PROCESS FOR THE PREPARATION OF PURE OCTACHLOROTRISILANES AND DECACHLOROTETRASILANES

Abstract

The invention relates to a process for producing trimeric and/or quaternary silicon compounds or trimeric and/or quaternary germanium compounds, where a mixture of silicon compounds or a mixture of germanium compounds is exposed to a nonthermal plasma, and the resulting phase is subjected at least once to a vacuum rectification and filtration.

Claims

1. A process for the preparation of at least one compound selected from the group consisting of trimeric and quaternary silicon compounds of the general formula Si.sub.3X.sub.8, Si.sub.4X.sub.10, or both or of at least one compound selected from the group consisting of trimeric and/or and quaternary germanium compounds of the general formula Ge.sub.3X.sub.8, and/or Ge.sub.4X.sub.10, or both, the process comprising: a) exposing a mixture of silicon compounds of the general formula
Si.sub.n(R.sub.1 . . . R.sub.2n+2) or a mixture of germanium compounds of the general formula
Ge.sub.n(R.sub.1 . . . R.sub.2n+2) to a nonthermal plasma to form a resulting phase wherein n2, and R.sub.1 to R.sub.2n+2 is at least one element selected from the group consisting of hydrogen and X wherein X is at least one halogen selected from the group consisting of chlorine, bromine, and iodine, and b) subjecting the resulting phase at least once to a vacuum rectification and filtration, thereby obtaining silicon compounds of the general formula Si.sub.3X.sub.8 or Si.sub.4X.sub.10 or germanium compounds of the general formula Ge.sub.3X.sub.8 or Ge.sub.4X.sub.10.

2. The process according to claim 1, wherein with n3.

3. The process according to claim 1, further comprising subjecting the resulting phase to an adsorption, after or before the subjecting to a vacuum rectification and filtration b.

4. The process according to claim 1, wherein the process exposing to a nonthermal plasma a), the process subjecting to a vacuum rectification and filtration b), or both take place continuously.

5. The process according to claim 1, wherein the exposing to a nonthermal plasma treatment in process a) takes place at pressures from 1 to 1000 mbar.sub.abs.

6. An apparatus configured for continuously carrying out the process according to claim 1, the apparatus comprising: a reactor suitable for generating the nonthermal plasma, and at least one vacuum rectification column, and at least one filtration apparatus, adsorption apparatus, or both.

7. The apparatus according to claim 6, wherein the reactor is an ozonizator.

8. The apparatus according to claim 6, wherein the reactor is equipped with glass tubes.

9. The apparatus according to claim 8, wherein the glass tubes in the reactor are kept at a distance by a spacer comprising an inert material.

10. The apparatus according to claim 9, wherein the inert material of the spacer is glass or Teflon.

11. A method, comprising: producing silicon nitride, silicon oxynitride, silicon carbide, silicon oxycarbide or silicon oxide, or germanium nitride, germanium oxynitride, germanium carbide, germanium oxycarbide or germanium oxide from the silicon compounds or the germanium compounds produced according to claim 1.

12. The method according to claim 11 comprising producing the silicon nitride, silicon oxynitride, silicon carbide, silicon oxycarbide or silicon oxide, or of the germanium nitride, germanium oxynitride, germanium carbide, germanium oxycarbide or germanium oxide in the form of layers.

13. The apparatus according to claim 8, wherein the glass tubes are quartz glass tubes.

14. The process according to claim 1, wherein the silicon compounds of the general formula Si.sub.3X.sub.8 or Si.sub.4X.sub.10 or the germanium compounds of the general formula Ge.sub.3X.sub.8 or Ge.sub.4X.sub.10 have a content of hydrogen atoms below 110.sup.3% by weight relative to the total weight of the compounds.

15. The process according to claim 1, wherein the silicon compounds of the general formula Si.sub.3X.sub.8 or Si.sub.4X.sub.10 or the germanium compounds of the general formula Ge.sub.3X.sub.8 or Ge.sub.4X.sub.10 have a total contamination content of less than or equal to 100 ppm by weight relative to the total weight of the compounds.

16. The process according to claim 15, wherein the total contamination content comprises at least one contaminant selected from the group consisting of aluminum, boron, calcium, iron, nickel, phosphorous, titanium, zinc, carbon, and hydrogen.

17. The process according to claim 1, wherein the silicon compounds of the general formula Si.sub.3X.sub.8 or Si.sub.4X.sub.10 or the germanium compounds of the general formula Ge.sub.3X.sub.8 or Ge.sub.4X.sub.10 are at least one compound selected from the group consisting of decachlorotetrasilane and decachlorotetragermane.

18. The process according to claim 1, wherein the nonthermal plasma is an electrically generated plasma.

19. A process for the preparation of quaternary silicon compounds of the general formula Si.sub.4X.sub.10 or of quaternary germanium compounds of the general formula Ge.sub.4X.sub.10, the process comprising: a) exposing a mixture of silicon compounds of the general formula
Si.sub.n(R.sub.1 . . . R.sub.2n+2) or a mixture of germanium compounds of the general formula
Ge.sub.n(R.sub.1 . . . R.sub.2n+2) to a nonthermal plasma to form a resulting phase wherein n2, and R.sub.1 to R.sub.2n+2 is at least one element selected from the group consisting of hydrogen and X wherein X is at least one halogen selected from the group consisting of chlorine, bromine, and iodine, and b) subjecting the resulting phase at least once to a vacuum rectification and filtration, thereby obtaining silicon compounds of the general formula Si.sub.4X.sub.10 or germanium compounds of the general formula Ge.sub.4X.sub.10.

20. The process according to claim 19, wherein n3.

Description

EXAMPLE 1 (ISOLATION OF OCTACHLOROTRISILANE)

[0077] In a rectification plant, 1212 g of silane mixture, which comprised tri- and oligosilanes, were introduced into the rectification pot under nitrogen atmosphere as protective gas.

[0078] The apparatus was then evacuated to 8 mbar and heated to 157 C. 269 g of octachlorotrisilane were obtained.

[0079] The octachlorotrisilane obtained as the result of the column distillation was filtered over a 0.45 m polypropylene filter under protective gas and high-purity octachlorotrisilane was obtained in this way in a gentle manner.

EXAMPLE 2 (ISOLATION OF OCTACHLOROTRISILANE)

[0080] In a rectification plant, 300 kg of silane mixture, comprising tri- and oligosilanes, were introduced into the rectification pot under protective-gas conditions (nitrogen atmosphere).

[0081] The rectification unit, packed with a stainless steel distillation packaging has between 80 and 120 theoretical plates.

[0082] The apparatus was evacuated to 9.3 mbar and heated to 170 C. 121.6 kg of octachlorotrisilane with a purity, measured by gas chromatography, of more than 95% were obtained.

[0083] The octachlorotrisilane obtained as the result of the column distillation was then filtered over a 0.45 pm polypropylene filter under protective gas. High-purity octachlorotrisilane was obtained in this way.

EXAMPLE 3 (ISOLATION OF DECACHLOROTETRASILANE)

[0084] In a rectification plant, 468 g of silane mixture, comprising oligosilanes, was introduced into the rectification pot under a nitrogen atmosphere as protective gas. The apparatus was then evacuated to 2 mbar and heated to 157 C. 160 g of decachlorotetrasilane were obtained.

[0085] The decachlorotetrasilane obtained as the result of the column distillation was filtered over a 0.45 m polypropylene filter under protective gas and high-purity decachlorotetrasilane was obtained in this way in a gentle manner. cl EXAMPLE 4 (ISOLATION OF DECACHLOROTETRASILANE)

[0086] In a rectification plant, 300 kg of silane mixture, comprising tri- and oligosilanes, were introduced into the rectification pot under protective-gas conditions (nitrogen atmosphere).

[0087] The rectification unit, packed with a stainless steel distillation packing, had between 80 and 120 theoretical plates.

[0088] After separating the octachlorotrisilane, as described in Example 2, the apparatus was evacuated to 3.33 mbar and heated to 184 C. 39.6 kg of decachlorotetrasilane with a purity, determined by gas chromatography, of more than 95% were obtained.

[0089] The decachlorotetrasilane obtained as the result of the column distillation was filtered over a 0.45 m polypropylene filter under protective gas and in this way high-purity decachlorotetrasilane was obtained in a gentle manner.