Polymerization Inhibitor for Silane

Abstract

A polymerization inhibitor for a silane enables purification of the silane to a high degree because a polymer is not formed even when heating to distill the silane, even when a cyclic silane monomer is present. A high-purity cyclic silane composition is obtained, in particular high-purity cyclopentasilane, that can be polymerized and applied onto a substrate as a coating-type polysilane composition and fired to produce a good silicon thin film with high conductivity. The polymerization inhibitor includes a secondary or tertiary aromatic amine. The aromatic group is a phenyl group or a naphthyl group. The polymerization inhibitor is present in a proportion of 0.01 to 10 mol % per mole of the silane. In the polymerization inhibitor, a boiling point of the aromatic amine is 196° C. or higher.

Claims

1. A polymerization inhibitor for a silane, the polymerization inhibitor comprising a secondary or tertiary aromatic amine.

2. The polymerization inhibitor according to claim 1, wherein the silane comprises a cyclic silane.

3. The polymerization inhibitor according to claim 1, wherein the silane comprises cyclopentasilane.

4. The polymerization inhibitor according to claim 1, wherein the aromatic amines are secondary aromatic amines.

5. The polymerization inhibitor according to claim 1, wherein an aromatic group of the aromatic amines is a phenyl group or a naphthyl group.

6. The polymerization inhibitor according to claim 1, wherein the polymerization inhibitor is contained at a proportion of 0.01 to 10 mol % per mole of the silane.

7. The polymerization inhibitor according to claim 1, wherein a boiling point of the aromatic amines is 196° C. or higher.

8. A method of producing a silane, the method comprising: obtaining a solution containing a cyclic silane expressed by Formula (2)
(SiR.sup.3R.sup.4)n  Formula (2) where R.sup.3 and R.sup.4 respectively indicate halogen atoms, and n is an integer of 4 to 6 by reacting a cyclic silane expressed by Formula (1):
(SiR.sup.1R.sup.2)n  Formula (1) where R.sup.1 and R.sup.2 indicate independently a hydrogen atom, a C.sub.1 to C.sub.6 alkyl group or a substituted or unsubstituted phenyl group, R.sup.1 and R.sup.2 are not hydrogen atoms simultaneously, and n is an integer of 4 to 6 with a hydrogen halide in the presence of an aluminum halide, obtaining a cyclic silane expressed by Formula (3):
(SiH.sub.2)n  Formula (3) where n is an integer of 4 to 6 by reducing the cyclic silane expressed by Formula (2) with hydrogen or a lithium aluminum hydride, and adding the polymerization inhibitor according to claim 1 to the cyclic silane expressed by Formula (3) and further distilling a resultant matter.

9. The method according to claim 8, wherein after obtaining the solution containing the cyclic silane expressed by Formula (2), the method further includes distilling the cyclic silane expressed by Formula (2).

10. A silane preservation method, comprising adding the polymerization inhibitor according to claim 1 to a silane-containing organic solvent.

Description

EXAMPLES

[0068] The weight-average molecular weight can be measured by gel permeation chromatography (GPC) (measurement equipment: HLC-8320GPC (manufactured by Tosoh Corporation); column: GPC/SEC (PLgel 3 μm, 300×7.5 mm, manufactured by Varian Inc.); column temperature: 35° C.; detector: RI; flow rate: 1.0 ml/min; measurement time: 15 minutes; eluent: cyclohexane; injection amount: 10 μL); sample concentration: 1.0% (in cyclohexane). Also, with CPS (Mw150, RT=11.040 minutes), CPS-dimer (Mw298, RT=10.525 minutes) and CPS-trimer (Mw446, RT=9.725 minutes) as primary standards, a calibration curve was generated. The polymerization progress indicating the degree of progress of polymerization is defined as: the ratio of the area of the spectrum indicated by initial CPS occupying the entire spectrum—the ratio of the area of the spectrum indicated by CPS after 4 hours occupying the entire spectrum)/the ratio of the area of the spectrum indicated by initial CPS occupying the entire spectrum)×100.

[0069] CPS means cyclopentasilane.

[Synthesis Example 1] Synthesis of Decachlorocyclopentasilane

[0070] In nitrogen atmosphere, decaphenylcyclopentasilane (500.0 g) and cyclohexane (453.7 g) were put into a 2 L-reaction flask as a solvent. After aluminum chloride AlCl.sub.3 (14.7 g) was added to it, the temperature of the resultant mixture was raised to room temperature in a water bath. A hydrogen chloride HCL gas was blown on it at a flow velocity (280 mL/min) for 8 hours. Thereafter, after pressure reduction and pressure recovery by means of nitrogen were repeated ten times to remove hydrogen chloride, the resultant mixture was filtered using a membrane filter; thereby, a cyclohexane solution of decachlorocyclopentasilane (1099.5 g) was obtained.

[Synthesis Example 2] Synthesis of Cyclopentasilane

[0071] Solvent removal was performed at 20 to 30° C. and 25 Torr for 2 hours on the cyclohexane solution of decachlorocyclopentasilane (1099.5 g) obtained in Synthesis Example 1, and thereafter the resultant mixture was distilled at 60° C. and 13 Torr for 4 hours; thereby, decachlorocyclopentasilane (268.56 g) from which cyclohexylbenzene was removed was obtained. After cyclohexane (814.5 g) was added to and dissolved in it, the resultant fixture was filtered using a membrane filter, and rinsed using cyclohexane (50 g); thereby, a cyclohexane solution of high-purity decachlorocyclopentasilane (1100.6 g) was obtained. This was put into a 2 L-reaction flask in argon atmosphere, and at 0 to 10° C., a diethyl ether (269.6 g) solution of lithium aluminum hydride LiAlH.sub.4 (57.5 g) was dripped over 2 hours. After the resultant mixture was agitated at room temperature for 1 hour, at 0 to 10° C., ion-exchanged water (592.7 g) was dripped onto the reaction solution over 1 hour. After being agitated for 10 minutes and allowed to stand still, water layer parts were removed. Subsequently, ion-exchanged water (592.7 g) was added to it at room temperature, and this rinsing operation was performed four times. Thereafter, the organic layer was dried for 1 hour using magnesium sulfate (23.7 g), and then filtration using a membrane filter and concentration were performed to obtain a cyclopentasilane (71.8 g).

[Example 1] Addition of DPPA (N,N′-Diphenyl-1,4-Diphenylenediamine)

[0072] In argon atmosphere, cyclopentasilane (3.0 g) obtained in Synthesis Example 2 was put into a 30-mL-reaction flask in the presence of, as a polymerization inhibitor, DPPA (N,N′-diphenyl-1,4-diphenylenediamine) (0.055 g, 1.0 mol %), and heating was performed thereon at 70° C. for 4 hours. Analysis by gel permeation chromatography (GPC) performed showed that the polymerization progress was less than 1%.

[Example 2] Addition of DNPA

(N,N′-Di-2-Naphthyl-1,4-Diphenylenediamine)

[0073] In argon atmosphere, cyclopentasilane (3.0 g) obtained in Synthesis Example 2 was put into a 30-mL-reaction flask in the presence of, as a polymerization inhibitor, DNPA (N,N′-di-2-naphthyl-1,4-diphenylenediamine) (0.075 g, 1.0 mol %), and heating was performed thereon at 70° C. for 4 hours. Analysis by gel permeation chromatography (GPC) performed showed that the polymerization progress was less than 1%.

[Example 3] Addition of DPA (Diphenylamine)

[0074] In argon atmosphere, cyclopentasilane (3.0 g) obtained in Synthesis Example 2 was put into a 30-mL-reaction flask in the presence of, as a polymerization inhibitor, DPA (diphenylamine) (0.034 g, 1.0 mol %), and heating was performed thereon at 70° C. for 4 hours. Analysis by gel permeation chromatography (GPC) performed showed that the polymerization progress was 1.3%.

[Example 4] Addition of TPA (Triphenylamine)

[0075] In argon atmosphere, cyclopentasilane (3.0 g) obtained in Synthesis Example 2 was put into a 30-mL-reaction flask in the presence of, as a polymerization inhibitor, TPA (triphenylamine) (0.050 g, 1.0 mol %), and heating was performed thereon at 70° C. for 4 hours. Analysis by gel permeation chromatography (GPC) performed showed that the polymerization progress was 7.7%.

[Example 5] Addition of DNPA

(N,N′-Di-2-Naphthyl-1,4-Diphenylenediamine)

[0076] In argon atmosphere, cyclopentasilane (5.0 g) obtained in Synthesis Example 2 was put into a 30-mL-reaction flask in the presence of, as a polymerization inhibitor, DNPA (N,N′-di-2-naphthyl-1,4-diphenylenediamine) (0.0125 g, 0.1 mol %), and heating was performed thereon at 70° C. for 4 hours. Analysis by gel permeation chromatography (GPC) performed showed that the polymerization progress was less than 1%.

[Example 6] Addition of DNPA

(N,N′-Di-2-Naphthyl-1,4-Diphenylenediamine)

[0077] In argon atmosphere, cyclopentasilane (5.0 g) obtained in Synthesis Example 2 was put into a 30-mL-reaction flask in the presence of, as a polymerization inhibitor, DNPA (N,N′-di-2-naphthyl-1,4-diphenylenediamine) (0.0013 g, 0.01 mol %), and heating was performed thereon at 70° C. for 4 hours. Analysis by gel permeation chromatography (GPC) performed showed that the polymerization progress was 2%.

[Comparative Example 1] No Polymerization Inhibitor

[0078] In argon atmosphere, cyclopentasilane (3.0 g) obtained in Synthesis Example 2 was put into a 30-mL-reaction flask in the absence of polymerization inhibitors, and heating was performed thereon at 70° C. for 4 hours. Analysis by gel permeation chromatography (GPC) performed showed that the polymerization progress was 29.1%.

[Comparative Example 2] Addition of AN (Aniline)

[0079] In argon atmosphere, cyclopentasilane (3.0 g) obtained in Synthesis Example 2 was put into a 30-mL-reaction flask in the presence of, as a polymerization inhibitor, AN (aniline) (0.019 g, 1.0 mol %), and heating was performed thereon at 70° C. for 4 hours. Analysis by gel permeation chromatography (GPC) performed showed that the polymerization progress was 26.8%.

[Comparative Example 3] Addition of DCA (Dicyclohexylamine)

[0080] In argon atmosphere, cyclopentasilane (3.0 g) obtained in Synthesis Example 2 was put into a 30-mL-reaction flask in the presence of, as a polymerization inhibitor, DCA (dicyclohexylamine) (1.0 mol %) (0.037 g), and heating was performed thereon at 70° C. for 4 hours. Analysis by gel permeation chromatography (GPC) performed showed that the polymerization progress was 21.0%.

[Comparative Example 4] Addition of HQ (Hydroquinone)

[0081] In argon atmosphere, cyclopentasilane (3.0 g) obtained in Synthesis Example 2 was put into a 30-mL-reaction flask in the presence of, as a polymerization inhibitor, HQ (hydroquinone) (0.022 g, 1.0 mol %), and heating was performed thereon at 70° C. for 4 hours. Analysis by gel permeation chromatography (GPC) performed showed that the polymerization progress was 20.0%.

[0082] In the present invention, as shown in the above-mentioned examples, in a silane preservation method or purification method using a polymerization inhibitor, the silane polymerization progress is suitably 15% or lower and preferably 10% or lower.

INDUSTRIAL APPLICABILITY

[0083] A composition containing polysilane obtained by using a polymerization inhibitor to obtain high-purity cyclic silane, in particular high-purity cyclopentasilane and polymerizing the cyclic silane is applied onto a substrate as a coating-type polysilane composition and fired, and this produces a good silicon thin film with high conductivity.