Tetrakis(trichlorosilyl)germane, process for the preparation thereof and use thereof

Abstract

A novel process provides for the preparation of the chlorinated, uncharged substance tetrakis(trichlorosilyl)germane, and for the use thereof.

Claims

1: A process for preparing a tetrakis(trichlorosilyl)germane of the formula (I), ##STR00003## the process comprising: (a) mixing at least one tris(trichlorosilyl)germanide salt of a formula [X][Ge(SiCl.sub.3).sub.3], wherein X=ammonium (R.sub.4N) and/or phosphonium (R.sub.4P), R=alkylic or aromatic radical, with AlCl.sub.3, thereby obtaining a mixture and (b) reacting the mixture in an environment comprising at least one chlorinated hydrocarbon at a temperature of 5 to 40° C. to obtain a crude product comprising at least one salt [R.sub.4N][AlCl.sub.4] and/or [R.sub.4P][AlCl.sub.4] and tetrakis(trichlorosilyl)germane, and subsequently (c) introducing said crude product into at least one nonpolar solvent and separating off insoluble residue, and subsequently (d) removing the nonpolar solvent, to obtain tetrakis(trichlorosilyl)germane.

2: The process according to claim 1, wherein in step (b) the reaction is conducted at room temperature, and/or in step (d) the nonpolar solvent is removed at room temperature.

3: The process according to claim 1, wherein, in step (b), the chlorinated hydrocarbon is dichloromethane CH.sub.2Cl.sub.2.

4: The process according to claim 1, wherein, in step (c), the at least one nonpolar solvent is at least one selected from the group consisting of hexane, n-hexane, pentane, and benzene.

5: The process according to claim 1, wherein, in step (a), the mixing of [X][Ge(SiCl.sub.3).sub.3] and AlCl.sub.3 comprises stirring, and, in step (b), the mixture obtained in step (a) is dissolved completely in the at least one chlorinated hydrocarbon, and, after a time of 0.1 to 24 hours, the at least one chlorinated are hydrocarbon is removed.

6: The process according to claim 1, wherein, in step (c), after the introducing of the crude product, the temperature of the at least one nonpolar solvent is brought for from 1 to 5 times from room temperature to elevated temperature, and subsequently the at least one nonpolar solvent is allowed to cool.

7: The process according to claim 1, further comprising: depositing at least one Si—Ge layer with the tetrakis(trichlorosilyl)germane as precursor.

8: A Si—Ge layer deposition process, comprising: depositing at least one Si—Ge layer with, as a precursor, a tetrakis(trichlorosilyl)germane obtained by the process according to claim 1.

9: The process according to claim 1, wherein, in step (c), the at least one nonpolar solvent comprises n-hexane.

10: The process according to claim 1, wherein, in step (a), the mixing of [X][Ge(SiCl.sub.3).sub.3] and AlCl.sub.3 comprises stirring [X][Ge(SiCl.sub.3).sub.3] and AlCl.sub.3 in a solid state, in an oxygen-free environment under protective gas, nitrogen or argon, in a glovebox, and, in step (b), the mixture obtained in step (a) is dissolved completely in the at least one chlorinated hydrocarbon, and, after a time of 1 to 5 hours, the at least one chlorinated hydrocarbon is removed at room temperature, in an oxygen-free, dry, isolated environment, under standard pressure or under a reduced pressure of from 1 to 500 hPa.

11: The process according to claim 1, wherein, in step (c), after the introducing of the crude product, the temperature of the at least one nonpolar solvent is brought for 3 times from room temperature to the boiling point of the at least one nonpolar solvent, and subsequently the at least one nonpolar solvent is allowed to cool to room temperature.

12: The process according to claim 1, wherein the crude product obtained in step (b) is uncharged tetrakis(trichlorosilyl)germane.

13: The process according to claim 1, wherein the process is free of added SiH.sub.4.

14: The process according to claim 1, wherein the process is free of added GeH.sub.4.

15: The process according to claim 1, wherein the process is free of added sodium.

16: The process according to claim 1, wherein no organic radicals are present in the tetrakis(trichlorosilyl)germane.

Description

EXAMPLE 1: PREPARATION OF TETRAKIS(TRICHLOROSILYL)GERMANE (I)

[0037] The synthesis was effected in accordance with Equation 1 from [Ph.sub.4P][Ge(SiCl.sub.3).sub.3] with AlCl.sub.3 while adding CH.sub.2Cl.sub.2.

##STR00002##

[0038] The reaction was conducted in a glovebox.

[0039] [Ph.sub.4P][Ge(SiCl.sub.3).sub.3] at an amount of 0.10 g, corresponding to 0.12 mmol, and AlCl.sub.3 at an amount of 0.016 g, corresponding to 0.12 mmol, were mixed in the solid state and subsequently completely dissolved in dichloromethane CH.sub.2Cl.sub.2.

[0040] After 3 hours, the dichloromethane was slowly evaporated at RT and under standard pressure. After one day, a mixture of Ge(SiCl.sub.3).sub.4 (I) and [Ph.sub.4P][AlCl.sub.4] had formed as crystalline crude product. The crude product was heated to boiling three times with in each case 7 ml of n-hexane.

[0041] Subsequently, the clear, colourless n-hexane solution was separated off from the insoluble residue with a syringe.

[0042] The nonpolar solvent was subsequently removed slowly at RT and under standard pressure, and after one day it was possible to isolate the inventive product Ge(SiCl.sub.3).sub.4 (I) as a crystalline substance. The yield was 0.018 g, corresponding to 0.029 mmol or 24%.

[0043] The .sup.29Si NMR spectrum of the inventive product I is presented in FIG. 1a, and the result of the analysis thereof by means of X-ray diffractometry is presented in FIG. 1b.

[0044] The data of the .sup.29Si NMR spectroscopy analysis:

[0045] .sup.29Si NMR (99.4 MHz, CD.sub.2Cl.sub.2, 298 K): δ=3.8 ppm.