EP2454195A1

EP2454195A1 - Method and use of amino-functional resins for the dismutation of halogen silanes and for removing foreign metals

Info

Publication number: EP2454195A1
Application number: EP10725064A
Authority: EP
Inventors: Ekkehard MÜH; Hartwig Rauleder; Jaroslaw Monkiewicz; Reinhold Schork
Original assignee: Evonik Degussa GmbH
Current assignee: Evonik Operations GmbH
Priority date: 2009-07-15
Filing date: 2010-05-18
Publication date: 2012-05-23
Also published as: TW201116485A; US9908781B2; DE102009027730A1; WO2011006697A1; CN102471075A; JP2012532828A; JP5738289B2; CN107253724A; US20120183464A1

Abstract

The invention relates to a method for the dismutation of at least one halogen silane and for reducing the content of foreign metal and/or of a compound containing foreign metal in the at least one halogen silane and in the at least one obtained silane, in which at least one halogen silane of the general formula (I), H_nSiCl_m, wherein n and m are whole numbers and n = 1, 2, or 3, and m = 1, 2, or 3, and n + m = 4, is brought into contact with a particulate organic amino-functional resin; and at least one silane of the general formula (II), H_aSiCl_b, wherein a and b are whole numbers and a = 0, 2, 3, or 4, and b = 0, 1, 2 or 4, and a + b = 4, is obtained in a step in which the content of foreign metal and/or of a compound containing foreign metal is reduced compared to the halogen silane of formula (I). The invention further relates to the use of said resin for the dismutation of halogen silanes and as an adsorbent of foreign metal or compounds containing foreign metal in a method for producing monosilane.

Description

Method and use of amino-functional resins for dismutation of halo-silanes and for removal of foreign metals

The invention relates to a process for the dismutation of at least one halosilane with simultaneous reduction of the content of foreign metal and / or a

A foreign metal-containing compound in a process step of the at least one halosilane and the resulting at least one silane, by at least one halosilane of the general formula I, H _n SiCL (I), where n and m are integers and n = 1, 2 or 3 and m = 1, 2 or 3 and n + m = 4, is contacted with a particulate, organic, amino-functional resin and at least one silane of the general formula II, H _a SiCl _b (II), where a and b are integers and a = 0, 2, 3 or 4 and b = 0, 1, 2 or 4 with a + b = 4, is obtained in one step, and the content of foreign metal and / or foreign metal-containing compounds in the silane over the halosilane of Formula I is reduced. The invention further relates to the use of this resin for dismutation of

Halosilanes and as an adsorber of foreign metals or foreign metal-containing compounds in a process for the preparation of monosilane.

In the semiconductor and solar industries silicon compounds, Si-H containing silicon compounds such as dichlorosilane or silane / monosilane, high and highest purity are needed. Silicon compounds used in microelectronics, such as for the production of high-purity silicon by means of epitaxy or silicon nitride (SiN), silicon oxide (SiO), silicon oxynitride (SiON), silicon oxycarbide (SiOC) or silicon carbide (SiC), also have to meet particularly stringent requirements to fulfill your purity. This is especially true in the production of thin layers of these materials. In chip production, contamination of the silicon compounds with metallic impurities results in undesirable doping of the epitaxial layers, e.g. Epitaxial silicon layers.

For example, silicon tetrachloride (SiCl ₄ ) is used inter alia for the production of optical waveguides. For these applications, SiCI ₄ is required in very high purity. In particular, metallic and / or metal-based

Contaminants of significant disadvantage, even if they are contained only in the detection limit or in quantities of a few μg / kg (= ppb). Metallic Impurities in halogenated silanes negatively affect the attenuation behavior of optical fibers by increasing the attenuation values and thus reducing signal transmission.

In addition, high-purity HSiCI ₃ for the production of monosilane or monosilane for thermal decomposition to ultrapure silicon is an important starting material in the production of solar or semiconductor silicon. In general, high purity halosilanes are desirable starting materials in the electronics, semiconductor, and pharmaceutical industries.

The preparation of hydrogen-containing chlorosilanes or monosilane is carried out by dismutation of higher chlorosilanes in the presence of a

Dismutization catalyst for faster adjustment of the chemical

Balance. Thus, monosilane (SiH ₄ ), monochlorosilane (CISiH ₃ ) and also

Dichlorosilane (DCS, H ₂ SiCl ₂ ) from trichlorosilane (TCS, HSiCl ₃ ) to form the

Coupling product produced silicon tetrachloride (STC, SiCI ₄ ). Corresponding processes and amine-functionalized inorganically supported and organopolysiloxane dismutation catalysts are disclosed in DE 371 1444 C2 and DE 3925357 C1.

Due to the production process of, for example, tetrachlorosilane or trichlorosilane from silicon, the impurities present in silicon are usually also chlorinated and sometimes entrained in the subsequent synthesis steps.

In particular, the chlorinated metallic impurities have a detrimental effect on the production of components in the field of electronics, in particular the difficult to separate dissolved compounds. Nearly complete removal of the metals and semimetals attributed to the metal before or after the subsequent dismutation is expensive and expensive.

The separation of boron-containing impurities from silicon compounds with CH ₃ CN to form complexes of higher-boiling boron adducts disclosed in US 2812235. The separation of the adducts requires a further costly

Process step. Usually a column distillation, such as a rectification.

Alternatively, the separation can also be carried out by adsorption on adsorber, the then mechanically, for example by filtration, or must be separated by distillation. Known adsorbers are activated carbons, silicic acids, for example pyrogenic silicic acids, or silicates, such as montmorillonites, as well as zeolites, for example

Wessalith F20, and organic resins, such as Amberlite XAD4.

From DE 28 52 598 a complex three-stage cleaning process using initially cationic resins, and subsequently anionic resins and in the third step of activated carbon is disclosed.

The object of the present invention was to develop an economical and simpler process which gives the hydrogen-containing silanes or chlorosilanes in high purity. Furthermore, the task was to make the use of methods more efficient.

The objects are achieved according to the information in the claims, preferred embodiments are set forth in the dependent claims and in detail in the description.

Surprisingly, it has been found that by contacting at least one halogenosilane of formula I with a particulate, especially purely organic, amino-functional resin, preferably a dialkylamino or

dialkylaminomethylene-functionalized or trialkylammonium or

trialkylammoniummethylen-functionalized divinylbenzene-styrene copolymer, at least one silane of the general formula II and / or a halosilane of the formula II is obtained in which the content of foreign metal and / or foreign metal-containing compound compared to the halosilane of the formula I used is significantly reduced , Thus, it has surprisingly been found that a dialkylamino- or dialkylaminomethylene-functionalized or trialkylammonium or

trialkylammoniummethylen-functionalized divinylbenzene-styrene copolymer can be used both as a dismutation catalyst and simultaneously as an adsorbent in a single process step to obtain from purified halosilanes of the formula I, in particular from trichlorosilane-containing halosilanes, purified silanes of the formula II. Preferred purified dismutation products are dichlorosilane and most preferably monosilane. The used amino-functionalized resin acts as adsorbent and catalyst. It is used according to the invention substantially anhydrous and free of organic solvents in the process or use.

The invention thus provides a process for the dismutation of at least one halosilane; and optionally a halosilane-containing mixture; while simultaneously reducing the content of foreign metal and / or a foreign metal-containing compound of the at least one halosilane and to obtain at least one silane,

by at least one halosilane of general formula I,

H _n SiCl (I) where n and m are integers and n = 1, 2 or 3 and m = 1, 2 or 3 and with the proviso n + m = 4, n = 1 and m = 3 (trichlorosilane) are preferred ; wherein preferably the halosilane is metered into the process continuously or discontinuously and / or refluxed;

- with a particulate, organic; especially pure organic;

amino-functional resin is brought into contact and at least one silane of the general formula II, preferably two silanes or a mixture containing at least one silane of the formula II,

HaSiClb (II) where a and b are integers and a = 0, 2, 3 or 4 and b = 0, 1, 2 or 4 with a + b = 4, preferably with x = 0, 2 or 4 and y = 4, 2 or 0; and in particular the halosilane of the formula I is different from the silane of the formula II,

- Is obtained in which the content of foreign metal and / or foreign metal

containing compounds is reduced compared to the halosilane of the formula I. According to the invention, the dismutation of the halosilane and the recovery takes place of the purified silane, the halosilane or a mixture containing them in a single process step, in particular during a reactive distillation or reactive rectification for the preparation of monosilane (a = 4) and / or dichlorosilane (a = 2, b = 2) from trichlorosilane (n = 1 , m = 3) and trichlorosilane containing

Partial streams.

The invention thus relates to a method for dismutating a

Halogensilans of the formula I to obtain a silane of the formula I, wherein the silane of the formula I is different from the halosilane of the formula II used, and dismutiert in particular with the contacting with the resin and at the same time containing a content of foreign metal and / or foreign metal Connection is reduced.

Preferably, the process is carried out such that trichlorosilane both

discontinuously or continuously fed to the process and at the same time in a trichlorosilane-containing substream is brought into contact with the resin. The trichlorosilane-containing partial stream can come about through the reactive distillation or reactive rectification.

The reactive distillation is characterized by a combination of reaction and distillative separation in a device, in particular a column and optionally in a side reactor associated with the column. Due to the constant distillative removal of the respective lightest boiling compound in each space element is always an optimal gap between the equilibrium state and actual content of low-boiling compound, such as monosilane, maintained so that a maximum reaction rate results.

The anhydrous and solvent-free resin is particularly suitable for dismutating and purifying the halosilane of the formula I, so that after the distillative removal of the silane of the formula II, in particular the monosilane, no further

Cleaning steps, such as contacting with activated carbons are more necessary. The silane of the formula I obtained can be directly thermally decomposed to ultrapure silicon, which is preferably used in the solar and electronics industry. Likewise, that can Thus obtained silicon tetrachloride can be used directly for the production of SiO ₂ for the production of optical waveguides.

For the process according to the invention and also for the use according to the invention, it is essential that the resin is essentially anhydrous and free from

organic solvents. Preferably, the resin, such as Amberlyst ^® A21 or A26OH, already anhydrous and solvent-free in the process and optionally in the apparatus for carrying out the process under a protective gas atmosphere, such as under nitrogen, argon introduced. This has hitherto been considered industrially unworkable. Therefore, in the prior art, the catalyst or an adsorbent is only washed in the system in which it is used with organic solvents or transferred in organic solvents in the system and then freed from the organic solvents. Preferably, a mixture of the resin with other adsorbents or Dismutierungskatalysatoren be used to achieve an optimal reduction in the content of foreign metals, such as iron, aluminum and also semi-metals, such as boron.

By definition, a resin is said to be substantially anhydrous and free of organic solvents when the content of water or organic solvent, respectively, relative to the total weight of the resin, is less than about 2.5 wt% to, for example, 0.0001 wt%, especially less than 1, 5 wt .-%, preferably less than 1, 0 wt .-%, preferably less than 0.5 wt .-%, particularly preferably 0.3 wt .-%, better less than 0.1 or ideally less than 0.01 Wt .-% to the detection limit is, for example, to 0.0001 wt .-%.

It is particularly advantageous that the foreign metal content and / or the content of the foreign metal-containing compound, - is usually a residual content of foreign metal or foreign metal-containing compound which can be poorly distilled or not further separate - especially independently each can be reduced to a content in the range of below 100 ug / kg, in particular below 75 ug / kg, preferably below 25 ug / kg, preferably below 15 ug / kg, more preferably below 10 ug / kg. The degree of reduction of the foreign metal content is also due to the ratio of resin to halosilane and / or silane and the contact time is determined. The person skilled in the art knows how to determine the optimum treatment conditions.

The purely organic, amino-functional resin used according to the invention is outstandingly suitable for dismutation and at the same time for the adsorptive removal of poorly separable foreign metal-containing compounds which dissolve in the halosilanes and / or the silanes of the formula II formed or are completely dissolved therein. The adsorptive separation of the foreign metal-containing compounds is believed to occur by complex formation of the foreign metal-containing compound and the resin. Particulate foreign metals are apparently more mechanically retained by the particulate-packed resin.

The determination of the foreign metals or of the foreign metal-containing compounds can generally be carried out by quantitative analysis methods, as known to those skilled in the art, for example by atomic absorption spectroscopy (AAS) or photometry, in particular by inductively coupled plasma mass spectrometry (ICP -MS) and Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) - to name but a few. The

Adsorbent is essentially anhydrous and solvent-free. The water content in the adsorbent can be determined via Karl Fischer (DIN 51 777) and the solvent content can be detected, for example, by means of TGA-MS, TGA-IR or other analytical methods known to the person skilled in the art. Solvents are alcohols, such as methanol, ethanol, or acetone and aromatic solvents, such as toluene.

As foreign metals and / or foreign metal-containing compounds are considered those in which the metal or semimetal does not correspond to silicon. The

Adsorption of the at least one foreign metal and / or foreign metal-containing compound takes place in particular selectively from the halosilanes and / or silanes, while the adsorption can be carried out both in solution and in the gas phase. As foreign metals or foreign metal-containing compounds are also understood half metals or compounds containing semimetals, such as boron and boron trichloride. In particular, the foreign metals and / or foreign metal-containing compounds to be reduced are metal halides,

Metallhydrogenhalogenide and / or metal hydrides and mixtures of these

Links. Metal halides can be removed with very good results. Examples thereof may be aluminum trichloride or else iron (III) chloride as well as entrained particulate metals, which may originate from continuous processes.

The contents of boron, aluminum, potassium, lithium, sodium,

Magnesium, calcium and / or iron are reduced, more preferably, the content of boron and iron in the halosilane and / or silane can be significantly reduced, in particular, compounds based on these metals are separated. As stated above, the compounds are often dissolved in the composition and can be poorly separated by distillation, such as BCI ₃ .

The inventive method and the inventive use are particularly suitable for the separation or reduction of foreign metal-containing

Compounds whose boiling point is in the range of the boiling point of a silane of formula II or would go with this as an azeotrope. This foreign metal

containing compounds can sometimes be difficult to remove by distillation or not at all. As the boiling point, which is in the range of the boiling point of a silane, a boiling point is considered, which is in the range of ± 20 ⁰ C of the boiling point of one of the silanes of formula II at atmospheric pressure (about 1013.25 hPa or 1013.25 mbar).

The compounds to be adsorbed are distinguished by the fact that, as a rule, they are completely dissolved in the halosilane, silane or the mixture containing them and can only be separated off poorly by distillation.

In general, the foreign metal and / or the foreign metal-containing

Compound be reduced by 50 to 99 wt .-%. Preferably, the foreign metal content is reduced by 70 to 90 wt .-%, preferably by 70 to 99 wt .-%, particularly preferably by 85 to 99 wt .-%. For iron-containing halosilanes, silanes, or mixtures containing them, the process allows reduction of the Residual content by 70 wt .-%, preferably 95 to 99 wt .-%. In general, for example, the iron content can be reduced by from 50 to 99% by weight, preferably from 70 to 99% by weight, and the boron content by at least 90% by weight, preferably by from 95 to 99.5% by weight, in particular a process step, preferably directly in the context of the disproportionation step.

The foreign metal content and / or the content of the foreign metal-containing compound in the halosilane, silane or mixture containing these may preferably in relation to the metallic compound, in particular independently of each other, each in a range ranging from below 100 ug / kg up to the detection limit, in particular of less than 25 μg / kg, preferably less than 15 μg / kg, particularly preferably 0.1 to 10 μg / kg, down to the respective detection limit.

To carry out the process, amino-functionalized, aromatic polymers having alkyl-functionalized secondary, tertiary and / or quaternary amino groups can be used particularly preferably as purely organic amino-functional resins. The alkyl groups may be linear, branched or cyclic, preferably methyl or ethyl. According to the invention, amino-functionalized divinylbenzene-styrene copolymers can be used, i. H. Divinylbenzene cross-linked polystyrene resin, wherein the from the group of dialkylamino-functionalized or dialkylamino-functionalized divinylbenzene-styrene copolymers or trialkylammonium-functionalized or tπalkylammoniummethylen-functionalized divinylbenzene-styrene copolymers, in particular with alkyl is methyl or ethyl, particularly preferred are the respective di- or trimethyl-substituted aforementioned species are preferred.

In addition to the dimethylamino-functionalized with divinylbenzene crosslinked, porous polystyrene resins, other functionalized with quaternary and optionally tertiary amino groups functionalized with divinylbenzene, porous polystyrene resins can be used in the process according to the invention or for use in the process according to the invention. The resins are all characterized by high specific surface area, porosity and high chemical resistance. The following formulas ideally illustrate the structure of the above-mentioned functionalized divinylbenzene-styrene copolymers:

alkyl

\ Dialkylamino-functionalized

I N R '

/ Divinylbenzene-styrene copolymer,

alkyl

\ Dialkylaminomethylene-functionalized

IN CH ₂ R '

/ Divinylbenzene-styrene copolymer,

alkyl

^Alk V ' _Δ θ

I ^A trialkylammoniumfunktionalisertes

Alkyl N R '

I divinylbenzene-styrene copolymer

Alkyl as well

Alkyl _Q

I A trialkylammoniummethylenfunktionalisiertes

Alkyl N CH ₂ R '

I divinylbenzene-styrene copolymer,

Where R 'is a polymeric carrier, in particular divinylbenzene crosslinked polystyrene, ie divinylbenzene-styrene copolymer, alkyl independently is preferably methyl, ethyl, n-propyl, i-propyl, n-butyl or i-butyl and A is ^® independently an anion - for example, but not exclusively - of the series ^θ OH (hydroxy) Cl ^"(chloride), CH ₃ ^COO" (acetate) or HCOO ^"(formate) is, in particular OH ^®.

Particularly suitable for the process according to the invention or the use is divinylbenzene crosslinked polystyrene resin having tertiary amino groups as Dismutierungskatalysator and at the same time as an adsorbent, such as Amberlyst ^® A 21 an ion exchange resin based on divinylbenzene cross-linked polystyrene resin Dimethylamino groups on the polymeric backbone of the resin. Amberlyst A21 is a weakly basic anion exchange resin, in the form of the free base and in spherical beads having an average diameter of about 0.49 to 0.69 mm and a water content of up to 54 to 60 wt .-% relative to the total weight can be purchased. The surface is about 25 m ² / g and the middle

Pore diameter at 400 Angstroms.

Likewise can Amberlyst ^® A 26 OH, which is based on a quaternary trimethylamino- functionalized divinylbenzene-styrene copolymer, and has a highly porous structure, can be used in the inventive process and the inventive use. The average particle diameter of the resin is usually 0.5 to 0.7 mm. The resin is sold as an ionic form (so-called hydroxide form, "OH") The water content can be from 66 to 75% by weight relative to the total weight The surface area is about 30 m ² / g with an average pore diameter of 290 angstroms.

The invention also provides a process in which a purely organic, in particular substantially anhydrous and solvent-free, amino-functional resin for dismutating at least one halosilane and for reducing the content of foreign metal and / or a foreign metal-containing compound thereof and the Dismutierungsprodukte, d. H. of the formula I and / or II, with

- (i) trichlorosilane, of the formula I, is brought into contact and, a silane of the formula II, such as monosilane, monochlorosilane, dichlorosilane and tetrachlorosilane or a mixture containing at least two of said compounds wins, or with

- (ii) dichlorosilane, of formula I, and a silane of formula II, such as monosilane, monochlorosilane, trichlorosilane and silicon tetrachloride or a

Mixture of at least two of said compounds wins, and after the contacting in (i) or (ii) the content of foreign metal or foreign metal-containing compound is reduced.

A particular advantage of the process according to the invention is that it does not accumulate, as in the processes of the prior art, the content of impurities in the higher chlorinated halosilanes, such as tetrachlorosilane. After this Processes according to the invention can be both pure monosilane, dichlorosilane,

Monochlorosilane and pure tetrachlorosilane, optionally after distillative separation, are obtained. Subsequent or upstream steps for the separation of foreign metals or foreign metal-containing compounds or organic impurities, with the exception of possibly phosphorus-containing compounds can be omitted.

According to a further aspect of the invention, a particulate, organic, amino-functional resin is used, preferably as defined above

Dismutation of at least one halosilane of the general formula I and for substantially simultaneous reduction of the content of at least one

Foreign metal and / or at least one foreign metal-containing compound of the halosilane and the resulting at least one silane of the formula II or

Mixtures containing these used, wherein the formulas I and II are as defined above.

The use preferably takes place for the dismutation of a halosilane or of mixtures comprising halosilanes and, in particular, simultaneous ones

Use, for reducing the content of at least one foreign metal and / or at least one foreign metal-containing compound of at least one

Halosilanes, silanes or mixtures comprising halosilanes according to

The process described above, more preferably according to any one of claims 1 to 8. According to the invention, the resin is used substantially anhydrous and free of organic solvents.

In general, the process according to the invention or the use according to the invention of amino-functional resins for dismutation and adsorption is carried out in a process step such that first the resin is optionally washed 1) with ultrapure, deionized water, and 2) subsequently

Water-containing resin, without further treatment, under the application of vacuum or vacuum and optionally with the regulation of the temperature is prepared anhydrous, especially at a temperature below 200 ⁰ C; optionally in a 3) step, a vacuum inert gas or dried air takes place; and the anhydrous and solvent-free catalyst is obtained after step 2) or 3). In the subsequent step, the catalyst thus prepared with the halosilane of the formula I for carrying out the inventive

Method are brought into contact, in particular according to one of claims 1 to 10.

Preferably, the resin is treated under vacuum at elevated temperature, more preferably below 150 ° C. According to an alternative, the treatment process of the resin may also be carried out without step 1). The treatment of

Amino-functional resin is preferably in the temperature range between -196 ⁰ C to 200 ⁰ C, in particular between 15 ⁰ C to 175 ⁰ C, preferably between 15 ° C to 150 ⁰ C, more preferably between 20 ° C to 135 ⁰ C, most preferably between 20 ⁰ C to 1 10 ⁰ C, in which case the temperature range of 20 ° C to 95 ⁰ C is particularly preferred. Usually, the treatment after adjusting the temperature in the temperature range between 60 ° C to 140 ⁰ C, in particular between 60 ⁰ C and 95 ⁰ C, carried out, preferably under reduced pressure and optionally with movement of the particulate resin.

It is preferred if the treatment of the amino-functional resin takes place under reduced pressure between 0.0001 mbar to 1012 mbar (mbar absolute). In particular, the vacuum is at values between 0.005 mbar to 800 mbar, preferably between 0.01 mbar to 600 mbar, more preferably between 0.05 to 400 mbar, more preferably between 0.05 mbar to 200 mbar, more preferably between 0.05 mbar to 100 mbar, in particular between 0.1 mbar to 80 mbar, more preferably between 0.1 mbar to 50 mbar, even better between 0.001 to 5 mbar, more preferably the pressure is below 1 mbar. Preferably, a vacuum or vacuum between 50 mbar to 200 mbar preferably up to less than 1 mbar and 50 mbar at elevated temperature, in particular at 15 ⁰ C to 180 ⁰ C, more preferably between 20 ⁰ C to 150 ⁰ C. Preference is given to treating at below 100 ^° C. and a pressure in the range from 0.001 to 100 mbar, preferably from 0.001 to 70 mbar. The

Fluctuation of the determinable water content can be increased by plus / minus

0.3 wt .-% are. The above treatment of the amino-functional, up to 40 to 70 wt .-% water-containing resin in the temperature range between 80 ^C C to 140 ⁰ C below

Underpressure at 50 mbar to 200 mbar to less than 1 mbar has proven to be particularly advantageous for adjusting a water content of less than 2 wt .-%, preferably from below 0.8 wt .-% to below 0.5 wt .-%, below at the same time preserving the structure. In addition, drying can be carried out industrially in an acceptable process duration under these conditions. On the use of organic

Solvents can be completely dispensed with in order to be able to use the resin as dismutation catalyst and as adsorbent for the preparation of highly pure silanes of the formula I and / or highly pure tetrachlorosilane. Particularly noteworthy is that the resin by drying under negative pressure its internal porous structure and its external shape, and thus its activity as an adsorbent and at the same time

Dismutierungskatalysator receives and maintains. The water content of the aminofunctional resin thus treated is preferably less than 2.5% by weight, especially

preferably between 0.00001 to 2% by weight.

The water content can be determined, for example, according to Karl Fischer (Karl Fischer Titration, DIN 51 777). The water contents of the amino-functional resin which can be adjusted after the treatment according to the invention are advantageously between 0, d. H. not detectable with KF, and 2.5 wt .-%, in particular between 0.0001 wt .-% to 2 wt .-%, preferably between 0.001 to 1, 8 wt .-%, particularly preferably between 0.001 to 1, 0 Wt .-%, more preferably between 0.001 to

0.8 wt .-%, more preferably 0.001 to 0.5 wt .-%, 0.001 to 0.4 wt .-% or 0.001 to 0.3 wt .-%. At the same time, said treatment of the resin allows the structure of the dismutation catalyst and adsorbent to be preserved while avoiding the use of organic solvents.

The above-mentioned treatment method of the resin ensures that in the reactive / distillative reaction zone with catalyst bed, a substantially anhydrous, solvent-free and at the same time highly pure resin which is free from

Impurities is, can be used. Thus, the resin itself does not lead to any additional entry of impurities that would have to be removed, for example, with a bottoms product from a reactive / distillative plant. For the dismutation of the at least one halosilane of the formula I and the

Reduction of the content of foreign metal or foreign metal-containing

Compounds, the resin is treated as described above to a

Prevent hydrolysis of the silanes to be purified, brought under inert gas with the halosilanes in contact, optionally stirred. Suitably, the contacting takes place at room temperature and atmospheric pressure for several hours. Typically, the halosilane is contacted with the resin for between 1 minute to 10 hours, typically up to 5 hours. The recovery or separation of the dismutated and purified silanes and / or halosilanes is usually carried out by distillation. Alternatively, it is preferable to carry out the process by reactive / distillation as described above.

The invention likewise relates to the use of a resin treated by the above process for dismutating chlorosilanes and for adsorption, in particular for simultaneous adsorption, of foreign metals and compounds containing them, in particular for the preparation of dichlorosilane, monochlorosilane or monosilane from more highly substituted chlorosilanes the educts are purer. Preferably, the treated resin may be used to dismutate (i) trichlorosilane to give monosilane, monochlorosilane, dichlorosilane and tetrachlorosilane or a mixture containing at least two of said compounds or (ii)

Dichlorosilane are used and monosilane, monochlorosilane, trichlorosilane and silicon tetrachloride or a mixture of at least two of the mentioned

Compounds are obtained.

The process according to the invention is particularly preferably integrated into a multistage overall process for the preparation of ultra-pure silicon, which comprises the following steps: 1) preparation of trichlorosilane, 2) disproportionation and adsorption of compounds containing foreign metals or foreign metals, 3) distillation to form the purest silane of the formula II and 4) thermal decomposition of the silane (monosilane) to ultrapure silicon. The term "ultra-pure silane" refers to a silane which is suitable for the production of ultra-pure silicon for use as solar silicon or semiconductor silicon. The invention is further illustrated by the following examples without being limited to these examples.

Example 1.1

Pretreatment of the resin or of the pure adsorbents. The adsorbents are carefully dried prior to use in the process to prevent hydrolysis of the halosilanes to be purified.

Example 1.2

General procedure for the treatment of contaminated with foreign metals and / or metallic compounds halosilane.

A defined amount of amino-functionalized resin or adsorbent are placed in a 500 ml stirred apparatus comprising a glass four-necked flask with condenser (water, dry ice), dropping funnel, stirrer, thermometer and nitrogen inlet and under vacuum (<1 mbar) and the a) amino -functionalized resin and Amberlite ™ XAD 4 dried at 95 ° C and b) the other adsorbents at 170 ° C each dried over 5 hours, then slowly aerated with dry nitrogen and cooled.

Subsequently, 250 ml of the halosilane are added via the dropping funnel. Over a period of 5 hours, the adsorption process is carried out under normal pressure at room temperature under a protective gas atmosphere. The adsorbent is separated from the silane by passing it through a frit (Por. 4) into an evacuated 500 ml glass flask with a vent. Subsequently, the

Vented glass flask with nitrogen and drained into a nitrogen-purged Schott glass bottle.

Example 1.3 - Comparative Example

The following example was carried out according to the general procedure with the amounts given here. 36.0 g of Amberlite ™ XAD 4 were pretreated according to the general procedure described in Example 1 .2 and 250 ml of trichlorosilane were added. The metal contents before and after treatment were determined by ICP-MS. The trichlorosilane content was determined by gas chromatography (area percent).

Table 1.3

Foreign metal contents before and after treatment:

Example 1.4 - Comparative Example

The following example was carried out according to the general procedure with the amounts given here.

36.9 g of montmorillonite K 10 were pretreated as described in the general procedure under Example 1 .2, and 250 ml of trichlorosilane were added. The metal contents before and after treatment were determined by ICP-MS. The trichlorosilane content was determined by gas chromatography (area percent).

Table 1.4

Foreign metal contents before and after treatment:

Example 1.5 - Comparative Example

20.0 g of Wessalith F 20 were pretreated as described in the general procedure under Example 1 .2, and 250 ml of trichlorosilane were added. The metal contents before and after treatment were determined by ICP-MS. The trichlorosilane content was determined by gas chromatography (area percent).

Table 1.5

Foreign metal contents before and after treatment:

Example 1.6 - Inventive

14.2 g of Amberlyst A21 ^® (dry mass) were prepared as described in the general procedure in Example 1 .2 pretreated and 250 ml of trichlorosilane were added. The metal contents before and after treatment were determined by ICP-MS. The composition was determined by gas chromatography (area percent). Table 1.6 Foreign metal contents before and after treatment and composition:

^* Monochlorosilane was detected in trace amounts. Due to the low boiling points, the reaction products monochlorosilane and monosilane could not be quantitatively retained in the reaction mixture.

Example 1.7 - according to the invention

80.2 g Amberlyst ^® A21 (28.9 g dry weight) were prepared as described in the general procedure in Example 1 .2 pretreated and 250 ml of trichlorosilane were added. The composition was determined by gas chromatography

(Area percent).

Table 1.7 - Composition

Monochlorosilane could be detected in traces. Due to the low boiling points, the reaction products monochlorosilane and monosilane could not be quantitatively retained in the reaction mixture.

Claims

claims

1 . Process for the dismutation of at least one halosilane and reduction of the content of foreign metal and / or a foreign metal-containing

Compound of the at least one halosilane and of the at least one silane obtained,

by at least one halosilane of general formula I,

H _n SiCL (I) where n and m are integers and n = 1, 2 or 3 and

m = 1, 2 or 3 and n + m = 4,

- Is brought into contact with a particulate, organic, amino-functional resin and at least two silanes of the general formula II

HaSiClb (II) where a and b are integers and a = 0, 2, 3 or 4 and b = 0, 1, 2 or 4 with a + b = 4, and formula I is different from formula II,

- Be won, in which the content of foreign metal and / or foreign metal-containing compounds compared to the halosilane of the formula I is reduced.

2. The method according to claim 1,

characterized,

that the halosilane of the formula I with n = 1 and m = 3, trichlorosilane.

3. The method according to claim 1 or 2,

characterized,

the halosilane of the formula I is contacted with n = 1 and m = 3 in a trichlorosilane-containing substream with the resin.

4. The method according to any one of claims 1 to 3,

characterized,

that the resin is substantially anhydrous and free of organic solvents.

5. The method according to any one of claims 1 to 4,

characterized,

that the resin is a dialkylamino- or dialkylaminomethylene-functionalized divinylbenzene-styrene copolymer or trialkylammonium or

trialkylammonium methylene functionalized divinylbenzene-styrene copolymer.

6. The method according to any one of claims 1 to 5,

characterized,

that the resin for the dismutation of at least one halosilane and

Reduction of the content of foreign metal and / or a foreign metal-containing compound of these, with

(i) trichlorosilane is contacted and monosilane, monochlorosilane,

Dichlorosilane and tetrachlorosilane or a mixture containing at least two of the compounds mentioned wins, or with

- (ii) contacting dichlorosilane and monosilane, monochlorosilane,

Trichlorosilane and silicon tetrachloride or a mixture of at least two of said compounds wins, and after the contacting in (i) or (ii) the content of foreign metal or foreign metal-containing compound is reduced.

7. The method according to any one of claims 1 to 6,

characterized,

in that the foreign metal and / or the foreign metal-containing compound comprises boron and / or iron.

8. The method according to any one of claims 1 to 7,

characterized,

a silane of formula II, as defined in claim 1, is in particular monosilane, which is distilled after being brought into contact with the resin and is thermally decomposed to ultrapure silicon.

9. Use of a particulate, organic, amino-functional resin for dismutating at least one halosilane of the general formula I and for substantially simultaneously reducing the content of at least one foreign metal and / or at least one foreign metal-containing compound of the halosilane and the resulting at least one silane of the formula II, wherein the formulas I and II are defined according to claim 1.

10. Use according to claim 9, for dismutating a halosilane or mixtures comprising halosilanes and for reducing the content of at least one foreign metal and / or at least one foreign metal-containing compound of at least one halosilane or mixtures comprising halosilanes according to one of claims 1 to 8.