JP2012207152A - Method for producing polyhydrosilane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a polyhydrosilane having a high molecular weight by polymerizing SiHin high activity and high efficiency.SOLUTION: The method for producing a polyhydrosilane comprises polymerization of SiHwith a catalyst produced by contacting a group 4 metallocene with an alkylation agent selected from alkyllithium, alkylaluminum, alkylmagnesium and alkylmagnesium halide, wherein the contact step of the group 4 metallocene with the alkylation agent is carried out in the presence of SiH. The polyhydrosilane produced by the method is suitably usable as a silicone precursor.

Description

The present invention relates to a method for producing polyhydrosilane. More specifically, the present invention relates to a method for producing polyhydrosilane by polymerizing silane (SiH ₄ ) with high activity and high efficiency using a metallocene catalyst.

Formation of a silicon film applied to a semiconductor device such as an integrated circuit or a thin film transistor is performed by a gas phase process such as a CVD (Chemical Vapor Deposition) method. However, according to this method, there is a problem in terms of cost, such as requiring a large vacuum device and low use efficiency of raw materials.
In recent years, a liquid phase process using polyhydrosilane as a silicon precursor has been proposed (Non-Patent Documents 1 and 2). This technique is a technique for forming a silicon film by heating a coating film obtained by applying a polyhydrosilane solution on a substrate in a non-oxidizing atmosphere. According to this technology, a vacuum apparatus is not required, and in addition to high use efficiency of the raw material compound, a processing method using a characteristic characteristic of a liquid (for example, formation of a patterned silicon film using a printing method) is possible. There are various advantages such as that, and practical application is expected.
The polyhydrosilane which is a precursor of silicon is synthesized by photopolymerization of a cyclosilane having 5 or 6 silicon atoms (Si _n H _2n , n = 5 or 6) (Patent Document 1). This cyclosilane can be synthesized, for example, by cyclizing diphenyldichlorosilane in the presence of a suitable alkali metal (eg, sodium, lithium, etc.) and then hydrogenating with a suitable hydrogenating agent (eg, lithium aluminum hydride). (Patent Document 2). However, since the raw material diphenyldichlorosilane itself is expensive and requires a large amount of reducing agent in the hydrogenation process, and generates a large amount of waste in both the cyclization process and the hydrogenation process, the cost and the environment are reduced. Has problems from both sides.

To solve these problems that arise when using polyhydrosilane, it is most desirable to synthesize polyhydrosilane directly from inexpensive silane (monosilane, SiH ₄ ).
To date, there have been no examples of synthesizing polyhydrosilane from SiH ₄ . For example, Non-Patent Document 3 describes that polyhydrosilane is generated by performing silent discharge in SiH ₄ gas. Patent Document 3 describes a method for synthesizing polyhydrosilane by heating SiH ₄ to 350 to 460 ° C. However, all of the main products of the methods described in these documents are disilanes, and the yield of polyhydrosilane over trisilane is extremely low. In these methods, even if a high molecular weight polyhydrosilane is produced by silent discharge or high temperature heating, it is considered that the polyhydrosilane is easily decomposed under such high energy conditions. Accordingly, it is not realistic to attempt to produce a high molecular weight polyhydrosilane in an amount required for the intended application by these methods.
Therefore, it is desired to directly synthesize a high molecular weight polyhydrosilane from SiH ₄ by dehydrogenative condensation polymerization using a transition metal catalyst. Since the catalytic reaction generally proceeds under mild conditions, it is possible to avoid decomposition of the high molecular weight polyhydrosilane once formed. Moreover, since the by-product of dehydrogenative condensation polymerization is only hydrogen, a clean reaction can be expected.
In this regard, many catalytic dehydrogenative condensation polymerizations of organosilanes have been reported, and it is known that relatively good results can be obtained when a transition metal complex is used as a catalyst. For example, “Negishi Reagent” obtained by treating zirconocene dichloride with n-butyllithium exhibits high activity in dehydrogenative condensation polymerization of primary or secondary organosilane (Non-patent Document 4).
However, a technique that can efficiently produce high molecular weight polyhydrosilane by efficiently performing catalytic dehydrogenative condensation polymerization of SiH ₄ has not yet been proposed.

JP 2003-313299 A JP 2001-262058 A Special table 2008-536784 gazette

Nature, 440, pp 783-786 (2006) J. et al. Non-Cryst. Solids, 354, pp2623-2626 (2008) Inorg. Chem. , 1, pp 432-433 (1962) Organometallics, 10, pp 924-930 (1991).

According to the study by the present inventors, even when the polymerization of SiH ₄ is performed using a known metallocene catalyst such as Negishi's reagent, the initial activity of the catalyst is not sufficient, and further, the catalyst is deactivated immediately after the start of the polymerization. It was found that polyhydrosilane cannot be obtained in high yield.
The present invention has been made based on the fact that such facts have been clarified, and an object of the present invention is to provide a method for producing polyhydrosilane by polymerizing SiH ₄ with high activity and high efficiency. is there.

According to the present invention, the above objects and advantages of the present invention are:
A process for producing polyhydrosilane, comprising polymerizing SiH ₄ with a catalyst obtained by contacting a group 4 metallocene with an alkylating agent selected from alkyllithium, alkylaluminum, alkylmagnesium and alkylmagnesium halide,
The contact between the group 4 metallocene and the alkylating agent is achieved by the method, characterized in that it is carried out in the presence of SiH ₄ .

The catalyst used in the method of the present invention has a high initial activity and a long catalyst life. Therefore, by polymerizing SiH ₄ by the method of the present invention using such a catalyst, polyhydrosilane can be produced with high activity and high yield.
The polyhydrosilane produced by the method of the present invention can be suitably used as a silicon precursor, for example, in the production of a semiconductor device.

The ATR-IR chart which measured the solid obtained in Example 2 as a sample. ²⁹ Si CP-MAS NMR chart of the measurement of the resulting solid in Example 2 as a sample. The graph which shows the time-dependent change of the polymerization reaction conversion rate in Experimental example ad of Example 4. FIG. The graph which shows the time-dependent change of the polymerization reaction conversion rate in Experimental example ei of Example 4. FIG. The graph which shows the time-dependent change of the polymerization reaction conversion rate in Experimental example j of Example 4. FIG. The graph which shows the time-dependent change of the polymerization reaction conversion rate in Experimental example ad of Example 5, and a comparative experimental example. The graph which shows the time-dependent change of the polymerization reaction conversion rate in Experimental example eg of Example 5, and a comparative experimental example. The graph which shows the time-dependent change of the polymerization reaction conversion rate in Experimental example ad of Example 6, and the comparative experimental example of Example 5. FIG. The graph which shows the time-dependent change of the polymerization reaction conversion rate in Experimental example e and f of Example 6, and the comparative experimental example of Example 5. FIG. The graph which shows the time-dependent change of the polymerization reaction conversion rate in Experimental example g and h of Example 6, and the comparative experimental example of Example 5. FIG. 10 is an XPS chart of zero-valent silicon obtained in Example 7. 10 is a Raman spectroscopic chart of the film-like material obtained in Example 9.

The present invention is as described above.
The present invention relates to a method for producing polyhydrosilane, in which SiH ₄ is polymerized by a catalyst obtained by contacting a Group 4 metallocene with an alkylating agent selected from alkyllithium and alkylaluminum.
The contact between the group 4 metallocene and the alkylating agent is performed under the condition where SiH ₄ is present. The contact between the group 4 metallocene and the alkylating agent may be carried out under conditions where a Lewis base is present in addition to SiH ₄ .
<Group 4 metallocene>
As the group 4 metallocene used in the present invention, a metallocene whose central metal is titanium, zirconium or hafnium can be preferably used. For example, the following formulas (1-1) and (1-2)

(Wherein M is titanium, zirconium or hafnium;
L ¹ and L ² are each independently a cyclopentadienyl group, an indenyl group or a fluorenyl group, provided that these groups may be substituted with an alkyl group having 1 to 4 carbon atoms or a trimethylsilyl group;
L ³ and L ⁴ are each independently a cyclopentadienylene group, an indenylene group or a fluorenylene group, provided that these groups may be substituted with an alkyl group having 1 to 4 carbon atoms or a trimethylsilyl group;
R is a methylene group, an alkylene group having 2 to 4 carbon atoms or a dimethylsilylene group; and X is a halogen atom. )
The complex represented by each of these can be mentioned, At least 1 sort (s) selected from these can be used.
L ¹ and L ² in the above formula (1-1) are each a cyclopentadienyl group, a t-butylcyclopentadienyl group, a trimethylsilylcyclopentadienyl group, a pentamethylcyclopentadienyl group, or an indenyl group. Be a group;
L ³ and L ⁴ in the formula (1-2) are each preferably an indenylene group.
X in the above formulas (1-1) and (1-2) is preferably a chlorine atom, a bromine atom or an iodine atom, and more preferably a chlorine atom.

Specific examples of the Group 4 metallocene used in the present invention include, for example, dicyclopentadienyl titanium dichloride (Cp ₂ TiCl ₂ ),
Bis (t-butylcyclopentadienyl) titanium dichloride (tBuCp ₂ TiCl ₂ ),
Bis (pentamethylcyclopentadienyl) titanium dichloride _^(Cp * ₂ TiCl 2),
Bis (indenyl) titanium dichloride (Ind ₂ TiCl ₂ ),
Dicyclopentadienyl zirconium dichloride (Cp ₂ ZrCl ₂ ),
Bis (t-butylcyclopentadienyl) zirconium dichloride (tBuCp ₂ ZrCl ₂ ),
Bis (pentamethylcyclopentadienyl) zirconium dichloride _^(Cp * ₂ ZrCl 2),
Bis (indenyl) zirconium dichloride (Ind ₂ ZrCl ₂ ),
ansa-ethylenebis (indenyl) zirconium dichloride (ansa-Ind ₂ ZrCl ₂ ),
Bis (t-butylcyclopentadienyl) hafnium dichloride _{(tBuCp 2} HfCl 2) and the like can be illustrated, can be preferably used one or more selected from these.
The use ratio of the group 4 metallocene is preferably 1 × 10 ⁻⁴ to 1 × 10 ⁻¹ mol, preferably 1 × 10 ^{−3 to} 5 × 10 ⁻² mol, relative to 1 mol of SiH _4. More preferred.

<Alkylating agent>
The alkylating agent used in the present invention is selected from alkyllithium, alkylaluminum, alkylmagnesium and alkylmagnesium halides.
As said alkyl lithium, the alkyl lithium which has a C2-C6 alkyl group is preferable. Examples of such alkyl lithium include ethyl lithium, n-propyl lithium, i-propyl lithium, n-butyl lithium, sec-butyl lithium, iso-butyl lithium, n-pentyl lithium, and n-hexyl lithium. Can do.
Examples of the alkylaluminum include a dialkylaluminum hydride having an alkyl group having 2 to 6 carbon atoms and a trialkylaluminum having an alkyl group having 2 to 6 carbon atoms. Here, as the alkyl group having 2 to 6 carbon atoms, for example, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, iso-butyl group, n-pentyl group, n- A hexyl group etc. can be mentioned. As the alkylaluminum, a trialkylaluminum having an alkyl group having 3 to 5 carbon atoms is preferable.
As said alkylmagnesium, the alkylmagnesium which has a C2-C6 alkyl group can be mentioned, for example.
Examples of the alkylmagnesium halide include alkylmagnesium chloride, alkylmagnesium bromide, and alkylmagnesium iodide having an alkyl group having 2 to 6 carbon atoms.
As the alkylating agent in the present invention, it is preferable to use an alkylating agent selected from alkyl lithium and alkyl aluminum, and it is more preferable to use alkyl lithium having a linear alkyl group having 3 to 5 carbon atoms. Particularly preferred is n-butyllithium.
The proportion of the alkylating agent used is preferably 1 to 20 mol, more preferably 1.5 to 10 mol, and even more preferably 2 to 3 mol with respect to 1 mol of the group 4 metallocene. .

<Lewis base>
Examples of the Lewis base optionally used in the present invention include organic compounds having 1 to 6 nitrogen atoms, oxygen atoms, phosphorus atoms or sulfur atoms, and at least one selected from these compounds It is preferable to use it.
Examples of the organic compound having a nitrogen atom include heteroaromatic compounds having a nitrogen atom as a member constituting an aromatic ring, trialkylamine, tetraalkylalkylenediamine, and pentaalkyldialkylenetriamine. The alkyl group of the trialkylamine, tetraalkylalkylenediamine, and pentaalkyldialkylenetriamine is preferably an alkyl group having 1 to 6 carbon atoms, and more preferably an alkyl group having 1 to 3 carbon atoms. ;
The alkylene group is preferably an alkyl group having 2 to 6 carbon atoms, and more preferably a 1,2-ethylene group or a 1,2-propylene group.

Specific examples of the organic compound having a nitrogen atom as the Lewis base in the present invention include, for example, pyridine, pyrimidine, pyrazine, triazine, bipyridine, terpyridine, biquinoline, phenanthroline and the like as the above heteroaromatic compound having a nitrogen atom;
Examples of trialkylamines include trimethylamine, triethylamine, triisopentylmethylamine, piperazine, 1,8-bis (dimethylamino) naphthalene and the like;
Examples of the tetraalkylalkylenediamine include N, N, N ′, N′-tetramethylethylenediamine and the like;
Examples of the pentaalkyl dialkylene triamine include N, N, N ′, N ″, N ″ -pentamethyldiethylenetriamine and the like.
Examples of the organic compound having an oxygen atom include heteroaromatic compounds having an oxygen atom as a member constituting an aromatic ring, ethers and the like. Examples of the ether include dialkyl ether, dialkoxyalkylene, polyalkylene oxide dialkyl ether, and cyclic ether. The number of carbon atoms of the alkyl group or alkoxy group of the dialkyl ether, dialkoxyalkylene and polyalkylene oxide dialkyl ether is preferably 1-6, more preferably 1-3.

As a specific example of an organic compound having an oxygen atom as a Lewis base in the present invention,
Examples of the heteroaromatic compound having an oxygen atom include furan;
Examples of dialkyl ether chain monoethers include dimethyl ether, diethyl ether, methyl ethyl ether, diisopropyl ether and the like;
Examples of dialkoxyalkylene include dimethoxyethane and diethoxyethane;
Examples of polyalkylene oxide dialkyl ethers include diethylene glycol dimethyl ether and diethylene glycol diethyl ether;
Examples of cyclic ethers include tetrahydrofuran and tetrahydropyran.

Examples of the organic compound having a phosphorus atom include the following formula (P-1) or (P-2)
R ¹ R ² R ³ P (P-1)
^{R 4 R 5 P-R 8} -PR 6 R 7 (P-2)
(In the above formula, R ^{1 to} R ⁷ are each independently an alkyl group having 1 to 6 carbon atoms or an aromatic group having a total of 6 to 12 carbon atoms and hetero atoms;
R ⁸ is a methylene group or an alkylene group having 2 to 6 carbon atoms. )
The compound represented by these can be mentioned.
Examples of the compound represented by the formula (P-1) include diphenylmethylphosphine, triphenylphosphine, diphenylpyridylphosphine, and tris (dimethylamino) phosphine;
Examples of the compound represented by the formula (P-2) include 1,2-bis (diphenylphosphino) ethane and 1,2-bis (dimethylphosphino) ethane.
Examples of the organic compound having a sulfur atom include dimethyl sulfide, diethyl sulfide, thiophene, thiobenzophenone, and sulfurane.

As the Lewis base in the present invention, it is preferable to use at least one selected from the group consisting of organic compounds having 1 to 6 nitrogen atoms, oxygen atoms or phosphorus atoms, and particularly triethylamine, N, N, N ′. , N′-tetramethylethylenediamine, N, N, N ′, N ″, N ″ -pentamethyldiethylenetriamine, pyridine, bipyridine, biquinoline, dimethoxyethane, diphenylmethylphosphine, 1,2-bis (diphenylphosphino) ethane, etc. It is more preferable to use at least one selected from these.
The use ratio of the Lewis base is preferably 100 mol or less, more preferably 0.1 to 50 mol, per 1 mol of the group 4 metallocene. The more preferable usage rate of the Lewis base varies depending on the type of the Lewis base used, and is as follows for each usage amount per 1 group 4 metallocene.
Organic compound having nitrogen atom: More preferably 0.5 to 10 mol, particularly preferably 1 to 5 mol Organic compound having oxygen atom or sulfur atom: More preferably 1 to 50 mol, particularly preferably 5 to 20 mol Organic compound having an atom: more preferably 0.5 to 10 mol, particularly preferably 1 to 5 mol

<Contact between Group 4 metallocene and alkylating agent>
The catalyst used in the method for producing a polyhydrosilane of the present invention is prepared by contacting a group 4 metallocene as described above with an alkylating agent under conditions where SiH ₄ is present. The contact between the group 4 metallocene and the alkylating agent may be carried out under conditions where a Lewis base is present in addition to SiH ₄ .
The contact between the SiH ₄ and optionally the Group 4 metallocene and the alkylating agent in the presence of a Lewis base may be carried out in a polymerization reaction vessel in which SiH ₄ is polymerized, or in another vessel other than the polymerization reaction vessel. After the contact, the mixture after contact may be added to the polymerization reaction vessel. The contact between the group 4 metallocene and the alkylating agent can be carried out in the presence or absence of a solvent, but in the presence of a solvent from the viewpoint of uniformly producing a highly active species. preferable.
When the contact between the Group 4 metallocene and the alkylating agent is carried out in another container other than the polymerization reaction container, the amount of SiH ₄ to be present in the container is 2 moles or more with respect to 1 mole of the Group 4 metallocene. It is preferable to make it 5-10 mol.

Examples of the solvent that can be used in the contact between the group 4 metallocene and the alkylating agent include an aliphatic hydrocarbon solvent and an aromatic hydrocarbon solvent. Specific examples of the aliphatic hydrocarbon solvent include n-hexane, cyclohexane, cyclohexene, n-heptane, n-octane, cyclooctane, cyclooctene, n-decane, decalin and the like;
Specific examples of the aromatic hydrocarbon solvent include benzene, toluene, xylene, indane, tetralin, and the like, and one or more selected from these can be used.
The use ratio of the solvent is preferably 10 L or more, more preferably 80 to 1,000 L, and further preferably 100 to 1,000 L with respect to 1 mol of the group 4 metallocene. In addition, the group 4 metallocene which is a dihalide represented by each of the above formulas (1-1) and (1-2) has low solubility in the above solvent, and the use ratio of the solvent is 1 mol of the group 4 metallocene. If it is less than 80 L, the Group 4 metallocene may not be completely dissolved and may remain as a solid. However, since the solubility of the Group 4 metallocene after being alkylated by contact with an alkylating agent is generally high, a uniform solution can be obtained after contact even if the proportion of the solvent used is small.
The contact temperature is preferably −78 to 50 ° C., more preferably −78 to 30 ° C.

<Polymerization of SiH ₄ >
When the contact between the group 4 metallocene and the alkylating agent is carried out in the polymerization reaction vessel, the polymerization of SiH ₄ is started as it is after a certain induction period.
On the other hand, when the contact between the group 4 metallocene and the alkylating agent is carried out in a container other than the polymerization reaction container, it is not necessary to significantly increase the contact time, and the catalytically active species immediately after contact (usually within a few seconds). Is generated, the polymerization of SiH ₄ is started by injecting the contact mixture into the polymerization reaction vessel.
In the polymerization of SiH ₄ , a solvent similar to that described above may be added to the polymerization reaction vessel as a solvent that can be used for contacting the group 4 metallocene and the alkylating agent, and polymerization may be performed under dilution. Permissible.
The proportion of the solvent that can be used in the polymerization of SiH ₄ is preferably a proportion that the amount of SiH ₄ charged in the solution is 20% by weight or less, and more preferably a proportion that is 10% by weight or less. The ratio is particularly preferably 5% by weight or less.
The polymerization temperature is preferably −78 to 100 ° C., more preferably −5 to 50 ° C.
The polymerization time is preferably 0.5 to 72 hours, more preferably 4 to 20 hours.

<Polyhydrosilane>
As described above, preferably a solid polyhydrosilane can be obtained. The polyhydrosilane can be suitably used as a silicon precursor after removing impurities such as catalyst residues by an appropriate purification method as required.
Examples of the purification method include solvent washing. Examples of the solvent used for the solvent washing include ethers, aromatic hydrocarbons and amines. Specific examples thereof include ethers such as tetrahydrofuran, tetrahydropyran, dioxane, 1,2-dimethoxyethane, anisole and the like;
Aromatic hydrocarbons such as toluene, xylene, tetralin;
Examples of the amine include triethylamine, N, N, N ′, N′-tetramethylethylenediamine, N, N, N ′, N ″, N ″ -pentamethyldiethylenetriamine, and the like. The use ratio of the solvent is preferably 100 to 10,000 parts by weight, and more preferably 2,000 to 5,000 parts by weight with respect to 100 parts by weight of polyhydrosilane.
In the solvent cleaning, it is preferable to stir the cleaning liquid by an appropriate stirring means such as shaking, using a rotary blade, applying ultrasonic waves, or the like.
The solvent washing is preferably performed for 10 minutes or more, more preferably 30 to 90 minutes, at a temperature and pressure at which the solvent to be used can maintain a liquid state.
The solvent washing can be performed once or a plurality of times, and is preferably performed twice or more, more preferably 3 to 5 times from the viewpoint of reducing the amount of impurities in the polyhydrosilane as much as possible.
The polyhydrosilane obtained and preferably purified by the method of the present invention as described above can be easily converted to zero-valent silicon by heating it in a non-oxidizing atmosphere. Examples of the non-oxidizing atmosphere include an inert gas or a mixed gas of an inert gas and a reducing gas. Examples of the inert gas include nitrogen, helium, and argon;
Examples of the reducing gas include hydrogen. The heating temperature can be, for example, 340 ° C. or higher, preferably 400-600 ° C., and the heating time can be, for example, 15 minutes or longer, preferably 30-90 minutes.

Since silane (SiH ₄ ) falls under the special high-pressure gas designated by the High-Pressure Gas Safety Act, all of the following polymerization reactions are installed within the National University Corporation, Japan Advanced Institute of Science and Technology (Nomi City, Ishikawa Prefecture) It was carried out at room temperature (23-27 ° C.) in an autoclave (with an internal capacity of about 27 mL or about 70 mL, withstand pressure of about 0.3 MPaG) approved by the governor of Ishikawa Prefecture. This autoclave has a charge / sampling septum, an air supply pipe, and an exhaust pipe, and the gas discharged from the exhaust pipe is made harmless by a dry-type detoxification facility and then discharged to the outside air.

In Example 1 and Comparative Example 1, the influence of the order of mixing the catalyst components was examined. Example 1 is the method of the present invention, and Comparative Example 1 is a method usually applied in the polymerization with a metallocene catalyst.
Example 1
In autoclave 27mL filled with SiH ₄ gas pressure 0.01MPaG, bis through the septum (pentamethylcyclopentadienyl) titanium dichloride solution in toluene _^(Cp * 2 TiCl ₂₎ (concentration 7.5 mmol / L) 4 mL of was injected using a syringe and stirred well. Next, 1 mL of a toluene solution (concentration: 60 mmol / L) of n-butyllithium (n-BuLi) was injected from the septum using a syringe to initiate polymerization. Wherein the amount of ^Cp _* 2 TiCl ₂ and n-BuLi used was the charged amount of SiH _4, respectively, equivalent to 3 mol% and 6 mol%.
After 4 hours from the start of the polymerization, a gas was sampled from the septum, and this was analyzed by gas chromatography (GC) to determine the amount of hydrogen generated by the dehydrogenative condensation polymerization of SiH _4. The polymerization reaction conversion rate of SiH ₄ was determined. As a result, the polymerization reaction conversion rate after 4 hours from the start of the reaction was 74.3 mol% with respect to the amount of SiH ₄ charged. A small amount of solid was recovered from the reaction system.

Comparative Example 1
In a glass container with an internal volume of 6 mL, 4 mL of a toluene solution of Cp ^* ₂ TiCl ₂ (concentration 7.5 mmol / L) and 1 mL of a toluene solution of n-BuLi (concentration 60 mmol / L) were mixed to obtain a catalyst solution. It was.
Into an autoclave filled with SiH ₄ gas at a pressure of 0.01 MPaG, the entire amount of the catalyst solution was injected from a septum using a syringe to start polymerization, and the polymerization reaction was started 4 hours after the start of the reaction in the same manner as in Example 1. Conversion was determined. As a result, the polymerization reaction conversion rate after 4 hours from the start of the reaction was 8.5 mol% with respect to the amount of SiH ₄ charged. A small amount of solid was recovered from the reaction system.

In Examples 2 and 3, the type of metallocene used was changed and examined.
Example 2
SiH ₄ was subjected to dehydrogenative condensation polymerization in the same manner as in Example 1 except that bis (pentamethylcyclopentadienyl) zirconium dichloride (Cp ^* ₂ ZrCl ₂ ) was used instead of Cp ^* ₂ TiCl _2. The polymerization reaction conversion rate 4 hours after the start was determined. As a result, the polymerization reaction conversion rate 4 hours after the start of the reaction was 76.2 mol% with respect to the amount of SiH ₄ charged. A small amount of solid was recovered from the reaction system.
An ATR-IR (Attenuated Total Reflection Infrared Spectroscopy) chart obtained by measuring a solid collected from the reaction system as a sample is shown in FIGS. 1 (a) and 1 (b).
A solid-state NMR ( ²⁹ Si CP-MAS (cross polarization-magic angle rotation) NMR, 80 MHz, apparatus used by Varian Inc.) chart is shown in FIG.
From these results, the recovered solid is considered to be polyhydrosilane.

Example 3
SiH ₄ was subjected to dehydrogenative condensation polymerization in the same manner as in Example 1 except that bis (t-butylcyclopentadienyl) hafnium dichloride (tBu-Cp ₂ HfCl ₂ ) was used instead of Cp ^* ₂ TiCl _2. The polymerization reaction conversion rate 4 hours after the start of the reaction was determined. As a result, the polymerization reaction conversion rate 4 hours after the start of the reaction was 16.7 mol% with respect to the amount of SiH ₄ charged. A small amount of solid was recovered from the reaction system.

In Example 4, various metallocenes were used to track the change over time in the polymerization reaction conversion rate of SiH ₄ .
Example 4
The dehydrogenative condensation polymerization of SiH ₄ was started in the same manner as in Example 1 except that various metallocenes were used instead of Cp ^* ₂ TiCl ₂ . By performing sampling of gas from the septum and GC analysis in Example 1 over time, the polymerization reaction conversion rate of SiH ₄ was obtained over time.
In each experimental example, the polymerization reaction conversion rate with respect to the amount of SiH ₄ charged 20 hours after the start of the reaction is shown in Table 1, and the change over time in the polymerization reaction conversion rate of SiH ₄ is shown in FIGS.

The types of metallocene used in each experimental example are as follows. The contents in parentheses are the notations in Table 1 and FIGS.
Experimental Example a: Dicyclopentadienyl titanium dichloride (Cp2TiCl2)
Experimental Example b: Bis (t-butylcyclopentadienyl) titanium dichloride (tBuCp2TiCl2)
Experimental Example c: Bis (indenyl) titanium dichloride (Ind2TiCl2)
Experimental Example d: Bis (pentamethylcyclopentadienyl) titanium dichloride (Cp ^* 2TiCl2)
Experimental Example e: Dicyclopentadienylzirconium dichloride (Cp2ZrCl2)
Experimental Example f: Bis (t-butylcyclopentadienyl) zirconium dichloride (tBuCp2ZrCl2)
Experimental Example g: Bis (indenyl) zirconium dichloride (Ind2ZrCl2)
Experimental Example h: ansa-ethylenebis (indenyl) zirconium dichloride (ansa-Ind2ZrCl2)
Experimental Example i: Bis (pentamethylcyclopentadienyl) zirconium dichloride (Cp ^* 2ZrCl2)
Experimental Example j: Bis (t-butylcyclopentadienyl) hafnium dichloride (tBuCp2HfCl2)

In Example 5, the effect when a Lewis base was added was examined. Experimental examples a to d are cases where an amine is added as a Lewis base,
Examples ef are cases where phosphine is added as a Lewis base,
Example g is a case where ether is added as a Lewis base. A comparative experimental example is the case where no Lewis base was added.
Example 5 (Experimental examples a to g)
In autoclave 25mL filled with SiH ₄ gas pressure 0.01MPaG, 3mL of bis through the septum (pentamethylcyclopentadienyl) zirconium dichloride a toluene solution of _^(Cp * 2 ZrCl ₂₎ (concentration 10 mmol / L) And a toluene solution of various Lewis bases (solution concentration and amount of solution used later) was injected with a syringe and sufficiently stirred. Next, 1 mL of a toluene solution (concentration 60 mmol / L) of n-butyllithium (n-BuLi) was injected from a septum with a syringe to initiate polymerization. ^Cp _* 2 ZrCl ₂ was used herein, amounts of Lewis base and n-BuLi is the charged amount of SiH _4, respectively, 1 mol%, corresponding to 1 mol% and 2 mol%.
After the start of the reaction, sampling of gas from the septum and GC analysis were performed over time in the same manner as in Example 4 to determine the polymerization reaction conversion rate of SiH ₄ over time.
In each experimental example, the type of Lewis base, the polymerization reaction conversion rate with respect to the amount of SiH ₄ charged 20 hours after the start of the reaction are shown in Table 2, and the change over time in the polymerization reaction conversion rate of SiH ₄ is shown in FIGS. Indicated.

The kind of Lewis base used in each experimental example, the solution concentration, and the amount of solution used are as follows. The information in parentheses is the notation in Table 2 and FIGS.
Experimental example a: N, N, N ′, N ″, N ″ -pentamethyldiethylenetriamine (PMDTA), solution concentration = 30 mmol / L, solution use amount = 1 mL
Experimental example b: N, N, N ′, N′-tetramethylethylenediamine (TMEDA), solution concentration = 30 mmol / L, solution use amount = 1 mL
Experimental Example c: Triethylamine (NEt3), solution concentration = 30 mmol / L, solution use amount = 1 mL
Experimental example d: pyridine (Py), solution concentration = 30 mmol / L, solution usage amount = 1 mL
Experimental example e: 1,2-bis (diphenylphosphino) ethane (DPPE), solution concentration = 30 mmol / L, amount of solution used = 1 mL
Experimental Example f: Diphenylmethylphosphine (Ph2PMe), solution concentration = 30 mmol / L, solution use amount = 1 mL
Experimental Example g: 1,2-dimethoxyethane (DME), solution concentration = 30 mmol / L, solution use amount = 1 mL
Example 5 (Comparative Experiment Example)
In addition to not using the Lewis base is carried out in the same manner as Experimental Example a to g, was obtained polymerization conversion rate of SiH ₄ over time. Table 2 shows the polymerization reaction conversion rate relative to the amount of SiH ₄ charged 20 hours after the start of the reaction, and FIGS. 6 and 7 show the change over time in the polymerization reaction conversion rate.

In Example 6, the effect of the added amount of Lewis base was examined.
Experimental examples a to d are cases where N, N, N ′, N ″, N ″ -pentamethyldiethylenetriamine (PMDTA) is used as the Lewis base,
Experimental examples e and f are cases where 1,2-bis (diphenylphosphino) ethane (DPPE) was used as the Lewis base, and experimental examples g and h were 1,2-dimethoxyethane (DME) as the Lewis base. This is the case.
Example 6 (Experimental examples a to h)
In autoclave 25mL filled with SiH ₄ gas pressure 0.01MPaG, 3mL of bis through the septum (pentamethylcyclopentadienyl) zirconium dichloride a toluene solution of _^(Cp * 2 ZrCl ₂₎ (concentration 10 mol / L) In addition, toluene solutions of various Lewis bases (the solution concentrations were the same as those in Example 5 above, and the amount of the solution used was changed so that the amount of Lewis base was the value shown in Table 3) were used as syringes. Pour and stir well. Next, 1 mL of a toluene solution (concentration 60 mmol / L) of n-butyllithium (n-BuLi) was injected from a septum with a syringe to initiate polymerization. Wherein the amount of ^Cp _* 2 ZrCl ₂ and n-BuLi used was the charged amount of SiH _4, respectively, equivalent to 1 mol% and 2 mol%.
After the start of the reaction, sampling of gas from the septum and GC analysis were performed over time in the same manner as in Example 4 to determine the polymerization reaction conversion rate of SiH ₄ over time.
In each example, the amount of addition on the type and charge of SiH ₄ Lewis base, a polymerization reaction conversion based on the charged amount of SiH ₄ after the start of the reaction 20 hours in Table 3, over time of the polymerization reaction conversion of SiH ₄ The changes are shown in FIGS. Table 3 and FIGS. 8 to 10 also show the results of the comparative experimental example in Example 5 above.

Example 7
In this example, it was verified that the polyhydrosilane obtained by the method of the present invention is suitable as a silicon precursor.
Each solid collected in Experimental Examples a to d of Example 4 was heated at 450 ° C. for 1.5 hours in a nitrogen atmosphere to obtain dark brown powders.
Using this powder as a sample, X-ray photoelectron spectroscopy (XPS) analysis was performed under the following conditions.
Measuring apparatus: Phi5600 ESCA System (manufactured by ULVAC-PHI Inc.)
The obtained XPS charts are shown in FIGS. 11 (a) and 11 (b). Since a Si (zero valent) peak was observed in the vicinity of a binding energy of 99 to 100 eV and a weak Si (tetravalent) peak was observed in the vicinity of 102 to 104 eV, the heated powder was zero-valent silicon. It has been confirmed that the polyhydrosilane obtained by the method of the present invention is suitable as a precursor for silicon.

Example 8
In this example, it was verified that silicon produced using polyhydrosilane obtained by the method of the present invention as a precursor had high purity.
Tetrahydrofuran (2 mL) was added to about 30 mg of the solid recovered in Example 2 to obtain a suspension. The obtained suspension was subjected to ultrasonic cleaning for 30 minutes at an output of 2 to 4 W using an ultrasonic liquid processor Sonifier 150 (manufactured by Branson Ultrasonics, 23 kHz). The suspension after washing was centrifuged into a solid and a washing solution using a small microcentrifuge PMC-060 (Tomy Seiko Co., Ltd., centrifugal acceleration of about 2,000 G). This solid was recovered and further subjected to ultrasonic cleaning / centrifugation twice more in the same manner.
The solid washed three times in total as described above was carried into a glove box under a nitrogen atmosphere and heated at 450 ° C. for 1 hour to obtain 25.1 mg of a dark brown powder.
When the obtained powder was used as a sample and the content of metal impurities was analyzed by inductively coupled plasma mass spectrometry (ICP-MS), Zr = 16 mg / g and Li = 2.4 mg / g.

Example 9
In this example, a silicon film was formed using polyhydrosilane obtained by the method of the present invention.
The solid recovered in Example 2 was washed with tetrahydrofuran in the same manner as in Example 8, and about 20 mg thereof was mixed with about 20 mg of cyclopentasilane to obtain a film-forming composition.
In a glove box in a nitrogen atmosphere, the film-forming composition described above is placed on a silicon substrate, and a smooth SiO ₂ mold about 1 cm square is placed on the composition, and 5 MPa at 0.5 MPaG at room temperature. And then pressed at 3.5 MPaG for 15 minutes at 200 ° C. and embossed. Thereafter, the mold was removed, and the molded product on the substrate was heated on a hot plate under nitrogen at 400 ° C. for 1 hour to obtain a film-like product.
The Raman spectroscopic chart measured for this film-like material is shown in FIG.
Further, FIG. 12 (b) shows a Raman spectroscopic chart measured for the product obtained in the same manner as described above except that cyclopentasilane was not used.

Claims (5)

A process for producing polyhydrosilane, comprising polymerizing SiH ₄ with a catalyst obtained by contacting a group 4 metallocene with an alkylating agent selected from alkyllithium, alkylaluminum, alkylmagnesium and alkylmagnesium halide,
Said method, characterized in that the contact between the Group 4 metallocene and the alkylating agent is carried out in the presence of SiH ₄ . The method according to claim 1, wherein the contact between the group 4 metallocene and the alkylating agent is performed under conditions in which a Lewis base is present in addition to SiH ₄ .   The method according to claim 2, wherein the Lewis base is at least one selected from the group consisting of organic compounds having 1 to 4 nitrogen atoms, oxygen atoms, phosphorus atoms or sulfur atoms. The group 4 metallocene is represented by the following formulas (1-1) and (1-2):

(Wherein M is titanium, zirconium or hafnium;
L ¹ and L ² are each independently a cyclopentadienyl group, an indenyl group or a fluorenyl group, provided that these groups may be substituted with an alkyl group having 1 to 4 carbon atoms or a trimethylsilyl group;
L ³ and L ⁴ are each independently a cyclopentadienylene group, an indenylene group or a fluorenylene group, provided that these groups may be substituted with an alkyl group having 1 to 4 carbon atoms or a trimethylsilyl group;
R is a methylene group, an alkylene group having 2 to 4 carbon atoms or a dimethylsilylene group; and X is a halogen atom. )
The method as described in any one of Claims 1-3 which is at least 1 sort (s) selected from the group which consists of a complex represented by each of these. A catalyst obtained by contacting a group 4 metallocene with an alkylating agent selected from alkyllithium, alkylaluminum, alkylmagnesium and alkylmagnesium halide,
The catalyst according to claim 1, wherein the contact between the group 4 metallocene and the alkylating agent is carried out under conditions where SiH ₄ is present, and is used to polymerize SiH ₄ to produce polyhydrosilane.

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