JP3123698B2 - Manufacturing method of fluorinated silane - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel method for producing fluorinated silane, which is useful as a raw material for producing semiconductor, electronic and optical materials.

[0002]

2. Description of the Related Art In general, fluorinated silanes are obtained by carrying out a halogen substitution reaction of chlorine and fluorine of silane chloride using an appropriate solid metal fluoride. The metal fluoride used at this time is SbF ₃ , ZnF ₂ ,
There are SnF _{4 and the} like, and as a method of reacting these solid fluorides with silane chloride, a method of passing silane chloride in a gaseous state through a fluoride-filled layer or a method of dropping silane chloride on fluoride is generally used. It is a target.

However, in this method, the reaction yield and purity are not sufficiently high, and at present, a method of suspending these solid metal fluorides in an appropriate organic solvent and reacting them with silane chloride is widely known. (JP-A-61-232215, JP-A-61-151016,
JP-A-63-201013).

[0004]

Problems to be Solved by the Invention When fluorinated silane is obtained by a conventional method, there are the following problems. The metal fluoride used for producing the fluorinated silane is expensive, and it is necessary to recover and regenerate the metal chloride by-produced by the reaction. Even when relatively inexpensive metal fluoride is used temporarily, metal chloride by-produced is often a harmful substance, and disposal requires detoxification treatment. In the case of producing fluorinated silane by the conventional method, if water is present in the reaction system, polyfluoride is by-produced and the product purity is reduced, so dehydration from the reaction system is important. Many of the metal fluorides used are hygroscopic substances and need to be dehydrated and purified. The present invention is to eliminate the problems of the conventional method.

[0005]

Means for Solving the problems] The present invention, silane chloride _{(Si x H y Cl 2 +} 2x-y (x is x ≧ 1 integer, y is 0 ≦ y
≦ 2x + 1 integers, provided that (x, y) = except (1,2))) and fluorinated silane for causing direct reaction of hydrogen fluoride _{(Si x H y F 2 +} 2x-y (x Is an integer of x ≧ 1,
y is an integer of 0 ≦ y ≦ 2x + 1, where (x, y) =
Preparation of excluded)) and (1,2), and fluorinated silanes containing hydrogen chloride by-produced by the process of the present invention (Si _x H _y F
_{2 + 2x-y} (x is an integer of x ≧ 1, y is an integer of 0 ≦ y ≦ 2x + 1, except (x, y) = (1, 2))), and only hydrogen chloride is injected into the ether. silane fluoride, characterized by selectively absorbed and removed _{(Si x H y F 2 +} 2x-y (x
Is an integer of x ≧ 1, y is an integer of 0 ≦ y ≦ 2x + 1, provided that (x, y) = (1,2) is excluded)).

According to the present invention, by using inexpensive hydrogen fluoride as the fluorinating agent, it is possible to synthesize silane fluoride with almost the same purity as that of the conventional method without using expensive metal fluoride. After separating and removing hydrogen chloride as a by-product from fluorinated silane, it can be easily removed by reaction with alkali. In addition, hydrogen fluoride is usually several ppm to several hundred p.
pm of water, but this level of water does not affect the by-product of polyfluoride.

In the present invention, when hydrogen fluoride is reacted with silane chloride, the silane chloride should be reacted in excess of the theoretical reaction equivalent. That, Si _x H
_When reacting _{yCl 2 + 2x-y} silane chloride with hydrogen fluoride, the molar ratio is silane chloride / hydrogen fluoride = 1 / (2+
2x-y) or more is preferable, and if it is smaller than this, polyfluoride is generated, which is not preferable. Further, when the silane chloride is present in a large excess, fluorinated silane partially advanced in fluorination is generated, which is not preferable. In addition, unreacted silane chloride remains in a large amount, which may not be efficient in consideration of its recovery and the like.

[0008] The reaction temperature is preferably from 10 to 100 ° C, most preferably from 30 to 50 ° C. When the reaction temperature is high, the reaction becomes violent and polyfluoride is generated, which is not preferable. In addition, at low temperatures, the reaction speed slows down,
Not only the excess silane chloride but also hydrogen fluoride remains partially unreacted, and this hydrogen fluoride tends to react with the generated silane fluoride again to form polyfluoride, which is not preferable.

The reaction pressure does not particularly depend on purity, yield, etc., but at extremely low pressure, the reaction rate decreases,
In addition, if the pressure is extremely high, the reaction becomes violent and it is dangerous.

As a method of reacting hydrogen fluoride with silane chloride, a method of dropping liquid hydrogen fluoride into liquid silane chloride and a method of bubbling hydrogen fluoride in a gaseous state with a suitable carrier gas in liquid silane chloride are used. And a method of reacting silane chloride and hydrogen fluoride with a gas. Chlorinated silanes with relatively high boiling points (SiCl ₄ , Si ₂ Cl ₆ etc.)
In the case of silane chloride having a low boiling point (SiH ₃ Cl, SiHCl _3, etc.), the latter method is preferred. In the latter reaction, there are a batch type and a flow type reaction system. preferable.

In the present invention, hydrogen chloride produced as a by-product of the reaction between silane chloride and hydrogen fluoride has a boiling point similar to that of silane fluorinated (particularly, silane fluoride x = 1). Therefore, removal by distillation is difficult. Even when producing fluorinated silane by the conventional method, a small amount of hydrogen chloride is by-produced due to a small amount of water present in the reaction system. It has been confirmed that the hydrogen chloride has an adverse effect on the semiconductor manufacturing process, and it is necessary to remove and purify the hydrogen chloride.

As the ether used to selectively remove only hydrogen chloride from the fluorinated silane containing hydrogen chloride, diethyl ether, isopropyl ether, n-dibutyl ether, diphenyl ether and the like can be used. Since it has high volatility and is difficult to remove when entrained with fluorinated silane, it is necessary to use an ether having as low a vapor pressure as possible. Specifically, there are n-dibutyl ether, diphenyl ether and the like, but n-dibutyl ether which is easy to handle at around room temperature is preferable. When hydrogen chloride is absorbed by ether, the lower the temperature, the higher the absorption performance. However, since the absorption amount of fluorinated silane similarly increases, it is necessary to select an appropriate temperature.
For n-dibutyl ether, a temperature of about −20 ° C. to 20 ° C. is suitable. In addition, the ether after absorbing the hydrogen chloride is separated from the hydrogen chloride by performing a reflux heat treatment near the boiling point,
Reproducible and reusable.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments. Examples 1 to 4 SiHCl ₃ was blown into a 1-liter reactor at a predetermined pressure, followed by introduction of hydrogen fluoride to cause a batch reaction for 10 minutes.
Was measured by Table 1 shows the results.

[0014]

[Table 1]

Examples 5 to 9 A predetermined flow rate of SiHCl ₃ and hydrogen fluoride were mixed and reacted under a pressure of 300 mmHg in a flow-type reaction tube (１ ／ inch × 500 L), and the resulting gas was ethanol-dry ice trap. (−74 ° C.) and high boiling point components (SiHC
l ₃ , HF, SiHFCl ₂ , and SiHF ₂ Cl) were removed, and the gas collected for 3 hours was measured by gas chromatography and FT-IR. Table 2 shows the results.
Shown in

[0016]

[Table 2]

Example 10 SiH _{3 was} passed through a flow-type reaction tube (１ ／ inch × 500 L).
Cl (50 SCCM) and hydrogen fluoride (50 SCCM) are mixed and reacted under atmospheric pressure.
The high boiling components (SiH ₃ Cl, HF) were removed with a dry ice trap (−74 ° C.), and the gas collected for 3 hours was measured by gas chromatography and FT-IR. Table 3 shows the results.

[0018]

[Table 3]

Examples 11 to 17 Into a 3 l trap equipped with a stirrer, 2 l of n-dibutyl ether (liquid temperature: 0 ° C.) sufficiently dehydrated with zeolite were charged, and the gas synthesized in Examples 1 and 5 to 10 was blown. It is. Table 4 shows the composition of the gas obtained by this operation. Hydrogen chloride in the purified gas is FT-I
As a result of quantification by R, it was less than 30 ppm. The recovery rate was about 70% for both SiHF ₃ and SiH ₃ F.

[0020]

[Table 4]

[0021]

According to the present invention, fluorinated silane can be obtained quantitatively, easily and inexpensively from silane chloride by using a new reaction route which has not existed in the past. Silane can be obtained.

────────────────────────────────────────────────── (5) References JP-A-6-287011 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C01B 33/08-33/107 B01D 3 / 00

Claims (2)

(57) [Claims] 1. A silane chloride _{(Si x H y Cl 2 +} 2x-y (x is x ≧ 1 integer, y is 0 ≦ y ≦ 2x + 1 integers, provided that (x, y) = a (1, 2) excluded)) and fluorinated silane for causing direct reaction of hydrogen fluoride (Si _x H _y F
_{2 + 2x-y} (x is an integer of x ≧ 1, y is an integer of 0 ≦ y ≦ 2x + 1, except for (x, y) = (1, 2)). 2. A silane chloride _{(Si x H y Cl 2 +} 2x-y (x is x ≧ 1 integer, y is 0 ≦ y ≦ 2x + 1 integers, provided that (x, y) = a (1, 2) excluded)) and fluorinated silanes containing hydrogen chloride produced by direct reaction of hydrogen fluoride (Si _{x
H y F 2 + 2x-y} (x is x ≧ 1 integer, y is 0 ≦ y ≦ 2x +
1 integers, provided that (x, y) = (1,2 ) except for)) was bubbled into ether, silane fluoride, characterized by selectively absorbing and removing only hydrogen chloride (Si _x H _y F
_{2 + 2x-y} (x is an integer of x ≧ 1, y is an integer of 0 ≦ y ≦ 2x + 1, except for (x, y) = (1, 2)).