JP2004217990A - Sputtering target, and production method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the increase in the generation rate of particles caused by joints or the like as for a large-sized sputtering target obtained by joining a plurality of target pieces made of an Mo-W alloy. <P>SOLUTION: The joined type sputtering target 1 is composed by subjecting a plurality of target pieces 2 made of an Mo-W alloy to solid phase diffusion joining, e.g., by HIP (hot isostatic press) treatment. In the Mo-W alloy composing the target 1, the average crystal grain size in the region in the vicinity of the joining boundary from the joining boundary 4 between the plurality of target pieces 2 to a width of 300 μm is controlled to the range of 3 to 50 μm. Further, the average crystal grain size in whole is controlled to, e.g., ≤200 μm. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００５５】
【表２】

【００５６】
上述した実施例１〜６、比較例１〜４および参考例１〜２による各接合型Ｍｏ−Ｗ合金ターゲットをスパッタリング装置に取り付けて、Ａｒガス圧を０．２７Ｐａとした条件下でスパッタリングを行い、それぞれ５インチのＳｉウェーハ面上に厚さ約２００ｎｍのＭｏ−Ｗ合金膜を成膜した。得られた各Ｍｏ−Ｗ合金膜中に存在する０．２μｍ以下のパーティクル数を測定すると共に、各Ｍｏ−Ｗ合金膜の膜厚分布を測定、評価した。パーティクル数はパーティクル測定器（ＷＭ３）を用いて測定した。膜厚分布については、膜厚測定装置（ＡＬｐｈａ−Ｓｔｅｐ２００）を用いて膜厚を測定し、膜厚の最大値と最小値から［｛（最大値−最小値）／（最大値＋最小値）｝×１００（％）］の式に基づいて膜厚のバラツキを求めた。これらの結果を表３に示す。
【００５７】
【表３】

【００５８】
表３から明らかなように、実施例１〜６の各接合型Ｍｏ−Ｗ合金ターゲットによれば、パーティクルの混入量が少なく、かつ膜厚分布に優れるＭｏ−Ｗ合金膜を得ることが可能であることが分かる。これらはＭｏ−Ｗ合金からなる配線膜、ひいてはそのような配線膜を用いた液晶表示装置などの製造歩留まりの向上に大きく寄与するものである。一方、比較例１〜４の各接合型Ｍｏ−Ｗ合金ターゲットはパーティクルの発生量が多く、また成膜したＭｏ−Ｗ合金膜の膜厚バラツキも大きいものであった。
【００５９】
実施例７〜８、比較例５
上記した実施例２において、ＭｏとＷの質量比をＷ＝２０原子％に変更したものを実施例７、Ｗ＝３５原子％に変更したものを実施例８として、これら以外の条件は実施例２と同様にして、接合型Ｍｏ−Ｗ合金ターゲットをそれぞれ作製した。また、平均粒径が６０μｍのＷ粉末だけを用いて、実施例２と同様にして接合型Ｍｏ−Ｗ合金ターゲットを作製した（比較例５）。これら各ターゲットについて、実施例１と同様な評価を行った。その結果を表４および表５に示す。
【００６０】
【表４】

【００６１】
【表５】

【００６２】
表４および表５からも分かるように、本発明のＭｏ−Ｗ合金ターゲットはＭｏ−Ｗ合金の組成比を変えたものに対しても有効である。また、比較例５のように、Ｗ粉末の平均粒径が１種類のみではＭｏの偏析が生じやすい。
【００６３】
【発明の効果】
以上説明したように、本発明のスパッタリングターゲットおよびその製造方法によれば、Ｍｏ−Ｗ合金ターゲットの大型化を図った上で、接合部などに起因するパーティクルの発生量の増加を再現性よく抑制することが可能となる。従って、Ｍｏ−Ｗ合金配線膜などの大面積化と高品質化に寄与するものである。
【図面の簡単な説明】
【図１】本発明の一実施形態によるスパッタリングターゲット（接合型Ｍｏ−Ｗ合金ターゲット）の概略構成を示す平面図である。
【図２】図１に示すスパッタリングターゲットの断面図である。
【符号の説明】
１……接合型スパッタリングターゲット，２……Ｍｏ−Ｗ合金からなるターゲット片，４……接合界面[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a large-sized sputtering target made of a Mo—W alloy and a method for manufacturing the same.
[0002]
[Prior art]
In recent years, an active matrix type liquid crystal display device using a thin film transistor (TFT) formed using an amorphous silicon (a-Si) film as a switching element has been widely used. This is because a large-area, high-definition, high-quality, low-cost display device can be realized by forming a TFT array using an a-Si film that can be formed at a low temperature on an inexpensive glass substrate. is there.
[0003]
When a large-area liquid crystal display device (display device) is configured, the total extension of the address wiring inevitably increases dramatically, and the resistance of the address wiring increases. With the increase in the resistance of the address wiring, the delay of the gate pulse applied to the switching element becomes remarkable, causing a problem that the control of the liquid crystal becomes difficult. For this reason, it is necessary to avoid the delay of the gate pulse while maintaining at least parameters such as the wiring width.
[0004]
As a wiring material that can avoid such a delay of the gate pulse, a Mo—W alloy film is used (for example, see Patent Literature 1 and Patent Literature 2). Since the Mo-W alloy film has low resistance, and is excellent in etchant resistance and taper workability, not only a liquid crystal display device with a large area but also a wiring for a high definition display. The present invention is also effective for a liquid crystal display device in which the width and the wiring interval are reduced, and a liquid crystal display device in which the wiring ratio is reduced and the aperture ratio is improved.
[0005]
The wiring film made of the Mo-W alloy described above is generally formed by sputtering film formation using a Mo-W alloy target, as described in Patent Literature 1 and Patent Literature 2. Here, in the case where a wiring film of a liquid crystal display device or the like is formed by sputtering film formation, it is necessary to suppress generation of particles (fine particles adhering to a substrate on which a film is formed) which may cause disconnection or short circuit of the wiring. This is important in increasing product yield. Since the number of generated particles is closely related to the density of the target, a target that has been densified by a vacuum melting method, hot pressing, or the like is used. For a large target, an integrated high-density target is realized by, for example, combining a powder sintering method and rolling.
[0006]
However, in the case of a difficult-to-process material such as the above-mentioned Mo-W alloy, it is difficult to produce a large-sized and high-density single target because cracks and the like are likely to occur during sintering or rolling. In particular, in a wiring film forming process of a liquid crystal display device, a large target having a side length of, for example, 800 mm or more, more than 1000 mm is required. It is very difficult to produce with Therefore, it is urgently necessary to establish a method for producing a large and high-density Mo-W alloy target.
[0007]
On the other hand, as a method of manufacturing a large sputtering target, a method of joining a plurality of target pieces has been conventionally known (for example, see Patent Document 3). However, when a plurality of target pieces are joined using, for example, a brazing filler metal, the generation of particles from the joined portions (divided portions) increases, which causes a reduction in product yield. Patent Literature 3 discloses that a large-sized target is manufactured by spraying a material having the same composition between a plurality of target pieces and integrating the plurality of target pieces. Even if applied, the generation of fine particles having a diameter of 0.2 μm or less cannot be sufficiently suppressed.
[0008]
[Patent Document 1] International Publication No. 95/16797 pamphlet
[Patent Document 2] JP-A-11-36067
[Patent Document 3] JP-A-11-269637
[0009]
[Problems to be solved by the invention]
As described above, in the case of a Mo—W alloy target used in a wiring film forming step of a liquid crystal display device or the like, it is difficult to manufacture a high-density large-sized target with a high yield by itself. Although it is required to realize a large target by joining a plurality of target pieces that have been combined, simply applying the conventional compounding method (joining method between target pieces) requires only There is a problem that generation of particles cannot be sufficiently suppressed.
[0010]
For this reason, a joint-type Mo-W alloy target capable of suppressing the generation of particles with good reproducibility, specifically, a large-sized Mo-W alloy target having a side of 800 mm or more, more than 1000 mm Is desired. In addition, in increasing the size of a Mo-W alloy target for forming a wiring film such as a liquid crystal display device, not only the suppression of particles but also the standard of film thickness and film quality uniformity at the time of film formation are compared with those of a conventional size target. Since it is required to be equal or more strict, there is a strong demand for a large Mo-W alloy target that can satisfy such required characteristics.
[0011]
The present invention has been made to address such a problem, and in a large-sized sputtering target obtained by joining a plurality of target pieces (Mo-W alloy target pieces), particles from a joining portion (divided portion) are generated. It is an object of the present invention to provide a sputtering target capable of suppressing generation thereof with good reproducibility and improving the uniformity of the film thickness and film quality of the Mo-W alloy film, and a method of manufacturing the same.
[0012]
[Means for Solving the Problems]
As described in claim 1, the sputtering target of the present invention is a sputtering target formed by joining a plurality of target pieces made of a Mo—W alloy, and has a width of 300 μm from a joining interface between the plurality of target pieces. The average crystal grain size of the Mo-W alloy in the region near the bonding interface is in the range of 3 to 50 μm. In the sputtering target of the present invention, the average crystal grain size of the Mo-W alloy as a whole target is preferably 200 μm or less as described in claim 2.
[0013]
In the sputtering target of the present invention, as described in claim 3, Mo in the target has a continuous portion where the count number of the measurement sensitivity is 150 or more in the measurement region of 500 × 500 μm in the mapping result of the EPMA analysis. Having, and the size of the segregated portion having a count number of 250 or more is 100 μm or less in maximum diameter, and as described in claim 4, when the measurement area of the EPMA analysis is divided into four equal areas, The area ratio of the Mo segregated portions having a count number of 250 or more in each divided region is characterized by a variation between the regions of 30% or less.
[0014]
As described in claim 5, the sputtering target of the present invention has a rectangular sputtering surface having a length of at least one side of 800 mm or more, or a sputtering target having a circular sputtering surface having a diameter of 800 mm or more, that is, a plurality of sputtering targets. It is suitable for a large sputtering target formed by joining target pieces (hereinafter, referred to as a junction type sputtering target).
[0015]
In the sputtering target of the present invention, a plurality of target pieces are joined so that the average crystal grain size of the Mo—W alloy in a region having a width of 300 μm from the joining interface is in the range of 3 to 50 μm, specifically, solid-phase joining ( Solid phase diffusion bonding). Based on such a configuration, while suppressing the coarsening of the crystal grains of the Mo-W alloy, which causes the generation of particles, the Mo-W alloy has practical strength and the like, and suppresses the increase in particles due to the joint. It is possible to realize a large junction type sputtering target. This corresponds to, for example, an increase in the size of a Mo—W alloy target for forming a wiring film accompanying an increase in the area of a liquid crystal display device.
[0016]
Further, according to the method for manufacturing a sputtering target of the present invention, as described in claim 7, when manufacturing a sputtering target by joining a plurality of target pieces made of a Mo-W alloy, mixing of Mo powder and W powder is performed. Forming the powder into a target piece shape to produce a plurality of compacts; sintering the plurality of compacts to produce a plurality of target pieces made of the Mo-W alloy; Bonding the target pieces by HIP processing.
[0017]
In the method for manufacturing a sputtering target according to the present invention, as described in claim 8, in the step of preparing a target piece, a plurality of compacts are pre-sintered at a temperature of 1000 to 1500 ° C. It is preferable to perform sintering, and it is preferable to perform HIP processing at a temperature of 1200 to 1600 ° C. to join a plurality of target pieces. Further, as described in claim 9, the mixed powder of the Mo powder and the W powder is obtained by adding the first W powder having an average particle diameter of 15 μm or less to the Mo powder having an average particle diameter of 30 μm or less by 10 to 30 mass. %, And the balance is preferably prepared by mixing a mixed W powder comprising a second W powder having an average particle diameter of 60 μm or less.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments for carrying out the present invention will be described.
1 and 2 are views showing a schematic configuration of a sputtering target according to an embodiment of the present invention. FIG. 1 is a plan view of the sputtering target, and FIG. 2 is a sectional view thereof. The sputtering target 1 shown in these figures has a plurality of target pieces 2, 2,... Made of a Mo—W alloy. The bonding between the plurality of target pieces 2, 2,..., Specifically, by solid phase diffusion bonding, constitutes a bonding type sputtering target 1. In the drawing, reference numeral 3 denotes a backing plate, and the bonding type sputtering target 1 is fixed to the backing plate 3 by brazing or the like.
[0019]
The alloy composition of the Mo—W alloy constituting each of the above-mentioned target pieces 2, 2,... Is not particularly limited, but, for example, contains W in the range of 20 to 50 atomic%, and the balance is substantially Mo and unavoidable. It is preferable to apply an alloy composition composed of a chemical impurity. If the ratio of W in the Mo—W alloy is less than 20 atomic%, the electrical resistance when the wiring film or the like is formed increases, and the etchant resistance (for example, the resistance to an etchant such as an interlayer insulating film) decreases. There is a risk. Also, when the W ratio exceeds 50 atomic%, the resistance similarly increases, and the sputter rate at the time of forming a wiring film also decreases.
[0020]
Note that the Mo—W alloy used in the sputtering target of the present invention preferably has as small an impurity element content as possible in order to improve the characteristics of the obtained wiring film and the like. For example, oxygen as an impurity is preferably at most 500 ppm, more preferably at most 100 ppm. This is because if the amount of oxygen is too large, holes (pores) are generated, which tends to cause a decrease in density. A decrease in density leads to an increase in the amount of generated particles. In order to reduce the amount of oxygen, it is effective to perform, for example, hydrogen reduction in the target manufacturing process.
[0021]
Each of the target pieces 2, 2,... Is preferably a Mo-W alloy powder sintered body, and the relative density of the powder sintered body is preferably 99% or more. If the relative density of each of the target pieces 2, 2,... Is too low, the amount of generated particles will increase regardless of the joint. That is, if a large amount of pores are present in the Mo-W alloy target, for example, sputter particles struck out by Ar ions that have entered the pores during sputtering accumulate on the edges of the pores to form protrusions. These projections cause abnormal discharge and generate particles. By making each of the target pieces 2, 2,... Dense, generation of such particles can be suppressed. Therefore, the relative density of each of the target pieces 2, 2,... Made of the Mo—W alloy is preferably 99% or more, and more preferably 99.5% or more.
[0022]
The target piece 2 made of the Mo—W alloy further satisfies the following conditions when the dispersion state of Mo and W is analyzed by EPMA (Electron Probe X-ray Microanalyzer: electron probe (X-ray) microanalyzer). Is preferred. That is, in the mapping result of the EPMA analysis of Mo with respect to the target piece 2, a continuous portion having a count number of Mo measurement sensitivity of 150 or more exists within a measurement area of 500 × 500 μm and Mo segregation having a count number of 250 or more. It is preferable that the size (as the maximum diameter) of the portion is 100 μm or less. The absence of a continuous portion having a measurement sensitivity count number of 150 or more or the size of the Mo segregation portion exceeding 100 μm indicates that the dispersion state of Mo and W is non-uniform (Mo segregation is remarkable. This means that the uniformity of the film thickness and the like are reduced based on the difference between the sputtering rates of Mo and W, and the amount of generated particles is also increased.
[0023]
Furthermore, when the measurement area in the mapping result of the above-described Mo EPMA analysis is divided into four equal areas, the area ratio of the Mo segregation section (the count number is 250 or more) in each area after division (the area of the Mo segregation section) It is preferable that the variation of (area of each region after 分割 division) between the regions is 30% or less. That is, by reducing the bias of the Mo segregation portion, it is possible to more reliably suppress the generation of particles and the unevenness of the film thickness. The size of the Mo segregation part is more preferably 50 μm or less, and the variation in the area ratio of the Mo segregation part between the regions is more preferably 15% or less.
[0024]
As described above, by making the dispersion state of Mo and W in the target piece 2 closer to a more uniform state, it is possible to suppress the generation of particles with good reproducibility and to improve the uniformity of the film thickness. . The above-mentioned dispersion state of Mo (the dispersion state defined by the mapping result of the EPMA analysis) is realized by producing the target piece 2 by powder sintering and controlling the sintering conditions as described later. It becomes possible. For example, a target piece made of a Mo-W alloy can be obtained by subjecting a molten material to rolling or the like. However, since the rolled material tends to have a large crystal grain size and Mo segregation, the target piece has a fine structure. Particles are likely to be generated on the basis of this, and the thickness of the formed film tends to be non-uniform. Also, when a large Mo—W alloy target is manufactured as a single body, segregation of Mo and the like becomes remarkable.
[0025]
The mapping of the EPMA analysis in the present invention is performed by accelerating current of 15 kV and irradiation current of 2.0 × 10 ⁷ A, measured under conditions of a time of 30 msec. In addition, the variation in the area ratio of the Mo segregated portion between the respective regions is obtained by calculating the maximum value and the minimum value of the area ratio of the Mo segregated portion (the area ratio in each region obtained by dividing the measurement region of the EPMA analysis into four) by [ {(Maximum value−minimum value) / (maximum value + minimum value)} × 100 (%)].
[0026]
The bonding type sputtering target 1 is configured by bonding a plurality of target pieces 2, 2,... Having the above-described characteristics, that is, a plurality of target pieces 2, 2,. . The solid phase diffusion bonding is performed between the plurality of target pieces 2, 2,... By heat treatment under pressure such as HIP processing. That is, the interface (joining interface) 4 between adjacent target pieces 2 is preferably joined by solid-phase diffusion between Mo-W alloys without the presence of a joining material such as a brazing material. As described above, if the target pieces are joined using a brazing material or the like, the joined portions may cause particles.
[0027]
As described above, after joining the plurality of target pieces 2, 2,... By solid-phase diffusion, the joining type sputtering target 1 is made of the Mo—W alloy in a region 300 μm wide from the joining interface 4 (region near the joining interface). The average crystal grain size is controlled in the range of 3 to 50 μm. Here, as shown in the enlarged view of the circle in FIG. 1, the region near the bonding interface indicates a range where the width w from the bonding interface 4 is 300 μm. Solid phase diffusion bonding using HIP processing or the like is a strong process, and generally tends to cause grain growth of a workpiece (here, a Mo-W alloy). Therefore, when the average crystal grain size of the Mo—W alloy in the region near the bonding interface exceeds 50 μm, the crystal grains of the Mo—W alloy of each target piece 2 itself become coarse, and the amount of generated particles increases. In addition, an increase in particles from the vicinity of the bonding interface and a decrease in bonding strength are also caused.
[0028]
On the other hand, the fact that the average crystal grain size of the Mo—W alloy in the region near the bonding interface is less than 3 μm means that the target pieces 2 are not sufficiently bonded. In this case, not only is the bonding strength between the target pieces 2 insufficient, but also the amount of generated particles is increased due to holes and the like existing at the bonding interface. In other words, by controlling the average crystal grain size of the Mo—W alloy in the region in the vicinity of the bonding interface to be in the range of 3 to 50 μm, the practical strength as a bonding type target and the like are sufficiently satisfied, and the particle It is possible to realize a large-sized Mo—W alloy target in which the generation amount is largely suppressed, that is, the junction type sputtering target 1. More preferably, the average crystal grain size of the Mo—W alloy in the region near the bonding interface is controlled in the range of 10 to 30 μm.
[0029]
Further, it is preferable that the average crystal grain size of the Mo—W alloy as the whole bonding type sputtering target 1 is 200 μm or less. When the average crystal grain size of the Mo—W alloy as a whole target exceeds 200 μm, an increase in the amount of generated particles due to coarsening of crystal grains is caused. That is, when the crystal grains of the Mo-W alloy are coarsened, a step is generated between the crystal grains based on a difference in the sputter rate depending on the crystal orientation of the crystal grains, so that the sputtered particles adhere to the step portion and the crystal surface. It becomes easy to deposit. In particular, at the center and at the end of the target, sputtered particles from an oblique direction are unstablely deposited. Such unstablely deposited sputtered particles tend to peel off and fall off during sputtering, which causes particles to be generated. Further, a splash due to abnormal discharge is likely to occur at a large step portion, which also increases the amount of generated particles.
[0030]
By reducing the average crystal grain size of the Mo—W alloy as a whole to 200 μm or less, generation of particles due to the above-described causes can be suppressed. Therefore, the average crystal grain size of the Mo—W alloy as a whole target is preferably 200 μm or less, more preferably 50 μm or less. However, if the average crystal grain size of the Mo—W alloy is too small, the density of the target may be reduced, and the like. Therefore, the average crystal grain size of the Mo—W alloy as a whole target is 5 μm or more. Preferably, there is.
[0031]
Here, the average crystal grain size of the Mo—W alloy in the region near the joining interface is obtained by measuring the grain size of the crystal grains existing in a circle having a radius of 300 μm centered on the joining interface 4 by microscopic observation at a magnification of 100 or more. The values are obtained at arbitrary three or more places, and the average value of these values is shown. The average crystal grain size of the Mo—W alloy as a whole target was determined by taking samples from any 10 or more locations on the sputter surface and measuring each sample by microscopic observation (magnification of 100 or more). Indicates the average value of 10 or more samples.
[0032]
The junction type sputtering target 1 described above is particularly suitable for a large-sized Mo—W alloy target. For example, a rectangular Mo—W alloy target as shown in FIG. 1 has a particle suppressing effect and a film thickness uniforming effect even when it has a rectangular sputtered surface with at least one side having a length of 800 mm or more. Thus, it is possible to realize a junction type sputtering target 1 having a high yield, such as a junction type sputtering target 1 having a high yield, for example, a wiring film (Mo-W alloy film) used for a liquid crystal display device or the like. In addition, as for the circular Mo-W alloy target, even when the target has a circular sputtering surface with a diameter of 800 mm or more, a junction type sputtering target having the effect of suppressing particles and the effect of equalizing the film thickness is similarly realized. can do.
[0033]
Further, the junction type sputtering target of the present invention is suitable for forming a Mo—W alloy film (wiring film) applied to an address wiring or the like of a liquid crystal display device. Such a Mo—W alloy wiring film has a large area, a liquid crystal display device with a large area, a liquid crystal display device with a small wiring and a small wiring interval with a high definition display, and a small wiring width with a small aperture ratio. This is effective for a liquid crystal display device or the like in which is improved. Further, the junction type sputtering target of the present invention is effective not only for forming wirings of a liquid crystal display device but also for forming wirings of a plasma display device, a solid display device, and a flat display device using a field emission cold cathode. is there.
[0034]
The junction type sputtering target 1 of this embodiment can be manufactured, for example, as follows. First, the Mo powder and the W powder are mixed so as to have the desired composition ratio described above to prepare a uniform mixed raw material powder. At this time, the mixed powder of the Mo powder and the W powder is a mixed W powder of a first W powder having an average particle diameter of 15 μm or less and a second W powder having an average particle diameter of 60 μm or less, and having an average particle diameter of 15 μm or less. It is preferable to prepare by mixing with Mo powder of 30 μm or less. By using such a mixed raw material powder, the density of the target piece can be increased, and the dispersion state of Mo (the dispersion state defined by the mapping result of the EPMA analysis) can be more reliably realized. It is possible to do.
[0035]
If the average particle size of the Mo powder exceeds 30 μm, the crystal grains of the Mo—W alloy may be coarsened, the density of the target piece may be reduced, and excessive segregation of Mo may be caused. In addition, as described above, by using a mixed W powder of the first W powder having an average particle diameter of 15 μm or less and the second W powder having an average particle diameter of 60 μm or less, coarse W powder is used. Since fine W particles enter the gaps between the particles, the sinterability of the Mo—W alloy can be increased to increase the density. The improvement of the sinterability also leads to the improvement of the bonding between the target pieces. When the average particle size of each W powder exceeds the above-mentioned value, the sinterability tends to decrease in any case.
[0036]
The mixing ratio of the first W powder and the second W powder is represented by the mass ratio of the first W powder [｛the mass of the first W powder / (the mass of the first W powder + the mass of the second W powder). (Mass)｝ 100 (%)] is preferably in the range of 10 to 30%. If the mixing ratio of the first W powder is less than 10% by mass, the effect of improving the sinterability by the mechanism described above cannot be sufficiently obtained, and excessive segregation of Mo tends to occur. On the other hand, also when the mixing ratio of the first W powder exceeds 30% by mass, the number of fine particles becomes too large, and the sinterability decreases. More preferably, the content ratio of the first W powder in the mixed W powder is in the range of 15 to 25% by mass.
[0037]
Next, the mixed powder of the Mo powder and the W powder as described above is molded into a desired target piece shape to produce a plurality of molded bodies. In molding the mixed powder of the Mo powder and the W powder, it is preferable to apply pressure molding such as CIP (Cold Isostatic Press) to increase the density of the target piece. Next, a plurality of shaped bodies in the shape of a target piece are sintered to produce a plurality of target pieces made of a Mo-W alloy. In the step of sintering the target piece, it is preferable to first pre-sinter the molded body at a temperature of 1000 to 1500 ° C. in a hydrogen atmosphere or the like, and then to perform main sintering at a temperature of 1600 ° C. or higher. Through these steps, a high-density target piece can be manufactured with good reproducibility.
[0038]
That is, by temporarily sintering the compact of the mixed powder of the Mo powder and the W powder in a hydrogen atmosphere or the like in advance, oxygen or the like attached to the raw material powder is reduced, and the density can be easily increased. After realizing the density, it is possible to suppress the coarsening of the crystal grains of the Mo-W alloy. If the sintering temperature is out of the range of 1000 to 1500 ° C., such effects cannot be sufficiently obtained. Then, the pre-sintered body pre-sintered under such conditions is subjected to main sintering at a temperature of 1600 ° C. or more in an inert atmosphere such as an Ar atmosphere, so that a high-density and Mo-dispersed state is obtained. And a target piece with excellent reproducibility can be obtained. It is also effective to apply HIP processing or the like to the main sintering.
[0039]
Next, the plurality of target pieces (the sintered body of the Mo-W alloy) are arranged in a desired shape and then subjected to HIP processing to join the plurality of target pieces. As described above, by applying the HIP processing to the bonding between the plurality of target pieces, the coarsening of the crystal grains of the Mo—W alloy as the entire target is suppressed, and then the region near the bonding interface between the target pieces (bonding). The average crystal grain size of the Mo—W alloy in a region having a width of 300 μm from the interface) can be controlled in a range of 3 to 50 μm. In other words, it is possible to satisfactorily join the plurality of target pieces, and to suppress an increase in particles caused by the joining portion.
[0040]
The HIP treatment conditions in the bonding step are such that the heating temperature is set in the range of 1200 to 1600 ° C. and the pressure is set to 100 to 180 MPa in order to suppress the crystal grains of the Mo—W alloy as the entire target from becoming coarse. It is preferable to set the range. The heating temperature during HIP bonding depends on the applied pressure, but is preferably set to a temperature lower than the main sintering temperature. This makes it possible to suppress the grain growth of the Mo—W alloy crystal grains of the target piece with higher reproducibility. The bonding target material thus obtained is subjected to machining such as grinding to produce a Mo-W alloy target (bonding sputtering target) having a predetermined shape.
[0041]
Note that, in the above-described method of manufacturing the bonding type sputtering target, a case has been described in which a plurality of target pieces made of the Mo-W alloy are prepared in advance by a powder sintering method, and then the plurality of target pieces are bonded by HIP processing. However, the method for manufacturing the junction type sputtering target of the present invention is not limited to this, and a plurality of target pieces can be sintered by, for example, HIP processing, and at the same time, can be manufactured by joining between the plurality of target pieces. . Also in such a manufacturing method, a junction sputtering target satisfying the configuration of the present invention can be obtained by appropriately selecting HIP processing conditions. Further, needless to say, other manufacturing methods may be applied, and the junction type sputtering target of the present invention is not limited to the manufacturing method.
[0042]
【Example】
Next, specific examples of the present invention and evaluation results thereof will be described.
[0043]
Example 1
First, a mixed W powder containing 30% by mass of a first W powder having a particle size of 15 μm or less and a balance of a second W powder having a particle size of 60 μm or less was converted into Mo powder having an average particle size of 10 μm by adding Mo and W. Were mixed so as to have a mass ratio of 1: 1 and then mixed for 48 hours in a ball mill replaced with high-purity Ar gas. After filling the mixed raw material powder into a rubber mold for molding, a pressure of 200 MPa was applied by CIP to produce a molded body. This molded body was temporarily sintered in a hydrogen atmosphere at 1400 ° C. for 6 hours, and then main-sintered in an Ar atmosphere at 1800 ° C. for 8 hours. In this way, four target pieces made of the sintered body of the Mo-W alloy were produced. The shape of each target piece was 32 × 32 × 6 mm.
[0044]
The Mo dispersion state of each target piece (Mo-W alloy sintered body) thus obtained was analyzed using an EPMA device (JXA-8600M manufactured by JEOL), and Mo color mapping in a 500 μm square area was performed. Got each. Each of these Mo color mappings had a continuous portion with a measurement sensitivity count of 150 or more, and the maximum size of the Mo segregation portion with a count of 250 or more was about 20 μm. Further, the Mo color mapping was equally divided into four parts, and the area ratios of the Mo segregated parts having a count number of 250 or more in each divided area were obtained. When the variation was determined from the area ratio of the Mo segregated portions based on the above-described formula, the variation in the area ratio of the Mo segregated portions between the regions was 5%.
[0045]
Next, the above-mentioned four target pieces (sintered body of Mo-W alloy) are arranged in a predetermined target shape, sealed in an iron capsule, and then heated to 1400 ° C. while applying an isotropic pressure of 176 MPa. HIP treatment was performed under the conditions of × 6 hours. By this HIP treatment, solid-phase diffusion bonding was performed between the respective target pieces. This HIP joined body was subjected to machining and grinding to obtain a joined Mo-W alloy target having a final shape of 127 mm in diameter and 5 mm in thickness.
[0046]
The relative density of the obtained joint type Mo-W alloy target was 99.5%. Further, according to the method described above, the average crystal grain size of the Mo—W alloy in a region having a width of 300 μm from the bonding interface between the target pieces and the average crystal grain size of the entire target were determined. As a result, the average crystal grain size of the Mo—W alloy in the region near the bonding interface was 10 μm, and the average crystal grain size of the entire target was 45 μm. Such a junction type Mo-W alloy target was subjected to characteristic evaluation described later.
[0047]
Examples 2 to 4
In Example 1 described above, the size of the target piece was set to 110 × 210 × 6 mm, and each starting material of the raw material mixed powder, the temporary sintering temperature of the compact, the main sintering temperature of the temporary sintered body, In the same manner as in Example 1 except that the joining conditions (pressure, temperature, and time during the HIP process) were changed to the conditions shown in Table 1, joint-type Mo-W alloy targets were produced. In addition, the final shape of the target was unified to 430 × 820 × 5 mm. The Mo dispersion state (by EPMA analysis), the relative density, the average crystal grain size in the region near the bonding interface, and the average crystal grain size of the entire target of each of these junction Mo-W alloy targets were set in the same manner as in Example 1. Measured and evaluated. Table 2 shows the results. In addition, each junction type Mo-W alloy target was subjected to the characteristic evaluation described later.
[0048]
Example 5
A joint type Mo-W alloy target having a final shape of 254 mm in diameter and 5 mm in thickness was produced in the same manner as in Example 1 except that the number of target pieces was changed to eight in Example 1 described above. The Mo dispersion state (by EPMA analysis), the relative density, the average crystal grain size in the region near the bonding interface, and the average crystal grain size of the entire target of the bonded Mo—W alloy target were measured in the same manner as in Example 1. ,evaluated. Table 2 shows the results. Moreover, the joint type Mo-W alloy target was subjected to characteristic evaluation described later.
[0049]
Example 6
A junction type Mo-W alloy target having a final shape of 870 × 1660 × 5 mm was produced in the same manner as in Example 2 except that the number of target pieces was changed to 8 in Example 2 described above. The Mo dispersion state (by EPMA analysis), the relative density, the average crystal grain size in the region near the bonding interface, and the average crystal grain size of the entire target of the bonded Mo—W alloy target were measured in the same manner as in Example 1. ,evaluated. Table 2 shows the results. Moreover, the joint type Mo-W alloy target was subjected to characteristic evaluation described later.
[0050]
Comparative Example 1
In Example 2 described above, the pre-sintering temperature of the molded body was set to 1000 ° C., the main sintering temperature of the pre-sintered body was set to 1400 ° C., and the HIP processing temperature at the time of joining the target pieces was set to 1200 ° C. A bonding type Mo-W alloy target was produced in the same manner as in Example 2 except for performing the above. As shown in Table 2, this junction type Mo-W alloy target had a low relative density and a slightly large Mo segregation size. And, since vacancies exist at the bonding interface between the target pieces, the average crystal grain size in the region near the bonding interface could not be measured. This junction type Mo-W alloy target was subjected to characteristic evaluation described later.
[0051]
Comparative Examples 2-3
As in Comparative Example 1 described above, the starting material of the raw material mixed powder, the pre-sintering temperature of the molded body, the main sintering temperature of the pre-sintered body, and the joining conditions (temperature and time during HIP processing) between the target pieces were determined. Except that the conditions shown in Table 1 were changed, bonding-type Mo-W alloy targets were produced in the same manner as in Example 2. As shown in Table 2, these bonded Mo-W alloy targets also have a low relative density, and vacancies are present at the bonded interface between the target pieces. Therefore, the average crystal grain size in the region near the bonded interface is measured. I couldn't do that. Each junction type Mo-W alloy target was subjected to characteristic evaluation described later.
[0052]
Comparative Example 4
In the above-described Example 2, a joined Mo-W alloy target was produced in the same manner as in Example 2 except that each starting material of the raw material mixed powder was changed and the sintering temperature of the compact was set to 1800 ° C. did. As shown in Table 2, the bonding type Mo-W alloy target had a low relative density and a large average crystal grain size in the region near the bonding interface between the target pieces as large as 64 μm. This junction type Mo-W alloy target was subjected to characteristic evaluation described later.
[0053]
Reference Examples 1-2
Example 2 was the same as Example 2 except that the starting materials of the raw material mixed powder, the temporary sintering temperature of the molded body, the main sintering temperature of the temporary sintered body, and the like were changed to the conditions shown in Table 1. Similarly, joint-type Mo-W alloy targets were produced. Although these bonded Mo—W alloy targets have an average crystal grain size in the vicinity of the bonded interface that satisfies the conditions of the present invention, the target of Reference Example 1 has a low relative density and a large variation in Mo segregated portions. In addition, the target of Reference Example 2 had a low relative density and a large maximum size and variation in the Mo segregation portion. Each of these joined Mo-W alloy targets was subjected to the characteristic evaluation described below.
[0054]
[Table 1]

[0055]
[Table 2]

[0056]
Each of the bonded Mo-W alloy targets according to Examples 1 to 6, Comparative Examples 1 to 4 and Reference Examples 1 and 2 was attached to a sputtering apparatus, and sputtering was performed under the conditions of an Ar gas pressure of 0.27 Pa. Then, a Mo-W alloy film having a thickness of about 200 nm was formed on a 5-inch Si wafer surface. The number of particles of 0.2 μm or less present in each of the obtained Mo—W alloy films was measured, and the thickness distribution of each of the Mo—W alloy films was measured and evaluated. The number of particles was measured using a particle measuring device (WM3). Regarding the film thickness distribution, the film thickness was measured using a film thickness measuring device (ALpha-Step 200), and [｛(maximum value−minimum value) / (maximum value + minimum value) was obtained from the maximum value and the minimum value of the film thickness. ｝ × 100 (%)] to determine the variation in the film thickness. Table 3 shows the results.
[0057]
[Table 3]

[0058]
As is clear from Table 3, according to each of the junction type Mo-W alloy targets of Examples 1 to 6, it is possible to obtain a Mo-W alloy film having a small amount of particles mixed therein and having an excellent film thickness distribution. You can see that there is. These greatly contribute to an improvement in the production yield of a wiring film made of a Mo—W alloy, and furthermore, a liquid crystal display device and the like using such a wiring film. On the other hand, each of the junction-type Mo-W alloy targets of Comparative Examples 1 to 4 generated a large amount of particles, and had a large variation in the thickness of the formed Mo-W alloy film.
[0059]
Examples 7 to 8, Comparative Example 5
In Example 2 described above, the mass ratio of Mo to W was changed to W = 20 at%, Example 7 was changed to W = 35 at%, and Example 8 was changed to W = 35 at%. In the same manner as in No. 2, joint-type Mo-W alloy targets were produced. Further, a junction type Mo-W alloy target was produced in the same manner as in Example 2 using only W powder having an average particle diameter of 60 μm (Comparative Example 5). The same evaluation as in Example 1 was performed for each of these targets. The results are shown in Tables 4 and 5.
[0060]
[Table 4]

[0061]
[Table 5]

[0062]
As can be seen from Tables 4 and 5, the Mo—W alloy target of the present invention is also effective for those in which the composition ratio of the Mo—W alloy is changed. Further, as in Comparative Example 5, when only one type of W powder has an average particle diameter, segregation of Mo is likely to occur.
[0063]
【The invention's effect】
As described above, according to the sputtering target and the method of manufacturing the same of the present invention, after increasing the size of the Mo—W alloy target, the increase in the amount of particles generated due to the joint and the like is suppressed with good reproducibility. It is possible to do. Therefore, it contributes to increase in area and quality of the Mo-W alloy wiring film and the like.
[Brief description of the drawings]
FIG. 1 is a plan view showing a schematic configuration of a sputtering target (junction type Mo—W alloy target) according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of the sputtering target shown in FIG.
[Explanation of symbols]
1 ... joint type sputtering target, 2 ... target piece made of Mo-W alloy, 4 ... joint interface

Claims (10)

A sputtering target obtained by joining a plurality of target pieces made of an Mo-W alloy,
A sputtering target, wherein an average crystal grain size of the Mo-W alloy in a region near a bonding interface having a width of 300 μm from a bonding interface between the plurality of target pieces is in a range of 3 to 50 μm. The sputtering target according to claim 1,
The sputtering target, wherein the average crystal grain size of the Mo-W alloy target as a whole is 200 μm or less. The sputtering target according to claim 1 or 2,
Mo in the target has a continuous portion where the count number of the measurement sensitivity is 150 or more in the measurement area of 500 × 500 μm in the mapping result of the EPMA analysis, and the size of the segregation portion where the count number is 250 or more is smaller. A sputtering target having a thickness of 100 μm or less. The sputtering target according to claim 3,
When the measurement region in the mapping result of the EPMA analysis of Mo is divided into four equal areas, the area ratio of the Mo segregation portion having a count number of 250 or more in each divided region has a variation of 30% or less between the regions. A sputtering target, characterized in that: In the sputtering target according to any one of claims 1 to 4,
A sputtering target having a rectangular sputtering surface having a length of at least one side of 800 mm or more or a circular shape having a diameter of 800 mm or more. The sputtering target according to any one of claims 1 to 5,
The sputtering target, wherein the Mo-W alloy contains W in the range of 20 to 50 atomic%, and the balance substantially consists of Mo and unavoidable impurities. In manufacturing a sputtering target by joining a plurality of target pieces made of a Mo-W alloy,
Forming a mixed powder of Mo powder and W powder into a target piece shape to produce a plurality of compacts;
Sintering the plurality of molded bodies to produce a plurality of target pieces made of the Mo-W alloy;
Bonding the plurality of target pieces by a HIP process. The method for manufacturing a sputtering target according to claim 7,
After temporarily sintering the plurality of compacts at a temperature of 1000 to 1500 ° C., main sintering is performed at a temperature of 1600 ° C. or more to produce the plurality of target pieces, and the HIP treatment is performed at a temperature of 1200 to 1600 ° C. And bonding the plurality of target pieces to each other by sputtering. In the method for manufacturing a sputtering target according to claim 7 or 8,
The mixed powder of the Mo powder and the W powder contains, in the Mo powder having an average particle diameter of 30 μm or less, the first W powder having an average particle diameter of 15 μm or less in a range of 10 to 30% by mass, with the balance being average. A method for producing a sputtering target, comprising mixing and preparing a mixed W powder comprising a second W powder having a particle size of 60 μm or less. In the method for manufacturing a sputtering target according to any one of claims 7 to 9,
A sputtering target wherein an average crystal grain size of the Mo-W alloy in a region near a bonding interface having a width of 300 μm from a bonding interface between the plurality of target pieces during the bonding step is controlled in a range of 3 to 50 μm.

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