JP2003171760A - Tungsten sputtering target - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tungsten sputtering target in which, even when a W film is deposited on a large substrate, the inplane uniformity of the specific resistance of the film can be reduced to ≤3%. <P>SOLUTION: The tungsten sputtering target has a relative density of ≥99%, and a Vickers hardness of ≥330 Hv. Further, variation in the Vickers hardness of the whole of the target is ≤30%. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an LSI, a liquid crystal, a P
The present invention relates to a tungsten sputtering target used when forming an electrode film or a wiring film by a sputtering method in the fields of electronics such as DP and magnetic recording, and can form a film by a particularly uniform sputtering operation. The present invention relates to a tungsten sputtering target capable of significantly improving internal uniformity.

[0002]

2. Description of the Related Art In recent years, semiconductor device technology has been rapidly progressing, and particularly in semiconductor elements represented by DRAM, logic, flash memory, etc., high integration, high reliability, high functionality, and high speed have been achieved. With further progress, the processing precision required for element microfabrication technology tends to become higher and higher.

In order to achieve the above high technical requirements, it is essential to reduce the resistance of the internal wiring material of the semiconductor element. A refractory metal silicide film typified by MoSix, WSix, etc. has been widely used as a constituent material of an electrode used in an LSI up to now, but it has a lower resistance and enables higher speed signal propagation. Research and development of materials are also underway. Among them, tungsten (W) has low resistance and is excellent in heat resistance, and has attracted attention as a future electrode wiring material, and has already been used by some.

Up to now, the sputtering method has been the main method for forming the electrode wiring film, but the W film can also be formed by a technique using the CVD method typified by the blanket W. In the sputtering method, a rare gas represented by Ar or Kr is caused to collide with a sputtering target generally formed of W at a high speed, and the ejected target component molecules are vapor-deposited on a substrate surface such as a silicon (Si) wafer. This is a film forming method for forming a W film or the like having a predetermined thickness. Compared with the CVD method, this sputtering method has advantages such as faster film formation rate, better mass productivity, less plasma damage to the underlying film, and easier handling. There is no doubt that the sputtering method will be mainly adopted as the method.

In the current semiconductor manufacturing equipment,
The size of the Si wafer used for manufacturing the LSI has been progressively increased in order to further improve the manufacturing efficiency. Specifically, the wafer size is shifted from 6 inches to 8 inches, and a wafer having a diameter of 200 mm is mainly used. However, as the size has increased, it will be 12 inches (diameter 300 mm) in the future.
Is expected to scale up.

The size of the sputtering target corresponding to the current 8-inch Si wafer is generally 300 mm in diameter, although it depends on the type of sputtering apparatus. When a 12-inch diameter Si wafer is realized in the future, a large target with a diameter of 400 mm or more is probably required. As a problem that occurs with the scale-up of the wafer size as described above, the decrease in the in-plane uniformity of the film resistivity is greatly highlighted. In particular, the electrode used in the LSI has a great influence on the characteristics of the transistor due to the difference in the specific resistance, which is an important factor in the characteristics of the LSI. In other words, if the in-plane uniformity of the resistivity of the thin film on which the electrodes are formed is not good, the manufacturing yield of the LSI is drastically reduced, and the yield rate of the LSI maker is greatly damaged due to the deterioration of the yield rate.

The in-plane uniformity of the resistivity is greatly influenced by various parameters such as sputtering conditions, specifically, the input power value and gas pressure in the sputtering apparatus, the distance between the target and the substrate. However, even with tight control of these parameters,
The in-plane uniformity of the specific resistance of the film formed by using a sputtering apparatus that is commercially available up to now has a limit of about 5%.

Various sputtering targets for forming a W film have been proposed up to the present and are described in the publication as known examples. For example, Japanese Patent Application Laid-Open No. 7-76771 proposes a sputtering target having a relative density of 99.5% or more and an average particle size of more than 10 μm and 200 μm or less. In addition, JP-A-5-9326
No. 7, gazette is characterized in that the C content is 50 ppm or less, the O content is 30 ppm or less, the relative density is 97% or more, and the crystal grain size has a shape squashed in a certain direction. Sputtering targets have been proposed. Further, in JP-A-5-222525, after a W powder is pressed to produce a molded body having a relative density of 60% or more, the molded body is heated in an atmosphere containing hydrogen at a temperature of 1400 ° C.
Or higher, preferably heated to 1600 ° C. or higher to obtain a relative density of 9
A sputtering target has been proposed, which is characterized in that a sintered body of 0% or more is obtained, and the sintered body is hot worked at 1600 ° C. or more to obtain a relative density of 99% or more.

However, even if the film formation is performed using these known W sputtering targets while strictly controlling the predetermined sputtering conditions, the in-plane uniformity of the specific resistance of the W film is currently about 5%. Is the limit, and this W
The effect of improving the manufacturing yield of the LSI using the film is small.

[0010]

In recent years, as the technical requirements for high integration, high speed, and high reliability required for LSIs have become more sophisticated, the resistance of electrode / wiring materials has been further reduced. Regarding the electrode constituent material, which is required, there is a tendency to shift from a conventional mainstream silicide-based material to a high-purity metal-based material such as W (pure metal). In the electrode portion of such an LSI, the uniformity of the specific resistance of film formation within the wafer surface (in-plane uniformity) is an important point. However, as described above, the in-plane uniformity of the resistivity of the W film obtained by using the currently known sputtering target is about 5%. Therefore, when the wafer size is further increased, The in-plane uniformity of the specific resistance tends to worsen. Unless this phenomenon is avoided, there is a problem that the manufacturing yield in a mass production line of LSIs is greatly reduced and a large amount of loss is inevitable.

The present invention has been made in order to solve the above problems, and even when a film is formed on a large Si wafer of 8 inches or more, the specific resistance of the W film is within the plane. It is an object of the present invention to provide a tungsten sputtering target capable of reducing the uniformity to 3% or less.

[0012]

In order to solve the above-mentioned problems, the present inventor has an effect on the in-plane uniformity of the resistivity of a film formed by the density and hardness of the sputtering target and the in-plane variation. Various studies were conducted. As a result, the ratio of the W film formed on the Si wafer of 8 inch size or more, which could not be achieved in the past, was achieved by densifying the entire target evenly and controlling the hardness and its variation. It was for the first time found that the in-plane uniformity of resistance could be reduced to 3% or less.

The present invention has been completed based on the above findings. That is, in the tungsten sputtering target according to the present invention, the relative density of the target is 99%.
The above is the Vickers hardness of 330 Hv or more, and the variation of the Vickers hardness of the entire target is 30% or less.

In the above tungsten sputtering target, the total content of Fe, Ni, Cr, Cu, Al, Na, K, U and Th as impurities contained in the target is less than 0.01% by mass. Is preferred. That is, it is preferable that the purity of the tungsten forming the target is 99.99% or more.

Further, the target is Cu, Al,
Alternatively, it is preferably integrally joined with a backing plate made of those alloys. Further, it is preferable that the target is integrally bonded to the backing plate by diffusion bonding or solder bonding.

As described above, the tungsten sputtering target according to the present invention has a relative density of 99% or more, a Vickers hardness of 330 Hv or more, and a variation in Vickers hardness of the entire target of 30%.
The sputtering target is characterized by the following. By forming a film using the sputtering target having the above-described structure, it is possible to significantly improve the in-plane uniformity of the specific resistance of the W film.

That is, when a W film is formed on an 8-inch Si substrate by a sputtering method using a W target, in order to improve the manufacturing yield of an LSI or the like using this W film, the W Improving the uniformity of the specific resistance of the film is an essential requirement.

However, when sputtering is performed using a conventionally known high-purity W target, even if the film forming conditions are strictly controlled, the in-plane uniformity of the specific resistance of the W film can be about 5%. It was the limit. Further, when the wafer size is increased, for example, in the case of a 12 inch wafer, the in-plane uniformity is increased to about 7%. In order to further improve the uniformity of such specific resistance, the emission distribution angle of neutral particles and ions scattered from the W target is an important factor. As a result of various studies on this point, the present inventors set the relative density of the target to 99% or more and set the Vickers hardness of the target to 3
It has been found that controlling the Vickers hardness variation over the entire target within a predetermined range by setting the HV to 30 Hv or more effectively works to increase the uniformity of the specific resistance of the W film.

Regarding the conventional W target, although a target having improved characteristics by paying attention to the grain size and impurities has been developed, there is no example focusing on the hardness of the target. The correlation between the film thickness and the film quality is an important factor for the uniformity of the specific resistance of the film formed by sputtering. In order to properly control both of these properties, it is important to manage and control the hardness of the target itself and its variation in addition to the particle size of the raw material powder and the content of impurities. That is, in the process of repeatedly bombarding the target with Ar ions and depositing the ejected target component on the substrate or the like to form a thin film, if there is a portion where the hardness is partially different on the target surface, A
It was found that the number of clusters of target components ejected by r ion collisions and the emission angle varied, and as a result, both film thickness and film quality were adversely affected.

Here, the relative density of the target is 99%.
It is necessary to do the above. When the relative density of the target is 99% or less, the target contains a large amount of gas components, so that the specific resistance of the film increases when the film is formed. In addition, there is concern that dust generation may increase due to abnormal discharge. From the above viewpoint, the relative density of the target is preferably 99.3% or more, more preferably 99.
It is more preferably 5% or more.

The Vickers hardness of the target is 330H
It is necessary to be v or more. When the Vickers hardness is 330 Hv or less, since recrystallization is not completely completed, a slight internal strain is affected by thermal energy generated by sputtering and partially causes coarsening of the grain size. The film thickness and the specific resistance distribution are adversely affected. From the above viewpoint, the Vickers hardness of the target is
It is more preferable to set it to 350 Hv or more, and further 37
More preferably, it is 0 Hv or higher.

The variation of the Vickers hardness in the whole target needs to be 30% or less.
If the variation in Vickers hardness exceeds 30%,
The depth at which the target is eroded varies, which adversely affects the emission distribution angle of the target component (tungsten). Therefore, the variation of the Vickers hardness in the entire target is specified to be 30% or less, preferably 20% or less, and more preferably 15% or less.

Here, the relative density of the tungsten sputtering target according to the present invention is a value measured by the following method. That is, as shown in FIG. 1, for example, a central portion (position 1) of the disk-shaped target T and four linear outer peripheral positions (positions 2 to 9) that pass through the central portion and divide the circumference evenly. 15m from the position (positions 10 to 17) and half the distance
A test piece of m × width 15 mm is collected. Using the Archimedes method for these 17 test pieces, the specific gravity was calculated,
The relative density was calculated by the following mathematical formula (1) using the value of theoretical specific gravity: 19.254 g / cm ³ , and the average value of the calculated values was used as the relative density of the sputtering target according to the present invention.

[0024]

[Equation 1]

The Vickers hardness of the sputtering target according to the present invention is a value measured by the following method. That is, as shown in FIG. 1, for example, a center portion of a disk-shaped target (position 1) and a position 90% from the center portion of four straight lines that pass through the center portion (position 2) ~ 9) and a position 50% from the center (positions 10 to 17), length of 15 mm x
A test piece having a width of 15 mm is collected. These 17 test pieces were subjected to a load of 500 by a Vickers hardness tester.
g, load time: 15 s, measurement points: average values at three points were calculated, and the average value of each test piece was further averaged to obtain the hardness of the target according to the present invention.

Further, the variation of the Vickers hardness of the entire target is a value obtained from the maximum value and the minimum value of the Vickers hardness obtained from the above-mentioned 17-point test piece based on the following calculation formula (2). And

[0027]

[Equation 2]

The sputtering target according to the present invention may contain the same level of impurities as a normal high-purity metal material. However, when a film is formed by using a target having an excessively high impurity element content, there is a possibility that the product characteristics may be deteriorated, for example, the leak current is increased and the specific resistance of the film is increased. Therefore, in the sputtering target of the present invention, Fe as an impurity element,
It is preferable that the total content of Ni, Cr, Cu, Al, Na, K, U, and Th is 100 ppm or less and that the high purity W is used. In other words, Fe, Ni, Cr, Cu, A
A value obtained by subtracting the total amount of each content (mass%) of 1, 1, Na, K, U, and Th from 100% [100- (Fe + Ni + Cr
+ Cu + Al + Na + K + U + Th)] is 99.99%
It is desirable to use high purity W of the above (4 N or more) as a constituent material.

The sputtering target according to the present invention can be manufactured, for example, as follows. For example, a small proportion of skeletal particles in which single particles are irregularly aggregated is small, and a high-purity W powder having a particle size distribution range of 20 μm or less is filled in a carbon mold or the like having a shape corresponding to an intended target size, Pressure sintering by the hot pressing method is effective for obtaining the Vickers hardness of the target and its variation defined by the present invention.

It should be noted that the high-purity W powder containing a large amount of the skeletal particles does not completely sinter to the inside of the skeletal particles even when sintered with a high pressure, and pores are generated in the target structure. Since a high-density sintered body cannot be obtained, it is preferable to use the W raw material powder containing a small amount of skeletal particles.

If coarse tungsten particles having a particle size distribution range of more than 20 μm are present, the crystallization speed in the sintering process tends to vary, so that the hardness and the positional variation of the obtained sintered body vary. There is a risk that it will grow. Therefore, the particle size distribution range of the tungsten raw material particles is preferably 20 μm or less, and more preferably 10 μm or less.

In the pressure sintering step described above, before the tungsten compact is heated to the maximum sintering temperature, it is heated at a temperature of, for example, 1150 ° C. to 1450 ° C. for 5 hours or more to perform degassing treatment. It is preferable. By this degassing treatment, adsorbed oxygen and other impurity elements attached to the raw material powder can be effectively removed. Here, if the temperature of the degassing treatment is too low, the effect of degassing cannot be sufficiently obtained, and conversely if the treatment temperature is too high, the sintering of the outer peripheral portion of the molded body progresses and gas is generated due to the generation of closed pores. Since it becomes difficult to remove the gas, the above degassing temperature range was set. The degassing atmosphere is preferably in a vacuum (1 Pa or less) or in an H ₂ gas atmosphere. After performing such degassing treatment, for example, the molded body is heated and sintered in a vacuum atmosphere of 1.0 Pa or less while applying a pressure of 20 MPa or more. Here, the temperature rising rate is 2 ° C / m before reaching the maximum sintering temperature.
The molded body is heated at in to 5 ° C / min, and the intermediate sintering temperature is 1
It is preferable to carry out an intermediate sintering step of holding at a temperature of 450 ° C. to 1700 ° C. for at least 1.0 hour. By performing such an intermediate sintering process, it is possible to improve the temperature uniformity of the target sintered body, and it is possible to effectively remove the voids or voids contained and formed in the sintered body. become. Here, if the intermediate sintering temperature is excessively low, the density does not sufficiently improve because the sintering does not proceed, and conversely, if the intermediate sintering temperature is excessively high, closed pores remain inside. The intermediate sintering temperature was set in the range.

Then, after carrying out the intermediate sintering step as described above, the sintered body to be sintered at the maximum sintering temperature is densified. This maximum sintering temperature is 1 / of the melting point of the target.
2 or more is preferable. The holding time of the sintered body at the maximum sintering temperature is preferably 5 hours or more. After carrying out such a maximum sintering step, it is preferable to release the pressurized sintering atmosphere pressure and cool the sintered body at a cooling rate of 10 ° C./min or more. The pressure-sintered sintered body may be further subjected to HIP (hot isostatic pressing) treatment. The heating temperature in this HIP process is 14
The pressure is set to 00 ° C-1800 ° C while the pressure is 150M
It is preferable to set Pa or more. HIP like this
By carrying out the treatment, it becomes possible to obtain a denser target sintered body.

As another manufacturing method, the above-mentioned fine tungsten raw material powder having a high purity and a small particle size range is used,
After forming the raw material powder into a predetermined shape by CIP (cold isostatic pressing) treatment, the above HIP treatment is performed, and then the formed body is hydrogen-sintered, and then the sintered body is hot-rolled or hot-rolled. The target sintered body may be formed by forging.

Specifically, the above-mentioned fine tungsten raw material powder having a high purity and a small particle diameter range is used, and the raw material powder is subjected to CIP treatment at 100 MPa or more to produce a temporary compact having a density of about 60%. . Here, the reason why the CIP processing pressure is set to the above value or more is that it is difficult to obtain the intended density if the processing pressure is too low. afterwards,
The HIP treatment is performed under the conditions of 1500 ° C. or higher and 150 MPa or higher, and then the compact is subjected to hydrogen sintering under the conditions of 1800 ° C. or higher and at least 5 hours or longer. For both,
When treated under the above conditions, it is not possible to completely avoid a decrease in density and a variation in hardness, so that hot rolling or hot forging may be performed thereafter.

Naturally, in order to achieve further densification, HIP
It is also possible to carry out a treatment to produce a dense target sintered body. Also, hot press processing or HIP
After performing the treatment, hydrogen sintering may be performed, and then hot forging or hot rolling may be performed. Further, the HIP process may be directly performed after the CIP process.

The target material thus obtained is machined into a predetermined target shape. The target material thus obtained is integrally joined to a backing plate made of Cu, Al, or an alloy thereof, so that a sputtering target having good handleability can be obtained.

As a joining method with the backing plate, a solder joining method (brazing joining method) using a brazing material such as solder or a diffusion joining method is applied. The brazing joining is performed using a known In-based or Sn-based joining material (brazing material). The heating temperature during diffusion bonding is 600
℃ or less. This is because the melting point of Al is 660 ° C.

In particular, by integrally bonding the backing plate made of Cu or Al having high thermal conductivity or an alloy thereof with the target, the heat generated by the target during sputtering can be efficiently removed from the system through the backing plate. It is possible to release it. Further, the backing plate integrally formed with the flow path of the cooling water is integrally joined to the target and the cooling water is circulated, whereby the cooling effect of the target can be further enhanced.

According to the tungsten sputtering target having the above structure, the relative density of the target is 99%.
Since the sputtering target has a Vickers hardness of 330 Hv or more and a Vickers hardness variation of 30% or less over the entire target, and is a dense sputtering target with little variation in hardness, a thin film is sputtered onto a large-diameter wafer. Even when it is formed, it is possible to form a uniform thin film having a resistivity in-plane uniformity of 3% or less. Therefore, as the wafer size increases, the manufacturing yield of semiconductor devices can be significantly improved, and the product cost can be significantly reduced.

[0041]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described based on the following specific examples, comparative examples and evaluation results thereof.

Examples 1 to 4 and Comparative Examples 1 to 7 First, the total content of impurity elements such as Fe, Ni and Cr was 0.01 mass% and the purity was 99.99 mass% (4N). As shown in 1, the particle size distribution range is 10μ each
m or less, 20 μm or less, 30 μm or less, 50 μm or less,
A high-purity W powder composed of particles of 100 μm or less was prepared.

Each of the high-purity W powders was filled in a carbon mold and set in a hot press machine, and first heated in a vacuum atmosphere of 1 Pa or less to each temperature shown in Table 1 to 10
The amount of impurity elements was reduced by carrying out degassing treatment for holding for a period of time. Then, in a similar vacuum atmosphere, while applying each pressure shown in Table 1 to the molded body, it is heated at a temperature rising rate of 2 ° C./min,
After each temperature shown in Table 1 was maintained for 10 hours, each maximum sintering temperature shown in Table 1 was maintained for 15 hours to carry out densification sintering to produce a W sintered body as each target material. . For cooling after sintering, the atmosphere was replaced with Ar, and 10
It was carried out at a cooling rate of ° C / min.

The W sintered body thus produced was machined into a desired target size (diameter Φ300 × thickness 5 mm) to obtain a sputtering target T. As shown in FIG. 2, the target T was made of Cu. Examples 1-4 by brazing to backing plate B
And 11 kinds of W sputtering targets according to Comparative Examples 1 to 7 were prepared.

The relative density of each of the thus prepared sputtering targets was analyzed by the Archimedes method. The Vickers hardness of each target and its variation were measured by the above-mentioned method using a Vickers hardness meter (manufactured by Shimadzu Corporation: HMV-2000).

Using each W sputtering target produced in this way, sputtering method: magnetron sputtering, back pressure: 1 × 10 ⁻⁵ (Pa), output DC: 2 (kW), Ar: 0.5 Pa, Under the condition of spatter time: 5 (min), a W film was formed on an 8-inch Si wafer substrate.

The uniformity of the specific resistance of each W film thus formed on the Si wafer substrate was measured as follows.
Ie 5 mm from the edge along the diameter of the wafer substrate
The measurement points are set at intervals, the specific resistance is calculated from the film thickness and the sheet resistance of the W film at each measurement point, and the maximum and minimum values are substituted into the following equation (3) to obtain the values obtained. The specific resistance of the W film was made uniform.

[0048]

[Equation 3]

The results of these measurement calculations are shown in Table 1 below.

[0050]

[Table 1]

As is clear from the results shown in Table 1 above,
A W film formed by using the sputtering target according to each example in which the relative density of the target is 99% or more, the Vickers hardness is 330 HV or more, and the variation in the Vickers hardness of the entire target is 30% or less. Is less than 3% in resistivity uniformity,
It was found that excellent in-plane uniformity can be achieved even when a film is formed on a large-diameter wafer substrate.

Examples 5 to 8 and Comparative Examples 8 to 13 Similar to Example 1, the total content of impurity elements such as Fe, Ni and Cr was 0.01% by mass and the purity was 99.99% by mass (4N). ), And as shown in Table 2, the particle size distribution ranges are 10 μm or less, 20 μm or less, 30 μm or less, and 5 respectively.
A high-purity W powder composed of particles of 0 μm or less and 100 μm or less was prepared.

Each of the high-purity W powders was subjected to CIP molding at a pressure of 100 MPa, and the obtained molded body was subsequently subjected to HIP treatment under the conditions of temperature and pressure shown in Table 2, A sintered body having the relative density shown in 2 was obtained. Then, after holding the sintered body for 10 hours in a hydrogen atmosphere, hot rolling was further performed in a hydrogen atmosphere at each temperature shown in Table 2 to obtain each sintered body as a target material. The W sintered body thus produced was machined to a desired target size (diameter Φ300 × thickness 5 mm), and further C
Examples 5-8 and Comparative Examples 8-1 by brazing integrally to the u-made backing plate, respectively.
Ten types of W sputtering targets according to No. 3 were prepared.

Using each of the W sputtering targets produced in this way, sputtering method: magnetron sputtering, back pressure: 1 × 10 ⁻⁵ (Pa), output DC: 2 (kW), Ar: 0.5 Pa, Under the condition of spatter time: 5 (min), a W film was formed on an 8-inch Si wafer substrate.

The uniformity of the specific resistance of each W film thus formed on the Si wafer substrate was measured in the same manner as in Example 1, and the relative density of the target and the Vickers hardness (H
v) and its variations were similarly measured. The results of these measurements are shown in Table 2 below.

[0056]

[Table 2]

As is clear from the results shown in Table 2 above,
A W film formed by using the sputtering target according to each example in which the relative density of the target is 99% or more, the Vickers hardness is 330 Hv or more, and the variation in the Vickers hardness of the entire target is 30% or less. Is less than 3% in resistivity uniformity,
It was found that excellent in-plane uniformity can be achieved even when a film is formed on a large-diameter wafer substrate.

[0058]

As described above, according to the tungsten sputtering target of the present invention, the relative density of the target is 99% or more and the Vickers hardness is 3%.
Since the sputtering target is 30 Hv or more and the variation in Vickers hardness of the entire target is 30% or less, and the sputtering target is dense and has little variation in hardness,
Even when a thin film is formed on a large-diameter wafer substrate by sputtering, it is possible to form a uniform thin film having a resistivity in-plane uniformity of 3% or less. Therefore, as the wafer size increases, the manufacturing yield of semiconductor devices can be significantly improved, and the product cost can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a plan view showing a sampling position and a measurement position of a sample piece for measuring characteristics of a tungsten sputtering target according to the present invention and a tungsten film formed by using the target.

FIG. 2 is a cross-sectional view showing an embodiment of the tungsten sputtering target according to the present invention integrally bonded to a backing plate.

[Explanation of symbols]

1 to 17 Collection position and measurement position of sample piece T tungsten sputtering target B backing plate

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yukinobu Suzuki             8th Shinsugita Town, Isogo Ward, Yokohama City, Kanagawa Prefecture             Ceremony company Toshiba Yokohama office (72) Inventor Naomi Fujioka             8th Shinsugita Town, Isogo Ward, Yokohama City, Kanagawa Prefecture             Ceremony company Toshiba Yokohama office (72) Inventor Takashi Ishigami             8th Shinsugita Town, Isogo Ward, Yokohama City, Kanagawa Prefecture             Ceremony company Toshiba Yokohama office (72) Inventor Yasuo Takasaka             8th Shinsugita Town, Isogo Ward, Yokohama City, Kanagawa Prefecture             Ceremony company Toshiba Yokohama office (72) Inventor Toru Komatsu             8th Shinsugita Town, Isogo Ward, Yokohama City, Kanagawa Prefecture             Ceremony company Toshiba Yokohama office F-term (reference) 4K029 AA02 BA23 BD02 DC03 DC21                       DC22 DC24                 4M104 BB18 DD40

Claims (5)

[Claims] 1. A tungsten sputtering target, wherein the target has a relative density of 99% or more, a Vickers hardness of 330 Hv or more, and a variation in Vickers hardness of the entire target of 30% or less. 2. The total content of Fe, Ni, Cr, Cu, Al, Na, K, U and Th as impurities contained in the target is less than 0.01% by mass. Item 2. The tungsten sputtering target according to Item 1. 3. The tungsten sputtering target according to claim 1, wherein the purity of tungsten constituting the target is 99.99% or more. 4. The tungsten sputtering target according to claim 1, wherein the target is integrally bonded to a backing plate made of Cu, Al, or an alloy thereof. 5. The tungsten sputtering target according to claim 4, wherein the target is integrally bonded to the backing plate by diffusion bonding or solder bonding.