JP2003327412A - Method for generating fluorine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for generating fluorine which is useful for obtaining materials for syntheses of fluoride and for cleaning an apparatus for depositing a thin film or the like. <P>SOLUTION: In the method for generating fluorine by heating a fluorine- generating agent, one operation of generating fluorine and subsequently the other operation of re-fluorinating the fluorine-generating agent with a fluorinating agent are alternately carried out. The fluorine-generating agent is K<SB>3</SB>NiF<SB>7</SB>or CoF<SB>3</SB>and the fluorinating agent is at least a kind of compound selected from ClF, ClF<SB>3</SB>, ClF<SB>5</SB>, BrF, BrF<SB>3</SB>, BrF<SB>5</SB>, IF<SB>3</SB>, IF<SB>5</SB>, IF<SB>7</SB>, NF<SB>3</SB>, N<SB>2</SB>F<SB>4</SB>, N<SB>2</SB>F<SB>2</SB>, N<SB>3</SB>F, H<SB>2</SB>NF, HNF<SB>2</SB>, NOF and NO<SB>2</SB>F or at least a kind of compound selected from these compounds corresponding to the fluorinating agent to which 1-20 vol.% F<SB>2</SB>is added. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for generating fluorine for safely supplying a large amount of fluorine useful for cleaning synthetic raw materials for fluoride and thin film deposition equipment.

[0002]

PRIOR ART AND PROBLEMS TO BE SOLVED BY THE INVENTION Fluorine (F ₂ ) is known to be a useful substance as a raw material for synthesizing various fluorides and as a cleaning gas. However, F ₂ has a problem that it cannot be transported in a large amount because it is very reactive and it is difficult to fill the cylinder with a high-concentration gas under high pressure. When used as a synthetic raw material or clean gas, the purity of F ₂ is preferably as high as possible. Usually, as a method for generating fluorine, a method by electrolysis of molten salt of hydrogen fluoride-potassium fluoride is most industrially used. Further, in recent years, an electrolysis device capable of supplying fluorine on-site has been commercially available. However, electrolysis has stability problems such as electrode wear and abnormalities due to the anode effect, and it is necessary to handle very dangerous hydrogen fluoride during maintenance, so high-purity F ₂ is supplied. As a method, K ₃ Ni
A method of heating F ₇ is known (see formula, Learned)
B Asprey, Journal Fluorine chemistry, vol.7, 359-3
61, 1976).

K ₃ NiF ₇ → K ₃ NiF ₆ + 0.5F ₂ ... However, in this method, the amount of fluorine that can be generated is small relative to the weight of the solid fluorine compound, and from the viewpoint of transporting a large amount of fluorine. Remains a problem. As an F ₂ supply method, a method is known in which NF ₃ plasma is generated and decomposed into N ₂ and F ₂ . However, in this method, F ₂ is N ₂
However, impurities may be generated due to the generation of NFx radicals, although it may be diluted with. In addition, since the active species have a long life, they cannot be used, for example, in the synthesis of organic substances when there is a risk of ignition.

[0004]

DISCLOSURE OF THE INVENTION As a result of intensive studies in view of the above problems, the present inventors have found that after the fluorine-generating agent is thermally decomposed to generate F ₂ , the fluorinating agent, or these gases. The present invention has found a method of extracting a large amount of F ₂ by regenerating with a fluorinating agent to which a small amount (1 to 20 vol%) of F ₂ is added.

That is, the present invention heats a fluorine generating agent.
In the method of generating fluorine by
Is generated, and then the fluorine generating agent is refreshed with a fluorinating agent.
Fluorine characterized by alternating fluorination operations
The fluorine generating agent is K₃NiF₇, CoF
₃And the fluorinating agent is ClF, ClF₃, ClF
_Five, BrF, BrF₃, BrF_Five, IF₃, IF_Five, IF₇,
NF₃, N₂F_Four, N₂F ₂, N₃F, H₂NF, HNF₂, N
OF, NO₂At least one compound selected from F
Or the fluorinating agent is F₂1 to 20 vol%
At least one selected from these compounds
Providing a method for generating fluorine characterized by being a compound
To do.

In the present invention, K _{3 is} used as the fluorine-generating agent.
When using NiF ₇ , the heating conditions for generating F ₂ are:
In the temperature range of 200 to 800 ° C., more preferably 300
The temperature range is up to 400 ° C., and the interhalogen gas (ClF, ClF ₃ , ClF ₅ , BrF, BrF ₃ , Br) is used.
The reproduction conditions in F ₅ , IF ₃ , IF ₅ , IF ₇ ) are 20 to 2
In the temperature range of 00 ° C, the temperature range of 50 to 150 ° C is more preferable, and the temperature range of 130 to 150 ° C is more preferable. Under the heating conditions of K ₃ NiF ₇ , 200
When the temperature is lower than 0 ° C, the generation rate (decomposition rate) is slow and inefficient, and when the temperature is higher than 800 ° C, the filling pipe is severely damaged (corroded) by fluorine, which is not preferable. Regeneration fluorination with an interhalogen gas is possible at a relatively low temperature, but since it is not particularly necessary to cool it, the temperature may be 20 ° C. or higher and 200 ° C. or lower. If the temperature is 200 ° C. or higher, a competitive reaction with the decomposition occurs and the regeneration efficiency decreases, which is not preferable. When NF ₃ is used for the regeneration reaction, it is necessary to activate (decompose) NF _{3 with} a heating activation device or a plasma activation device before introducing it into a K ₃ NiF ₇ filled tube. The heating temperature of K ₃ NiF ₇ at this time is the same as the heating condition with the interhalogen gas. The activation of NF ₃ in the heating device is preferably carried out in the temperature range of 300 to 800 ° C. In the case of the plasma activation device, the frequency used for decomposition may be in the high frequency region or the microwave region, but it is preferable that the decomposition can be performed as close to atmospheric pressure as possible because it is device simple.

Next, when CoF ₃ is used as a fluorine generating agent and heated to generate F ₂ , 450 to 800 ° C.
Is more preferable, and a temperature range of 550 to 700 ° C. is more preferable. The reason why the temperature is preferably 800 ° C or lower is that K ₃ Ni
Similar to F ₇ , there is a problem that decomposition does not proceed efficiently at 450 ° C or lower. Decomposition of CoF ₃ produces CoF ₂ . When an interhalogen gas is used for regeneration of CoF ₂ into CoF ₃ or when NF ₃ is previously activated in the same manner as in the above-mentioned method, it is preferable to carry out at a temperature of 500 ° C. or lower. When the temperature is 500 ° C. or higher, the production and decomposition of CoF ₃ occur competitively, which is inefficient.

[0008]

The present invention is described in detail below with reference to examples, but the present invention is not limited to these examples.

Example 1 As a result of charging K ₃ NiF ₇ in a differential thermogravimetric analyzer and heating it in an Ar stream, the weight rapidly decreased from about 200 ° C. The generated gas was F ₂ . In addition, K ₃ Ni
When a sample (presumed to be K ₃ NiF ₆ ) after heating F ₇ and generating F ₂ was heated in a ClF ₃ atmosphere, it was exposed to ClF ₃ from differential thermogravimetric analysis, and weight increase occurred, A rapid weight gain occurred above 130 ° C. Also,
Similar results could be obtained using other interhalogen gases. From the above, when a fluorine-based interhalogen gas is used, the generation of F ₂ from K ₃ NiF ₇ is 200 ° C. or higher, and the regeneration treatment may be performed at room temperature.
It was found that 0 ° C or higher is preferable.

Example 2 A double-ended stainless steel cylinder having an internal volume of 50 cc filled with 5 g of K ₃ NiF ₇ was degassed to about 1 Pa by a vacuum pump and heated to 300 ° C. Increased to 0.25 MPa. The gas in the cylinder was F ₂ when analyzed by GC-MS. The gas in the tube was degassed with a vacuum pump, the temperature was lowered to 200 ° C., ClF ₃ was charged to 0.1 MPa, and the operation was allowed to stand until the pressure decrease stopped about 5 times. Then, when the inside of the tube was degassed to vacuum and heated again to 300 ° C., the pressure inside the tube rose to 0.25 MPa. This operation was further repeated about 4 times, but after treatment with ClF ₃ , K ₃ Ni was added.
It could be obtained F ₂ by heating the F _7. Also, instead of ClF ₃ , BrF ₃ , BrF ₅ , IF ₅ , I
Similar experiments were conducted with F ₇ , N ₂ F ₂ , N ₂ F ₄ , NOF and NO ₂ F, but F ₂ could be obtained after the regeneration treatment.

Example 3 100 g of K ₃ NiF ₇ was filled in a stainless steel cylinder having a diameter of 2.5 cm and a length of 100 cm shown in FIG.
When heated to 0 ° C., fluorine generated generated the internal pressure of the reactor to about 6 MPa. After reducing the pressure inside the pipe to 1 Pa and the temperature inside the pipe to approximately 150 ° C, NF ₃ (100S
CCM) was circulated in the cylinder for 2 hours through a microwave transmission tube, and the pressure was maintained at 13.3 kPa. Then, microwaves (1.45 GHz, 1.5 KW) were applied to the transmitter tube to decompose NF ₃ , and the decomposed gas was passed through the cylinder. Then, when it was reheated, the pressure in the cylinder rose to about 6 MPa due to the generation of F ₂ . This operation was repeated 5 times by repeating heating and retreatment with NF ₃ , but when heating after the regeneration treatment, F ₂ was generated and the pressure in the cylinder increased due to the gas.

Example 4 The same apparatus as in Example 3 was filled with 100 g of K ₃ NiF ₇ , and 3
Fluorine generated when heated to 50 ° C. raised the internal pressure of the reactor to about 6 MPa. After reducing the pipe pressure to 1 Pa and the pipe temperature to approximately 150 ° C, NF ₃ (100
SCCM) was circulated in the cylinder for 3 hours through an alumina tube heated to 800 ° C. and the pressure was maintained at 13.3 kPa. Then microwave (1.45 GHz, 1.5
(KW) was applied to the transmitter tube to decompose NF ₃ and the decomposed gas was passed through the cylinder. Then, when it was reheated, the pressure in the cylinder rose to about 6 MPa due to the generation of F ₂ . This operation was repeated 5 times by repeating heating and retreatment with NF ₃ , but when heating after the regeneration treatment, F ₂ was generated and the pressure in the cylinder increased due to the gas.

Example 5 Instead of the microwave plasma generator used in Example 3, an inductively coupled high frequency plasma generator (1.2 kW, 2
(MHz) was attached and the same experiment was conducted (however, the pressure was 0.1 kPa). NF _3, NOF as gas were each performed in F ₂ addition _{NF 3, N 2 F 4,} N 2 F 2. As a result, K ₃
The result was that NiF ₇ was regenerated and repeated generation of F ₂ was possible.

Example 6 The cylinder of the experimental apparatus used in Example 3 was replaced with an alumina tube, CoF ₃ was used in place of K ₃ NiF ₇ , and F ₂ generation and subsequent regeneration tests were conducted. CoF ₃ generated F ₂ by heating at 650 ° C. Also, the heater was set to 450 ° C. during the regeneration process, but due to the structure of the tube, CoF ₃
The temperature of the filling part was 400 to 100 ° C. As a result of the regeneration treatment, it was possible to re-emit F ₂ from CoF ₃ . Also NF
₃ instead of N ₂ F ₂ , N ₂ F ₄ , NOF, NO ₂ F, 5 vol
Similar results were obtained using NF ₃ with% F ₂ .

Embodiment 7 FIG. 2 shows a conceptual diagram of the F ₂ generator.
A column (φ25 cm ×) packed with K ₃ NiF ₇ (50 g)
L40 cm) two (column A, column B) are connected in parallel, and they are heated (250 ° C.), and first, column A
F ₂ was extracted with 2 to 10 SCCM. When the pressure in the column A2 drops to atmospheric pressure, the column B3 to F ₂
The column B3 was cooled to 150 ° C., and the ClF ₃ packed tube (fluorinating agent packed tube 1) was used to remove ClF ₃
Was taken out and filled (0.2 MPa). C in column A2
After filling with 1F ₃ , when the pressure drops to atmospheric pressure, Cl
While F ₃ was discarded from the exhaust port via the gas exhaust device 7, it was supplied to the column A 2 at 10 SCCM by the gas flow control device 4 for 1 hour. After the supply of ClF ₃ was stopped and the column A2 was purged with N ₂ , the column A2 was evacuated and heated to 250 ° C. Next, when the supply of F ₂ from column B3 was stopped, 250
F ₂ was taken out from the column A2 heated to 10 ° C. with 10 SCCM. During this time, ClF ₃ was circulated in the column B3 to carry out the regeneration treatment by the same operation as in the column A2. Continuously by repeating the series of operations described above it it was possible to supply the F _2, F ₂ in the CVD apparatus 6 through the gas flow controller 5. Also, while supplying F ₂ , S
When the glass plate with the i film was washed (1
(00 ° C., 1 kPa), the Si film was removed and washed. F
_When the regeneration treatment of No. ₂ was performed with NF ₃ plasma, continuous F ₂ supply was possible.

[0016]

INDUSTRIAL APPLICABILITY According to the present invention, since a highly reactive gas cannot be charged at a high pressure, it cannot be transported and supplied in a large amount.
₂ can be supplied in large quantities. As a result, in a device manufacturing apparatus or the like in the semiconductor industry, it is possible to promote the use of F ₂ as a cleaning gas or a synthetic raw material for removing unnecessary deposits accumulated on the inner walls of the apparatus, jigs, pipes and the like.

[Brief description of drawings]

FIG. 1 shows the structure of a stainless steel cylinder.

FIG. 2 shows a conceptual diagram of an F ₂ generator.

[Explanation of symbols]

1 ... Fluorinating agent filling tube 2 ... Column A 3 ... Column B 4, 5 ... Gas flow rate control device 6 ... CVD equipment 7 ... Gas exhaust system 8: Plasma generator (installed if necessary)

Claims (3)

[Claims] 1. A method of generating fluorine by heating a fluorine generating agent, wherein fluorine is generated, and thereafter, an operation of refluorinating the fluorine generating agent with a fluorinating agent is alternately performed. How to occur. 2. The fluorine-generating agent is K ₃ NiF ₇ , CoF ₃
The method for generating fluorine according to claim 1, wherein 3. The fluorinating agent is ClF, ClF ₃ , Cl
F ₅ , BrF, BrF ₃ , BrF ₅ , IF ₃ , IF ₅ , I
F ₇ , NF ₃ , N ₂ F ₄ , N ₂ F ₂ , N ₃ F, H ₂ NF, HNF
1 to 20 vol% of F ₂ in at least one compound selected from ₂ , NOF and NO ₂ F, or the fluorinating agent
At least one selected from these added compounds
The method for generating fluorine according to claim 1, which is a compound of a species.