JPH06234523A - Production of germanium tetrafluoride - Google Patents

Abstract

PURPOSE:To stably obtain a high purity germanium tetrafluoride over a long time. CONSTITUTION:In a method for producing germanium tetrafluoride by allowing fluorine gas or nitrogen trifluoride gas to flow to a reactor 1 having a reacting part filled with metallic germanium and kept at 250-500 deg.C, germanium tetrafluoride is produced by supplying fluorine gas or nitrogen trifluoride gas from a bottom part 5 and upper part 7 of the reactor 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing germanium tetrafluoride (GeF ₄ ) by reacting metallic germanium with fluorine (F ₂ ) gas or nitrogen trifluoride (NF ₃ ) gas. More specifically, GeF ₄ is GeH
_4, the germanium doping agents in the amorphous silicon thin film shape with such GeCI _4, but are being recently extensively used, it is required that in order to use in these applications high purity.

[0002]

2. Description of the Related Art As a method for producing GeF ₄ , (1) a halogen exchange method in which SbF ₃ / SbCl ₅ is added to germanium tetrachloride and reacted [H. S. Booth et a
l. , Janal of American Chemical Society (J. Am. Chem. Soc.) 58, 90
(1936)], (2) hexafluorogermanate (B
aGeF ₆ etc.) (in organic
Synthesis (Inorganic Synthese
s) IV 147], (3) Method by reaction of GeO ₂ and BrF ₃ [H. J, Emelon set al, Journal of Chemical Society (J. Che
m. Soc. ) 164, (1950), (4) Direct fluorination method using metal germanium and F ₂ gas or NF ₃ gas is well known.

However, (1), (2) and (3)
GeF obtained by_FourAmong them, germanium fluoride chloride,
HF, CO₂, SO₂, SiF_Four, CF_Four, CO,
N₂, O ₂It contains many kinds of gases as impurities,
GeF obtained in (4)_FourIs metallic germanium or N
F₃GeF is available because high purity gas is available._FourAlso pure
Good degree.

[0004]

However, the direct fluorination method has the following problems. That is, when the metal germanium layer filled in the reactor is heated to 250 to 500 ° C. and then F ₂ gas or NF ₃ gas is supplied from one side, germanium difluoride (GeF ₂ ) is produced as a by-product. The reason for the generation of GeF ₂ is assumed as follows. The F ₂ gas and the NF ₃ gas react when passing through the heated metal germanium layer to produce GeF ₄ , but a part of the reaction further proceeds as shown in Chemical formula 1, the reaction proceeds in the metal germanium layer. , GeF ₂ seems to be a by-product.

[0005]

[Chemical formula 1] GeF ₄ + Ge → 2GeF ₂

GeF ₂ is a substance that is gaseous at high temperatures, but is a white solid at room temperature and has deliquescent properties when exposed to the atmosphere. The GeF ₂ produced as a by-product adheres to the inside of the outlet flange and the conduit between the reactor and the collection container to block the aeration line. Therefore, there arises a problem that the yield is lowered and the long-time steady operation cannot be performed.

[0007]

In view of the above situation, the present inventors have conducted various studies on a method for producing GeF ₄ in a stable and high yield by suppressing the formation of GeF ₂ as a by-product. The inventors have found that the object can be achieved by supplying F ₂ gas or NF ₃ gas to the lower and upper parts of the metal germanium layer filled in the reactor, and have completed the present invention.

That is, according to the present invention, fluorine gas or nitrogen trifluoride gas is passed through a reactor having a reaction part filled with metal germanium and maintained at 250 to 500 ° C. to produce germanium tetrafluoride. In the method, fluorine gas or nitrogen trifluoride gas is supplied from the lower part and the upper part of the reactor, and relates to a method for producing germanium tetrafluoride.

The present invention will be described in detail below. The shape of the metal germanium used in the present invention is not particularly limited, and a lump or powder can be used. Moreover, since the purity directly affects the purity of the reaction product GeF ₄ , 99.99% or more is desired. Such a germanium metal is GeCl ₄
Is purified and then hydrolyzed to GeO _2, and this is reduced with hydrogen to give germanium powder, and further, it is highly purified by a zone melting refining method.

F ₂ gas or NF ₃ gas is used as a source gas for fluorinating metallic germanium. However, since the purity of this gas also directly affects the purity of GeF ₄ , it is desired to be 99% or more. The material used for the reactor must be able to withstand fluorine-based gases at high temperatures, such as nickel or monel. Also, the shape is easily corroded when there is a seam such as welding in the part in contact with high temperature, so in the body part of the reactor that becomes hot, a seamless tube of the above material, that is, a cylindrical shape, with flanges at both ends Attachment A reactor in which this is installed vertically is preferably used.

The reactor was filled with metallic germanium and F
It is composed of a reaction part for reacting with ₂ gas or NF ₃ gas and a heating part provided above the reaction part. The reaction part and the heating part are equipped with a heater capable of heating from the outside. As for the structure of the heating unit, it is sufficient that the heating unit can achieve a desired temperature sufficiently by using an external heater. Further, a method in which a nickel wire mesh is attached to the heating portion or a material which can withstand a fluorine-based gas at high temperature such as Monel is filled can obtain more preferable results.

The F ₂ gas or NF ₃ gas supply pipes are provided at the portions located below and above the reaction portion filled with the metal germanium. An upper supply port for F ₂ gas or NF ₃ gas is provided between the metallic germanium surface layer which is the reaction part and the upper end of the heating part.
More preferably, it is installed so as to be located between the surface of the metal germanium and the lower end of the heating part.

GeF ₂ production can be suppressed by installing the upper supply port for F ₂ gas or NF ₃ gas at the above-mentioned position. The reason for this is not clear, but it is guessed as follows. That is, it is considered that GeF ₂ which byproduct of metal germanium layer and the F ₂ gas or NF ₃ gas supplied to the metal germanide layer upper, GeF ₄ is produced by the reaction shown in 2 of the heating unit.

[0014]

[Chemical Formula 2] GeF ₂ + F ₂ → GeF ₄ GeF ₂ + 2/3 NF ₃ → GeF ₄ + 1/3 N
₂

When F ₂ gas or NF ₃ gas is aerated in the reaction section, the concentration may be 100%, but since both have strong oxidizing power at high temperature, N ₂ or He is used.
It may be diluted with an inert gas such as. The diluent gas is also useful as a carrier gas at the time of collecting the gas, and its concentration is preferably about 10 to 50%. Also, F ₂ gas or N
The gas supply amount and the supply ratio of the upper and lower parts of the F ₃ gas differ depending on the reaction temperature of the reactor and the filling amount of the metal germanium, but the normal gas supply amount is 10 to 10000 cc / m 2.
In, the supply ratio is such that the lower part is 1 volume part and the upper part is 0.1.
~ 1 volume part.

The reaction temperature in the present invention is preferably 250 to 500.degree. C., more preferably 300 to 400.degree. C. in both the reaction section and the heating section. 2 reaction and heating sections
Below 50 ° C, metallic germanium and F ₂ gas or N
It is not preferable because the reaction of F ₃ gas does not proceed sufficiently and unreacted F ₂ gas or NF ₃ gas is mixed. If it exceeds 500 ° C., the temperature of the reaction section rises above the control temperature, and the reaction temperature cannot be controlled. Further, germanium nitride is partly produced as a by-product in the NF ₃ gas, but if it exceeds 500 ° C., the by-product increases, which causes a decrease in the yield of GeF ₄ , which is not preferable.

The pressure during the reaction is not particularly limited and may be of course reduced pressure, but it is usually carried out at a pressure of from normal pressure to 9 kg / cm ² . GeF ₄ obtained by the reaction contains by-produced N ₂ and diluted gas such as N ₂ and He, unreacted F ₂ gas or NF ₃ gas, and is collected from the reactor through the produced gas discharge pipe. (Not shown in the drawing). Ge
The container for collecting F ₄ is cooled to about −90 ° C., and these diluting gas and unreacted gas are separated to collect GeF ₄ .

[0018]

The present invention will be described in more detail with reference to the following examples. In the following,% is expressed on a weight basis, unless otherwise specified.

Example 1 250 g of a metal germanium powder having a purity of 99.99%,
Made of nickel shown in Fig. 1 with an inner diameter of 40 mm and a height of 800 mm
The portion of the vertical reactor 1 located in the reaction section 2 was filled.
Next, from the lower gas supply pipe 5, a normal pressure N ₂ gas of 300 cc /
The air in the system was completely removed by ventilating min for about 1 hour. Then, the reaction part 2 is heated to 350 ° C. and the heating part 3 is heated to 400 ° C.
From the lower gas supply pipe 5 to N _{2 while} being heated to a temperature of ℃
In addition to gas 400cc / min, purity 99.99% NF
₃ gas of 90 cc / min and NF ₃ gas of 30 cc / min were passed from the gas upper supply pipe 6 between the reaction part 2 and the heating part 3 to carry out the reaction for 6 hours. The product gas generated from the reactor 1 was introduced from the product gas discharge pipe 8 into a collection container cooled to a temperature of −90 ° C. and collected. After completion of the reaction, the inside of the collection container was evacuated by a vacuum pump, and N ₂ gas used as a diluent gas, N ₂ gas produced as a by-product, and unreacted NF ₃
The gas was removed. Incidentally, these reactions were carried out under normal pressure.

As a result, the GeF ₄ yield was 174 g, the Ge consumption in the reactor was 91 g, and the yield based on Ge was 93%, which was a high yield. Further, at the bottom of the reactor 1, there was a material that appeared to be a germanium nitride, but there was no adhered material of GeF ₂ . Incidentally, in analyzing the content of the elemental metal in the collected GeF ₄ , the content of the sample absorbed in ethanol was measured by ICP (high frequency inductively coupled plasma) analysis to find that Na, Mg, Ca, Fe,
The five elements of Si were each 0.05 ppm or less based on GeF ₄ . Moreover, CF ₄ was 10 ppm or less in the gas analysis by gas chromatography.

Example 2 Eight (252 g) pieces of metal germanium having a purity of 99.999% obtained by the zone melting and refining method and cut into a size of about 2 cm × 2 cm × 1 cm were used in the same reactor as in Example 1. 1 was filled. Then, while the reaction part 2 was heated to 300 ° C. and the heating part 3 was heated to 400 ° C., N ₂ gas was introduced from the lower gas supply pipe 5 to a flow rate of 400 cc / min, and N was added.
F ₃ gas of 100 cc / min and NF ₃ gas of 20 cc / min were passed from the gas upper supply pipe 6 between the reaction section 2 and the heating section 3 to carry out a reaction for 12 hours. The produced gas generated from the reactor 1 was collected by the same operation as in Example 1.
Incidentally, these reactions were carried out under normal pressure. As a result, GeF ₄
Yield of 320g, G consumption of 171g in the reactor
The yield based on e was 91%, which was a high yield. Further, at the bottom of the reactor 1, there was a material that appeared to be a germanium nitride, but there was no adhered material of GeF ₂ . Incidentally, when the content thereof was measured by ICP analysis as in the example, the five elements of Na, Mg, Ca, Fe and Si were found to be GeF ₄
Each was 0.05 ppm or less on the basis. Also, in gas analysis by gas chromatography, CF ₄
Was 10 ppm or less.

Example 3 N ₂ gas flow rate from the lower gas supply pipe 5 is 400 cc /
In addition to min, normal pressure 99% F ₂ gas 160 cc / mi
n, and from the upper gas supply pipe 6, F ₂ gas 40 cc / mi
n was vented to the reactor 1 to carry out the reaction for 10 hours,
The same operation as in Example 1 was performed. As a result, the yield of GeF ₄ was 305 g, and the Ge consumption in the reactor was 145 g.
The yield based on the standard was as high as 98.6%. Incidentally, when the content was measured by ICP analysis as in Example 1, the five elements Na, Mg, Ca, Fe and Si were found to be GeF ₄
Each was 0.05 ppm or less on the basis. In gas analysis by gas chromatography, CF ₄
Was 200 ppm.

Example 4 The temperature of the reaction part 2 was set to 450 ° C. and the temperature of the heating part 3 was set to 300 ° C.
Change to ℃ and NF ₃ gas from the lower supply pipe to 100cc / m
in, except 50 cc / min from the upper supply pipe,
The same operation as in Example 1 was performed. As a result, the GeF ₄ yield was 214 g, and the Ge consumption in the reactor was 115 g.
The yield based on the standard was as high as 91%. Further, in the lower part of the reactor, there were some that were considered to be germanium nitride, but no GeF ₂ adhered substances were present. The collected G
In analyzing the content of the elemental metal in eF ₄ , the content of the sample absorbed in ethanol was measured by ICP (high frequency inductively coupled plasma) analysis.
The five elements of a, Mg, Ca, Fe and Si were each 0.05 ppm or less based on GeF ₄ . Also, in gas analysis by gas chromatography, CF ₄ was 10
It was below ppm.

Comparative Example 1 250 g of a metal germanium powder having a purity of 99.99%,
Made of nickel shown in Fig. 2 with an inner diameter of 40 mm and a height of 800 mm
The portion of the vertical reactor 1 located in the reaction section 2 was filled.
With the reaction part 2 heated to a temperature of 350 ° C., the lower part of the gas
Supply pipe 5 to N ₂Purity in addition to 400 cc / min of gas
99.99% NF₃90 cc / min of gas is used in the reaction part 2
The reaction was carried out for 6 hours by aeration. Other operations are examples
Method 1 was followed. But NF₃About 2 after starting gas ventilation
Over time, the pressure in reactor 1 began to rise. NF₃Of gas
When ventilation and heating of the reaction part 2 were stopped and the inside was observed
GeF₂Is stuck inside the upper flange lid,
The part was blocked. GeF_FourYield is based on Ge
The yield was 62%, which was a low yield.

[0025]

According to the present invention, a part of the reactor 1 is improved so that the gas supply pipe is divided into the lower part and the upper part of the reaction part 2 and is supplied in a simple manner. The unprecedented improvement in the GeF ₄ yield was achieved, and the large effect of eliminating the blockage of the line due to the by-product of GeF ₂ could be achieved. Therefore, the method of the present invention is suitable for obtaining a high yield of GeF ₄ by carrying out steady operation for a long period of time.

[0026]

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of an embodiment according to the present invention.

FIG. 2 is a sectional view showing an example of an embodiment by a conventional method.

[Explanation of symbols]

 1 Reactor 2 Reaction part 3 Heating part 4 Heating heater 5 Gas lower supply pipe 6 Gas upper supply pipe 7 Gas upper supply port 8 Generated gas discharge pipe

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Takashi Hashimoto 7-1, 1-1 Hikoshimasako-cho, Shimonoseki-shi, Yamaguchi Prefecture Mitsui Toatsu Chemical Co., Ltd.

Claims (3)

[Claims] 1. A metal germanium filled layer, 25
In a method for producing germanium tetrafluoride by passing a fluorine gas or a nitrogen trifluoride gas through a reactor having a reaction section maintained at 0 to 500 ° C., fluorine gas or A method for producing germanium tetrafluoride, which comprises supplying nitrogen trifluoride gas. 2. The reactor comprises a reaction section and a heating section,
The method for producing germanium tetrafluoride according to claim 1, wherein the heating part is located above the reaction part, and the temperature of the heating part is 250 to 500 ° C. 3. The tetrafluoride according to claim 1, wherein a gas upper supply port of fluorine gas or nitrogen trifluoride gas supplied from the upper part of the reactor is located between the upper end of the heating part and the surface layer of the reaction part. Germanium manufacturing method.