description

A process for the preparation of chlorinated oligosilanes

The present invention relates to a method for

The preparation of chlorinated oligosilanes and the use of chlorinated oligosilanes produced by the process for the production of semiconductors and / or hard

Coatings.

M. Schmeisser, P. Voss, Journal of Polymer Science, 1964, 334, 50-56 describe the reaction of solid chlorinated polysilanes (SiCl 2) x with chlorine gas. A l: l mixture of chlorine gas and nitrogen is bubbled at 60 ° C through a vessel containing the solid material. A clear layer low-viscous forms gradually in the solid. After three days the

Solid disappeared and the remaining liquid mixture is fractionated. Isolated components have

Si2Clg, Si3Clg, Si4Cl] _Q and Si5Cl] _2- S1CI4 is not formed during this reaction, and also not in a second reaction with a solution of (SiCl 2) x in CCI4.

The process of Schmeisser and Voss does not lead to full implementation of the Chlorpolysilans and

particularly unsuitable for larger batch quantities, if only a poor contact between gas phase and Chlorpolysilan is given.

E. Bonitz, Applied Chemistry, 1966, 78, 475-482 and DE

B 1132901 describe the reaction of chlorine gas with CaSi2, the chlorine-containing by grinding in the presence of

Diluents has been activated. The silicide initially reacts with chlorine gas at 20-40 ° C to elemental silicon and CaCl2 and thereafter silicon monochloride SiCl. Further addition of chlorine gas, results in the cleavage of Si-Si bonds and, depending on the ratio of added chlorine gas

Starting material, various Si-Cl compounds

receive. Continued chlorination will ultimately lead to

chain-like compounds Si n Cl 2 n +2 m it molecular mass M = 170 - 700. DE 1132901 B additionally discloses that in

Presence of catalytically active metals and silicon or silicon alloys such as Cu or Fe react similarly.

Reaction temperatures between 0 ° C and 250 ° C are

specified, preferably from 20 ° C to 150 ° C. As

Diluents mentioned CCI4, S1CI4, tetrachloroethane and liquid chlorinated polysilanes. The

Reaction rate may be accelerated by elevated pressure during the introduction of chlorine. SiCl4 is not formed during the reaction.

The method of Bonitz requires the activation of the solid silicon-containing materials by milling in

Presence of chlorine-containing diluent before the

Reaction can be carried out with chlorine gas. This

corresponds to an additional processing step in addition to the chlorination, which either requires a special, very mechanically robust reactor design or an additional device, with subsequent transfer of the activated reactive material in the chlorination reactor. In addition, remaining after the reaction CaCl2 and / or the catalyst metals in the reaction mixture as metal impurities

cause problems for the isolation of very pure end products to be.

An object of the present invention to provide an improved process for preparing chlorinated oligosilanes, produced by the method chlorinated oligosilanes and a use for the manufactured chlorinated oligosilanes available.

This object is achieved by the method of claim 1. The product of claim 14 and the use according to claim 15 °. Preferred embodiments are set forth in the dependent claims.

In the novel process for the preparation of

chlorinated oligosilanes is chlorinated polysilane having an empirical formula of SiCl] _ g-2,8 and / or the

chlorinated polysilane containing mixture with elemental chlorine or a chlorine-containing mixture was reacted.

Preferably chlorinated polysilane having an empirical formula of SiCl] _ 6 to 2.2 is used. This process enables the production of chlorinated oligosilanes in good

Yield and high purity, said process is simple to carry out.

Chlorinated polysilanes in the sense of invention

Procedure are compounds which consist of silicon and chlorine, and having at least one Si-Si direct bond. The chlorinated polysilanes possibility for implementing the process both in pure form or as

isomer mixture or are present as a mixture of compounds with different molecular weight. As oligosilanes within the meaning of the process is a

designated subset of the polysilanes containing the molecules of less than or equal to six silicon atoms.

the chlorinated polysilane 6 preferably has an average chain length of n = 4 to n = 50, preferably n = to n = 30, more preferably n = 10 to n = 25 and / or n =. 3

As the chain length n for the purposes of the inventive method, the number of silicon atoms in a polysilane

denotes that are directly or indirectly connected with each other without involving a further chemical element.

In the inventive method chlorinated polysilanes with chlorine gas or chlorine-containing mixtures are reacted. The chlorine-containing blends include gaseous mixtures with inert gases as well as liquid mixtures, and in which chlorine was dissolved in appropriate solvents. Examples of inert gases are helium, nitrogen or argon. Examples of suitable solvents are chlorinated silanes (eg S1CI4) or polysilanes, preferably oligosilanes, particularly preferably Si2Clg, Si3Clg,
and / or Polychlorsilan. The solvent may be converted to the desired product and / or may be either with chlorine, preferably by

Distillation, are separated. If the solvent is separated, it is preferably recycled, that is fed to the process again.

The inventive method can mean a polysilane or a mixture of said polysilanes

Chain lengths without the addition be performed diluents. The polysilane or the mixture of polysilanes can be used in a mixture with at least one diluent. Such diluents which do not react under the reaction conditions with chlorine being preferred. Particularly suitable diluents for carrying out the process are chlorinated polysilanes Si n Cl 2 n +2 ( n = 2, 3, 4) or mixtures thereof, especially S12CI5 and / or Si3Clg. Chlorinated polysilanes as diluent applies the

Condition is not a stability against chlorine under the reaction conditions.

The resulting during the execution of the inventive process product mixture contains SiCl4 and S12CI5. S1CI4 is thereby formed in a stoichiometric ratio compared to S12CI5. The molar ratio of S1CI4 to Si2Clg in the product formed is 0.1 to 1.5, preferably 0.2 to 1.2, particularly preferably 0.25 to first

The inventive method may be

Reaction conditions are carried out, under which

at least partially distilled off within the reaction period S1CI4 from the reaction mixture. The

Reaction conditions may also be selected such that, in addition, at least one chlorinated S1CI4 oligosilane contained in recovered during the reaction period distillate. This is especially true for S12CI5 and / or Si3Clg. contained in the recovered during the reaction period, distillate

Compounds may be outside of the reaction vessel with

Chlorine gas are added and the chlorine solution thus obtained are recycled into the reactor.

Preferably, the chlorination reaction is different in at least two stages at least two

performed temperature ranges. In this way, higher yields and higher purity of the products are obtained. More preferably at the first

Temperature range 100 ° C to 140 ° C and the second

Temperature range 145 ° C to 175 ° C, preferably 155 ° C to 170 ° C. The first temperature range may be achieved exclusively or predominantly by the released reaction enthalpy. In carrying out such a two-stage process, a spontaneous ignition of the reaction mixture can be avoided, which can take place with immediate heating to the higher temperature range.

The chlorination reaction is preferably in a

Pressure range from 100 hPa to 2000 hPa, preferably from 800 hPa to 1500 hPa, more preferably 100 hPa to 1400 hPa,

particularly preferably carried out 1100 hPa to 1300 hPa.

In the inventive method, a further process step may be for the production of chlorinated oligosilanes to the reaction with chlorine to connect, in particular a

Distillation.

The inventive method is adapted to produce products which are suitable for producing semiconductors or hard material layers, in particular the compounds Si2Clg, Si3Clg,
and Si5Cl] _2 or mixtures thereof.

In a first embodiment of the inventive method as a batchwise process is also

Batch process or badge procedure called) are carried out. Here is an intensive mixing of the

Reaction mixture advantageous, for example by vigorous stirring.

If carried out as a batch process, the inventive method and the liquid mixture is brought into contact with chlorine gas, the gas absorption can take place only by the liquid surface, particularly when the liquid is vigorously stirred. It is preferable to flow the chlorine gas in the form of bubbles through the liquid. improve while the contact between gas and liquid and thus the chlorine gas uptake by the reaction solution, a large bubble surface and thus fine bubbles.

When the inventive method is carried out as a batch process, as may additionally fixed

chlorinated polysilanes having the empirical formula SiCl x with x = 0.05 are added to x = 1, preferably x = 0.2 to 0.8. These are also in the process of

Chlorgas in compounds with higher chlorine content implemented.

In a second embodiment of the present invention

This method is a continuous process

carried out. To this end, the chlorinated polysilane or the mixture of chlorinated polysilane or the mixture with at least one diluent may be in a

metered tubular reactor and be brought into contact with chlorine gas in its interior. Is an immovable reactor is used, it is advantageous for these

Increase the contact area between the gas phase and

carry out liquid in the manner of a vertical packed column and to meter the fluid from the top of the reactor.

When the inventive method is carried out as a continuous process, as can liquid phase and

Gas phase are conducted in countercurrent through the tubular reactor.

When the inventive method is carried out as a continuous process, as liquid phase and gas phase can be passed countercurrently through the tubular reactor.

Also in the second embodiment of the inventive method, the reaction conditions can be chosen such that SiCl4 the reactor at least partially gaseous

leaves. The reaction conditions can also be selected such that in addition to SiCl4 at least one chlorinated

Oligosilane contained in the gaseous mixture exiting. This is especially true for Si2Clg and / or Si3Clg.

In the second, continuous embodiment, the liquid reaction mixture can be successively zones

flow through different temperatures within the tubular reactor. It is advantageous if the reaction mixture is initially a zone with lower

Temperature and then a higher temperature zone

crosses.

embodiments

example 1

3052.7 g plasma-chemically produced polysilane chlorinated be diluted with 1388.7 g Si2Clg and filled into an apparatus equipped with stirrer, reflux condenser and gas inlet tube. The reflux condenser is maintained at 60 ° C. Chlorosilanes exiting the reactor are condensed in a cold trap at 0 ° C. The temperature of the

Reaction mixture is maintained between 110 ° C and 120 ° C and within 25.5 h, 950 g of chlorine gas under vigorous

Stir into the reaction mixture. The pressure in the apparatus is kept in the range between 1013 hPa and 1213 hPa. Fractionation of the reaction product yields 760.1 g S1CI4, 3354.9 g Si 2 Cl 6 and 861.8 g of Si 3 Cl 8 . The 401.7 g fractionation residue contained according 29g1 NMR spectroscopy in addition to residues of S13CI8 the compounds i-tetrasilane, neo-pentasilane, and neo-hexasilane in their

perchlorierten Form.

example 2

To 505.7 g S13CI8 100.1 g of a solid having the empirical composition SiClg 7 are placed in a

Apparatus equipped with stirrer and gas inlet tube. The mixture is applied with stirring over 30 h with about 200 g of chlorine gas. The temperature of the

Liquid increases during the chlorine addition by the

exothermic reaction of initially 23 ° C to a maximum of 125 ° C. This maximum temperature is maintained by controlling the chlorine addition rate. Once the reaction rate decreases, which reduced chlorine absorption and decreasing

See temperature, the reaction with heating from the outside is continued to 120 ° C. fractionation of

202, 4 reaction mixture gives g S1CI4, 362, 5 g Si2Clg and 181.7 g Si3Clg. The distillation residue weighs 42.6 g.

example 3

5.710 kg plasma-chemically produced polysilane chlorinated and 5.327 kg fractionation residue from the preceding

Chlorierungsansätzen be with 19.215 kg Si3C18 diluted into an apparatus where, equipped with reflux condenser, stirrer and gas inlet tube. The reflux condenser is maintained at 150 ° C. The reaction mixture is heated to 165 ° C and within 36 h 6.7 kg of chlorine gas was introduced with vigorous stirring into the liquid. The pressure in the

Apparatus is kept between 1013 hPa and 1113 hPa.

During the reaction period, leave 17.82 kg of a chlorosilane mixture containing mainly S1CI4 and S12CI5 and a small amount Si3C18 the apparatus through the reflux condenser, and are condensed in a second condenser at 12 ° C. The oligosilanes be concentrated by distilling off the main part of S1CI4 and

Distillation residue with the content of

Chlorination reactor combined. After fractionation of these liquid 12.660 kg S12CI5 and 3.370 kg S13CI8 addition 1.629 kg mixed fractions are isolated. The 5.745 kg

Fractionation residue is to contain 29g1 NMR spectroscopy in addition to residues of S13CI8 the compounds i-tetrasilane, neo-pentasilane, and neo-hexasilane in their

perchlorierten Form.

example 4

26.27 kg plasma-chemically produced chlorinated polysilanes are with 18.20 kg fractionation residues from the preceding Chlorierungsansätzen and 2.50 kg S12CI5 diluted in an apparatus equilibrated with stirrer, reflux condenser and

Gas inlet tube is fitted. The reflux condenser is maintained at 60 ° C. The temperature of the reaction mixture is initially maintained at 120 ° C, subsequently at a slower

Chlorine uptake at 140 ° and finally heated to 155 ° C. Within 50 h 9.5 kg of gaseous chlorine with vigorous stirring. The pressure inside the apparatus is kept between 1013 hPa to 1250 hPa. Within the

Reaction period are distilled off 14.3 kg of chlorine-containing Sic14 by pressure reduction about every 2 h and condensed in a second condenser at 12 ° C. fractionation of

Reactor contents yields 1.12 kg of S1CI4 / S12CI 5 mixture,

20.39 kg of pure Si 2 Cl 6 and 0.30 kg Si2Cl 6 / Si 3 Cl 8 mixture. 20.20 kg fractionation of residue remain, which contain a mixture of S13CI8 and perchlorinated i-tetrasilane, neo-pentasilane, and neo-hexasilane.

example 5

63.88 g plasma-chemically produced chlorinated polysilanes are dissolved in 52.65 g S12CI5. The solution is in a

Dropping funnel at the upper end of a vertical

Packed column (diameter 2.4 cm, length 25 cm)

transferred, which is filled with 3 mm Raschig rings. The

Column is heated to a constant temperature of 90 ° C. The reaction products are collected in a Schlenk flask at the lower end of the column, which is cooled to 0 ° C. A slow stream of chlorine gas through the column and the collecting flask during the reaction time

maintained. The solution is within 3 hours in the

Column is added dropwise and the chlorine gas stream is maintained for a further 30 minutes, until most of the liquid has passed through the column. A small amount of product remains in the column. Volatile components of the product mixture is vacuum stripped at 200 ° C (63.37 g) and

subsequently fractionally vacuum distillation

subjected (distillation temperatures and yields: 50 ° C: 46.28 g; 100 ° C: 6.45 g; 130 ° C: 1.35 g).

Example 6 (Comparative Example)

223.4 g plasmachemically generated PCS are mixed with 65.4 g Si3Clg. The solution is in the dropping funnel in

Example transferred apparatus described. 5 The column is heated to 155 ° C. After a weak stream of chlorine gas is set by the apparatus, the faucet is

Dropping funnel slightly open. In striking the

Chlorosilane mixture to the column packing the mixture immediately ignited and burns with local and orange glowing of Red flame in the column packing

into beats. The attempt is aborted.

Example 7:

The apparatus described in Example 5 through a further, non-heated and non-insulated packed column (3 cm diameter, 25 cm long, 3 mm Raschig rings) supplemented, that is inserted between a dropping funnel and heated column.

524.9 g plasmachemically generated PCS with 153.7 g

Si3C18 mixed and transferred to the dropping funnel of the apparatus. A weak stream of chlorine gas through both

Packed columns and the collecting flask is set and according to the gas consumption during the reaction

readjusted. The chlorosilane is within 13.5 hours dropped into the upper packed column. The top half of this column heated slowly to less than 50 ° C. The viscosity of the mixture decreased significantly on the way through the upper column and the color intensity of the orange-yellow mixture is also lower. From the top

Column leaking material does not ignite with him

Contact with the heated to 155 ° C column filling. Upon completion of liquid addition a further 30 min maintaining a slight chlorine gas flow. fractionated

Distillation of 892.3 g product mixture under reduced

Pressure gives 185.2 g of a mainly composed of SiCl4 and little Si2Clg fraction, 354.7 g of a mainly composed Si2Clg and little Si3Clg fraction and 223 g of a 9 mainly composed of Si3Clg and little Si2Clg fraction. a residue of 118.5 g of it remains.

claims

1. A process for the preparation of chlorinated oligosilanes, wherein chlorinated polysilane having an empirical formula of SiCl 3 -g and a chlorinated polysilane-containing mixture is reacted with elemental chlorine or a chlorine-containing mixture.

2. The method of claim 1, wherein chlorinated polysilane having an empirical formula of SiCl 6-2.2 is used.

3. The process as claimed in claim 1, wherein the chlorinated polysilane has an average chain length of n = 4 to n = 50, preferably n = 6 to n = 30, more preferably n = 10 to n = 25 and / or n = ,

4. The process as claimed in claim 1, wherein the chlorination reaction is carried out at a temperature of 20 ° C. to 300 ° C., preferably 80 ° C. to 200 ° C., more preferably 110 ° C. to 190 ° C., more preferably 130 ° C. to 170 ° C. ° C.

5. The process according to claim 4, wherein the chlorination reaction is carried out in at least two steps at least two

Different temperature ranges.

6. The method according to claim 5, wherein the first

Temperature range is 100 ° C to 140 ° C and the second temperature range is 145 ° C to 175 ° C, preferably 155 ° C to 170 ° C.

7. The process as claimed in claim 1, wherein the chlorination reaction is carried out in a pressure range from 100,000 PaPa to 2000hPa, preferably 800hPa to 1500hPa, more preferably 10000hPa to 1400hPa, particularly preferably HOOhPa to 1300hPa.

8. The process as claimed in one of the preceding claims, wherein the chlorination reaction is carried out in solution with a

Preferably selected from the group consisting diluents, selected from Si2Clg, Si3Clg, Si4Cl ] _ Q ,

Si5Cl] _2, or mixtures thereof, preferably S12CI5, S13CI8 or mixtures thereof.

9. The process according to claim 1, wherein S1CI4 is distilled off during the chlorination reaction.

10. The method according to claim 9, wherein at least one

Additional chlorinated oligosilane, preferably S12Cl5, S13Cl8 or mixtures thereof, particularly preferably S12Cl5, are distilled off.

11. The process according to claim 1, wherein the chlorination reaction is carried out under full or partial reflux of S1Cl 4 or a mixture of S1Cl 4 and at least one additional chlorinated oligosilane.

12. The process as claimed in one of the preceding claims, wherein the chlorination reaction is carried out continuously, preferably under countercurrent of chlorine-containing gas, to chlorinated polysilane and / or a chlorinated oligosilane in a column.

13. The method as claimed in one of claims 1 to 11, wherein the process is carried out discontinuously.

14. Chlorinated oligosilanes obtainable by the process according to one of claims 1 to 13.

Use of the chlorinated oligosilanes according to claim for the production of semiconductors and / or hard coatings.