JP4367677B2 - Sputtering target and manufacturing method thereof - Google Patents

Description

ここで、測定は超音波探傷器を使用した。実験Ｎｏ．１，２は下地金属層のＣｒ膜２を省略した場合であり、超音波探傷結果は９０％、８７％で、部分的に接合不十分の所があることを示す。なお、実験Ｎｏ．２はサンプル数ｎ＝２でその平均値を示した。実験Ｎｏ．３〜７はいずれも実施の形態に係る３層成膜の場合であり、超音波探傷結果は１００％で、全く傷が無い状態を示している。なお、実験Ｎｏ．７はサンプル数ｎ＝６でその平均値を示した。この実施の形態のように３層の金属層（Ｃｒ，Ｃｕ，Ａｇ）を設けることで、極めて良好なろう付けによる接合が得られることがわかる。
【００２９】
この実施の形態によれば、次の通りの効果を得ることができる。
【００３０】
(1) バッキングプレート１０がＣｕ又はＣｕ合金材であるために、ターゲット材としてのＳｉ板１の接合面への主成膜材をＣｕとした。Ｃｕ対Ｃｕにすることにより、接合が容易で、強固な接合強度が得られる。
【００３１】
(2) Ｃｕの食われを想定して、Ｃｕ膜３の下地にＣｒ膜２を成膜している。Ｃｒはろう材２０としてのＩｎとの合金を作りにくく、薄いＣｒ膜でもＳｉがＩｎと直接接触することはなくなり、ＳｉがＩｎと直接接することになって接合強度の大幅低下を招くことを防止できる。
【００３２】
(3) Ｃｕは酸化し易く、酸化銅を作るが、Ｃｕ膜３上にＡｇ膜４を成膜することで、Ｃｕ膜３の酸化を防ぐことができ、ろう付けによる接合を容易にすることができる。Ａｇは容易にＩｎと合金を作るため、Ａｇ膜４の存在はＩｎによるろう付けを一層容易、かつ確実にすることができる。
【００３３】
(4) 図２に示すように、線膨張係数は、Ｓｉ＜Ｃｒ＜Ｃｕ＜Ａｇ＜ＩｎのようにＳｉからＩｎに向けて徐々に大きくなる関係となり、ＳｉとＩｎ間にＣｒ，Ｃｕ，Ａｇが介在することで、ＳｉとＩｎとの線膨張係数の差を緩和できる。これによってもＣｒ，Ｃｕ，Ａｇの３層成膜構造がＳｉとＩｎの中間材として適しているのがわかる。
【００３４】
(5) ろう材２０としてＩｎを用いて接合のための濡らし作業、つまりＳｉ板１の接合面とバッキングプレート１０の接合面にろう材２０を付着させる作業を行う場合、超音波振動子内蔵はんだ鏝３５で超音波振動をろう材２０に加えながら実行することで、フラックスを使用しないようにできる。これによりフラックス使用に伴う不都合、例えばフラックスが残留して、ターゲットとして使用時に蒸発すること等を回避できる。
【００３５】
(6) ろう付け時にバッキングプレート１０とＳｉ板１とを重ね合わせた構造体を加圧する重り４０として、予め１００〜２００℃に昇温したものを用いることで、ターゲット材とバッキングプレート１０の冷却速度を緩やかとしてろう付けによる接合の信頼性をいっそう向上させることができる。なお、重り４０が常温では、急冷となり、接合に際してろう材に傷が発生する危険性が出てくる。
【００３６】
なお、前述の実施の形態では、非金属のターゲット材としてＳｉを例示したが、Ｓｉ以外のセラミック材等にも本発明は適用できる。また、ろう材はＩｎとしたが、Ｉｎを主体としたＩｎ合金であっても差し支えない。さらに、Ｃｒ膜、Ｃｕ膜、Ａｇ膜をスパッタリングで設けたが、スパッタリング以外の蒸着、イオンプレーティング、プラズマＣＶＤ等の真空乃至気相中での薄膜技術で成膜することも可能である。
【００３７】
以上本発明の実施の形態について説明してきたが、本発明はこれに限定されることなく請求項の記載の範囲内において各種の変形、変更が可能なことは当業者には自明であろう。
【００３８】
【発明の効果】
以上説明したように、本発明によれば、非金属のターゲット材の接合面に形成する金属層の構造を工夫することで、ターゲット材とバッキングプレート間のろう付けの接合強度を向上させることが可能である。
【００３９】
また、製造過程において、ターゲット材側及びバッキングプレート側にろう材付着させる工程を、超音波振動子内蔵はんだ鏝で超音波振動をろう材に加えながら行うようにすれば、フラックスを使用しないろう付け処理とすることができ、フラックス使用に伴う不都合を除去できる。
【図面の簡単な説明】
【図１】本発明に係るスパッタリング用ターゲット及びその製造方法の実施の形態を工程順に示す説明図である。
【図２】ターゲット材とろう材、及びそれらの間に介在する金属層の線膨張係数を示す説明図である。
【符号の説明】
１ Ｓｉ板
２ Ｃｒ膜
３ Ｃｕ膜
４ Ａｇ膜
１０ バッキングプレート
２０ ろう材
３０ ホットプレート
３５ 超音波振動子内蔵はんだ鏝
４０ 重り[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sputtering target in which a non-metallic target material such as Si is bonded to a backing plate made of Cu or Cu alloy, and in particular, a sputtering target having improved bonding strength between the non-metallic target material and the backing plate. And a manufacturing method thereof.
[0002]
[Prior art]
In general, a sputtering target is configured by joining a target material and a backing plate such as a Cu material for cooling and energization. When the target material is a non-metal such as Si, it is difficult to directly braze (or solder) the non-metal. Therefore, it has been proposed to form a metal film on the non-metal bonding surface. For example, Japanese Patent Application Laid-Open No. 7-48667 proposes forming a thin film of any one of Cu, Ni, and Cu—Ni alloy on the joint surface of the target material.
[0003]
[Problems to be solved by the invention]
By the way, the metal film to be formed on the joint surface of the non-metallic target material is selected according to the brazing material to be used, but when using a brazing material of In or In alloy, Cu of the same material as the backing plate is used as the metal film. As a result, the Cu film is eroded by the brazing material of In or In alloy at the time of brazing (Cu is taken into In and becomes an alloy), and the brazing material is in direct contact with the target material, thereby joining strength. There is a problem of significantly lowering.
[0004]
Further, since the Cu film is easily oxidized, it is difficult to braze to the backing plate without using the flux together. However, the use of the flux causes a problem when the flux remains on the target.
[0005]
Thus, how to make the surface of the non-metallic target material ready for brazing with high bonding strength is an important issue in target fabrication.
[0006]
In view of the above points, the first object of the present invention is to improve the brazing joint strength between the target material and the backing plate by devising the structure of the metal layer formed on the joint surface of the non-metallic target material. It is providing the target for sputtering and its manufacturing method.
[0007]
A second object of the present invention is to provide a sputtering target that can be brazed without using a flux and eliminate the disadvantages associated with the use of the flux, and a method for manufacturing the same.
[0008]
Other objects and novel features of the present invention will be clarified in embodiments described later.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 of the present application is a sputtering target obtained by bonding a nonmetallic target material to a backing plate made of Cu or Cu alloy with a brazing material of In or In alloy.
A Cr film is formed as a base metal layer on the bonding surface of the target material, and a Cu film is formed as an upper metal layer laminated on the base metal layer, and the brazing material is interposed between the Cu film and the backing plate. It is bonded, and Ag is contained in the bonded portion between the Cu film and the brazing material .
[0011]
The invention of claim 2 of the present application is a method for producing a sputtering target in which a nonmetallic target material is joined to a Cu or Cu alloy backing plate by brazing using a brazing material of In or In alloy.
After sequentially forming a Cr film as a base metal layer on the bonding surface of the target material, a Cu film as an upper metal layer laminated on the base metal layer, and an Ag film as an antioxidant film covering the Cu film, the Ag film is formed. The brazing material is adhered on the film and the backing plate, and the target material and the backing plate are overlapped and joined in a heated state.
[0012]
The invention of claim 3 of the present application is that, in claim 2 , the Cr film, the Cu film and the Ag film are sequentially formed by a thin film technique in vacuum or gas phase, such as vapor deposition, sputtering, ion plating, plasma CVD. It is characterized by.
[0013]
The invention of claim 4 of the present application is characterized in that, in claim 2 or 3 , the film thickness of the Cu film is 1 to 5 μm, and the Cr film and the Ag film are less than or equal to the film thickness of the Cu film. .
[0014]
The invention of claim 5 of the present application is the soldering material according to claim 2, 3 or 4 , wherein the step of adhering the brazing material on the Ag film and on the backing plate It is characterized by performing without using flux while adding to the above.
[0015]
The invention of claim 6 of the present application is the method of claim 2, 3, 4 or 5 , wherein the step of superposing and joining the target material and the backing plate is performed on a hot plate that has been heated, and the temperature is increased in advance after joining. It is characterized by slowly cooling while placing a heated weight on it and applying pressure.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a sputtering target and a method for producing the same according to the present invention will be described below with reference to the drawings.
[0017]
1A to 1D, an embodiment of the present invention will be described by taking as an example the case of producing a sputtering Si target.
[0018]
First, as shown in FIG. 1A, a Cr film 2 as a base metal layer is formed on a bonding surface of a Si plate 1 as a target material to a backing plate (Cu or Cu alloy plate for cooling and energization). A Cu film 3 is formed as an upper metal layer stacked on the metal layer, and an Ag film 4 is sequentially formed by sputtering as an antioxidant film covering the Cu film.
[0019]
Here, since the backing plate 10 shown in FIGS. 1B and 1C is Cu or an alloy material thereof, the main film forming material on the bonding surface of the Si plate 1 is Cu.
[0020]
If the thickness of the Cu film 3 is less than 1 μm, most of the deposited Cu material is eroded by In (ie, an alloy of In and Cu) when the In brazing material 20 is wetted. If it exceeds 5 μm, it takes time to form a film, which is disadvantageous in terms of cost. Therefore, the film thickness of the Cu film 3 is set to 1 to 5 μm.
[0021]
Further, assuming that the Cu film 3 as the main film forming material is eaten, the Cr film 2 is formed on the base of the Cu film. Cr is difficult to make an alloy with In as a brazing material (although not made at all), and the Si plate 1 is not in direct contact with In even with a thin Cr film. Note that when the In brazing material is in direct contact with the Si plate 1, the brazing joint strength is significantly reduced. The film thickness of the Cr film 2 may be equal to or less than the film thickness of the Cu film 3 and is about 0.3 μm to 2 μm. If the film thickness is less than 0.3 μm, there is a risk that a part of the film thickness becomes zero due to variations during film formation. If it exceeds 2 μm, it takes time to form the film, which is disadvantageous in terms of cost. .
[0022]
Furthermore, when the main film forming material is Cu, Cu is easily oxidized and copper oxide is produced. Copper oxide is said to be a difficult material to handle. It is not suitable for brazing because it is brittle. Further, since gas is generated, there is a possibility that the wall surface of the vacuum chamber for film formation and the substrate surface of the film formation partner will be soiled when used as a target. Therefore, in order to prevent oxidation of the Cu film 3, the Ag film 4 is formed immediately after the Cu film formation. The Ag film 4 may be thin as long as it is uniform. The film thickness of the Ag film 4 may be equal to or less than the film thickness of the Cu film 3 and is about 0.1 μm to 2 μm. If the film thickness is less than 0.1 μm, there may be a risk that a part of the film thickness becomes zero due to variations during film formation. If it exceeds 2 μm, it takes time to form the film, which is disadvantageous in terms of cost. . Ag easily forms an alloy with In, which is said to be suitable as a brazing material.
[0023]
It is preferable that the Cr film 2, the Cu film 3 thereon, and the Ag film 4 thereon are sequentially formed by sputtering in the same film formation chamber in order to prevent generation of useless oxides.
[0024]
When a multilayer metal layer 5 of a Cr film, a Cu film, and an Ag film is formed on the bonding surface of the Si plate 1 as a target material as shown in FIG. 1A, a hot plate ( The Si plate 1 is placed on the electric surface 30) with the bonding surface facing upward, and the backing plate 10 of the Cu or Cu alloy plate is also placed with the bonding surface facing upward, and the hot plate 30 is heated to 180 to 250 ° C. The temperature is raised, and the Si plate 1 and the backing plate 10 are heated and heated. In this state, the wetting operation for bonding using In as the brazing material 20, that is, the operation of attaching the brazing material 20 to the bonding surface of the Si plate 1 and the bonding surface of the backing plate 10, In step 35, ultrasonic vibration is applied to the brazing material 20 without using flux.
[0025]
After completion of the wetting operation of the brazing filler metal 20 in FIG. 1B, while continuing heating and raising the temperature on the hot plate 30, the bonding surface (In wetting surface) of the backing plate 10 and Si as shown in FIG. The bonding surface (In wetting surface) of the plate 1 is opposed and brought into close contact with each other to form a structure in which the backing plate 10 and the Si plate 1 are overlapped, and a weight 40 of 400 to 2000 g is placed thereon. At this time, the weight 40 that has been heated to 100 to 200 ° C. in advance is used. After placing the weight 40, the hot plate 30 is turned off and gradually cooled on the hot plate (slowly cooled by natural cooling). Thereby, the sputtering target in which the Si plate 1 as the target material and the backing plate 10 are joined and integrated with the In brazing material 20 as shown in FIG. 1D is completed. After bonding, since the Ag film 4 is a thin film, it dissolves in the In brazing material 20 and does not remain as a film, but Ag is contained in the joint between the Cu film 3 and the brazing material 20. Thus, it can be confirmed that the Ag film 4 was present before bonding.
[0026]
FIG. 2 shows the linear expansion coefficients of Si, Cr, Cu, Ag, and In. The linear expansion coefficient gradually increases from Si to In as Si <Cr <Cu <Ag <In, and the target material Si is assumed to be interposed by the presence of Cr, Cu, and Ag metal layers. The difference in coefficient of linear expansion from the material In can be relaxed. This also shows that the three-layer structure of Cr, Cu, and Ag is suitable as an intermediate material between Si and In.
[0027]
Table 1 below shows the bonding experiment results of the three-layer film formation and the Cu-Ag two-layer film formation.
[0028]
[Table 1]

Here, an ultrasonic flaw detector was used for the measurement. Experiment No. Reference numerals 1 and 2 are cases in which the Cr film 2 of the base metal layer is omitted, and the ultrasonic flaw detection results are 90% and 87%, indicating that there is a part of insufficient bonding. Experiment No. 2 was the number of samples n = 2 and the average value was shown. Experiment No. 3 to 7 are all cases of the three-layer film formation according to the embodiment, and the ultrasonic flaw detection result is 100%, indicating that there is no scratch. Experiment No. 7 is the number of samples n = 6 and the average value is shown. It can be seen that by providing three metal layers (Cr, Cu, Ag) as in this embodiment, it is possible to obtain extremely good joining by brazing.
[0029]
According to this embodiment, the following effects can be obtained.
[0030]
(1) Since the backing plate 10 is made of Cu or a Cu alloy material, the main film forming material on the bonding surface of the Si plate 1 as the target material is made of Cu. By using Cu vs. Cu, bonding is easy and strong bonding strength can be obtained.
[0031]
(2) The Cr film 2 is formed on the base of the Cu film 3 on the assumption of Cu bite. Cr is difficult to form an alloy with In as the brazing material 20, and even in a thin Cr film, Si is not in direct contact with In and prevents Si from being in direct contact with In and causing a significant decrease in bonding strength. it can.
[0032]
(3) Cu is easy to oxidize and makes copper oxide. By forming the Ag film 4 on the Cu film 3, the Cu film 3 can be prevented from being oxidized, and bonding by brazing is facilitated. Can do. Since Ag easily forms an alloy with In, the presence of the Ag film 4 can make brazing with In easier and more reliable.
[0033]
(4) As shown in FIG. 2, the linear expansion coefficient gradually increases from Si to In as Si <Cr <Cu <Ag <In, and Cr, Cu, Ag between Si and In By interposing, the difference in linear expansion coefficient between Si and In can be relaxed. This also shows that the three-layer structure of Cr, Cu, and Ag is suitable as an intermediate material between Si and In.
[0034]
(5) When performing a wetting operation for bonding using In as the brazing material 20, that is, an operation for attaching the brazing material 20 to the bonding surface of the Si plate 1 and the bonding surface of the backing plate 10, the solder built in the ultrasonic vibrator By performing the ultrasonic vibration while applying the ultrasonic vibration to the brazing material 20 with the rod 35, it is possible to prevent the flux from being used. As a result, it is possible to avoid inconvenience associated with the use of the flux, for example, the flux remaining and evaporating during use as a target.
[0035]
(6) Cooling of the target material and the backing plate 10 by using a weight 40 that has been heated to 100 to 200 ° C. in advance as the weight 40 that pressurizes the structure in which the backing plate 10 and the Si plate 1 are superposed at the time of brazing. The reliability of joining by brazing can be further improved by reducing the speed. In addition, when the weight 40 is normal temperature, it will be rapidly cooled, and there is a risk that the brazing material may be damaged during joining.
[0036]
In the above-described embodiment, Si is exemplified as the non-metallic target material, but the present invention can also be applied to ceramic materials other than Si. In addition, although the brazing material is In, an In alloy mainly containing In may be used. Furthermore, although the Cr film, the Cu film, and the Ag film are provided by sputtering, it is also possible to form the film by a thin film technique in a vacuum or gas phase such as vapor deposition other than sputtering, ion plating, or plasma CVD.
[0037]
Although the embodiments of the present invention have been described above, it will be obvious to those skilled in the art that the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the claims.
[0038]
【The invention's effect】
As described above, according to the present invention, it is possible to improve the bonding strength of brazing between the target material and the backing plate by devising the structure of the metal layer formed on the bonding surface of the nonmetallic target material. Is possible.
[0039]
Also, in the manufacturing process, if the process of attaching the brazing material to the target material side and the backing plate side is performed while applying ultrasonic vibration to the brazing material with a soldering iron with a built-in ultrasonic vibrator, brazing without using flux. It is possible to remove the inconvenience associated with the use of flux.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing an embodiment of a sputtering target and a method for producing the same according to the present invention in the order of steps.
FIG. 2 is an explanatory diagram showing a linear expansion coefficient of a target material, a brazing material, and a metal layer interposed therebetween.
[Explanation of symbols]
1 Si plate 2 Cr film 3 Cu film 4 Ag film 10 Backing plate 20 Brazing material 30 Hot plate 35 Solder rod 40 with built-in ultrasonic vibrator Weight

Claims (6)

In a sputtering target formed by joining a nonmetallic target material to a backing plate made of Cu or Cu alloy with a brazing material of In or In alloy,
A Cr film is formed as a base metal layer on the bonding surface of the target material, and a Cu film is formed as an upper metal layer laminated on the base metal layer, and the brazing material is interposed between the Cu film and the backing plate. A sputtering target characterized in that Ag is contained in a bonded portion between the Cu film and the brazing material . In a method for producing a sputtering target in which a nonmetallic target material is joined to a Cu or Cu alloy backing plate by brazing using a brazing material of In or In alloy,
After sequentially forming a Cr film as a base metal layer on the bonding surface of the target material, a Cu film as an upper metal layer laminated on the base metal layer, and an Ag film as an antioxidant film covering the Cu film, the Ag film is formed. A method for producing a sputtering target, comprising: attaching the brazing material on a film and the backing plate, and superposing and bonding the target material and the backing plate in a heated state. 3. The method for producing a sputtering target according to claim 2 , wherein the Cr film, the Cu film, and the Ag film are sequentially formed by a thin film technique in a vacuum or gas phase such as vapor deposition, sputtering, ion plating, and plasma CVD. 4. The method for manufacturing a sputtering target according to claim 2, wherein the Cu film has a thickness of 1 to 5 μm, and the Cr film and the Ag film have a thickness equal to or less than the Cu film. Depositing the brazing material to the Ag film and the backing plate is claimed in claim 2, 3 or 4, executed without using a flux while applying ultrasonic vibration to the brazing material in the ultrasonic transducer built soldering iron The manufacturing method of the sputtering target of description. Wherein the step of the target material by superposing the backing plate bonded to the claim performed at warmed on a hot plate, gradually cooling under pressure put a previously heated the weight after bonding 2,3,4 Or the manufacturing method of the sputtering target of 5 .

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