JPS59500416A - Purification method of silicon halide - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Purification and removal of silicon halide This invention relates to the preparation of one helical []rosilane for electronic grade silicon. However, in more detail, trace impurities that are proton donor contaminants, especially boron and A novel method for removing other Lewis acid or proton-donating impurities.

Very high purity for complex electronics applications such as semiconductors and transistors degree of silicon is required. Even the smallest amount of impurity can affect the properties of silicon-containing electronic components. It is well known that it can seriously impair performance.

Single silicon for semiconductors is generally silicon tetrachloride (SLCf+) or trichlorosilane. silicon halides such as (HSLJ) and dichlorosilane (H2SLC22). obtained by reducing with hydrogen, zinc, sodium or metal hydride .

Silicon is also derived from the thermal decomposition of silane (5LH4), although the latter material It is difficult to handle because it burns explosively when it comes into contact with air.

The most difficult impurity to remove from high purity silicon is boron. copper, iron and other common impurities such as manganese by conventional methods (e.g. While it is relatively easy to remove by crystal pulling method), boron is very sensitive to silicon. Due to similar physical properties, separation can only be achieved by repeated attempts. be done. In addition, chlorosilane forms corresponding compounds with similar properties, so chlorosilane It is equally difficult to focus purification efforts on starting materials such as orchids.

This is used to complex and bond with impurities in the nearly pure halogenated silicon solution. For example, phenols, triphenols, and nitrogen-containing compounds Various compounds have been used. For example, U.S. Patent No. 3.403.003 (Mo rganthaler), No. 3.126,248 (Pohl et al.) and No. No. 3,041,141 (Shoellaker et al.) describes these processes. It is. A commonly used method for removing porosity contaminants (U.S. special method) No. 4,112.507 (disclosed in Lan (I et al.)), One method is to introduce water vapor into the run solution over silica gel. But this is accompanied by problems of impurity regeneration and corrosion.

Here, by introducing organosiloxane, chloride is removed from the chlorosilane solution. It has been found that almost all of the boronate and other Lewis acids can be removed. Siroxa The compound reacts or complexes with impurities, and then the reaction produces a thermally stable compound, i.e., borosilicate. Loxane is formed, which is what remains in the distillation of chlorosilane.

Therefore, it is an object of the present invention to obtain a new method for purifying silicon halides. That is.

Another object of the invention is to extract boron halides, Lewis acids and An object of the present invention is to provide a method for removing bib[]ton-donating compounds.

Another object of the invention is to provide an irreversible and non-corrosive purification process.

Another object of the present invention is to obtain electronic grade silicon from high purity 1~lichlorosilane. The objective is to provide a method for

These and other purposes are: <A) Halogenation contaminated with Lewis acid impurities Add a stoichiometric excess of organosiloxane to (B) at about 25°C until almost all impurities form a non-volatile product. The impurities in the solution are reacted with the siloxane at a temperature of 200°C to 200°C. After that, (C) a halogenation process consisting of removing the H-produced silicon halide by distillation; This is achieved by a method of purifying silicon halides.

Detailed description of the invention The method of the present invention is based on the method of the present invention. The Lewis acid impurity is brought into contact with a molar excess of organosiloxane and the solution is heated. This causes a reaction between impurities and siloxane, resulting in lower evaporation than silicon halides. Atmospheric compounds are obtained, then pure silicon halide is distilled out, and the siloxane mixture is Including. This method removes boron contaminants from silicon chlorides such as trichlorosilane. very effective in removing it from solution.

The boron concentration in the trichlorosilane solution can be reduced to 501) Ot or higher by the treatment of the present invention. go down.

Here, ``Lewis acid salt is any substance that accepts an electron pair and forms a covalent bond (i.e. ``electron pair acceptor''). This includes the concept of a ``proton donor,'' which is a proton donor. 3> is a typical Lewis acid because it has 6 electrons in the outermost shell of the electron orbit. . BF3 accepts a free electron pair and completes its eight electron orbitals.

Siloxane compounds suitable for this purpose include boron, which is present in silicon halides. or with other impurities, a pure silicon-containing solution is distilled out of the reaction vessel; Lower vapor pressure than the purified solution so that non-volatile siloxane compounds remain behind Any non-volatile siloxane compound (e.g. borosiloxane) having It is an organosiloxane. These siloxanes include alkyl, aryl, and halide Halogenated alkyl, halogenated aryl or hydrogen-substituted alkyl or arylcyclo rotorisiloxane and Schiftetrasiloxane, such as hexamethylsiloxane. Lotrisiloxane, octamethylcyclotetrasiloxane, polydimethylsiloxane Sun oil, dimethyl (methyl hydrogen) siloxane copolymers, and other cyclic siloxane There is a san monomer. Cyclotrisiloxane, alkylcyclotrixane, halogen Preferred are alkylcyclotrisiloxanes, and hexamethylcyclotrisiloxanes are preferred. Sun is most preferred.

The siloxane is added in an amount to ensure reaction between the siloxane and the Lewis acid impurity. , add to the silicon halide solution which has been ridden with impurities. This amount is the concentration of contaminants. For example, if there is a large excess of molar, such as 5 to 100 times, the best result will be obtained. Ru. However, the amount of siloxane is adequate to effectively bind impurities in solution. Any amount is acceptable.

After mixing the siloxane into the solution, the mixture is heated to remove the siloxane and Lewis acid impurities. Proceed with the reaction of things. At very high temperatures, i.e. over 200℃, the Some decomposition of solids and non-volatile balates occurs. At low temperatures, B (J3) The reaction is not sufficient to effectively remove all. For these reasons, the reaction The temperature range is preferably 25°C to about 200°C, most preferably about 0°C to about 130°C. Although preferred, the reaction products are distilled into the same fraction as the silicon halide, making purification difficult. Higher temperatures may be used as long as they do not cause harm. Best results are obtained at approximately 100°C. It will be done.

As mentioned above, the reaction continues until almost all impurities are bound to the siloxane compound. You can continue with. Of course, the time will vary depending on the substance used, temperature, pressure, etc.

By simple experimentation, the optimal reaction time for a given purification can easily be determined.

The final step of the present invention is to distill pure silicon halide from the reaction solution. Is Rukoto. The volatility of impurities bonded to silicon halide and hesiloxane is The low temperature makes this final distillation possible.

Distillation is carried out at atmospheric pressure or when the temperature of the liquid substance reduces the borates formed during the process. If it does not exceed the decomposition temperature of , it can be carried out at a higher pressure. The temperature of the liquid is approximately 2 It is preferable to keep the temperature below 00°C.

The following examples are provided to enable those skilled in the art to easily understand the implementation of this invention. Indicated for, but limited to, hexamethylcyclotrisiloxane (trimer) 7 parts by weight of trichlorosilane (Te3) containing 50001111 m of boron trichloride ) Mix with 150 fflN parts of solution and stir periodically for 1 hour. reaction mixture A sample of Te3 distilled from a substance has an infrared component with a detection limit of 25 B did not contain CR3 or borate as determined by light.

Implementation example 2 TC8 solution containing 5 ppb B C23 and 25 ppb trimer at 12 ops :a, Mix at 120°C. Detection limit of 25 ppt for distillate samples Spectroscopic analysis with shows that all B(J, 3) has been consumed.

Implementation example 3 Add 200 l1l) ill of trimer to the TC3 solution containing 32 ppm of B(J). Ru. The mixture was heated to 130-135 °C in an oil bath for 4 hours at 1 oops:g. Ru. - After overnight incubation, four fractions were distilled out and determined to be boron-containing by colorimetric method using Example 2C. Analyze quantity.

2000') was added to the distiller, and 99% of the material was recovered and distilled. The presence of boron in each fraction is less than 50 ppt.

Examples 4 and 5 The method of Example 3 was repeated twice and the following results were obtained.

12 50 I! Implementation example 6 400 parts by weight of TC8 solution containing 0.018 mol BC93 (5000 ppm) , into a reaction vessel with enough trimer to make the solution 0.09 molar. reaction The mixture was stirred under pressure and analyzed by infrared spectroscopy as in Example 1. Distill the sample periodically.

pressure prison abbreviation Distillation (ρsig) Temperature (ppm) 1 (initial 0.23℃ 5,000 rejected i~sample) 2 20 55℃ 1.000 3 40 75°C undetectable 4 60 85℃ Undetectable 5　80　95℃unable to detect 6 ioo 110℃ undetectable 7 120, 120℃ Undetectable "Koriki page" bottom margin Visual inspection report

Claims (1)

[Claims] 1. (A) The concentration of impurities in a silicon halide solution contaminated with Lewis acid impurities Add orcasiloxane in excess of the stoichiometric amount to (B) about 25°C to 2°C until substantially all impurities are covered forming a non-volatile product. At a temperature of 00°C, the impurities in the solution are reacted with the siloxane, and then (C) Halogen made of purified silicon halide that is not removed by distillation Of silicone! Method. 2. The method according to claim 1, wherein the impurity contains boron. 3. The method according to claim 2, wherein the boron impurity is halogenated boron. . 4. The silicon halide is silicon tetrachloride, trichlorosilane and dichlorosilane. 2. The method of claim 1, wherein the method is selected from the group consisting of: 5. The method according to claim 4, wherein the silicon halide is trichlorosilane. . 6. Organosiloxane is cyclotrisiloxane, cyclotetrasiloxane, Consisting of polydimethylsiloxane oil and dimethylmethylhydrogen siloxane copolymer A method according to claim 1, wherein the method is selected from the group. 7. According to claim 6, the orcasiloxane is cyclotrisiloxane. the method of. 0 8. Cyclotrisiloxane is cyclotrisiloxane, arylcyclotrisiloxane Xane, alkylcyclotrisiloxane, halogenated alkyltrisiloxane? The compound according to claim 7, which is selected from the group consisting of: 9. Claim 8, wherein the organosiloxane is an alkylcyclotrisiloxane. Section method. 10. Alkylcyclotrisiloxane or hexamethylcyclotrisiloxane The method of claim 9. 11. Claim No. 1 in which the organosiloxane is octamethyltetrasiloxane. Method of Section 6. 12. Organosiloxane at a concentration of 5 to 100 times the molar concentration of the Lewis acid impurity. The method according to claim 1, appended hereto. 13. The silicon halide is trichlorosilane, and the Lewis acid impurity is mainly trisalt. The chloride is boronate, and the alkylsiloxane is hexamethylcyclotridiOxane. The alkylsiloxane is added at a concentration approximately 100 times that of the boron trichloride impurity. A method according to claim 1. 14. A method for producing electronic equipment grade silicon from high purity trichlorosilane There, (A) To the trichlorosilane solution contaminated with Lewis acid impurities, Add a stoichiometric excess of organosiloxane, (B) substantially all impurities form non-volatile products; The impurities in the solution are reacted with the xyloquiline at a temperature of about 25°C to 200°C. let, then (C) A method consisting of removing purified trichlorosilane by distillation. Therefore, an improved method characterized by purifying trichlorosilane.