JPH10298675A - Method for refining high purity titanium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the using efficiency of coarse titanium, to prevent the parting space in a reaction vessel in which high purity titanium is precipitated over the surface of a substrate by an iodine method and to increase the precipitation reaction rate by arranging plural bar-shaped coarse titanium around the precipitating substrate in the reaction vessel. SOLUTION: Plural coase titanium 7 is arranged around a hollow precipitating substrate 5 sagged in a reaction vessel 1. Preferably, the coase titanium 7 is composed of a casting material or rolled melting material in which the cross-section is a circular round bar, and the cross-sectional area is regulated to 10 to 200cm<2> . The inside of the reaction vessel 1 is evacuated and heated, and the vapor of titanium tetraiodide is introduced into the reaction vessel 1. The hollow precipitating substrate 5 is heated by a heater. The coarse titanium in the reaction vessel 1 is converted into titanium diiodide, which is thermally decomposed on the surface of the hollow precipitating substrate 5 and is converted into high purity titanium. By the following operation, the coarse titanium 7 high in consumption is arranged at positions distant from the hollow precipitating substrate 5, and each coarse titanium 7 is allowed to be uniformly consumed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In recent years, thin films of high-purity titanium have begun to be used as gate electrode materials, diffusion barrier materials, wiring materials and the like in semiconductor devices such as LSIs and ULSIs. This high-purity titanium thin film is usually formed by sputtering, and its sputtering target is generally manufactured from melting, forging, rolling, and heat-treating a high-purity titanium purified by an iodine method. .

In the purification of high-purity titanium by the iodine method used here, crude titanium having a low purity and a titanium substrate having a high purity are accommodated in a reaction vessel and heated in various heating modes by a synthesis reaction and a thermal decomposition reaction. Is to deposit high-purity titanium on the titanium substrate thus formed. Since the iodine reaction here is a diffusion-controlled reaction, increasing the surface area of the deposition substrate has a great effect in terms of accelerating the thermal decomposition rate.

[0004] From this viewpoint, the present applicant has previously proposed changing the deposition substrate from a conventional linear filament to a tube (Japanese Patent Publication No. 7-62183), and succeeded in significantly increasing the productivity. I have.

On the other hand, in the case of coarse titanium, it is a general arrangement that sponge-like titanium is charged along the inner surface of a reaction vessel and surrounds a deposition substrate disposed at a central portion in the reaction vessel. However, when sponge-like titanium is used as coarse titanium, there is a problem of deformation shrinkage due to heat and instability of the iodination rate.
A plurality of plate-like crude titanium 7, 7,... Made of ingot material obtained by casting and rolling sponge-like titanium are arranged around the above-mentioned tubular precipitation substrate 5 to operate. I have.

By arranging a plurality of plate-like crude titanium 7, 7,... Around the tubular deposition substrate 5, a uniform iodination reaction can be progressed locally, and a sponge-like titanium , The packing density can be increased as compared with the case of disposing.

[0007]

However, a plurality of plate-like crude titanium 7, 7,...
Is arranged, the distance from the individual coarse titanium 7 to the deposition substrate 5 becomes non-uniform in the plate width direction of the coarse titanium 7, and as a result, the coarse titanium 7 Is locally consumed in the central portion in the plate width direction where the distance is the shortest, and if the device is used twice, the device becomes unusable despite having sufficient thickness on both sides.

For this reason, the use efficiency of crude titanium is very low.

On the side of the deposition substrate 5, the inside and outside of the crude titanium 7 surrounding the deposition substrate 5,
Because the space inside is divided and the effective reaction space is narrowed,
There was a problem that productivity fell.

Furthermore, since the coarse titanium 7, 7... Effectively contributes to the deposition only in the central portion in the plate width direction, the effective array density is small even if it is arranged around the deposition substrate 5 without gaps. Therefore, the deposition rate per unit filling amount of crude Ti decreases.

An object of the present invention is to improve the use efficiency of crude titanium, to avoid the alienation of the iodination reaction due to the division of the reaction space by the crude titanium, and to reduce the deposition rate by limiting the effective array density. An object of the present invention is to provide a method for purifying high-purity titanium, which can avoid the reduction.

[0012]

According to the present invention, there is provided a method for purifying high-purity titanium, comprising the steps of: placing crude titanium and a deposition substrate in a reaction vessel; and depositing the high-purity titanium on the substrate surface by an iodine method. The method is characterized in that a plurality of rod-shaped crude titanium are arranged around the deposition substrate.

As the rod-shaped coarse titanium, those having a circular, semi-circular, sectoral, elliptical, rhombic, square or trapezoidal cross section can be used. A circular round bar is preferred, and
In terms of the structure, the reaction from the surface, rather than simply pressing the sponge-like titanium,
A cast material and a so-called ingot material obtained by rolling the cast material are preferable.

As the deposition substrate, a conventionally used linear filament can be used. However, a hollow substrate having a large surface area is preferable from the viewpoint of increasing the production amount. Preferably, they are arranged in parallel.

When a plurality of hollow deposition substrates are arranged in parallel, the surface area of the deposition substrates increases without reducing the effective reaction space in the reaction vessel, and the production amount increases. However, on the other hand, the reaction conditions vary depending on the arrangement position of the deposition substrate, and as a result, the variation in the consumption depending on the arrangement position of the coarse titanium increases. However, since the consumption of individual coarse titanium is uniform and it is possible to use the whole titanium repeatedly until the usage limit is reached, the fluctuation of the consumption depending on the arrangement position increases. Rod-shaped coarse titanium is particularly effective when the hollow deposition substrates are arranged in parallel.

In the method for purifying high-purity titanium according to the present invention, since the coarse titanium disposed around the deposition substrate is rod-shaped,
Local consumption such as when plate-like coarse titanium is used does not occur, and individual titanium can be repeatedly used until the entire coarse titanium reaches a use limit. That is, when viewed microscopically, the consumption of the side facing the deposition substrate may proceed, but if the operation of turning the back side to the deposition substrate is performed in the next operation, the entire crude titanium will be entirely removed. It can be used repeatedly until the usage limit is reached. Therefore, the use efficiency of crude titanium is dramatically improved.

Further, when plate-like coarse titanium is arranged around the deposition substrate, only the center portion of the coarse titanium in the plate width direction effectively contributes to the deposition. Therefore, the same effective array density as in this case is selected. However, when the rod-shaped coarse titanium is disposed around the precipitation substrate, the gap between the adjacent coarse titanium becomes large, and the separation of the reaction space by the coarse titanium is avoided.
Therefore, productivity per unit time and per unit amount of filled Ti is improved.

Further, since the effective array density can be increased while securing a gap between adjacent coarse titanium, the productivity per unit volume of the reaction region is improved.

The thickness of the rod-shaped coarse titanium is preferably 10 to 200 cm ² in terms of a sectional area. If the coarse titanium is too thin, the breaking productivity will be reduced in a short time, and if it is too thick, the area ratio with the precipitation tube will increase, and the deposition rate will decrease.

The interval between adjacent coarse titanium is 10
~ 50 mm is preferred. If the interval is too small, adhesion and contamination occur during the reaction. If it is too large, the deposition rate will decrease.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view showing a schematic structure of a purification apparatus suitable for carrying out the method for purifying high-purity titanium of the present invention, and FIG. 2 is a cross-sectional view showing an arrangement of coarse titanium and a hollow precipitation substrate in a reaction vessel. FIG.

The reaction vessel 1 is a cylindrical airtight vessel made of stainless steel or the like, and is inserted into the heating furnace 2.
A lid 4 is placed on the reaction vessel 1 via an exhaust chamber 3.
Are connected. The lid 4 has a hollow structure which also serves as an exhaust chamber for a hollow deposition substrate described later. A titanium tetraiodide supply device 8 is connected to the bottom of the reaction vessel 1, and a trap 9 is connected to the exhaust chamber 3.

Inside the reaction vessel 1, there are provided three hollow deposition substrates 5, 5, and 5 each formed of a circular pipe of high-purity titanium, and a large number of round rod-shaped substrates surrounding each of the hollow deposition substrates 5. Are provided.

The three hollow deposition substrates 5, 5, 5 are symmetrically arranged at 120 ° intervals around the center of the reaction vessel 1, and are held in the reaction vessel 1 by being suspended from the lid 4. Have been. The inside of each hollow precipitation substrate 5 communicates with a cover 4 having a hollow structure also serving as an exhaust chamber, and a heater 6 such as a carbon heater is provided inside the cover 4. The heater 6 is connected to an external power supply via the inside of the lid 4 having a hollow structure.

A large number of crude titanium 7, 7,... Are cast materials (ingots) obtained by dissolving low-purity sponge-like titanium.
And three hollow deposition substrates 5, 5 are arranged symmetrically around each of the three hollow deposition substrates 5, 5, 5 at equal intervals.
It is hung on the lid 4 together with 5 and 5.

In operation, after assembling the refining apparatus as shown in FIGS. 1 and 2, the inside of the reaction vessel 1 is evacuated to a predetermined degree of vacuum through the exhaust chamber 3 and the trap 9 and also serves as an exhaust chamber. The inside of each of the hollow deposition substrates 5, 5, 5 is evacuated to a predetermined degree of vacuum through the lid 4 having a hollow structure.

The inside of the reaction vessel 1 is heated to a predetermined temperature from the outside by the heating furnace 2, and the three hollow deposition substrates 5, 5, 5 are heated to the predetermined temperature from the inside by the heaters 6.

In this state, titanium tetraiodide (melting point: 428 K) distilled and purified is evaporated by the titanium tetraiodide supply device 8 and introduced into the reaction vessel 1. At this time, the inside of the reaction vessel 1 is continuously evacuated to maintain a predetermined degree of vacuum.

The titanium tetraiodide introduced into the reaction vessel 1 converts the crude titanium 7,7,... In the reaction vessel 1 into titanium diiodide, and then the three hollow precipitated substrates 5,5. 5,
5 is thermally decomposed on each surface and deposited on each surface as high-purity titanium. The iodination reaction and the thermal decomposition reaction of titanium proceed unidirectionally due to the temperature difference, and the hollow precipitation substrate 5,
Continue to deposit high-purity titanium on each surface of 5,5.

The titanium iodide and iodine after the reaction are cooled and recovered in the trap 9, and only titanium tetraiodide is reused after distillation.

At the end of the operation, a large number of coarse titaniums 7, 7,... Have been consumed and are thinner than before the operation. Here, the crude titanium 7 disposed near the center in the reaction vessel 1 has a high reaction temperature and is consumed from a plurality of directions by being sandwiched by the plurality of hollow deposition substrates 5. Many. On the other hand, the crude titanium 7 arranged in the peripheral portion in the reaction vessel 1 has a low reaction temperature and is consumed only in one direction, so that its consumption is small.

Therefore, in the next operation, the thin coarse titanium 7 having consumed a large amount is arranged in the peripheral portion in the reaction vessel 1, and the thick coarse titanium 7 having small consumption is located in the vicinity of the central portion in the reaction container 1. Deploy. Further, the coarse titanium 7 whose consumption has progressed on one side is directed to the hollow precipitation substrate 5 on the side where the consumption has not progressed.

By repeating the operation with such considerations, a large number of coarse titanium 7, 7,... Are consumed relatively uniformly, and each coarse titanium 7 is also consumed uniformly. As a result, the number of times that the coarse titanium 7, 7,... Can be repeatedly used is greatly increased. Depending on the total consumption, it is possible to add new coarse titanium 7 or replace old coarse titanium 7 with new one. Old coarse titanium 7 is mixed with new coarse titanium 7 and used in another operation. can do.

In this embodiment, since the three hollow deposition substrates 5, 5, 5 are arranged inside the reaction vessel 1, the total surface area of the deposition substrates is increased, and the productivity is improved.
That is, when the height of the deposition substrate is the same (H) and the volume of the space occupied by the deposition substrate is the same (V), the total surface area of the deposition substrate is 2 × (V / V πH)
^1/2 × π × H, but 3 × 2 when there are three precipitation substrates
× (V / 3πH) ^1/2 × π × H, and the latter is 1.73 times the former.

The operation is carried out for several days, during which there is a risk that defective and purified products will be produced. Even if one hollow deposition substrate 5 produces a defective product, the other two hollow deposition substrates 5 In order to obtain a healthy precipitated product in 5,
Long operation time is not wasted, and the yield is improved.

Further, in the purification reaction, titanium diiodide, which is a lower iodide, is thermally decomposed instead of directly pyrolyzing titanium tetraiodide. Thus, the reaction temperature is lowered, and the possibility that impurities are thermally decomposed together is small. It is of course possible to use a normal iodine method for directly pyrolyzing titanium tetraiodide.

FIG. 3 is a cross-sectional view showing another arrangement of the coarse titanium and the hollow precipitation substrate in the reaction vessel.

Here, four hollow deposition substrates 5, 5,
Are arranged symmetrically around the center of the reaction vessel 1 at equal intervals, and a large number of round rod-shaped crude titanium 7, 7,. Are distributed within.

When four hollow deposition substrates 5, 5, 5, 5 are used, the total surface area is 4 × 2 × (V / 4πH)
^1/2 × π × H, which is about twice as large as when one deposition substrate is used.

FIG. 4 is a cross-sectional view showing still another arrangement of the coarse titanium and the hollow precipitation substrate in the reaction vessel.

Here, a number of round rod-shaped crude titaniums 7, 7... Are symmetrically arranged at equal intervals around one hollow deposition substrate 1 arranged in the center of the reaction vessel 1. ing.

In this case, a large number of coarse titanium 7, 7,.
Is consumed under almost the same conditions.
・ ・ There is little variation in consumption between the two. Therefore, it is not necessary to change the arrangement position of the coarse titanium 7, 7,... Every operation. On the other hand, since the consumption of the coarse titanium 7 on the side facing the hollow precipitation substrate 5 advances, the direction is changed for each operation so that the consumption proceeds evenly.

The result of the actual operation in the arrangement shown in FIG. 4 will be described below.

A hollow precipitation substrate made of a high-purity titanium tube having an outer diameter of 100 mm is arranged at the center of a reaction vessel having an inner diameter of 250 mm, and eight coarse titanium members made of a cast material having an outer diameter of 30 mm are arranged around the base. They were arranged at equal intervals. The distance from the center of the coarse titanium to the surface of the hollow precipitation substrate is 20 mm.
In this state, the refining operation was continued for 100 hours, and 8 m
An m-thick high-purity titanium was deposited.

In one operation, the cross-sectional area of each coarse titanium is on average
Reduced from 7.1 cm ² to 4 cm ² . The operation is repeated while changing the direction of each coarse titanium, and the outer diameter is 30 mm from the middle
The new crude titanium was placed between the original crude titanium and the operation was repeated. As a result, the initial eight crude titanium
It could be used for the operation of times. The cross-sectional area of coarse titanium when use is stopped is a minimum of 0.8 cm in the rod axis direction average.
² , maximum 1.5 cm ² . The use was stopped because there is a risk of breaking if continued use in this state.

A similar operation is conventionally performed with a plate width of 50 mm and a plate thickness of 2 mm.
This was performed by arranging four pieces of coarse titanium consisting of a 5 mm cast rolled plate around the hollow precipitation substrate (FIG. 5).
), Coarse titanium could be used only once because the central portion in the plate width direction was locally thinned.

Further, in the operation using coarse titanium rods, a large gap is formed between adjacent coarse titanium particles, so that the iodination and precipitation reaction rates are higher than those in the conventional operation using plate-like coarse titanium particles. Increased. Also, the increase in the effective arrangement density of the crude titanium in the circumferential direction of the substrate also facilitated the iodination reaction and increased the deposition rate.

[0048]

As described above, the method for purifying high-purity titanium according to the present invention uses rod-like crude titanium in the purification of high-purity titanium by the iodine method, thereby increasing the use efficiency of the crude titanium. Can be improved
It contributes to the reduction of manufacturing cost of high purity titanium. Further, even if a sufficient effective array density is secured, a large gap can be secured between adjacent coarse titanium, and there is no possibility of dividing the reaction space in the reaction vessel. can do. Further, since the effective arrangement density can be increased, the concentration of iodine gas can be increased, and the deposition rate of high-purity titanium can be increased.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a schematic structure of a refining apparatus suitable for performing a method for purifying high-purity titanium of the present invention.

FIG. 2 is a cross-sectional view showing an arrangement of a crude titanium and a hollow precipitation substrate in a reaction vessel.

FIG. 3 is a cross-sectional view showing another arrangement of the coarse titanium and the hollow precipitation substrate in the reaction vessel.

FIG. 4 is a cross-sectional view showing still another arrangement of the coarse titanium and the hollow precipitation substrate in the reaction vessel.

FIG. 5 is a cross-sectional view showing an arrangement of a conventional coarse titanium and a hollow precipitation substrate in a reaction vessel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction container 2 Heating furnace 3 Exhaust chamber 4 Lid 5 Hollow precipitation base 6 Heater 7 Crude titanium 8 Titanium tetraiodide supply device 9 Trap

Claims (3)

[Claims] 1. A method for purifying high-purity titanium in which coarse titanium and a deposition substrate are disposed in a reaction vessel and high-purity titanium is deposited on the surface of the substrate by an iodine method. A method for purifying high-purity titanium, comprising disposing titanium. 2. The method for purifying high-purity titanium according to claim 1, wherein the crude titanium is a round bar-shaped ingot having a circular cross section. 3. The method for purifying high-purity titanium according to claim 1, wherein the deposition substrate has a hollow shape.