EP2334599A1

EP2334599A1 - Method for producing neopentasilanes

Info

Publication number: EP2334599A1
Application number: EP09783870A
Authority: EP
Inventors: Wolfgang Knies; Hans Eiblmeier
Original assignee: Wacker Chemie AG
Current assignee: Wacker Chemie AG
Priority date: 2008-10-17
Filing date: 2009-10-09
Publication date: 2011-06-22
Also published as: US20110171098A1; DE102008042934A1; JP5373094B2; WO2010043551A1; US8883111B2; CN102186774A; JP2012505815A; KR20110063502A; KR101336407B1

Abstract

The invention relates to a method for producing neopentasilanes of the general formula (1) Si (SiR3) 4 (1), wherein silicon compounds of the general formula (2) R3Si-(Si-)xSiR3 (2), wherein R is selected from H, Cl, Br, and I and x stands for a nonnegative integer up to 5, are reacted in the presence of ether compounds (E).

Description

Process for the preparation of neopentasilanes

The invention relates to a process for the preparation of neopentasilanes from polysilanes in the presence of ether compounds.

Neopentasilanes (tetrakis (silyl) silanes) are used for the deposition of Si-C in CVD processes.

The preparation of neopentasilanes is described in WO 20080513281. There, hexahalodisilane is reacted with tertiary amines as catalysts to give mixtures containing tetrakis (trihalosilyl) silane. The tetrakis (trihalosilyl) silane is reduced to tetrakis (silyl) silane with diisobutylaluminum hydride, which suffers from the disadvantage that tertiary amines are often corrosive and must be handled with care, and traces of nitrogen also affect the semiconducting properties of silicon In many applications, therefore, the content of nitrogen is specified.

The invention relates to a process for the preparation of neopentasilanes of the general formula (1)

Si (SiR ₃ ) ₄ (1),

in which silicon compounds of the general formula (2)

R ₃ Si (Si) _x SiR ₃ (2),

wherein R is selected from H, Cl, Br and J and x is a nonnegative integer to 5, in the presence of ether compounds (E) are reacted. Ether compounds (E) are readily available and easily separated chemicals.

Preferred ether compounds (E) are cyclic organic ether compounds which preferably have at least 5 ring atoms and preferably at most 30 ring atoms, such as 1,3-dioxolane, tetrahydrofuran, tetrahydropyran, tetrahydropyran, 1,4-dioxane, [12] crown-4, [15 ] crown-fifth The cyclic ether compounds (E) may have hydrocarbon substituents, in particular alkyl radicals having 1 to 6 carbon atoms, preferably methyl and ethyl. Examples of substituted cyclic ether compounds (E) are 4-methyl-1,3-dioxolane, 3-methyl-tetrahydrofuran, 2, 2-dimethyl-1,4-dioxane. Also preferred are linear or branched organic ether compounds (E), such as mono- and polyethers. Preferred monoethers are ethers having a boiling point of at least 60 ^° C. at 1 bar, for example di-n-propyl ether.

Polyethers which can also be used are polyalkylene glycols, such as polyethylene glycol and polypropylene glycol. The average molar masses Mn of the polyalkylene glycols are preferably at least 150, in particular at least 500 and preferably at most 10000, in particular at most 5000.

The neopentasilane of the general formula (1) can have identical or different meanings of R in one molecule.

Preferably, all R have the same meanings. Particularly preferred are the meanings H and Cl. x is preferably 0 or 1.

The reaction is preferably carried out at least -5 ⁰ C, more preferably at least 50 ° C and in particular at least 100 ⁰ C, and preferably at most 300 ⁰ C, in particular at most 25O ⁰ C. The reaction is preferably carried out for at least 1 hour, more preferably at least 3 hours and in particular at least 10 hours and preferably at most 10 days,

On 100 parts by weight of silicon compound of the general formula (2) are preferably at least 0.1, more preferably at least 0.5 and especially at least 2 parts by weight of ether compounds (E), and preferably at most 50, more preferably at most 20 and in particular at most 10 parts by weight of ether compounds (E), used.

The reaction mixture is preferably separated by distillation after the reaction. This can be done either under normal pressure, overpressure or reduced pressure.

The reaction may be carried out in the presence or absence of inert gas, such as nitrogen, helium or argon; but it can also be carried out in air, as long as the moisture content is a maximum of 10 ppbw. For reasons of cost, the distillation is preferably carried out in the presence of nitrogen.

Unless stated otherwise, the examples below are carried out at a pressure of the surrounding atmosphere, ie at about 1000 hPa, and at room temperature, ie at about 23 ^° C. and at a relative atmospheric humidity of about 50%.

In the following examples, the content of impurities was determined by gas chromatography.

example 1

In a nitrogen-overlaid three-necked flask equipped with a thermocouple, reflux condenser and stopper, 127 g of hexachlorodi- silane and 10 g of tetrahydrofuran were initially charged and added with stirring to Boil boiling. At about 100 ⁰ C, the formation of a condensate was already observed on the cooler, although hexachlorodisilane boiling only at 154 ⁰ C. With increasing duration, the temperature required for the formation of a condensate decreased further down to about 7O ⁰ C. After 7 hours, the heat was turned off. The initially low-viscosity reaction mixture cooled to 30 ⁰ C. At this temperature, the mixture suddenly became cloudy, the temperature rose without external heating again to about 35 ⁰ C. It is a crystalline solid formed, but the mix could be easily stirred terhin WEI.

The next day, the resulting solid was separated from the supernatant solution and characterized by Si29 NMR. The signals of tetrachlorosilane and dodecachlorone pentasilane were observed.

Example 2

Subsequently, at room temperature, various mixtures of THF (1 g) and hexachlorodisilanes {10 g) were stored for several days. It formed again next to unreacted hexachlorodisilane tetrachlorosilane and dodecachloroneopentasilane. (Proof via Si29)

Example 3 For this experiment were added about 5 g of hexachlorodisilane and about I g catalyst in a mutually versσhraubtes steel tube and heated in an oil bath at 170 ⁰ C.

The investigated catalysts were ~ 15 -Crown- 5 98%, 1, 4, 10, 13 -pentaossacidopentadecano (crown ethers)

- Silicone oil AK20 (not according to the invention)

- THF

- 1,4-dioxane All substances caused the formation of a complex mixture of tetrachlorosilane, octachlorotrisilane, decachloroisopertazilane and dodecachlorneopentasilane. In the case of the silicone oil, however, the decomposition occurred only to a small extent. A pure hexachlorodisilane as a reference remained opaque, even at a temperature of 21O ⁰ C / 24 hours.

Example 4

In an argon-overlaid flask equipped with thermometer, reflux condenser and magnetic stirrer, 106 g of hexachlorodisilane and 10 g of tetrahydrofuran were charged. The mixture was heated at reflux for 5 hours and then cooled. At 26 ⁰ C, this time again an exothermic reaction occurred (temperature increase by about 4 ° C). The next day a further 5 hours was refluxed, again on cooling at 26 ⁰ C, a temperature increase of 4 ° C on. It was concluded that in the crystallization of the adduct tetrachlorosilane and dodecachlorneopentasilan heat is released. After cooling, each colorless crystals were formed, which were filtered off in a glove box and washed with tetrachlorosilane. It could be obtained about 32 g of pesticide.

Si29 NMR confirmed that this was the adduct. In the thermogravimetry, two stages are observed, one at approximately 8O ⁰ C (cleavage of the Tetrachlorsilanes) and at about 280 ⁰ C (evaporation of Dodekachlorneopentasilans). In the DSC (evaporating excess tetrachlorosilane) and at 74 ⁰ C {elimination of the tetrachlorosilane from the ad domestic product) are seen two peaks at 54 ° C. The evaporation, which starts at approx. 290 ^° C, is replaced by an exothermic reaction. This is consistent with gravimetry, which left a non-volatile residue of about 14%. Example 5

Investigation of the dependence of decomposition hexachlorodisilane on the amount of tetrahydrofuran

The investigations were as described in Example 3 in

Steel tube performed at 210 ⁰ C / 3 days. The mixtures were also stored at room temperature for the same time.

9.3% THP: Formation of a mixture of oligochlorosilanes analogous to Example 3 and solid.

5.1% THF: dto

1% THF: dto

0.5% THF: dto

0.25% THF: dto 470 ppm THF: traces of decomposition

240 ppm THF: traces of decomposition

Example 6

The investigations were carried out as described in Example 3 in a steel tube at 100 or 150 ⁰ C for 1.3 days.

At 100 ^° C., 0.1% THF is sufficient to begin the decomposition. Even with minor additions of THF, the formation of the solid dodecachloroneopentasilane is observed.

Claims

claims

1. Process for the preparation of neopentasilanes of the general formula (1)

Si (SiR ₃ ) ₄ (1),

in which silicon compounds of the general formula (2)

R ₃ Si (Si-U _x SiR ₃ (2),

in which

R is selected from H, Cl, Br and J, and x is a nonnegative integer to 5, in the presence of ether compounds (E).

2. The method of claim 1, wherein the cyclic organic ether compounds (E), which have at least 5 Riπgatome and at most 30 ring atoms are used.

3. The method of claim 1 or 2, wherein the Weopentasilan in a molecule has the same meanings of R, which are selected from H and Cl.

4. The method of claim 1 to 3, wherein x is 0 or 1 means.

5. The method of claim 1 to 4, wherein at least 0.2 parts by weight of ether compounds (E) are used for 100 parts by weight of silicon compound of the general formula (2).