JP4904047B2 - Method for producing borazine compound and reaction vessel for borazine compound synthesis - Google Patents

Description

  The present invention relates to a borazine compound. The borazine compound is used, for example, to form an interlayer insulating film for semiconductor, a barrier metal layer, and an etch stopper layer.

  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.

Various compounds have been proposed as borazine compounds so far. For example, an alkyl borazine compound in which a boron site is substituted with an alkyl group has very excellent characteristics as a low dielectric constant material (see, for example, Patent Document 2).
JP 2000-340689 A JP 2003-119289 A

  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 borazine compounds, it is expected that it will be necessary to synthesize a large amount in a larger scaled-up reaction vessel with future mass production in mind.

  Here, the upper limit of the temperature condition when synthesizing the borazine compound is usually about 200 to 250 ° C. On the other hand, for example, N, N ′, N ″ -trimethylborazine, which is one of borazine compounds, has an ignition point of 192 ° C. Therefore, when the borazine compound flows out of the reaction vessel and contacts oxygen during the reaction, Depending on the situation, the borazine compound that has flowed out may ignite, and the production of the borazine compound must be stopped.

  Here, when manufacturing a borazine compound in large quantities, the case where the reaction container made from a metal used for the synthesis | combination of a general compound is employ | adopted as a reaction container is considered. Such a reaction vessel normally breathes in an atmosphere of about atmospheric pressure, and the gas in the reaction vessel and the outside air are moved back and forth between the inside and outside of the vessel to some extent. Therefore, if an attempt is made to synthesize a borazine compound using a reaction vessel generally used for synthesis of the compound as it is, the synthesized borazine compound may flow out of the reaction vessel and ignite.

  In view of the above, an object of the present invention is to provide means for suppressing the outflow of the borazine compound during the reaction out of the reaction vessel and preventing the borazine compound from being ignited during the synthesis of the borazine compound.

  The present inventors have conducted intensive research to solve the above problems. As a result, by adopting a container having a pressure pressure higher than a predetermined value as a reaction container for borazine compound synthesis, outflow of the borazine compound during the reaction to the outside of the reaction container, and the accompanying borazine compound during the synthesis. It has been found that ignition can be effectively prevented, and the present invention has been completed.

  That is, this invention is a manufacturing method of a borazine compound which has the step which synthesize | combines a borazine compound in the reaction container which has a pressure-resistant pressure of 0.1 Mpa or more.

  Moreover, this invention is a reaction container for borazine compound synthesis | combination which has a proof pressure of 0.1 Mpa or more.

  According to the present invention, when synthesizing a borazine compound, the outflow of the borazine compound during the reaction to the outside of the reaction vessel is suppressed, and the ignition of the borazine compound during the synthesis can be prevented.

  The first of the present invention is a method for producing a borazine compound, comprising a step of synthesizing the borazine compound in a reaction vessel having a pressure resistance of 0.1 MPa or more.

  In the production method of the present invention, a borazine compound is synthesized in a reaction vessel having a predetermined pressure resistance. Thereby, when synthesizing the borazine compound, the outflow of the borazine compound during the reaction to the outside of the reaction vessel is suppressed, and the ignition of the borazine compound during the synthesis can be prevented. Therefore, according to the present invention, a very safe method for producing a borazine compound can be provided. In addition, according to the present invention, the inflow of outside air into the reaction vessel being synthesized can be suppressed, but the outside air also contains impurities other than oxygen. Therefore, according to the production method of the present invention, a high-purity borazine compound can be produced.

  Then, the manufacturing method of this invention is demonstrated in detail.

  The specific form of the synthesis method of the borazine compound synthesized in the production method of the present invention is not particularly limited, and conventionally known knowledge can be appropriately referred to.

As an example, the borazine compound has an alkali borohydride represented by MBH ₄ (M is a lithium atom, a sodium atom or a potassium atom) and (RNH ₃ ) as shown in the following chemical reaction formula 1. reacting with an amine salt represented by _n X (R is a hydrogen atom or an alkyl group, X is a halogen atom when n = 1, and a sulfate group when n = 2) in a solvent. (See, for example, Howard Steinberg, ORGANOBORON CHEMISTRY Volume 2, Interscience Publishers, p. 221-222).

  Hereinafter, although such a synthesis method will be described in detail as an example, the technical scope of the present invention is not limited to only a form in which a borazine compound is synthesized by such a synthesis method.

In the alkali borohydride (MBH ₄ ), M 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. When X is a halogen atom, n is 1, and when X is a sulfate group, n is 2. The halogen atom is preferably a chlorine atom. When n = 2, R may be the same or different. In consideration of the yield of the synthesis reaction and ease of handling, R is preferably the same alkyl group. The alkyl group may be linear, branched or cyclic. Although carbon number which an alkyl group has is not specifically limited, Preferably it is 1-8, More preferably, it is 1-4, More preferably, it is one. Specific examples of the alkyl group include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group, hexyl group, heptyl group. Octyl group, nonyl group, decyl group, cyclopropyl group, cyclopentyl group, cyclohexyl group, and the like. Alkyl groups other than these may be used. Examples of amine salts include 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 hydrofluoride (CH ₃ CH ₂ NH ₃ F), ammonium sulfate ((NH ₄ ) ₂ SO ₄ ), monomethylamine sulfate ((CH ₃ NH ₃ ) ₂ SO ₄ ) Can be mentioned.

  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 N, N ′, N ″ -trimethylborazine in which a methyl group is bonded to three nitrogen atoms constituting the borazine ring is produced, R is methyl as the amine salt, such as monomethylamine hydrochloride. An amine salt that is a group may be used.

  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. .

  Furthermore, a hydrogen atom bonded to a boron atom (derived from an alkali borohydride) can be further substituted with an alkyl group. As such a technique, for example, the borazine compound obtained by the above chemical reaction formula 1 may be reacted with a Grignard reagent.

  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. Furthermore, it is preferable to age at a temperature of about 200 to 250 ° C. even after the reaction. 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.

  The alkyl borazine compound is prepared by using a halogenated borazine compound such as B, B ′, B ″ -trichloro-N, N′-N ″ -trialkylborazine as a starting material, and using the Grignard reagent as a chlorine. It can also be synthesized by substituting an atom with an alkyl group (see DT HOWORTH and LF HOHNSTEDT, J. Am. Chem. Soc., 82, 3860 (1960)).

  The borazine compound synthesized by the above synthesis method is represented by the following chemical formula 1.

In the formula, each R ₁ and each R ₂ may be the same or different, and are a hydrogen atom or an alkyl group. Examples of borazine compounds include borazine, N, N ′, N ″ -trimethylborazine, N, N ′, N ″ -triethylborazine, N, N ′, N ″ -tri (n-propyl) borazine, N, N ', N ″ -tri (iso-propyl) borazine, N, N ′, N ″ -tri (n-butyl) borazine, N, N ′, N ″ -tri (sec-butyl) borazine, N, N ′, N ″ -tri (iso-butyl) borazine, N, N ′, N ″ -tri (tert-butyl) borazine, N, N ′, N ″ -tri (1-methylbutyl) borazine, N, N ′, N ″ -Tri (2-methylbutyl) borazine, N, N ', N "-tri (neo-pentyl) borazine, N, N', N" -tri (1,2-dimethylpropyl) borazine, N, N ', N "-Tri (1-ethylpropyl) borazine, N, N ', N" -tri (n-he Syl) borazine, N, N ′, N ″ -tricyclohexylborazine, N, N′-dimethyl-N ″ -ethylborazine, N, N′-diethyl-N ″ -methylborazine, N, N′-dimethyl-N "-Propylborazine, B, B ', B" -trimethylborazine, B, B', B "-triethylborazine, B, B ', B" -tri (n-propyl) borazine, B, B', B " -Tri (isopropyl) borazine, B, B ', B "-tri (n-butyl) borazine, B, B', B" -tri (isobutyl) borazine, B, B ', B "-tri (tert-butyl) ) Borazine, B, B ′, B ″ -tri (1-methylbutyl) borazine, B, B ′, B ″ -tri (2-methylbutyl) borazine, B, B ′, B ″ -tri (neopentyl) borazine, B , B ′, B ″ -tri (1,2-dimethylpropyl) bo Razine, B, B ′, B ″ -tri (1-ethylpropyl) borazine, B, B ′, B ″ -tri (n-hexyl) borazine, B, B ′, B ″ -tricyclohexylborazine, B, B Examples include '-dimethyl-B "-ethylborazine, B, B'-diethyl-B" -methylborazine, and B, B'-dimethyl-B "-propylborazine. In view of such stability and handleability, the borazine compound is preferably N-alkylborazine.

  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.

  The production method of the present invention is characterized in that the borazine compound is synthesized in a reaction vessel having a pressure resistance of 0.1 MPa or more.

  “Pressure pressure” means that when a sealed container is placed in an atmosphere having a certain initial pressure (0.1 MPa in the present application) and the pressure of the atmosphere is increased, It means the pressure obtained by subtracting the initial pressure (0.1 MPa) from the atmospheric pressure at the time when it can flow into the interior. That is, when the pressure of the atmosphere exceeds “pressure resistance + initial pressure (0.1 MPa)”, the atmosphere can flow into the container. Therefore, in the present invention, when the borazine compound is synthesized under an atmosphere where the initial pressure is 0.1 MPa (approximately equal to atmospheric pressure), the atmosphere flows even if the atmospheric pressure becomes 0.2 MPa or more. The borazine compound is synthesized in a reaction vessel that does not.

  The second aspect of the present invention also provides a synthesis container that can be used in the first synthesis method of the present invention. That is, the second of the present invention is a borazine compound synthesis reaction vessel having a pressure resistance of 0.1 MPa or more.

  As described above, the pressure resistance of the synthesis reaction vessel of the present invention is 0.1 MPa or more, preferably 0.2 MPa or more, and more preferably 0.3 MPa or more. If the pressure resistance of the reaction vessel is less than 0.1 MPa, the borazine compound may flow out of the reaction vessel during the synthesis of the borazine compound and may ignite due to contact with oxygen.

  Here, from the viewpoint of preventing the atmosphere from flowing into the reaction vessel, the upper limit value of the pressure resistance of the reaction vessel is not particularly limited. However, from the viewpoint of ease of handling such as the weight of the reaction vessel, the pressure resistance of the reaction vessel is preferably 2.0 MPa or less, more preferably 0.5 MPa or less. However, forms outside these ranges can also be employed.

  There are no particular restrictions on the specific form such as the size and material of the reaction vessel. In order to synthesize a small amount of borazine compound at the laboratory level, a small reaction vessel may be used. In addition, a large reaction vessel may be used to synthesize a large amount of borazine compounds at an industrial level. Further, the pressure resistance of the reaction vessel can be controlled by appropriately selecting the type of material constituting the reaction vessel and appropriately adjusting the thickness of the vessel wall. In addition, it is preferable that the reaction container is compatible with the definition of the second type pressure container based on the Industrial Safety and Health Law.

  As the material of the reaction vessel, for example, metal materials such as hastelloys and stainless steels can be employed. Among these, from the viewpoint of high pressure resistance, the reaction vessel is preferably composed of Hastelloys.

  The borazine compound is not particularly limited, but can be used for forming an interlayer insulating film for a semiconductor, a barrier metal layer, an etch stopper layer, and the like. In that case, the borazine compound may be used as it is, or a compound obtained by modifying the borazine compound may be used. A polymer obtained by polymerizing a borazine compound or a borazine compound derivative may be used as a raw material for an interlayer insulating film for a semiconductor, a barrier metal layer, or an etch stopper layer. Hereinafter, the “borazine compound”, “derivative of borazine compound”, and “polymer derived therefrom” are collectively referred to as “borazine ring-containing compound”.

  As a method for forming an interlayer insulating film for semiconductor, a barrier metal layer, or an etch stopper layer using a borazine ring-containing compound, for example, a solution-like or slurry-like composition containing a borazine ring-containing compound is prepared. A technique of forming a coating film by applying to a desired site can be used.

  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>
First, a Hastelloy C reaction vessel was prepared as a reaction vessel for borazine compound synthesis. When the pressure resistance of the prepared reaction vessel was measured, it was 1.0 MPa. At this time, the pressure resistance of the reaction vessel is measured by installing a leak valve in the reaction vessel, filling the reaction vessel with nitrogen gas at 23 ° C., and supplying nitrogen gas from the reaction vessel through the leak valve. The filling pressure at the start of the leak was measured using a pressure gauge, and calculated by subtracting the atmospheric pressure from the measured value.

  The reaction vessel prepared above was set up with a cooling tube, charged with methylamine hydrochloride (33.5 g) as a dehydrated amine salt and triglyme (98.6 g) as a solvent while purging with nitrogen, and the reaction system The temperature was raised to 100 ° C.

  On the other hand, sodium borohydride (21.0 g), which is an alkali borohydride, was prepared and added to separately prepared triglyme (88.7 g) to prepare a slurry.

  The sodium borohydride slurry prepared above was slowly added to the reaction vessel heated to 100 ° C. over 1 hour.

  After the addition of the slurry, the reaction system was heated to 200 ° C. over 2 hours and further aged at 200 ° C. for 2 hours to synthesize N, N ′, N ″ -trimethylborazine.

Incidentally, in the above synthesis, N from the reaction vessel during the synthesis by installing Kitagawa type detecting tube into the reaction vessel, N ', N "- was monitored for leakage trimethyl borazine, a borazine compound in the synthesis No leakage was detected.

<Comparative example>
First, a Hastelloy C reaction vessel was prepared as a reaction vessel for borazine compound synthesis. The pressure resistance of the prepared reaction vessel was measured by the same method as in the above example and found to be 0.05 MPa.

Then, N by the same method as the above example, N ', N "-. Was synthesized trimethyl borazine However, when raising the temperature of the reaction system to 100 ° C., N from the reaction vessel by Kitagawa type detecting tube , N ′, N ″ -trimethylborazine was detected and the reaction was stopped by cooling the reaction vessel. The reaction was stopped at 100 ° C. when the borazine compound leaked out of the reaction vessel at 100 ° C., and the temperature was about 200 ° C., which is a general condition for reaction and aging. This is because the borazine compound naturally flows out of the container under conditions and is expected to ignite.

  Therefore, from the results shown in the above Examples and Comparative Examples, by synthesizing a borazine compound in a reaction vessel having a pressure pressure higher than a predetermined value, ignition of the borazine compound during synthesis is prevented, and borazine is very safely used. It is shown that the compound can be synthesized.

Claims (2)

Having a step of synthesizing a borazine compound by reacting an amine salt ((RNH ₃ ) _n X) and an alkali borohydride (MBH ₄ ) in a metal reaction vessel having a pressure pressure of 0.1 MPa or more, A method for producing a borazine compound;
R is a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 8 carbon atoms, X is a sulfate group or a halogen atom, and when X is a halogen atom, n is 1. When X is a sulfate group, n is 2. When n = 2, Rs are the same or different.   The production method according to claim 1, wherein the pressure resistance of the reaction vessel is 0.2 to 2.0 MPa.