JPS6247479A - Device for producing crystal bar titanium - Google Patents

Abstract

PURPOSE:To improve the durability by reinforcing the filament of Ti wire with a material highly resistant to halogen in the method for decomposing halides and preventing the rupture due to halogen. CONSTITUTION:A filament 9' held by feeder jigs 3a and 3b is formed with titanium wire 10, the surface of both end parts are coated with a material having resistance to halogen and a coated film 12 is formed. Both end parts of the titanium wire 10 which are brought into contact with the jigs 3a and 3b consist of a wire rod 11 resistant to halogen and are bonded to the titanium wire 10. The filament 9 is electrically heated, sponge Ti 6 as the raw material reacts with halogen 7 and Ti halide 8 is formed and sublimed. The Ti halide 8 is decomposed on the filament 9 at high temp. and Ti is deposited.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to improvements in equipment used for the production of crystal vertitanium by a halide decomposition process, particularly an iodide decomposition process.

[Technical background of the invention and its problems]

Currently, aluminum is used as metal for wiring and electrodes of large-scale integrated circuits (LSI). However, as higher integration progresses in the future, structures will become finer and the density of current flowing through aluminum wiring will become larger.
This can cause various problems. For example, electromigration, in which aluminum atoms are carried in the direction of electron movement, can cause aluminum bumps where they are deposited. In addition, vacancies are generated on the opposite side where aluminum atoms are depleted. Such defects cause short circuits with other interconnects and disconnections due to increased interconnect resistance. therefore.

Molybdenum will be used in response to the future trend toward higher integration.

Refractory metals such as tungsten or titanium will be used. In particular, titanium has excellent mechanical properties and good workability. In addition, it has excellent corrosion resistance and heat resistance, and electromigration is less likely to occur. therefore,
It is fully compatible with the thinning of wiring due to higher integration, and is most suitable as a metal material for future large-scale integrated circuits.

However, metals used in semiconductor devices are required to have high purity, and in particular, the following impurities may have an adverse effect on semiconductor devices.

Alkali metals such as a, Na, etc. (deterioration of interfacial properties)
Radioactive elements such as b, 'v', and Thfi (soft errors)
c, heavy metals such as Fe, Or, etc. (trouble at interfacial joints) d, o (property deterioration) However, the pure titanium currently produced industrially is
In addition to heavy metal elements and gas components, it contains large amounts of the above-mentioned elements. Since even trace amounts of these elements have a negative effect on the performance of the element, it is necessary to further purify pure titanium. One of them is the halide decomposition method, in particular,
The iodide decomposition method is used to purify titanium. High-purity titanium produced by this method is called crystal bar titanium because of its shape. The iodide decomposition method is a type of chemical transport method, and is a method used for purifying active metals such as titanium, hafnium, and zirconium. Purification is performed using the reactions of the following formulas +1) and +2+.

Ti+2I2--Til4(250~350'0)T
iI4-1 → T++2I2 (1100~1500
°C), that is, titanium (melting point 1800 °C) is iodine (melting point 1800 °C)
Melting point 114°C2 Boiling point 185'0) and 250-350°
m formula that reacts violently at temperatures of C to produce TiI4 (a sublimable solid). Furthermore, TiI4 is 1100-1500'
It has the property of decomposing into titanium and iodine at a high temperature of C, as shown in formula (2) above. Specifically, crystal bar titanium has conventionally been deposited using an apparatus shown in FIG.

(1) in the figure is a vapor deposition container that houses the raw materials, titanium sponge and iodine. This container 1 is maintained at 250-350'O by external heating. Inside the container 1, a filament 2 having a U-shape, for example, is suspended. Both ends of this filament 20 are connected to the power supply jig 3
a, 3b, and each power supply jig 3a,
3b is connected to the direct source 5 via lead wires 4a and 4b. In order to produce crystal bar titanium using such an apparatus, first, sponge titanium (
(Other titanium or titanium alloys can also be used in some cases)
6 and iodine 7, and the power supply jig 3a, 3 from the 7 mingen 5
Pass filament 2 through b and heat to 110
Maintain the temperature at about 0 to 1500°C. Subsequently, the entire vapor deposition container 1 is heated from the outside and maintained at 250 to 350°C. Raw materials sponge titanium 6 and iodine 7, 250
It reacts at low temperatures of ~350°C to produce TiI48.

The generated TiI+ sublimes and decomposes on the high-temperature filament 2, and among the decomposition products, TI adheres to the filament 2, and iodine (■2) reacts with the raw material titanium sponge 6 again. In other words, iodine acts as a carrier to transport titanium onto the filament 2. In this way, only the titanium that reacts with iodine is carried onto the filament 2,
Purification takes place. By repeating this process,
Pure titanium grows on filament 2.

By the way, in the above-mentioned apparatus, since iodine exists in the vapor deposition container 1, at least the portions of the lead wires 4a and 4b inside the container 1 and the power supply jig 3a.

3b is a material with high corrosion resistance against iodine (~1o, W
etc.) is generally formed. In addition, in addition to the structure shown in Figure 11, there are structures in which the power supply jig and lead wire are integrated, and structures in which the power supply jig is connected to the lead wire outside the vapor deposition container, but in either case. However, at least the portion located inside the vapor deposition container is made of Mo or W.

Connect filament 2 to the power supply jig and lead wire.
When formed from Mo or W, ■ After the crystal bar titanium is evaporated, it becomes difficult to separate the crystal bar titanium from the filament made of Mo, W, etc., ■ The crystal bar titanium is contaminated with Mo, W, etc. The filament is usually made of titanium wire for reasons such as the fear of However, the communication using ri, 5
Due to heating, the titanium filament 2 part is connected to the power supply jig 3a.
, 3b is known to drop to about 300°C. As a result, the reaction of formula (1) above progresses, often causing breakage in the filament.

Therefore, countermeasures have been considered to prevent the above-mentioned breakage, such as improving the shape of the filament and the method of attaching the power supply jig, but the reality is that sufficient results have not yet been obtained.

[Purpose of the invention]

An object of the present invention is to provide an apparatus for producing crystal bar titanium with excellent durability, which prevents breakage of titanium wire constituting a filament due to iodine when producing crystal bar titanium by a halide decomposition method, particularly an iodide decomposition method. The purpose is to

[Summary of the invention]

The present invention uses, as a filament, a titanium wire in which at least the surfaces of both ends that come into contact with a power supply jig are made of a material impregnated with corrosion resistance against halogen, in an apparatus for manufacturing crystal bar titanium by a halide decomposition method. It is characterized by:

EMBODIMENT OF THE INVENTION Hereinafter, the apparatus for producing crystal bar titanium of the present invention will be explained in detail with reference to the drawings, taking an iodide decomposition method as an example. Note that the same members as those shown in FIG. 11 described above are given the same reference numerals, and the description thereof will be omitted.

FIG. 1 is a schematic cross-sectional view showing one form of the manufacturing apparatus of the present invention. 9 in the figure is a filament held by the power supply jig, ia, and 3b. As shown in FIGS. 1 and 2, this filament 9 touches at least the surface of both ends of the titanium wire 100 that come into contact with the power supply jigs 3a and 3b.
Made of material that has corrosion resistance against rogen (iodine) K.
For example, it has a structure in which wire rods 11 made of the above-mentioned materials are joined. According to such a configuration, the sponge,
Contains titanium (other titanium or titanium alloys may be used in some cases) 6 and iodine 7, and connects the power supply jig 3 to the power source 5.
a, 3b, filament) 9 is energized and heated to 110
When the temperature is maintained at about 0 to 1500°C and the entire vapor deposition container 1 is heated from the outside and maintained at 250 to 350°C, the raw materials, titanium sponge 6 and iodine 7, are heated to 250 -
It reacts at a low temperature of 350°C to produce TiI48. The generated TiI4 sublimes and decomposes on the high-temperature filament 2, and among the decomposition products, T1 is a filament)9171:
The iodine (T2) is attached to the raw material sponge titanium 6 again.
reacts. By repeating this process,
Pure titanium is grown on filament 9 to produce crystal bar titanium. In this process, the power supply jig 3
The wire rod 11 made of a material with excellent corrosion resistance against iodine is joined to the filament 90 strands and the joint portions, which are in contact with a and 3b and have a low temperature (approximately 300°C), so the filament at that part It is possible to obtain a device that can prevent the breakage of 9 and has excellent durability.

For example, M
Examples include o, W, and P, or alloys based on these. These materials can be used at room temperature to about 1500℃
It is hardly corroded by iodine in the temperature range of It shows strong breakage resistance. The wire rods 11 at both ends of the filament 9 do not necessarily have to be made of the same material or have the same shape, but from the viewpoint of ease of manufacture and controllability of the filament temperature, they may be made of the same material or have the same shape.
It is desirable to have the same shape. Regarding the length of the wire 11, the shorter the length, the higher the production yield of crystal par and titanium, and the lower the power consumption.
When the central part of the titanium wire 10 of the filament 9 is heated to approximately 1100 to 1500°C while being held in the power supply jigs 3a and 3b, the temperature near the boundary between the wire 11 and the titanium wire 10 is such that crystal bar titanium precipitates. conditions (approximately 900°O
) K is required. Wire rod 11
The length of is appropriately determined in consideration of the method of attachment to the power supply jigs 3a, 3b, the shape of the filament 9, the manufacturing conditions of crystal bar titanium, etc. The diameter of the wire 11 is titanium wire 10
need not be the same as the diameter of

However, if the diameter of the wire 11 becomes thicker, the power supply jig 3a,
3bK instead, the wire 11 exerts a cooling effect on the titanium wire 10, and if it is made too thin, the diameter of the wire 11 will be
Shape of filament 9, diameter of titanium wire 10, titanium wire 1
It is determined as appropriate in consideration of the electrical resistance between 0 and the wire 11, the manufacturing conditions of crystal bar titanium, etc.

Possible methods for joining the titanium wire 10 and wire 11 include resistance welding, laser welding, inert gas arc bath welding, and electron beam welding. Welding is preferred. For example, Ti and M.

In resistance welding, Mo does not melt, only Tl melts, so the joint strength becomes extremely low. In laser welding,
Mo and Ti are hardly welded together. Furthermore, although the bonding itself is good in inert gas arc bath welding, if crystal bar titanium is manufactured using a filament formed by such bonding, there is a risk that breakage will occur near the bonded portion during manufacturing. On the other hand, filaments obtained by joining by electron beam welding have extremely high tensile strength and bending strength, and are sound even during the production of crystal bar titanium. It precipitates and grows.

The shape of the filament 9 is not limited to that shown in FIGS. 1 and 2, but may be the shape shown in FIG. 3 or 4. The filament 9 shown in FIG. 4 is constructed by using a wire rod 11 made of a material with excellent corrosion resistance against iodine at both ends of the titanium wire 10 and at a portion supported by a support (not shown) in the vapor deposition container. There is.

On the other hand, as a means of forming at least the surface of both ends of the titanium wire that comes into contact with the power supply jig with a material immersed in corrosion resistance against iodine, as shown in FIGS. As shown in FIG. 5, both ends of the titanium wire 100 are coated with a coating 12 made of a material having excellent corrosion resistance against iodine, and the filament 9'
may be configured.

As in the case of the wire, Mo, W, Pt, or alloys based on these can be cited as materials with excellent corrosion resistance against iodine that form the coating 12 coated on both ends of the titanium wire 10. I can do it.

These materials are hardly corroded by iodine in the temperature range of about 300° C. to 1500° C., and therefore a filament 9′ constructed with such a coating 12 as shown in FIG. , exhibits strong breakage resistance against the cooling effect of the power supply jigs 3a and 3b.

The broken membranes 12 at both ends of the filament 2' do not have to be made of the same material, but from the viewpoint of ease of manufacture and controllability of the filament temperature, it is desirable that they be made of the same material. Even if the shape of the film is determined, it is not necessary that both ends have the same shape, but from the viewpoint of ease of manufacture and controllability of the filament temperature, it is desirable to have the same shape. Such coating 1
Regarding the length of 2, the shorter the length, the higher the production yield of crystal bar titanium and the lower the power consumption. The center part is about 1100~l
When heated to 500' OK, the coating 12 and the titanium wire 10
It is necessary at least to have a length such that the temperature near the boundary with the crystal bar titanium is at a temperature (approximately 900° C.) for precipitation of crystal bar titanium. The length of the coating 12 is the same as that of the power supply jigs 3a and 31.
) is appropriately determined in consideration of the method, the shape of the filament 9', the manufacturing conditions of crystal bar titanium, etc. Regarding the thickness of the coating 12, if it is too thick, the coating 12 will exert a cooling effect on the titanium wire 10 instead of the power supply jigs 3a and 3b, and if it is too thin, the titanium wire 10 under the V-film will There is a risk that the parts may react with iodine and break. Regarding the thickness of the coating 12, the shape of the filament 9/),
It is determined as appropriate in consideration of the diameter of the titanium wire 10, the electrical resistance between the titanium wire 10 and the coating 12, the manufacturing conditions of crystal bar titanium, etc. Further, the breakage resistance of the filament 9' against iodine can be improved by coating not only the outer periphery of the titanium wire 10 but also the tip of the titanium wire 10 as shown in FIG. 5.

The above film can be formed by coating the entire surface of the titanium wire 10 by electron beam evaporation, sputter deposition, plating, etc., and then removing unnecessary film parts, or by masking so that both ends of the titanium wire 100 are exposed. , electron beam evaporation, sputter evaporation, plating, or the like may be employed. The filaments obtained by these methods are
Both tensile strength and bending strength are excellent, and the adhesion of the coating to the titanium wire IO is also extremely good. When crystal bar titanium is manufactured using a device incorporating the filament 9' on which the corrugated film is formed, the filament 9'
' is sound even during manufacture, and crystal vertitanium precipitates and grows well on the filament.

The shape of the filament 9' is not limited to the shape shown in FIG. 5. For example, as shown in FIGS. 6 and 7, a titanium wire 100 covering the coating 12 has a filament 9' with thinner ends, or a titanium wire 10 as shown in FIG.
A filament 9' in which the titanium wire 10 is straight and linear and a coating 12 is formed on both ends thereof, or a filament 9' in which the thickness of the coating 12 is gradually thinned from the tip of the titanium wire 10 toward the center as shown in FIG. There are various shapes. In addition, as shown in FIG. 10, a coating 1 made of a material with excellent corrosion resistance against iodine
2 are formed on both ends of the titanium wire 10 and at a portion supported by a support (not shown) in the vapor deposition container to form a filament 9'.
may be configured.

[Embodiments of the invention]

The present invention will be explained in detail below.

Example 1 A crystal bar titanium wire with a diameter of 0.9 mm and a length of 40 m and two Mo wires with a diameter of 0.7 mm and a length of 3 mm were each finished with a flat joint surface, and the titanium wires were After attaching the ends of the Mo wire to the Mo wire, vacuum degree 1 (Y'mln
Hg ~I Q-5 mml (g, acceleration voltage 60 keV
A filament plate having the shape shown in FIG. 2 was manufactured by electron beam welding at a beam current of 3 mA. The obtained filament 9 exhibited satisfactory values for both tensile strength and bending strength.

The obtained filament 9 is transferred to the power supply jig 3a in the vapor deposition container 1.
, 3b to assemble the apparatus shown in FIG.

After degassing the inside of the vapor deposition container 1 of such an apparatus, 29 kg of titanium sponge and 100 g of iodine are stored, and the filament 9 is heated by the power source 5 to about 1500'O&C, and the vapor deposition container 1 is heated from the outside to about 300°C. Then, crystal bar titanium was deposited on filament 9. When this precipitation operation was carried out for 30 hours, the average diameter was 1.9 cm.
! rL crystal bar titanium can be obtained, and the power supply jig, filament 9 near '(a, 3b)
No breakage occurred.

Example 2 A crystal bar titanium wire with a diameter of 3.9 am and a length of 40C:In and a long 3-piece W wire with an iK diameter of Q of 7 mm were each polished to a flat surface. After attaching the tips of both ends and the W wire, the degree of vacuum is 1g-'
mmHg ~10 ffllHg % acceleration voltage 70k
Electron beam welding was performed at an evt beam current of 4 mA to produce a filament 9 having the shape shown in FIG.

The obtained filament 9 exhibited satisfactory values for both tensile strength and bending strength.

The transferred filament 9 is transferred to the power supply jig 3 in the vapor deposition welder 1.
The apparatus shown in FIG. 1 was assembled by holding a and 3bK. After degassing the inside of the vapor deposition container 1 of such an apparatus, the sponge titanium 3
．． 9 contains 9 and 120 g of iodine, and the filament 9 is heated by the power supply 5 to about 1500'CVc, and the vapor deposition container 1 is heated from the outside to about 300' (:), and crystal vertitanium is deposited on the filament 9. After 20 hours of such precipitation, the average diameter was 154 m.
of crystal bar titanium can be obtained, and the supply is
No breakage of the filament 9 occurred near the jigs 3a and 3b.

Example 3 A crystal bar titanium wire with a diameter Q of 911 Im and a length of 40° and two PT wires each with a diameter of 0.77 mm and a length of 3 cm were each finished with a flat joint surface, and their joint surfaces were After attaching the ends of both ends of the wire to the PT wire, the degree of vacuum was 10 [mHg ~ 10 Hg, and the acceleration voltage was 60
Electron beam welding was performed under the conditions of keV and beam current of 3 mA to produce a filament 9 having the shape shown in FIG. The obtained filament 9 exhibited satisfactory values for both tensile strength and bending resistance.

The obtained filament 9 is transferred to the power supply jig 3a in the vapor deposition container 1.
, 3b to assemble the apparatus shown in FIG. After deaerating the inside of the vapor deposition container 1 of such an apparatus, the titanium sponge 3.
The filament 9 was heated to about 1500°C by the E15 source 5, and the vapor deposition vessel 1 was heated by CVC from the outside to about 300°C to precipitate crystal bar hafnium on the filament 9. I let it happen. When this precipitation operation was carried out for 25 hours, the average diameter was 1.
．． 61 glue+) Star/L/Vertitanium could be obtained, and no fracture of the filament 9 occurred near the power supply jigs 3a and 3b.

Furthermore, when the components of the crystal bar titanium produced in Examples 1 to 3 were analyzed, the results shown in the IEI table were obtained. Table 1 also shows the analysis values of the titanium sponge components used as raw materials. As is clear from Table 41, the crystal bar titanium produced in Examples 1 to 3 has a much lower oxygen content.

Example 4 After masking the surface of a crystal pertitanium wire with a diameter Q of 9 m + n and a length of 40 crrL except for both ends (each 3 cm long from the tip) with aluminum foil, the wire was placed in an argon atmosphere under a pressure of 6 x 10 torr. +voltage 4
Glow discharge sputtering was performed for 30 minutes under the conditions of 00V and 7A current to form an average thickness of 7.5mm on both ends of the titanium wire, including the tip.
A filament 9' having the shape shown in FIG. 5 was manufactured by depositing a Mo film as shown in FIG. The Mo coating of this filament 9' exhibited sufficiently satisfactory adhesion to titanium kneading.

The obtained filament 9' is transferred to the power supply jig 3 in the vapor deposition container 1.
A device similar to that shown in FIG. 1 was assembled by holding parts a and 3b. After the vapor deposition container 1 of such an apparatus was degassed, 2.9/cq of titanium sponge and 8 Qg of iodine were placed therein.

The filament 9' was heated to about 1500°0 by the power source 5, and the vapor deposition container was heated from the outside to about 300°0 to deposit crystal bar titanium on the filament 9'. After carrying out this precipitation operation for 30 hours, it was possible to obtain crystal bar titanium with an average diameter of 1.7 CrIL, and no breakage of the filament 9' occurred near the power supply jigs 3a and 3b.

Example 5 A crystal pertitanium wire with a diameter of 0.9mm and a length of 40mm was masked with aluminum foil except for both ends (each 3CTL length from the tip), and then heated in an argon atmosphere under pressure of 6X10 torr. , voltage 450V + k
Glow discharge sputtering was carried out for 35 minutes at a flow rate of 8A to form an average of 0.15% at both ends of the titanium wire, including the tip. Isa7
A μm thick W film was deposited and 2 [! A filament 9' having the shape shown in Fig. 5 was manufactured. The W coating on the filament 9' exhibited sufficiently satisfactory adhesion to the titanium wire.

The obtained filament 9' is transferred to the power supply jig 3 in the vapor deposition container 1.
a, 3b A device substantially similar to that shown in FIG. 1 was assembled with VC maintained. After degassing the inside of the vapor deposition container 1 of such an apparatus, 3.91 cg of sponge titanium and 120 g of iodine were stored,
The filament 9' was accommodated by the power supply 5, and the filament 9' was heated to about 1500°C by the power supply 5, and the vapor deposition container was heated from the outside to about 300°C, so that crystal bar titanium was deposited on the filament 9'. . When this precipitation operation was carried out for 18 hours, the average diameter was 1.41.
of crystal bar titanium was obtained, and no breakage of the filament 9' occurred near the power supply jigs 3a, 3t).

Example 6 After masking the surface of a crystal pertitanium wire with a diameter of 0.9 mm and a length of 40 cm, except for both ends (each having a length of 36 inches from the tip) with aluminum foil, the wire was heated in an argon atmosphere under pressure of 6×I. 0-3torr, pressure 40
Glow discharge sputtering was performed for 15 minutes under the conditions of 0V and 7A to form an average thickness of 20mm on both ends of the titanium wire, including the tip.
A filament 9' having the shape shown in FIG. 5 was manufactured by depositing a PT film with a thickness of μm. The PT coating of this filament 9' showed sufficiently satisfactory adhesion to the titanium wire.

The obtained filament 9' is transferred to the power supply jig 3 in the vapor deposition container 1.
A and 3b were held, and a device approximately similar to that shown in Fig. m1 was assembled. After degassing the inside of the vapor deposition container 1 of such an apparatus, the sponge titanium 3.3. The filament 9' was heated to about 1500°C by the low source 5, and the vapor deposition container 1 was heated from the outside to about 300°C to precipitate crystal bar titanium on the filament 9'. Ta. When this precipitation operation was carried out for 25 hours, the average diameter was 1.
．． 6 m of crystal bar titanium can be obtained, and the filament 9' does not break near the power supply jigs 3a and 3b at all.

Furthermore, when the components of the crystal bar titanium produced in Examples 4 to 6 were analyzed, the results shown in Table 2 below were obtained. In addition, in Table 2, the analysis values of the sponge components used as Vr-ke raw materials are also listed.

As is clear from Table 2, the crystal bar titanium produced in Examples 4 to 6 has an extremely low oxygen content.

In addition, in the above example, a case was explained in which crystal bar titanium was produced by storing solid T1 and silicon in a vapor deposition container, but solid TiI4 and solid TiI4 and Tl, or solid TiI4 and Crystal bar titanium may be produced by supplying Ti and titanium into a deposition container.

Table 1 (blank below) Table 2 [Effects of the invention] As detailed above, according to the present invention, when producing crystal bar titanium by a halide decomposition method, particularly an iodide decomposition method, titanium wires constituting filaments can be used. It is possible to provide an apparatus for producing crystal bar titanium with excellent durability, which prevents breakage due to iodine.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing one embodiment of the apparatus for producing crystal bar titanium of the present invention, FIG. 2 is a sectional view of a filament used in the apparatus for producing crystal bar titanium of FIG. 1, and FIG. 10 are sectional views showing other forms of filaments used in the crystal bar titanium manufacturing apparatus of the present invention, and FIG. 11 is a schematic sectional view showing a conventional crystal bar titanium manufacturing apparatus. 1... Vapor deposition container, 3a, 3b... Power supply jig, 4a,
4b...Lead wire, 5...Power supply, 6...Sbonne titanium, 7...Iodine, 8...TiI4.9.9'
... filament), 10... titanium wire, 11...
Wire rod, 12... coating. Agent Patent Attorney Yudo Nori Chika Kikuo Takehana Figure 1 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10

Claims (4)

[Claims] (1) In an apparatus for manufacturing crystal bar titanium using a halide decomposition method, use a titanium wire as a filament, with at least the surface of both ends in contact with the power supply jig made of a material with excellent corrosion resistance against halogens. Equipment for producing crystal bar titanium. (2) Manufacturing the crystal bar titanium according to claim 1, wherein both ends that come into contact with the power supply jig are made of a wire made of a material that is resistant to corrosion against halogen and is bonded to a titanium wire. equipment. (3) The crystal bar titanium according to claim 1, wherein both ends that come into contact with the power supply jig are coated with a film of a material that is corrosion resistant to halogen and coated with a titanium wire. Equipment for the production of. (4) The apparatus for producing crystal bar titanium according to claim 1, wherein the material having corrosion resistance against halogen is selected from molybdenum, tungsten, and platinum.