JP4574949B2 - Sputtering target and manufacturing method thereof - Google Patents

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]
BACKGROUND OF THE INVENTION
The present invention relates to a large sputtering target made of a Mo—W alloy and a method for manufacturing the same.
[0002]
[Prior art]
In recent years, an active matrix liquid crystal display device in which a thin film transistor (TFT) formed using an amorphous silicon (a-Si) film is applied as a switching element is widely used. This is because a TFT array can be constructed using an a-Si film that can be formed at low temperature on an inexpensive glass substrate, thereby realizing a display device with a large area, high definition, high image quality, and low cost. is there.
[0003]
When a large-area liquid crystal display device (display device) is configured, the total length of the address wiring inevitably increases, so that the resistance of the address wiring and the like increases. As the resistance of the address line increases, the delay of the gate pulse applied to the switching element becomes remarkable, and there arises a problem that it becomes difficult to control the liquid crystal. For this reason, it is necessary to avoid 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 (see, for example, Patent Document 1 and Patent Document 2). In addition to low resistance, the Mo-W alloy film is excellent in etchant resistance and taper workability, so wiring is not only used for liquid crystal display devices with a large area, but also for high-definition displays. This is also effective for a liquid crystal display device in which the width and wiring interval are narrowed, and a liquid crystal display device in which the wiring width is narrowed to improve the aperture ratio.
[0005]
As described in Patent Literature 1 and Patent Literature 2, the wiring film made of the Mo—W alloy is generally formed by sputtering film formation using a Mo—W alloy target. Here, when a wiring film such as a liquid crystal display device is formed by sputtering film formation, it is possible to suppress generation of particles (fine particles adhering to the film formation substrate) that cause wiring disconnection or short circuit. This is important for increasing product yield. Since the number of generated particles is closely related to the density of the target, a target whose density is increased by a vacuum melting method or hot pressing is used. For large targets, an integrated high-density target is realized by combining, for example, a powder sintering method and rolling.
[0006]
However, in the case of a difficult-to-process material such as the Mo-W alloy described above, it is difficult to produce a large and high-density single target because cracks and the like are likely to occur during sintering and rolling. In particular, in the wiring film forming process of a liquid crystal display device, for example, a large target having a side length of 800 mm or even more than 1000 mm is required. It is very difficult to manufacture with. Therefore, it is an urgent task to establish a method for producing a large, high-density Mo—W alloy target.
[0007]
On the other hand, as a method for producing 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 bonded using, for example, a brazing material, the generation of particles from the bonded portion (divided portion) increases, causing a decrease in product yield. Further, Patent Document 3 describes that a large target is produced by spraying a material having the same composition between a plurality of target pieces and integrating the plurality of target pieces. Even if it is applied, 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]
Japanese Patent Laid-Open No. 11-36067
[Patent Document 3]
Japanese Patent Laid-Open No. 11-269637
[0009]
[Problems to be solved by the invention]
As described above, in a Mo-W alloy target used in a wiring film forming process of a liquid crystal display device, it is difficult to produce a single high-density large target with high yield. It is required to realize a large target by joining multiple target pieces, but only by applying the conventional composite method (joining method between target pieces), There is a problem that the generation of particles cannot be sufficiently suppressed.
[0010]
For this reason, it is possible to suppress the generation of particles with high reproducibility. A joint type Mo-W alloy target, specifically, a large Mo-W alloy target with a side of 800 mm or more than 1000 mm. Is desired. Furthermore, 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 standards such as film thickness and film quality uniformity at the time of film formation are compared with the target of the conventional size. There is a strong demand for a large-scale Mo—W alloy target capable of satisfying such required characteristics because it is strictly demanded to be equivalent or higher.
[0011]
The present invention has been made to cope with such a problem, and in a large-scale sputtering target formed by joining a plurality of target pieces (Mo-W alloy target pieces), particles from the joined parts (divided parts) are obtained. An object of the present invention is to provide a sputtering target capable of suppressing the occurrence with good reproducibility and improving the uniformity of the film thickness and film quality of the Mo-W alloy film, and a method for manufacturing the sputtering target.
[0012]
[Means for Solving the Problems]
  As described in claim 1, the sputtering target of the present invention includes a plurality of powder firings composed of a Mo—W alloy containing W in a range of 20 to 50 atomic% and the balance being substantially made of Mo and inevitable impurities. A rectangle formed by bonding target pieces produced by ligation and having a length of at least one side of 800 mm or moreIn shapeA sputtering target having a sputtering surface, wherein the average crystal grain size of the Mo-W alloy target as a whole is 50 μm or less, and the region in the vicinity of the bonding interface having a width of 300 μm from the bonding interface between the plurality of target pieces. The average crystal grain size of the Mo—W alloy is in the range of 3 to 50 μm, and the density of the entire target is 99% or more.
[0013]
  The sputtering target of the present invention is further claimed2As described above, Mo in the target isUsing an EPMA apparatus (JXA-8600M manufactured by JEOL), an acceleration current of 15 kV and an irradiation current of 2.0 × 10 ⁷ A, measured under the condition of time 30msecIn the mapping result of the EPMA analysis, there is a continuous portion having a measurement sensitivity count number of 150 or more in a measurement area of 500 × 500 μm, and the segregation part having a count number of 250 or more has a maximum diameter of 100 μm or less. And claims3As described above, when the measurement area of the EPMA analysis 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 area is 30% variation between the areas. It is characterized by the following.
[0014]
  As described in claim 1, the sputtering target according to the present invention is a rectangular sputter having a length of at least one side of 800 mm or more.FaceIt is suitable for a sputtering target having, that is, a large sputtering target formed by bonding a plurality of target pieces (hereinafter referred to as a bonding type sputtering target).
[0015]
In the sputtering target of the present invention, a plurality of target pieces are bonded so that the average crystal grain size of the Mo—W alloy in the region of 300 μm width from the bonding interface is in the range of 3 to 50 μm, specifically, solid phase bonding ( Solid phase diffusion bonding). Based on such a configuration, while suppressing the coarsening of the crystal grains of the Mo-W alloy, which is a cause of generation of particles, it has practical strength and the like, and suppresses the increase in particles caused by the joint. A large junction type sputtering target can be realized. This corresponds to the demand for larger size of the Mo-W alloy target for forming a wiring film associated with an increase in the area of the liquid crystal display device, for example.
[0016]
  In addition, as described in claim 4, the method for manufacturing a sputtering target according to the present invention is a method for manufacturing a sputtering target by joining a plurality of target pieces made of a Mo—W alloy. The powder and the first W powder having an average particle size of 15 μm or less are included in the range of 10 to 30% by mass, and the balance is the average particle size.Over 15μmA step of forming a plurality of molded bodies by forming a mixed powder with a mixed W powder, which is a second W powder of 60 μm or less, into a target piece shape, and temporarily forming the plurality of molded bodies at a temperature of 1000 to 1500 ° C. After sintering, a step of producing a plurality of target pieces made of the Mo—W alloy by performing main sintering at a temperature of 1600 ° C. or higher, and a HIP process at a temperature of 1200 to 1600 ° C. between the plurality of target pieces. And a step of bonding by the above.
[0017]
  In the sputtering target manufacturing method of the present invention, as described in claim 5, the average crystal grains of the Mo—W alloy in a region near the bonding interface having a width of 300 μm from the bonding interface between the plurality of target pieces during the bonding step. It is preferable to control the diameter in the range of 3 to 50 μm. In addition, as described in claim 6, the sputtering target is a rectangle having a length of at least one side of 800 mm or more.In shapeIt is preferable to have a sputter surface.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, modes for carrying out the present invention will be described.
1 and 2 are diagrams 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 drawings has a plurality of target pieces 2 made of a Mo—W alloy. The plurality of target pieces 2, 2... Are bonded, specifically, solid phase diffusion bonding, to form a bonded sputtering target 1. In the figure, reference numeral 3 denotes a backing plate, and the junction 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 target pieces 2, 2... Is not particularly limited. For example, W is contained in a range of 20 to 50 atomic%, and the balance is substantially Mo and inevitable. It is preferable to apply an alloy composition consisting of mechanical impurities. When the ratio of W in the Mo—W alloy is less than 20 atomic%, the electrical resistance when forming a wiring film or the like increases, and the etchant resistance (for example, resistance to an etchant such as an interlayer insulating film) decreases. There is a fear. Similarly, when the W ratio exceeds 50 atomic%, the resistance similarly increases, and the sputtering rate when the wiring film is formed also decreases.
[0020]
Note that the Mo—W alloy used for the sputtering target of the present invention preferably has as little impurity element content as possible in order to improve the properties of the obtained wiring film and the like. For example, oxygen as an impurity is preferably 500 ppm or less, and more preferably 100 ppm or less. This is because if the amount of oxygen is too large, voids (pores) are generated and the density tends to decrease. A decrease in density leads to an increase in the amount of particles generated. In order to reduce the amount of oxygen, for example, it is effective to perform hydrogen reduction or the like in the target manufacturing process.
[0021]
Each of the target pieces 2, 2... Is preferably a powder sintered body of Mo—W alloy, and the relative density of the powder sintered body is preferably 99% or more. When the relative density of each of the target pieces 2, 2... Is too low, the amount of particles generated increases regardless of the joint. That is, if a large amount of pores are present in the Mo—W alloy target, for example, sputtered particles sputtered by Ar ions that have entered the pores during sputtering accumulate on the edge of the pores to form protrusions. This protrusion causes abnormal discharge to generate particles. The generation of such particles can be suppressed by densifying each of the target pieces 2. Accordingly, the relative density of each of the target pieces 2, 2... Made of Mo—W alloy is preferably 99% or more, and more preferably 99.5% or more.
[0022]
The target piece 2 made of a Mo—W alloy satisfies the following conditions when the dispersion state of Mo and W is further analyzed by EPMA (Electron Probe X-ray Microanalyzer). It is preferable. That is, in the mapping result of the EPMA analysis of Mo on the target piece 2, there is a portion where the count number of Mo measurement sensitivity is 150 or more in a measurement area of 500 × 500 μm, and Mo segregation with a count number of 250 or more. The size of the part (as the maximum diameter) is preferably 100 μm or less. If there is no continuous portion with a measurement sensitivity count of 150 or more, or the size of the Mo segregation part exceeds 100 μm, the dispersed state of Mo and W is not uniform (Mo segregation is remarkable). This means that the uniformity of the film thickness is reduced based on the difference in sputtering rate between Mo and W, and the amount of particles generated is also increased.
[0023]
Furthermore, when the measurement area in the mapping result of the above-described EPMA analysis of Mo is divided into four equal areas, the area ratio of Mo segregation parts (count number is 250 or more) in each area after division (area of Mo segregation part) It is preferable that the variation between the respective regions) is 30% or less. That is, by reducing the deviation of the Mo segregation part, it is possible to more reliably suppress the generation of particles and the non-uniformity 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]
Thus, by making the dispersed state of Mo and W in the target piece 2 closer to a more uniform state, the generation of particles can be suppressed with good reproducibility and the uniformity of the film thickness can be improved. . The Mo dispersion state (dispersion state defined by the mapping result of EPMA analysis) as described above is realized by preparing 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 rolling the melted material, but the rolled material tends to cause coarsening of the crystal grain size and segregation of Mo. Based on this, particles are likely to be generated, and the thickness of the formed film tends to be non-uniform. In addition, even when a large Mo—W alloy target is fabricated as a single unit, segregation of Mo and the like become remarkable.
[0025]
The mapping of EPMA analysis in the present invention is as follows: acceleration current 15 kV, irradiation current 2.0 × 10⁷A, measured under conditions of time 30 msec. Further, the variation in the area ratio of the Mo segregation part between the respective areas is based on the maximum value and the minimum value of the above-described area ratio of the Mo segregation part (the area ratio in each area obtained by dividing the measurement area of the EPMA analysis). {(Maximum value−minimum value) / (maximum value + minimum value)} × 100 (%)].
[0026]
The joining type sputtering target 1 is configured by joining a plurality of target pieces 2, 2... Having the above-described characteristics, that is, a plurality of target pieces 2 made of Mo—W alloy. . The plurality of target pieces 2 are bonded by solid phase diffusion bonding by heat treatment under pressure such as HIP treatment. That is, the interface (bonding interface) 4 between the adjacent target pieces 2 is preferably bonded by solid phase diffusion between Mo—W alloys without the presence of a bonding material such as a brazing material. As described above, when the target pieces are bonded using a brazing material or the like, the bonded portion causes generation of particles.
[0027]
As described above, after joining the plurality of target pieces 2, 2... By solid phase diffusion, the junction type sputtering target 1 is made of Mo—W alloy in a region 300 μm wide from the junction interface 4 (region near the junction interface). The average crystal grain size is controlled in the range of 3 to 50 μm. Here, the region near the bonding interface indicates a range where the width w from the bonding interface 4 is 300 μm, as shown in the enlarged view in a circle in FIG. 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, Mo—W alloy). Accordingly, 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 particles generated 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 the bonding strength between the target pieces 2 is insufficient, but also the amount of particles generated is increased due to voids existing at the bonding interface. In other words, by controlling the average crystal grain size of the Mo—W alloy in the region near the bonding interface to a range of 3 to 50 μm, after sufficiently satisfying the practical strength as a bonding type target, It becomes possible to realize a large Mo—W alloy target, that is, a junction type sputtering target 1, in which the generation amount is greatly suppressed. It is more preferable to control the average crystal grain size of the Mo—W alloy in the region in the vicinity of the bonding interface within the range of 10 to 30 μm.
[0029]
  Further, the average crystal grain size of the Mo—W alloy as the whole of the junction type sputtering target 1 is50below μmTheThe average grain size of the Mo-W alloy as a whole target is50If it exceeds μm, an increase in the amount of particles generated due to the 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 sputter rate depending on the crystal orientation of the crystal grains. Easy to deposit. In particular, the sputtered particles from an oblique direction are deposited in an unstable manner at the center or end of the target. Such unstablely deposited sputtered particles easily peel off and fall off during sputtering, which causes generation of particles. Furthermore, since a splash due to abnormal discharge is likely to occur at a large step portion, this also increases the amount of particles generated.
[0030]
  Average grain size of Mo-W alloy as a whole target50By miniaturizing to μm or less, it becomes possible to suppress the generation of particles due to the above-mentioned causes.. TheHowever, if the average crystal grain size of the Mo-W alloy is too small, it may cause a decrease in the density of the target, so 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 joint interface is measured by microscopic observation of the grain size of a crystal grain existing in a circle having a radius of 300 μm centering on the joint interface 4 at a magnification of 100 times or more. The values are averaged to obtain these values at three or more arbitrary locations, and the average value of these values is shown. The average crystal grain size of the Mo—W alloy as the entire target was measured by taking samples from any 10 or more locations on the sputtering surface and observing these samples under a microscope (magnification of 100 times or more). Is an averaged value for 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, in the case of a rectangular Mo—W alloy target as shown in FIG. 1, even when it has a rectangular sputter surface with at least one side having a length of 800 mm or more, the effect of suppressing particles and the effect of making the film uniform That is, it is possible to realize a junction type sputtering target 1 that can produce a wiring film (Mo—W alloy film) used in a liquid crystal display device or the like with a high yield. In addition, for circular Mo-W alloy targets, even when having a sputter surface with a circular shape with a diameter of 800 mm or more, a junction-type sputtering target having the same effect of suppressing particles and equalizing the film thickness is realized. can do.
[0033]
Moreover, 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 of a liquid crystal display device. Such a Mo-W alloy wiring film is used for a liquid crystal display device with an increased area, a liquid crystal display device with a reduced wiring and wiring interval as the display becomes higher in definition, and an aperture ratio with a reduced wiring width. This is effective for a liquid crystal display device and the like with improved characteristics. Furthermore, the junction type sputtering target of the present invention is effective not only for the formation of wiring for liquid crystal display devices, but also for the formation of wiring for plasma display devices, solid state display devices, flat display devices using field emission cold cathodes, and the like. is there.
[0034]
  The junction type sputtering target 1 of this embodiment can be produced as follows, for example. First, Mo powder and W powder are mixed so as to have the desired composition ratio described above to produce a uniform mixed raw material powder. At this time, the mixed powder of Mo powder and W powder has an average particle diameter of the first W powder having an average particle diameter of 15 μm or less.Over 15μmIt is preferable to prepare by mixing the mixed W powder with the second W powder of 60 μm or less into the Mo powder having an average particle size of 30 μm or less. By using such mixed raw material powder, the density of the target piece can be increased, and the Mo dispersion state (the dispersion state defined by the mapping result of EPMA analysis) as described above can be realized more reliably. It becomes 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. As for the W powder, as described above, the first W powder having an average particle size of 15 μm or less and the average particle size areOver 15μmBy using the mixed W powder with the second W powder of 60 μm or less, fine W particles enter the gaps between the coarse W particles, so that the Mo-W alloy is increased in sinterability and densified. It becomes possible. Improvement in sinterability also leads to improvement in bondability between target pieces. When the average particle diameter of each W powder exceeds the above-described value, any of them tends to cause a decrease in sinterability.
[0036]
The mixing ratio of the first W powder and the second W powder is the mass ratio of the first W powder [{mass of the first W powder / (mass of the first W powder + the mass of the second W powder] Mass)} × 100 (%)] is preferably adjusted to be in the range of 10 to 30%. When the mixing ratio of the first W powder is less than 10% by mass, the effect of improving the sinterability by the mechanism as described above cannot be sufficiently obtained, and excessive segregation of Mo is likely to occur. On the other hand, when the mixing ratio of the first W powder exceeds 30% by mass, too many fine particles increase and the sinterability decreases. The content ratio of the first W powder in the mixed W powder is more preferably in the range of 15 to 25% by mass.
[0037]
Next, a mixed powder of the Mo powder and the W powder as described above is formed into a desired target piece shape to produce a plurality of formed bodies. In forming the mixed powder of Mo powder and W powder, it is preferable to apply pressure forming such as CIP (cold isostatic pressing) in order to increase the density of the target piece. Next, a plurality of target piece-shaped compacts are sintered to produce a plurality of target pieces made of a Mo-W alloy. In the sintering process of the target piece, first, the compact is first temporarily sintered at a temperature of 1000 to 1500 ° C. in a hydrogen atmosphere or the like, and then main sintering is preferably performed at a temperature of 1600 ° C. or higher. By passing through such a process, it becomes possible to produce a high-density target piece with high reproducibility.
[0038]
That is, by pre-sintering a molded body of a mixed powder of Mo powder and W powder in a hydrogen atmosphere or the like, oxygen attached to the raw material powder is reduced, making it easy to achieve high density, It is possible to suppress the coarsening of the crystal grains of the Mo—W alloy after realizing the density. If the pre-sintering temperature is out of the range of 1000 to 1500 ° C., such an effect cannot be sufficiently obtained. And by pre-sintering the pre-sintered body pre-sintered under such conditions at a temperature of 1600 ° C. or higher in an inert atmosphere such as Ar atmosphere, it is possible to obtain a high density and dispersed state of Mo. Can be obtained with good reproducibility. It is also effective to apply HIP processing or the like for the main sintering.
[0039]
Next, the plurality of target pieces (Mo-W alloy sintered body) are arranged in a desired shape and then subjected to HIP treatment to join the plurality of target pieces. In this way, by applying the HIP process 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 the vicinity of the bonding interface between the target pieces (bonding) The average grain size of the Mo—W alloy in the region 300 μm in width from the interface can be controlled in the range of 3 to 50 μm. In other words, it is possible to satisfactorily join between a plurality of target pieces, and to suppress an increase in particles caused by the joined portion.
[0040]
The HIP treatment conditions in the joining process are as follows: 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 coarsening of the crystal grains of the Mo—W alloy as the entire target. It is preferable to be in the range. Although the heating temperature at the time of HIP bonding depends on the applied pressure, it is preferably set to a temperature lower than the main sintering temperature. This makes it possible to suppress the growth of Mo—W alloy crystal grains of the target piece with higher reproducibility. The joint type target material thus obtained is subjected to mechanical processing such as grinding to produce a Mo-W alloy target (joint type sputtering target) having a predetermined shape.
[0041]
In addition, although the manufacturing method of the joining type sputtering target mentioned above demonstrated the case where several target pieces which consist of Mo-W alloy previously were produced by the powder sintering method, between several target pieces were joined by HIP processing. The manufacturing method of the bonding type sputtering target of the present invention is not limited to this, and it is also possible to sinter a plurality of target pieces by, for example, HIP treatment, and simultaneously bond the plurality of target pieces. . Also in such a manufacturing method, the junction type sputtering target which satisfies the structure of this invention can be obtained by selecting HIP processing conditions suitably. Furthermore, it goes without saying that 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,average30% by mass of the first W powder having a particle size of 15 μm or less, with the remainder beingaverageParticle sizeOver 15μmThe mixed W powder composed of the second W powder of 60 μm or less was mixed with Mo powder having an average particle diameter of 10 μm so that the mass ratio of Mo to W was 1: 1, and then replaced with high-purity Ar gas. Mix for 48 hours on a ball mill. After this mixed raw material powder was filled into a molding rubber mold, a pressure of 200 MPa was applied by CIP to produce a molded body. The compact was pre-sintered in a hydrogen atmosphere at 1400 ° C. for 6 hours, and then sintered in an Ar atmosphere at 1800 ° C. for 8 hours. In this way, four target pieces made of a Mo-W alloy sintered body 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 apparatus (JXA-8600M manufactured by JEOL), and Mo color mapping in a 500 μm square range was obtained. I got each. Each of these color mappings of Mo had a portion where the count number of measurement sensitivity was 150 or more, and the maximum size of the Mo segregation part having a count number of 250 or more was about 20 μm. Furthermore, the color mapping of Mo was equally divided into four, and the area ratio of the Mo segregation part having a count number of 250 or more in each divided region was obtained. When the variation was determined from the area ratio of these Mo segregation portions based on the above-described formula, the variation in the area ratio of the Mo segregation portion between the regions was 5%.
[0045]
Next, after placing the above four target pieces (Mo-W alloy sintered bodies) in a predetermined target shape and encapsulating them in an iron capsule, 1400 ° C. while applying an isotropic pressure of 176 MPa X HIP treatment was performed under conditions of 6 hours. By this HIP treatment, solid phase diffusion bonding was performed between the target pieces. This HIP bonded body was subjected to machining and grinding to obtain a bonded type Mo—W alloy target having a final shape having a diameter of 127 × thickness of 5 mm.
[0046]
The relative density of the obtained bonded Mo—W alloy target was 99.5%. Further, according to the above-described method, the average crystal grain size of the Mo—W alloy in the 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 obtained. As a result, the average crystal grain size of the Mo—W alloy in the vicinity of the bonding interface was 10 μm, and the average crystal grain size as a whole target was 45 μm. Such a joining type Mo—W alloy target was subjected to the characteristic evaluation described later.
[0047]
Examples 2-4
In Example 1 described above, the size of the target piece is 110 × 210 × 6 mm, each starting material of the raw material mixed powder, the preliminary sintering temperature of the compact, the main sintering temperature of the preliminary sintered body, and between the target pieces A joining type Mo—W alloy target was prepared in the same manner as in Example 1 except that the joining conditions (pressure, temperature and time during HIP treatment) were changed to the conditions shown in Table 1. The final target shape was unified to 430 x 820 x 5 mm. The Mo dispersion state (by EPMA analysis), the relative density, the average crystal grain size in the vicinity of the joint interface, and the average crystal grain size of the target as a whole are the same as in Example 1. Measurement and evaluation. The results are shown in Table 2. Moreover, each joining type Mo-W alloy target was used for the characteristic evaluation mentioned later.
[0048]
Example 5
In Example 1 described above, a bonded 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 8. In the same manner as in Example 1, the Mo dispersion state (by EPMA analysis), the relative density, the average crystal grain size in the vicinity of the joint interface, and the average crystal grain size of the target as a whole were measured. ,evaluated. The results are shown in Table 2. Moreover, the joining type Mo-W alloy target was used for the characteristic evaluation mentioned later.
[0049]
Example 6
In Example 2 described above, a bonded Mo—W alloy target having a final shape of 870 × 1660 × 5 mm was produced in the same manner as Example 2 except that the number of target pieces was changed to 8. In the same manner as in Example 1, the Mo dispersion state (by EPMA analysis), the relative density, the average crystal grain size in the vicinity of the joint interface, and the average crystal grain size of the target as a whole were measured. ,evaluated. The results are shown in Table 2. Moreover, the joining type Mo-W alloy target was used for the characteristic evaluation mentioned later.
[0050]
Comparative Example 1
In Example 2 described above, the temporary sintering temperature of the compact is set to 1000 ° C., the main sintering temperature of the temporary sintered body is set to 1400 ° C., and the HIP processing temperature at the time of joining between the target pieces is set to 1200 ° C. A bonded Mo—W alloy target was produced in the same manner as in Example 2 except that. As shown in Table 2, this bonded Mo-W alloy target had a low relative density and a slightly large Mo segregation size. And since the void | hole exists in the joining interface between target pieces, the average crystal grain diameter in the joining interface vicinity area | region could not be measured. This bonded Mo-W alloy target was subjected to the characteristic evaluation described later.
[0051]
Comparative Examples 2-3
In the same manner as in Comparative Example 1 described above, the starting material 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 joining conditions between the target pieces (temperature and time during HIP processing) A junction type Mo—W alloy target was prepared in the same manner as in Example 2 except that the conditions were changed to the conditions shown in Table 1. These bonded Mo-W alloy targets also have a low relative density as shown in Table 2, and there are vacancies at the bonding interface between the target pieces, so the average grain size in the region near the bonding interface is measured. I couldn't. Each joining type Mo-W alloy target was used for the characteristic evaluation mentioned below.
[0052]
Comparative Example 4
In Example 2 described above, a joining type Mo—W alloy target was prepared in the same manner as in Example 2 except that each starting material of the raw material mixed powder was changed and the pre-sintering temperature of the compact was set to 1800 ° C. did. As shown in Table 2, this bonded Mo-W alloy target had a low relative density, and the average grain size in the vicinity of the bonded interface between the target pieces was as large as 64 μm. This bonded Mo-W alloy target was subjected to the characteristic evaluation described later.
[0053]
Reference Examples 1-2
In Example 2 described above, Example 2 and Example 2 were changed except that the starting raw materials of the raw material mixed powder, the temporary sintering temperature of the compact, the main sintering temperature of the temporary sintered body, and the like were changed to the conditions shown in Table 1. In the same manner, bonded Mo-W alloy targets were produced. Although these bonded Mo-W alloy targets satisfy the conditions of the present invention in terms of the average crystal grain size in the vicinity of the bonded interface, the target of Reference Example 1 has a low relative density and a large variation in the Mo segregation part. The target of Reference Example 2 had a low relative density and a large maximum size and variation in the Mo segregation part. Each of these joining type Mo—W alloy targets was subjected to the characteristic evaluation described later.
[0054]
[Table 1]

[0055]
[Table 2]

[0056]
Each of the bonding type Mo—W alloy targets according to Examples 1 to 6, Comparative Examples 1 to 4 and Reference Examples 1 to 2 described above was attached to a sputtering apparatus, and sputtering was performed under the condition that the Ar gas pressure was 0.27 Pa. A Mo-W alloy film having a thickness of about 200 nm was formed on the surface of a 5-inch Si wafer. The number of particles of 0.2 μm or less present in each obtained Mo—W alloy film was measured, and the film thickness distribution of each Mo—W alloy film was measured and evaluated. The number of particles was measured using a particle measuring device (WM3). Regarding the film thickness distribution, measure the film thickness using a film thickness measuring device (ALpha-Step200), and calculate the maximum value and the minimum value [{(maximum value−minimum value) / (maximum value + minimum value)]. } × 100 (%)], the variation in film thickness was determined. These results are shown in Table 3.
[0057]
[Table 3]

[0058]
As is apparent from Table 3, according to each of the bonded 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 and excellent in film thickness distribution. I know that there is. These greatly contribute to the improvement of the manufacturing yield of a wiring film made of a Mo—W alloy, and thus a liquid crystal display device using such a wiring film. On the other hand, each joining type Mo—W alloy target of Comparative Examples 1 to 4 had a large amount of particles generated, and the film thickness variation of the formed Mo—W alloy film was also large.
[0059]
Examples 7-8, Comparative Example 5
In Example 2 described above, the mass ratio of Mo and W was changed to W = 20 atomic%, Example 7 was changed to W = 35 atomic%, and Example 8 was changed. In the same manner as in Example 2, bonded Mo-W alloy targets were produced.
Further, using only W powder having an average particle diameter of 60 μm, a bonded Mo—W alloy target was produced in the same manner as in Example 2 (Comparative Example 5). Each of these targets was evaluated in the same manner as in Example 1. 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 size, segregation of Mo is likely to occur.
[0063]
【The invention's effect】
As described above, according to the sputtering target and the manufacturing method thereof of the present invention, the increase in the amount of particles generated due to the joining portion and the like is suppressed with high reproducibility after the Mo-W alloy target is enlarged. It becomes possible to do. Therefore, this contributes to an 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 (bonded 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]
DESCRIPTION OF SYMBOLS 1 ... Joining type sputtering target, 2 ... Target piece which consists of Mo-W alloy, 4 ... Joining interface

Claims (6)

A target piece made by sintering a plurality of powders made of a Mo-W alloy containing W in a range of 20 to 50 atomic% and the balance being substantially made of Mo and inevitable impurities is joined. length a sputtering target having a rectangular sputtering surface over 800 mm,
The average crystal grain size of the Mo—W alloy as a whole target is 50 μm or less, and the average crystal grain size of the Mo—W alloy in the vicinity of the junction interface having a width of 300 μm from the junction interface between the plurality of target pieces. A sputtering target having a range of 3 to 50 μm and a density of the entire target of 99% or more. The sputtering target according to claim 1, wherein
Mo in the target is 500 × in the mapping result of EPMA analysis measured using an EPMA apparatus (JXA-8600M manufactured by JEOL) under the conditions of an acceleration current of 15 kV, an irradiation current of 2.0 × 10 ⁷ A, and a time of 30 msec. A sputtering target characterized in that it has a portion where the count number of the measurement sensitivity is 150 or more in a measurement region of 500 μm, and the size of the segregation part whose count number is 250 or more is 100 μm or less. The sputtering target according to claim 2, wherein
When the measurement area in the mapping result of the Mo EPMA analysis is divided into four equal areas, the area ratio of the Mo segregation part having a count number of 250 or more in each divided area is 30% or less. The sputtering target characterized by being. In manufacturing a sputtering target by joining a plurality of target pieces made of Mo-W alloy,
Mo powder with an average particle size of 30 μm or less and a first W powder with an average particle size of 15 μm or less in the range of 10 to 30% by mass, the balance being the second W with an average particle size of more than 15 μm and 60 μm Forming a mixed powder with a mixed W powder, which is a powder, into a target piece shape, and producing a plurality of molded bodies;
A step of pre-sintering the plurality of molded bodies at a temperature of 1000 to 1500 ° C. and then performing main sintering at a temperature of 1600 ° C. or higher to produce a plurality of target pieces made of the Mo—W alloy;
A step of joining the plurality of target pieces by HIP treatment at a temperature of 1200 to 1600 ° C. In the manufacturing method of the sputtering target of Claim 4,
Sputtering target production characterized in that the average crystal grain size of the Mo-W alloy is controlled in the range of 3 to 50 µm in the region near the joining interface having a width of 300 µm from the joining interface between the plurality of target pieces during the joining step. Method. In the manufacturing method of the sputtering target of Claim 4 or 5,
The sputtering target manufacturing method of a sputtering target characterized by having at least a rectangular sputtering surface length of more than 800mm of one side.

Images