JP3177816B2 - Purification method of high purity titanium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for purifying high-purity titanium by an iodine method.

[0002]

2. Description of the Related Art With the rapid integration of VLSIs, titanium, which is a metal having a high melting point and a low resistance, is expected as a gate electrode material and a barrier material. Titanium as such an electronic material is mainly formed on a substrate by sputtering. An iodine method is known as one of the purification methods for obtaining high-purity titanium used for a sputtering target.

Conventional titanium purification by the iodine method will be described with reference to FIG. A U-shaped deposition substrate 2 made of a titanium filament is accommodated in a reaction vessel 1, and crude titanium 3 of low purity is accommodated surrounding the deposition substrate 2. Iodine is supplied into the reaction vessel 1 while the reaction vessel 1 is heated from the outside by the heating furnace 4 to cause an iodination reaction (Ti + 2I ₂ → TiI ₄ ) at 200 to 400 ° C. The synthesized titanium tetraiodide is thermally decomposed on the surface of the deposition substrate 2 heated to a temperature of 1300 to 1500 ° C. to deposit high-purity titanium 9 (TiI ₄ → Ti + 2I ₂ ). Here, the deposition substrate 2 is suspended in the reaction vessel 1 by an attachment member 5 also serving as a lid of the reaction vessel 1, and is welded to a rod-shaped support member 6, which is provided on the attachment member 5 and also serves as a current-carrying electrode. Connected by

[0004] Apart from this conventional general iodine method, the present applicant has developed a method for purifying high-purity titanium via a lower iodide. We have also developed a purification method using a tube as the deposition substrate. A method of purifying high-purity titanium via a lower iodide and using a tubular deposition substrate is described in, for example, JP-A-4-246136.

In the iodine method via lower iodide, titanium tetraiodide is temporarily converted to titanium diiodide by reaction with crude titanium, and this is thermally decomposed in the same reaction vessel. The reaction formula is as follows. Iodination reaction: Ti + TiI ₄ → 2TiI ₂ (up to 900
° C) Ti + 2I → TiI ₂ precipitation reaction: TiI ₂ → Ti + 2I (up to 1100 ° C.)

[0006] In this method, titanium diiodide, which is a lower iodide, is pyrolyzed instead of directly pyrolyzing titanium tetraiodide, thereby lowering the pyrolysis temperature by about 200 ° C and reducing contamination from a reaction vessel or the like. To allow for increased purification efficiency and continuous deposition for extended periods of time. In addition, by using a tube having a large surface area as the deposition substrate, it is possible to greatly improve productivity, such as 100 times that of the conventional one, and at the same time, the indirect heating by the heater in the tube allows the temperature of the deposition substrate to be higher than that of the conventional energization heating. Easy adjustment.

[0007]

In the purification of high-purity titanium by the iodine method, the deposition base 2 is removed by the mounting member 5, so that the deposition base 2 and the supporting members 6, 6 are removed.
In the vicinity of the connection portions 7 and 7, the temperature becomes low, not only the precipitation of the titanium 9 is hindered, but also etching occurs, and the accident that the deposited substrate 2 falls due to rupture without being able to withstand the deposited weight often occurs. As a countermeasure, a technique for preventing etching by vapor deposition of Mo, W or the like is disclosed in Japanese Patent Application Laid-Open No. Sho 62-474.
Although described in Japanese Patent Publication No. 79, even if etching can be prevented, the maximum deposition weight is slightly increased, and a significant improvement in productivity cannot be expected. In the conventional purification of high-purity titanium by the general iodine method, 1%
The deposition weight per batch is 1-3 kg. As described above, the present applicant has reduced the production per batch to 20 to 200 k by using lower iodide and using a tubular deposition substrate in combination.
g, but the falling off of the precipitation substrate 2 is a major obstacle.

An object of the present invention is to provide a method for purifying high-purity titanium, which can reliably prevent a falling and falling of a deposition substrate regardless of a deposition weight.

[0009]

According to the method for purifying high-purity titanium of the present invention, in the purification of high-purity titanium by the iodine method, a deposition substrate comprising a titanium tube is mounted on the upper part of a reaction vessel.
A support made of a titanium tube attached and thicker than the deposition substrate.
The support member suspends and supports the inside of the reaction vessel,
Crude titanium is placed around the deposited substrate, and the upper end is
Installed at a height above the connection with the support member to support
Indirect heating means arranged from the member to the inside of the deposition substrate
The step allows the vicinity of the connection between the support member and the deposition substrate
By heating more strongly than the part,
To the precipitation temperature of the high-purity titanium.
It is to be heated .

[0010]

[Function] High purity of the part from the deposition substrate to the upper part
By heating to the deposition temperature of titanium,
High-purity titanium also precipitates in the vicinity of the connection portion with the holding member in the same manner as in the lower portion, and the vicinity of the connection portion is reinforced by the deposited titanium. Titanium deposited near the joint becomes thicker as the deposition weight increases, and increases with increasing strength.
In addition, since the supporting member is thicker than the deposition substrate, it is possible to reliably prevent the deposition substrate from breaking and falling regardless of the deposition weight.

The use of tubes as the deposition substrate and the support member
Thus, the amount of heating can be arbitrarily adjusted in the longitudinal direction by indirect heating by the heater inside. Therefore, the vicinity of the connection portion having a large heat loss can be easily heated to the deposition temperature.

The vicinity of the connection between the deposition substrate and the support member is highly pure.
In addition to heating to the deposition temperature of titanium , the upper end of the coarse titanium installed around the deposition substrate is made higher than the connection part
It the titanium deposition is accelerated at the connecting portion near the connecting portion vicinity can be more effectively reinforced.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

In the present embodiment, the present invention is applied to a method of purifying high-purity titanium using a tubular deposition substrate and passing through lower iodide.

As shown in FIG. 2, the purifying apparatus used in the apparatus has a cylindrical reaction vessel 1 having an open top.
The reaction vessel 1 is housed in a heating furnace 4 and the inside is evacuated. A precipitation substrate 2 and a crude titanium 3 are accommodated in a reaction vessel 1. The deposition substrate 2 is formed of a U-shaped high-purity titanium tube, and is suspended and supported in the vessel by a mounting member 5 also serving as a lid of the reaction vessel 1. The attachment member 5 has a pair of support members 6 and 6 made of a high-purity titanium tube in order to connect and hold the deposition substrate 2. The supporting members 6 and 6 are thicker than the deposition substrate 2 and are connected to the deposition substrate 2 by welding. The inside of the mounting member 5 communicates with the inside of the deposition substrate 2 via the inside of the support members 6 and 6, and is evacuated separately from the inside of the reaction vessel 1. An electric heater 8 is inserted into the inside of the deposition substrate 2 via the inside of the support members 6 and 6. The electric heater 8 heats not only the deposition substrate 2 but also the portion above the connection between the deposition substrate 2 and the supporting members 6 and 6 from the inside, and the temperature is controlled in multiple stages in the longitudinal direction,
The heating temperature of the connection portions 7, 7 can be adjusted arbitrarily.

To purify high-purity titanium, crude titanium 3 is set in a reaction vessel 1. At this time, the upper end of the coarse titanium 3 is made higher than the connection portion, and the coarse titanium 4 completely surrounds not only the deposition base 2 but also the vicinity 7 of the connection portion. After sealing the inside of the reaction vessel 1 with the support members 6 and 6, the inside of the vacuum vessel 1 is evacuated to 10 ^-1 to 10 ^-3 Torr, and the heating furnace 4
To 700 to 900 ° C. Also, the mounting member 5
Then, the inside of the deposition substrate 3 is evacuated to 10 ^-1 to 10 ^-5 Torr through the heater, and the portion from the deposition substrate 2 to the upper portion thereof is heated to the deposition temperature by the electric heater 8. That is, the vicinity 7, 7 of the connection portion is heated more strongly than the portion below the connection portion, and the vicinity of the connection is also maintained at the deposition temperature. In this state, the vapor of titanium tetraiodide is supplied to the inside of the reaction vessel 1, and the inside of the reaction vessel 1 is continuously evacuated so that the inside of the reaction vessel 1 is maintained at 10 ^-1 to 10 ^-3 Torr.

The titanium tetraiodide supplied into the reaction vessel 1 reacts with the crude titanium 3 to produce titanium diiodide. The generated titanium diiodide is thermally decomposed on the surface of the deposition substrate 2 to deposit titanium 9 of high purity. At this time, since the vicinity 7, 7 of the connection portion is heated to a temperature required for deposition, high-purity titanium 9 'also precipitates on the surface of the vicinity 7, 7 of the connection portion. Therefore, the vicinity 7, 7 of the connection portion is deposited titanium 9 '.
Reinforced by In addition, the titanium 9 'deposited in the vicinity 7, 7 of the connection portion becomes thicker as the reaction time is extended and the weight of the titanium 9 deposited on the deposition substrate 2 increases, so that the titanium 9' is surely not affected by the weight increase. In addition, it is possible to prevent the precipitation substrate 3 from dropping due to fracture.

In addition, in the present embodiment, since the vicinity 7, 7 of the connection portion is completely surrounded by the coarse titanium 3, the increase in the iodide concentration and the heat retaining effect by this result in the vicinity of the connection portion 7, 7, The precipitation of titanium 9 'is promoted. Further, by making the support members 6 and 6 thicker than the deposition substrate 2, the strength of the support members 6 and 6 is increased. Therefore, the falling of the precipitation substrate 2 due to the fracture is more effectively prevented.

In the case where the vicinity 7, 7 of the connection portion is heated to the deposition temperature, it is desirable to heat the range from 10 to 200 mm above the connection portion to this temperature. If the thickness is less than 10 mm, a difference in thickness occurs between the titanium 9 deposited on the deposition substrate 2 and the titanium 9 ′ deposited on the vicinity of the connection portion 7, and if it exceeds 200 mm, the product yield decreases. The deposition temperature is preferably 1100 to 1300 ° C. in the case of the method using lower titanium iodide, since an etching phenomenon occurs at a temperature lower than 1100 ° C. and a mechanical strength lowers at a temperature exceeding 1300 ° C.

It is desirable that the upper end level of the coarse titanium 3 be such that a range of 10 mm or more above the connection portion can be surrounded by the coarse titanium.

The thickness T of the support members 6, 6 is desirably t ≦ T ≦ 2t, where t is the thickness of the substrate after deposition. t>
In the case of T, the mechanical strength in the non-precipitated portions of the support members 6 and 6 is inferior to the mechanical strength after the deposition of the deposition base 2, and the non-precipitated portions of the support members 6 and 6 may be broken.
In the case of T <2T, the heat radiation in the support members 6 becomes large, and it becomes difficult to uniformly heat the vicinity 7 of the connecting portion.

A reaction vessel having an inner diameter of 400 mm × a height of 800 mm, an outer diameter of 60 mm × an inner diameter of 56 mm × a length of 1500 mm
80 kg of crude titanium, a heating temperature of 900 ° C., a heating temperature of the deposition substrate of 1200 ° C., a supply amount of titanium tetraiodide of 150 g / h, and a pressure of 10 ⁻² To in the reaction vessel.
When purifying high-purity titanium under the condition of rr, up to 20 mm above the connection was heated to 1200 ° C., and the same level was surrounded by coarse titanium. Further, the thickness of the supporting members 6 and 6 was set to 27 mm corresponding to the thickness of the substrate after deposition. As a result, about 32 kg of titanium was obtained in a reaction for 200 hours. At this time, the substrate thickness including the initial thickness (2 mm) was 27
mm. Further, titanium having a thickness of 25 mm, which is almost the same as the final substrate thickness, was also deposited on the connection portions 7 and 7.

For comparison, the upper limit position of the heating by the heater was made to coincide with the connection portion, and the upper end position of the coarse titanium was similarly set. The thickness of the mounting portion was also set to 10 mm. When the reaction was carried out under the same conditions, the connection was broken by 100 hours of reaction (precipitation amount: about 15 kg), and the reaction was interrupted. Titanium was hardly precipitated at the connection part, and it was determined that the mechanical strength of the connection part was insufficient.

In the above embodiment, via lower titanium iodide,
In addition, although a tubular deposition substrate is used, the invention can also be applied to a conventional general iodine method and a method using a filament type deposition substrate.

[0025]

As described above, the method for purifying high-purity titanium of the present invention can be applied to the vicinity of the connection between the supporting member and the deposition substrate.
Is heated more strongly than the part below it.
And the upper part to the deposition temperature of high-purity titanium.
Crude titanium that is heated and placed around the deposition substrate
The upper end of the substrate is higher than the connection between the deposition substrate and the support member.
And the reinforcing lines stomach according to the deposition weight to precipitate titanium in the vicinity of the connecting portion, the thickness of the deposition substrate supporting member combined
Since meat is used , even when the reaction time is long, it is possible to reliably prevent the precipitation substrate from falling due to rupture. Therefore, there is an effect of removing the restriction of the reaction time due to the breakage and greatly increasing the amount of precipitation per batch.

[Brief description of the drawings]

FIG. 1 is a schematic view of a refining apparatus used for purifying high-purity titanium by a conventional general iodine method.

FIG. 2 is a schematic view of a purification device used in an example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction container 2 Deposition base 3 Crude titanium 4 Heating furnace 5 Attachment member 6 Support member 7 Near connection part 8 Electricity heater 9, 9 'Deposited titanium

Claims (1)

(57) [Claims] In the purification of high-purity titanium by the iodine method, a deposition substrate composed of a titanium tube is placed on an upper part of a reaction vessel.
It consists of a titanium tube that is attached and is thicker than the deposition substrate
While being suspended and supported in the reaction vessel by a support member,
Crude titanium is provided around the deposition substrate, and the upper end thereof is the deposition substrate.
At a height above the connection between the
Indirect heating arranged from the holding member to the inside of the deposition substrate
By means, the vicinity of the connection between the support member and the deposition substrate is
By heating more strongly than the lower part,
The upper part is the deposition temperature of the high-purity titanium.
A method for purifying high-purity titanium , comprising heating to a high temperature .