contact with the piping connecting the devices so that the borazine compound can flow between these devices. Therefore, these synthesis devices, distillation purification devices, filtration devices, pipes, etc. are all included in the concept of “device for borazine compounds”.

  However, the form of the apparatus for borazine compounds is not limited to these. Usually, industrially synthesized borazine compounds are filled in borazine compound storage containers and stored in a sealed state. If necessary, the holazine compound is transported in a state of being filled in the container, taken out from the container at the transport destination, and used for the purpose of forming an interlayer insulating film for a semiconductor. Here, similarly in the used borazine compound storage container, problems may occur in the synthesis apparatus and its piping. That is, since it is almost impossible to completely remove the borazine compound filled in the container from the container at the time of use, a certain proportion of the borazine compound has to remain in the container. The borazine compound remaining in the container is hydrolyzed by the NB bond by contact with moisture in the air, and decomposed products (for example, methylamine and boric acid) are generated as impurities. Therefore, even if the purity of the originally filled borazine compound is extremely high, it is inevitable that impurities are mixed during the collection of the used borazine compound storage container. Even if the used borazine compound storage container in which impurities are mixed during the recovery is washed with water or alcohol, hydrogen is generated in the same manner, which may cause an explosion.

  On the other hand, when such a used borazine compound storage container is washed by the method of the present invention, generation of hydrogen as described above is prevented and the borazine compound adhering to the container is safely treated. Is possible. Therefore, the “borazine compound storage container” can also be included in the concept of “the apparatus for borazine compound” in the present invention.

  Next, the “contact process” which is a characteristic configuration of the present invention will be described in detail.

  In the wood process, the borazine compound represented by the above chemical formula 1 is brought into contact with an organic solvent capable of oxidative cleavage of the BH bond in the borazine compound. Thereby, a borazine compound is processed.

  In this step, the organic solvent brought into contact with the borazine compound has a function of oxidative cleavage of the B—H bond in the borazine compound as described above. As long as it has such a function, the specific example of the organic solvent used in this step is not particularly limited. Examples of organic solvents that can be used in this step include, for example, ketones such as acetone, methyl ethyl ketone, cyclopentanone, and cyclohexanone; aldehydes such as formaldehyde, acetaldehyde, and propionaldehyde; esters such as ethyl acetate; Examples thereof include carboxylic acids such as acetic acid and propionic acid; amides such as formamide and acetamide; nitriles such as acetonitrile, propionitrile and isobutyronitrile. However, organic solvents other than these may be used for the treatment of the borazine compound. Only one kind of these organic solvents may be used alone for the treatment, or two or more kinds thereof may be mixed and used for the treatment.

  There is no restriction | limiting in particular also about the specific form of a process of a borazine compound, A conventionally well-known knowledge can be referred suitably. For example, for the treatment of a borazine compound adhering to a borazine compound apparatus, conventionally known knowledge relating to the treatment of a compound adhering to an apparatus used for compound synthesis or storage can be referred to as appropriate. For example, when the borazine compound attached to the synthesizer at the end of the synthesis of the borazine compound is treated, the borazine compound attached to the synthesizer is contacted with the organic solvent as described above to treat the borazine compound. do it. Although the specific operation of contacting the organic solvent is not particularly limited, for example, washing with a hose or a spray is exemplified. In addition, wiping is also effective for cleaning parts that are difficult to wash. Such a cleaning operation may be performed manually, or may be performed using a semi-whitened or automated apparatus. On the other hand, in consideration of washing of the borazine compound storage container, the above-described over-washing and wiping are effective, but a method of leaving the container filled with the above-described organic solvent and allowing to stand may be used. . Moreover, the washing | cleaning in this process can be accelerated | stimulated by applying a vibration to the apparatus wash | cleaned as needed. Examples of the vibration device used at this time include an ultrasonic wave application device, but are not limited thereto.

There is no particular limitation on the number of contact times of the organic solvent in this step, and it may be one or more times. From the viewpoint of achieving sufficient treatment of the borazine compound, the number of times of treatment using the organic solvent Is preferably 2 to 50 times, more preferably 3 to 10 times.
If the number of treatments is too large, there is a possibility that a cleaning effect corresponding to the increase in the number of treatments cannot be obtained.

  Although the temperature conditions in particular when this process is performed are not restrict | limited, Preferably it is -80-100 degreeC, More preferably, it is 0-50 degreeC, More preferably, it is 0-30 degreeC. A borazine compound can be efficiently processed by performing a contact process under the temperature conditions in such a range.

  The amount of the organic solvent used in this step is not particularly limited, but is preferably 1.0 to 10 mol, more preferably 1.0 mol, relative to 1 mol of the B—H bond in the borazine compound to be treated. It is -5.0 mol, More preferably, it is 1.0-2.0 mol. When the amount of the organic solvent used is within such a range, the borazine compound can be efficiently treated without wasting the organic solvent.

  In the treatment method of the present invention, after completion of the above-described contact step, water is brought into contact with the treated product to hydrolyze the borazine compound still contained in the treated product (hereinafter simply referred to as “hydrolysis step”). It is preferable to carry out. In this process, hydrogen can be generated by hydrolysis of the borazine compound. However, since most of the borazine compound is oxidized and converted into other compounds in the above-described contact process, the hydrolysis of the borazine compound The amount of hydrogen generated is negligible. Therefore, there is no risk of explosion due to hydrogen generated in the hydrolysis step.

  In the hydrolysis step, the specific form when water is brought into contact with the treated product is not particularly limited, and the same form as described in the column of the contact step described above can be adopted. For example, the amount of water to be contacted with the treated product, the contact time, and the like can be appropriately determined according to the amount of the borazine compound that appears to remain in the treated product.

In addition, if possible, it is preferable that a contact process and the hydrolysis process as needed are performed in the clean room which has a predetermined | prescribed cleanness (cleanliness class). This embodiment is particularly suitable when the borazine compound apparatus is a borazine compound storage container. Specifically, this step is preferably performed in a clean room that is cleaner than class 10000. In this specification, “cleanness (cleanliness class)” is a value according to FED-STD-209D (US Federal Standard, 1988). In this standard, “cleanness (cleanliness class)” is defined as the number of particles having a particle size of 0.5 μm or more per 1 ft ³ . Therefore, for example, “clean room cleaner than class 10000” means a clean room in which the number of particles having a particle diameter of 0.5 μm or more in the atmosphere is 10,000 / ft ³ or less. In addition, it is more preferable that this process is performed in a clean room cleaner than class 1000, and it is more preferable that it is performed in a clean room cleaner than class 100.

  Hereinafter, embodiments of the present invention will be described in more detail using examples and comparative examples. However, the technical scope of the present invention is not limited to the following embodiments.

<Example>
In the reactor, 5.0 g of N, N ′, N ″ -trimethylborazine (TMB), which is a borazine compound, and 10.0 g of acetone, which is an organic solvent capable of oxidative cleavage of the B—H bond in TMB, are obtained for 1 hour. After mixing and treating the borazine compound, 10.0 g of water was added to the reaction system to complete the reaction.

  Thereafter, the reaction solution was analyzed by GC-MS to confirm the disappearance of TMB and the production of isopropyl alcohol that could be produced by the reduction of acetone. Moreover, generation | occurrence | production of hydrogen during reaction was not confirmed by the gas detection pipe | tube (north side type | mold, model 137U). The measurement conditions for GC-MS are as follows.

[Measurement conditions for GC-MS]
Apparatus: POLARIS Q manufactured by Thermo Electron Co., Ltd.
Column: TC-WAX manufactured by GL Sciences Inc.
Length: 30m, inner diameter: 0.25mm, film thickness: 0.25μm
Carrier gas: Nitrogen Carrier gas flow rate: 1.0 mL / min Sample injection temperature: 250 ° C.
Column temperature: 40 ° C. (5 minutes) → heated to 230 ° C. at a rate of temperature increase of 15 ° C./min Retention time: 2.18 minutes (isopropyl alcohol)

<Comparative example>
The borazine compound N, N ′, N ″ -trimethylborazine (TMB) 5.0 g and 10.0 g of methanol were mixed in the reactor for 1 hour to treat the borazine compound. 0 g of water was added to complete the reaction.

  Thereafter, the reaction solution was analyzed by GC-MS to confirm disappearance of TMB. Moreover, generation | occurrence | production of hydrogen during reaction was confirmed by the gas detection pipe | tube (north side type | mold, type 137U).

  From the results shown in the above Examples and Comparative Examples, according to the treatment method of the present invention, a borazine compound can be safely treated without generating hydrogen by treating the borazine compound with a predetermined organic solvent. It is shown that.

Claims (7)

The following chemical formula 1:

In the formula, each R ₁ is independently a hydrogen atom or an alkyl group, each R ₂ is independently a hydrogen atom, an alkyl group or an alkoxy group, and at least one R ₂ is a hydrogen atom.
It possesses a borazine compound represented in an organic solvent for oxidative cleavage of the B-H bonds in the borazine compound, a contact step of contacting,
A method for cleaning a borazine compound , wherein the organic solvent is one or more selected from the group consisting of ketones, aldehydes, carboxylic acids, amides, and nitriles . The processing method according to claim ₁ , wherein all of R ₁ are alkyl groups.   The processing method according to claim 2, wherein the alkyl group is a methyl group. The processing method according to claim 1, wherein the organic solvent is acetone. The usage-amount of the said organic solvent used in the said contact process is 1.0-10 mol with respect to 1 mol of BH bonds in the said borazine compound, The any one of Claims 1-4 . Processing method. It said contacting step is carried out at a temperature of -80 to 100 ° C., the processing method according to any one of claims 1-5. The treatment according to any one of claims 1 to 6 , further comprising a hydrolysis step of hydrolyzing a borazine compound contained in the treated product by bringing water into contact with the treated product after completion of the contacting step. Method.