JP2008266196A - Method for producing borazine compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means for producing a high-purity borazine compound having low metal element contents as impurities and no problem even if used as an element film of semiconductor apparatus. <P>SOLUTION: In the method for producing a borazine compound, having a stage for reacting a metal borohydride with an amine salt represented by formula: (RNH<SB>3</SB>)<SB>n</SB>X (wherein R is a hydrogen atom, an alkyl group or a cycloalkyl group; X is a sulfate group or a halogen atom; n is 1 or 2) in a solvent to synthesize the borazine compound, at least one of the metal borohydride having the content of each metal element (excluding the content of the constituent element of the metal borohydride) of ≤100 mass ppm and the amine salt having the content of each metal element of ≤100 mass ppm is used in the reaction or at least one of the metal borohydride having the total content (excluding the content of the constituent element of the metal borohydride) of aluminum, zinc, chromium, cobalt, iron, copper, lead, nickel and magnesium of ≤20 mass ppm and the amine salt having the total content of aluminum, zinc, chromium, cobalt, iron, copper, lead, nickel and magnesium of ≤100 mass ppm is used in the reaction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing 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 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 Documents 1 and 2). Since a borazine compound having a borazine ring skeleton has a low molecular polarizability, the formed film has a low dielectric constant. In addition, the formed film is excellent in heat resistance.

As a method for producing a borazine compound, a method is known in which a metal borohydride salt (for example, sodium borohydride) and an amine salt (for example, methylamine hydrochloride) are reacted in a solvent (for example, patents). Reference 3).
JP 2000-340689 A JP 2003-119289 A JP 2006-327964 A

  By the way, when the borazine compound obtained by the above reaction is analyzed, the borazine compound contains a metal element as an impurity, and the purity of the borazine compound is lowered. Such a decrease in the purity of the borazine compound has a problem that it ultimately causes a decrease in performance of a semiconductor interlayer insulating film manufactured using the borazine compound.

  SUMMARY OF THE INVENTION An object of the present invention is to provide means for producing a high-purity borazine compound that has a low content of metal elements as impurities and can be used for an element film of a semiconductor device.

  In view of the above problems, the present inventors have conducted intensive research. As a result, by controlling the content of the metal element as an impurity in the synthetic raw material of the borazine compound to a low value, the content of the metal element as an impurity is small, and there is no problem even if it is used for an element film of a semiconductor device. It has been found that pure borazine compounds can be produced.

  Specifically, it has been found that the above-mentioned problems can be solved when the content of each metal element contained in the synthesis raw material of the borazine compound is a predetermined value or less, and the present invention has been completed. It was.

That is, the first of the present invention is a borohydride metal salt, (RNH ₃ ) _n X (R is a hydrogen atom, an alkyl group, or a cycloalkyl group, X is a sulfate group or a halogen atom, and n is A method for producing a borazine compound comprising reacting an amine salt represented by 1 or 2 in a solvent to synthesize a borazine compound, wherein each metal element (however, a metal borohydride salt) The borohydride metal salt with a content of 100 mass ppm or less, or the amine salt with a content of each metal element of 100 mass ppm or less. A method for producing a borazine compound, characterized by being used in the above.

  In addition, the present inventors also include the total content of specific metal elements (specifically, aluminum, zinc, chromium, cobalt, iron, copper, lead, nickel, and manganese) as impurities in the borazine compound synthesis raw material. The inventors have found that the above problem can be similarly solved even when the value is not more than a predetermined value, and have completed the present invention.

That is, the second of the present invention is a borohydride metal salt and (RNH ₃ ) _n X (R is a hydrogen atom, an alkyl group, or a cycloalkyl group, X is a sulfate group or a halogen atom, and n is A borazine compound comprising a step of reacting an amine salt represented by 1 or 2 in a solvent to synthesize a borazine compound, the aluminum, zinc, chromium, cobalt, iron, copper , Borohydride metal salt having a total content of lead, nickel, and manganese (excluding the content of constituent elements of borohydride metal salt) of 20 ppm by mass or less, or aluminum, zinc, chromium, cobalt, A borazine compound characterized in that at least one of the amine salts having a total content of iron, copper, lead, nickel, and manganese of 100 mass ppm or less is used in the reaction. It is a manufacturing method of a thing.

  According to the present invention, it is possible to produce a high-purity borazine compound having a low content of metal elements as impurities and having no problem even when used for an element film of a semiconductor device.

In the first aspect of the present invention, a metal borohydride and (RNH ₃ ) _n X (R is a hydrogen atom, an alkyl group, or a cycloalkyl group, X is a sulfate group or a halogen atom, and n is 1 or 2 is a process for producing a borazine compound by reacting in a solvent with an amine salt represented by 2), each metal element (however, the constitution of the borohydride metal salt) In the reaction, at least one of the borohydride metal salt having a content of 100 ppm by mass or less or the amine salt having a content of each metal element of 100 ppm by mass or less is used. It is the manufacturing method of the borazine compound characterized by the above-mentioned.

The second aspect of the present invention is a metal borohydride, (RNH ₃ ) _n X (R is a hydrogen atom, an alkyl group, or a cycloalkyl group, X is a sulfate group or a halogen atom, and n is A borazine compound comprising a step of reacting an amine salt represented by 1 or 2 in a solvent to synthesize a borazine compound, the aluminum, zinc, chromium, cobalt, iron, copper , Borohydride metal salt having a total content of lead, nickel, and manganese (excluding the content of constituent elements of borohydride metal salt) of 20 ppm by mass or less, or aluminum, zinc, chromium, cobalt, A borazine compound characterized in that at least one of the amine salts having a total content of iron, copper, lead, nickel, and manganese of 100 ppm by mass or less is used for the reaction. It is a manufacturing method.

  Hereinafter, the production method of the present invention will be described in detail.

In the synthesis step of the borazine compound, a metal borohydride and (RNH ₃ ) _n X (R is a hydrogen atom, an alkyl group, or a cycloalkyl group, X is a sulfate group or a halogen atom, and n is 1 or 2) is reacted in a solvent to synthesize a borazine compound.

  The metal element constituting the borohydride metal salt is not particularly limited. Examples of the metal element include, for example, lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium, radium, zirconium, hafnium, aluminum, lanthanum, scandium, europium, iron, nickel, chromium, and the like. Preferably, it is a monovalent metal element (lithium, sodium, potassium, rubidium, cesium) or a divalent metal element (beryllium, magnesium, calcium, strontium, barium, radium). More preferred is sodium, lithium or calcium from the viewpoint of availability. In other words, the metal borohydride is preferably sodium borohydride, lithium borohydride or calcium borohydride.

On the other hand, in the amine salt ((RNH ₃ ) _n X), R is a hydrogen atom, an alkyl group, or a cycloalkyl group, and X is a sulfate group or a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom) It is. And when X is a sulfate group, n is 2, and when X is a halogen atom, n is 1. 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 the ease of handling, R is preferably the same alkyl group or the same cycloalkyl group. The alkyl group may be linear or branched. 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, for example, 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, A heptyl group, an octyl group, a nonyl group, a decyl group, etc. are mentioned. Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. Alkyl groups and cycloalkyl groups other than these may be used. Thus, 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 ) And the like.

  The kind of borohydride metal salt and amine salt as a synthesis raw material can be selected according to the structure of the borazine compound to be synthesized. 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 the borohydride metal salt and the amine salt is not particularly limited, but when the use amount of the amine salt is 1 mol, the use amount of the borohydride metal salt is 1 to 1.5 mol. Is preferred.

  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 borohydride metal salt and the amine salt are not particularly limited. The reaction temperature is preferably room temperature to 250 ° C, more preferably 50 to 240 ° C, and still more preferably 100 to 220 ° C. 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 borazine compound is a compound represented by the following formula.

  In the formula, R is as described for the amine salt in the description of the synthetic raw material, and thus the description thereof is omitted here. 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 (isopropyl) borazine, N, N ′, N ″ -tri (n-butyl) borazine, N, N ′, N ″ -tri (sec-butyl) borazine, N, N ′, N ″ -Tri (isobutyl) 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 (neopentyl) borazine, N, N', N" -tri (1,2-dimethylpropyl) borazine, N, N ', N "-tri (1- Ethylpropyl) borazine, N, N ′, N ″ -tri ( -Hexyl) borazine, N, N ', N "-tricyclohexylborazine, N, N'-dimethyl-N" -ethylborazine, N, N'-diethyl-N "-methylborazine, N, N'-dimethyl- N "-propylborazine and the like can be mentioned. In consideration of the stability of the produced borazine compound such as water resistance, the borazine compound is preferably N, N ′, N ″ -trialkylborazine.

  The present invention is characterized in that a metal borohydride metal salt or amine salt having a low metal element content is used as a raw material for synthesizing a borazine compound.

  Specifically, in the first aspect of the present invention, the content of each metal element (excluding the content of the constituent element of the borohydride metal salt) is 100 ppm by mass or less. Alternatively, at least one amine salt having a content of each metal element of 100 mass ppm or less is used for the reaction. In addition, although the borohydride metal salt includes the metal element as described above as a constituent element, the “metal element content” is a value as an impurity, and thus the metal element as a constituent element of the borohydride metal salt. Naturally, this amount is not included in the “metal element content”. In addition, as the value of “metal element content”, a value obtained by the method described in Examples described later is adopted.

  In the first aspect of the present invention, it is preferable to use a borohydride metal salt or an amine salt in which each metal element content is 80 mass ppm or less, and each metal element content is 50 mass ppm or less. More preferably, a metal borohydride salt or an amine salt is used. In another preferred embodiment, the content of each metal element in both the borohydride metal salt and amine salt used in the reaction is preferably 100 ppm by mass or less, more preferably 80 ppm by mass or less. More preferably, it is 50 mass ppm or less. According to such a form, the content of the metal element contained as an impurity in the produced borazine compound can be further reduced, and a borazine compound with higher purity can be produced.

  In the second aspect of the present invention, the total content of aluminum, zinc, chromium, cobalt, iron, copper, lead, nickel, and manganese (excluding the content of constituent elements of the metal borohydride) At least one of a borohydride metal salt of 20 ppm by mass or less or an amine salt having a total content of aluminum, zinc, chromium, cobalt, iron, copper, lead, nickel, and manganese of 100 ppm by mass or less is used for the reaction. In the second aspect of the present invention, as in the first aspect of the present invention, the amount of the metal element as a constituent element of the borohydride metal salt is not included in the “total content”. Moreover, the value obtained by the method described in the examples described later is also adopted as the value of the “total content” of the metal elements described above.

  In the second aspect of the present invention, the total content of the above-described nine metal elements in the hydrogen boron metal salt is preferably 15 ppm by mass or less, more preferably 10 ppm by mass or less. Moreover, the total content of the above-described nine metal elements in the amine salt is preferably 80 ppm by mass or less, and more preferably 60 ppm by mass or less. In another preferred form, the total content of the nine metal elements described above is within the above-described preferred range in both the borohydride metal salt and the amine salt. According to such a form, the content of the metal element contained as an impurity in the produced borazine compound can be further reduced, and a borazine compound with higher purity can be produced.

  In particular, in the first and second aspects of the present invention, the iron element content in the borohydride metal salt is preferably 5 ppm by mass or less, more preferably 4 ppm by mass or less. The lead element content in the borohydride metal salt is preferably 1 ppm by mass or less, more preferably 0.8 ppm by mass or less.

  Moreover, in the 1st and 2nd of this invention, the iron element content in an amine salt becomes like this. Preferably it is 10 mass ppm or less, More preferably, it is 5 mass ppm or less. Moreover, lead element content in amine salt becomes like this. Preferably it is 50 mass ppm or less, More preferably, it is 30 mass ppm or less.

  By synthesizing a borazine compound using a borohydride metal salt or amine salt having such a low metal element content, the content of the metal element as an impurity in the synthesized borazine compound is reduced, and the element of the semiconductor device A high-purity borazine compound that can be used as a film can be synthesized. From the above viewpoint, the smaller the content of each metal element and the total content of metal elements in the borohydride metal salt and amine salt, the better, and the lower limit is not particularly limited.

  There are no particular restrictions on the route through which the metal borohydride metal salt or amine salt having a reduced metal element content is obtained. When products of borohydride metal salts and amine salts with low metal element content are commercially available, those purchased may be used, or the content of relatively commercially available metal element content may be used. After purchasing a large number of products, the content of the metal element in the product itself may be reduced and used for the synthesis of the borazine compound.

  The method for reducing the content of the metal element of the borohydride metal salt or amine salt is not particularly limited, and conventionally known knowledge can be appropriately referred to in the field of chemical synthesis. As an example of a technique for reducing the content of the metal element of the borohydride metal salt or amine salt, for example, a sublimation purification method, a recrystallization method, or the like can be given. Among these, a recrystallization method can be preferably used.

  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.

  Conditions such as temperature and pressure during distillation purification are not particularly limited, and can be appropriately set according to the type of borazine compound synthesized. As an example of these conditions, a form of distillation at about 70 to 100 ° C. under reduced pressure conditions (about 22 kPa) and further distillation and purification at about 100 to 170 ° C. under normal pressure conditions can be exemplified.

  As described above, according to the production method of the present invention, the content of metal elements as impurities can be reduced, and a high-purity borazine compound can be produced. Here, although there is no restriction | limiting in particular about metal element content in the borazine compound manufactured, Preferably the total content of aluminum, zinc, chromium, cobalt, iron, copper, lead, nickel, and manganese is 1 mass ppm or less. Yes, more preferably 0.5 mass ppm or less, still more preferably 0.3 mass ppm or less. Further, the content of each metal element in the produced borazine compound is not particularly limited, but the iron element content in the produced borazine compound is preferably 20 mass ppb or less, more preferably 15 mass ppb or less. It is. The lead element content in the produced borazine compound is preferably 20 mass ppb or less, more preferably 15 mass ppb or less. However, the technical scope of the production method of the present invention is not limited only to the form in which the content of the metal element is a value within these ranges.

  Although the manufactured borazine compound is not particularly limited, the borazine compound 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.

  In the following Examples and Comparative Examples, the content of the metal element in the raw material borohydride metal salt and amine salt was measured using ICP (Emission Spectrometer, manufactured by Seiko Denshi Kogyo Co., Ltd.). Moreover, content of the metal element in the manufactured borazine compound was measured using ICP-MS (High Frequency Luminescence Mass Analyzer, manufactured by PerkinElmer Japan Co., Ltd., ELAN DRCII).

<Example>
First, sodium borohydride was prepared as a metal borohydride salt as a reaction raw material. Moreover, methylamine hydrochloride was prepared as an amine salt which is a similar reaction raw material. The contents of the nine metal elements of aluminum, zinc, chromium, cobalt, iron, copper, lead, nickel, and manganese in the prepared sodium borohydride and methylamine hydrochloride were as shown in Table 1 below. It was. Moreover, as a result of measuring similarly content of another metal element about sodium borohydride, the metal element contained 80 mass ppm or more did not exist. Furthermore, as a result of measuring the content of other metal elements in the same manner for methylamine hydrochloride, there was no metal element contained in an amount of 50 mass ppm or more.

  A three-necked round bottom flask (1000 mL) equipped with a dropping funnel and a condenser tube was charged with methylamine hydrochloride (60 g) prepared above and triglyme (200 g) as a solvent while purging with nitrogen. The temperature was raised to ° C.

  On the other hand, sodium borohydride (38 g) prepared above was added to triglyme (200 g) prepared separately to prepare a slurry.

  The sodium borohydride slurry prepared above was slowly added to the reaction vessel heated to 150 ° C. over 90 minutes.

  After the addition of the slurry, the reaction system was heated to 170 ° C. over 20 minutes, and further aged at 170 ° C. for 2 hours to synthesize N, N ′, N ″ -trimethylborazine.

  Thereafter, the cooling pipe was removed, the Claisen connecting pipe and the Liebig cooling pipe were attached, the reaction solution was heated from 170 ° C. to 210 ° C. over 3 hours, and N, N ′, N ″ -trimethylborazine was taken out by distillation. The N, N ′, N ″ -trimethylborazine was further distilled at atmospheric pressure at a distillation temperature of 155 to 160 ° C., and a fraction having a distillation temperature of 130 to 133 ° C. was fractionated to obtain N, N ′, N "-Trimethylborazine was purified. This purification operation was performed twice in total.

<Comparative example>
Nine kinds of metal elements such as aluminum, zinc, chromium, cobalt, iron, copper, lead, nickel, and manganese as reaction raw materials, borohydride metal salt (sodium borohydride) and amine salt (methylamine hydrochloride) N, N ′, N ″ -trimethylborazine was obtained in the same manner as in the above-described example except that the content of N was the value shown in Table 2 below. Further, sodium borohydride was obtained. As a result of measuring the content of other metal elements in the same manner, it was found that both potassium and tin were contained in an amount of 100 ppm by mass or more. As a result of measuring similarly, it became clear that calcium was contained 100 mass ppm or more.

<Evaluation>
The metal element content in N, N ′, N ″ -trimethylborazine obtained in the above Examples and Comparative Examples was measured. The results are shown in Table 3 below.

  From the results shown in the above Examples and Comparative Examples, it is included in the synthesized borazine compound by controlling the content of the metal element of the borohydride metal salt and / or amine salt, which are the raw materials for synthesis of the borazine compound, to a low value. It is shown that the content of the metal element can be reduced.

Claims (6)

A metal borohydride and (RNH ₃ ) _n X (R is a hydrogen atom, an alkyl group, or a cycloalkyl group, X is a sulfate group or a halogen atom, and n is 1 or 2) A process for synthesizing a borazine compound by reacting with an amine salt in a solvent,
The content of each metal element (excluding the content of the constituent element of the borohydride metal salt) is 100 mass ppm or less, or the content of each metal element is 100 mass ppm. A method for producing a borazine compound, characterized in that at least one of the amine salts of ppm or less is used in the reaction.   In the reaction, both the borohydride metal salt having a content of each metal element of 100 mass ppm or less and the amine salt having a content of each metal element of 100 mass ppm or less are used in the reaction. The manufacturing method as described. A metal borohydride and (RNH ₃ ) _n X (R is a hydrogen atom, an alkyl group, or a cycloalkyl group, X is a sulfate group or a halogen atom, and n is 1 or 2) A process for synthesizing a borazine compound by reacting with an amine salt in a solvent,
The borohydride metal having a total content of aluminum, zinc, chromium, cobalt, iron, copper, lead, nickel, and manganese (excluding the content of constituent elements of the borohydride metal salt) of 20 mass ppm or less A borazine compound characterized in that a salt or at least one of the amine salts having a total content of aluminum, zinc, chromium, cobalt, iron, copper, lead, nickel, and manganese of 100 mass ppm or less is used in the reaction. Production method.   The manufacturing method of Claim 3 which uses both the said borohydride metal salt whose said total content is 20 mass ppm or less, and the said amine salt whose said total content is 100 mass ppm or less.   The manufacturing method of any one of Claims 1-4 whose iron element content in the said borohydride metal salt used for reaction is 5 mass ppm or less, and whose lead element content is 1 mass ppm or less.   The manufacturing method of any one of Claims 1-5 whose iron element content in the said amine salt used for reaction is 10 mass ppm or less, and whose lead element content is 50 mass ppm or less.