JP2005223229A - Bonding method, manufacturing method of semiconductor apparatus using the same, and semiconductor apparatus - Google Patents

Bonding method, manufacturing method of semiconductor apparatus using the same, and semiconductor apparatus Download PDF

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JP2005223229A
JP2005223229A JP2004031519A JP2004031519A JP2005223229A JP 2005223229 A JP2005223229 A JP 2005223229A JP 2004031519 A JP2004031519 A JP 2004031519A JP 2004031519 A JP2004031519 A JP 2004031519A JP 2005223229 A JP2005223229 A JP 2005223229A
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metal material
fine particles
bonding
semiconductor element
metal members
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Katsuhiko Yoshihara
克彦 吉原
Yoshinari Ikeda
良成 池田
Mitsuo Yamashita
満男 山下
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Fuji Electric Co Ltd
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Fuji Electric Holdings Ltd
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    • H—ELECTRICITY
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    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L24/34—Strap connectors, e.g. copper straps for grounding power devices; Manufacturing methods related thereto
    • H01L24/39—Structure, shape, material or disposition of the strap connectors after the connecting process
    • H01L24/40—Structure, shape, material or disposition of the strap connectors after the connecting process of an individual strap connector
    • H—ELECTRICITY
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    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/34—Strap connectors, e.g. copper straps for grounding power devices; Manufacturing methods related thereto
    • H01L2224/39—Structure, shape, material or disposition of the strap connectors after the connecting process
    • H01L2224/40—Structure, shape, material or disposition of the strap connectors after the connecting process of an individual strap connector
    • H—ELECTRICITY
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    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/44—Structure, shape, material or disposition of the wire connectors prior to the connecting process
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    • H01L2924/30105—Capacitance

Abstract

<P>PROBLEM TO BE SOLVED: To exclude the oxide films formed on the surfaces of metal materials when bonding the metal materials to each other, without using such a large-sized equipment as a reduction furnace in the ultrasonic bonding of metals. <P>SOLUTION: Micro-grains 4 are so interposed between the bonding surfaces of two metal members (1, 2), and ultrasonic vibrations are so applied to at least one of the metal members as to bond the metal members to each other. As the micro-grains, there are used the ones whose grain sizes are not smaller than the larger thickness of the thicknesses of the natural oxide films formed on the bonding surfaces of the two metal members. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

この発明は、半導体装置などで使用されるリードフレームを超音波接合する方法に関する。   The present invention relates to a method for ultrasonic bonding a lead frame used in a semiconductor device or the like.

近年、電力変換装置の小型化・高密度化が進んできている。電力変換装置のパッケージ内部の配線，パッケージ構造，放熱方法などの改良によって電力変換装置の小型化・高密度化が図られている。パッケージ内部の配線方法においては、半導体素子，絶縁基板上の配線パターン，外部導出端子などを接続する際にアルミワイヤーによるワイヤーボンディング方法で行われていたものを、金属導体板による接合方法を導入されている。これによって配線スペースが縮小するなど、電力変換装置の小型化・高密度化が図られている。
金属導体板の接合にははんだによる接合（はんだ接合）や超音波接合がある。
図２は、従来の超音波接合方法の工程を示す図である。同図（ａ）は超音波接合前の材料の状態を示したものである。１は固定側金属材料、２は可動側金属材料である。図３は電力変換装置を構成する半導体装置１０の要部を示す図であって、固定側金属材料１は、半導体装置１０において、半導体素子１１の電極パッド部や、絶縁基板１３上の回路パターン１１などに相当し、同様に、可動側金属材料２は、半導体素子１１，絶縁基板上の配線パターン１１，外部導出端子（図示せず）などを相互に接続する金属導体板（リードフレームなど）１２に相当する。図３において、１４は絶縁基板１３の裏面に設けられた導体パターン、１５は絶縁基板を固定する放熱ベースである。 In recent years, power converters have been reduced in size and density. The power converter has been reduced in size and density by improving the wiring inside the package of the power converter, the package structure, and the heat dissipation method. In the wiring method inside the package, the bonding method using the metal conductor plate was introduced instead of the wire bonding method using the aluminum wire when connecting the semiconductor element, the wiring pattern on the insulating substrate, the external lead-out terminal, etc. ing. As a result, the power conversion device is reduced in size and density, for example, the wiring space is reduced.
The metal conductor plates can be joined by soldering (soldering) or ultrasonic joining.
FIG. 2 is a diagram showing the steps of a conventional ultrasonic bonding method. FIG. 4A shows the state of the material before ultrasonic bonding. 1 is a fixed-side metal material, and 2 is a movable-side metal material. FIG. 3 is a diagram showing a main part of the semiconductor device 10 constituting the power conversion device. The fixed-side metal material 1 is a circuit pattern on the electrode pad portion of the semiconductor element 11 and the insulating substrate 13 in the semiconductor device 10. Similarly, the movable-side metal material 2 is a metal conductor plate (such as a lead frame) that interconnects the semiconductor element 11, the wiring pattern 11 on the insulating substrate, the external lead-out terminal (not shown), and the like. This corresponds to 12. In FIG. 3, 14 is a conductor pattern provided on the back surface of the insulating substrate 13, and 15 is a heat dissipation base for fixing the insulating substrate.

固定側金属材料１及び可動側金属材料２の表面にはそれぞれ薄い酸化膜３（自然酸化膜）が形成されている。通常、この酸化膜３の厚さは数ｎｍ〜十数ｎｍである。
同図（ｂ）は超音波接合時の材料の状態を示したものである。固定側金属材料１の上面に可動側金属材料２を所定加圧力で押し当て、可動側金属材料２に超音波振動を印加し、固定側金属材料１と可動側金属材料２とを図1（ｂ）に矢印で示すように左右（あるいは紙面に対して前後）に相対変位させる。同図（ｃ）は接合後の状態を示したものであり、固定側金属材料１と可動側金属材料２との間にそれぞれの材料表面に形成されていた酸化膜３が残存している状態である。
同図（ｄ）は接合後の状態を示したものであるが、同図（ｃ）よりも酸化膜３が薄くなっている。これは、超音波接合の際に、金属材料表面の酸化膜が金属材料同士の摺動により破壊され、金属材料の新生面が現れ、金属間の界面でお互いの結晶が結びつき、凝着、相互拡散、再結晶することで強固な接合となっているためである。 Thin oxide films 3 (natural oxide films) are formed on the surfaces of the fixed metal material 1 and the movable metal material 2, respectively. Usually, the thickness of the oxide film 3 is several nm to several tens of nm.
FIG. 5B shows the state of the material during ultrasonic bonding. The movable metal material 2 is pressed against the upper surface of the fixed metal material 1 with a predetermined pressure, and ultrasonic vibration is applied to the movable metal material 2 so that the fixed metal material 1 and the movable metal material 2 are shown in FIG. As shown by arrows in b), they are displaced relative to the left and right (or back and forth with respect to the paper surface). FIG. 4C shows a state after bonding, in which the oxide film 3 formed on the surface of each material remains between the fixed-side metal material 1 and the movable-side metal material 2. It is.
FIG. 4D shows a state after bonding, but the oxide film 3 is thinner than that in FIG. This is because, during ultrasonic bonding, the oxide film on the surface of the metal material is destroyed by the sliding of the metal material, a new surface of the metal material appears, and the crystals of each other are bonded at the interface between the metals, and adhesion and interdiffusion occur. This is because of strong bonding by recrystallization.

図２の（ｃ），（ｄ）で示した従来の超音波接合方法の接合後の状態では、金属材料表面に形成された酸化膜３の破壊が不充分であり、を固定側金属材料１と可動側金属材料２の境界に依然として酸化膜３が残存しており、強固な接合が得られず信頼性上問題となる。
ここで、電子部品の電極表面に形成された自然酸化膜を破壊する方法として、異方性導電膜を用いて電子部品を接続する方法が知られている。異方性導電膜の貫通孔部に突起電極構造の導電部を形成し、導電部（金）内にアルミナの粒子を含有させる。この異方性導電膜を電子部品間に介在させて圧着し超音波を印加することによって酸化膜の破壊を行っている（特許文献１参照）。
特開平5-47428号公報（要約など） In the state after bonding by the conventional ultrasonic bonding method shown in FIGS. 2C and 2D, the oxide film 3 formed on the surface of the metal material is insufficiently broken, and the fixed-side metal material 1 The oxide film 3 still remains on the boundary between the movable metal material 2 and a strong joint cannot be obtained, which causes a problem in reliability.
Here, as a method of destroying the natural oxide film formed on the electrode surface of the electronic component, a method of connecting the electronic component using an anisotropic conductive film is known. A conductive portion having a protruding electrode structure is formed in the through hole portion of the anisotropic conductive film, and alumina particles are contained in the conductive portion (gold). The anisotropic conductive film is interposed between electronic components and pressed to apply an ultrasonic wave to destroy the oxide film (see Patent Document 1).
Japanese Patent Laid-Open No. 5-47428 (summary)

金属の超音波接合においては、上述のように金属材料表面に形成された酸化膜３を接合時にどう排除するかが技術ポイントとなる。
この酸化膜３を排除する方法として、上記特許文献１に記載の方法があるが、電力変換装置等に適用するパワー半導体装置の接続に、異方性導電膜を用いたのでは、電気抵抗が大きく損失が大きくなってしまう他、熱抵抗が大きくなって十分な放熱ができないこと、所望のヒートサイクル特性が得られないなどの問題がある。
これに対して、金属導体板を用いて前記パワー半導体装置を接続すれば、上記特許文献１に記載の方法の問題点（損失，熱抵抗，対ヒートサイクル）がある程度改善されるものの、依然として、接合界面に残留する酸化膜の影響を受けて、所望の特性を得ることができない。 In the metal ultrasonic bonding, the technical point is how to eliminate the oxide film 3 formed on the surface of the metal material as described above at the time of bonding.
As a method for eliminating the oxide film 3, there is a method described in Patent Document 1 described above. However, if an anisotropic conductive film is used for connection of a power semiconductor device applied to a power conversion device or the like, the electrical resistance is reduced. In addition to a large loss, there is a problem that the heat resistance becomes large and sufficient heat dissipation cannot be performed, and desired heat cycle characteristics cannot be obtained.
On the other hand, if the power semiconductor device is connected using a metal conductor plate, the problems (loss, thermal resistance, heat cycle) of the method described in Patent Document 1 are improved to some extent, The desired characteristics cannot be obtained under the influence of the oxide film remaining at the bonding interface.

上記従来例における固定側金属材料１と可動側金属材料２を、水素雰囲気中で還元し、金属の新生面を露出させた状態で超音波接合を行えば、残留する酸化膜を除去することができるが、これにも次の２つの問題が生ずる。１つは、水素雰囲気中で酸化膜３を還元により除去した金属材料を、還元炉より大気中に取り出すと、超音波接合するまでに、また新たに吸着などにより酸化膜が形成されてしまう点である。２つめには、酸化還元された金属材料を空気中に取り出さず、そのまま還元炉の中で超音波接合する場合には、装置規模が大きくなり、設備費用が増大してしまう点である。
この発明は、前記のような従来の超音波接合方法の問題点に鑑みてなされたものであって、良好な超音波接合を得ることを課題とすものである。 If the fixed-side metal material 1 and the movable-side metal material 2 in the conventional example are reduced in a hydrogen atmosphere and ultrasonic bonding is performed with the new metal surface exposed, the remaining oxide film can be removed. However, this also has the following two problems. One is that if a metal material from which the oxide film 3 has been removed by reduction in a hydrogen atmosphere is taken out from the reduction furnace to the atmosphere, an oxide film is newly formed by ultrasonic adsorption or the like before ultrasonic bonding. It is. Secondly, when the oxidized and reduced metal material is not taken out into the air and is ultrasonically bonded in a reduction furnace as it is, the scale of the apparatus increases and the equipment cost increases.
The present invention has been made in view of the problems of the conventional ultrasonic bonding methods as described above, and it is an object of the present invention to obtain good ultrasonic bonding.

上記の課題を解決するため、この発明は、２つの金属部材の接合表面に微粒子を介装し、前記金属部材の少なくとも一方に超音波振動を印加して、前記２つの金属部材を接合するものとする。
前記微粒子には、前記２つの金属部材の接合表面に形成される自然酸化膜のうち、厚い方の酸化膜厚以上の粒径を有するものや、前記２つの金属部材の硬度以上の硬度を有するものを用いるのが好適であって、前記微粒子には無機材料を適用しても良い。
さらに、前記２つの金属部材のうち、一方を半導体素子の電極パッドもしくは該半導体素子が搭載された基板上の回路パターンとし、他方を前記半導体素子の電極パッドもしくは該半導体素子が搭載された基板上の回路パターンを接続する金属導体として、両者を上記の接合方法によって接合することによって半導体装置の製造するとよい。 In order to solve the above-mentioned problems, the present invention joins the two metal members by interposing fine particles on the joining surfaces of the two metal members and applying ultrasonic vibration to at least one of the metal members. And
Of the natural oxide film formed on the bonding surface of the two metal members, the fine particles have a particle diameter equal to or greater than the thicker oxide film thickness, and have a hardness equal to or greater than the hardness of the two metal members. It is preferable to use one, and an inorganic material may be applied to the fine particles.
Further, one of the two metal members is a circuit pattern on the electrode pad of the semiconductor element or the substrate on which the semiconductor element is mounted, and the other is on the substrate on which the electrode pad of the semiconductor element or the semiconductor element is mounted. As a metal conductor for connecting the circuit pattern, a semiconductor device may be manufactured by bonding the two by the above bonding method.

２つの金属部材間を超音波接合する際に、酸化膜を積極的に破壊し金属表面同士を摺動させるため、凝着部の増大にともなう充分な接合強度を得ることが可能となる。このことにより接合前に厚い酸化膜が形成されていても充分な接合強度が得られる。
また、半導体装置の製造に適用することにより、高い接合信頼性を有した半導体装置が得られ、この半導体装置を用いた電力変換装置の信頼性を向上させることができる。
水素などによる還元炉といった大掛かりな設備が不要となり、大気中でも信頼性の高い超音波接合を行うことができる。 When ultrasonic bonding is performed between two metal members, the oxide film is actively destroyed and the metal surfaces are slid to each other, so that it is possible to obtain a sufficient bonding strength with an increase in adhesion. As a result, sufficient bonding strength can be obtained even if a thick oxide film is formed before bonding.
Moreover, by applying to the manufacture of a semiconductor device, a semiconductor device having high junction reliability can be obtained, and the reliability of a power conversion device using this semiconductor device can be improved.
Large equipment such as a hydrogen reduction furnace is not required, and highly reliable ultrasonic bonding can be performed even in the atmosphere.

以下にこの発明を、図に示す実施例に基づいて説明する。   The present invention will be described below based on the embodiments shown in the drawings.

図１はこの発明の実施例を示すものである。同図（ａ）は超音波接合前の金属材料の状態を示し、固定側金属材料１及び可動側金属材料２の表面に酸化膜３が形成されている。
以下において、固定側金属材料１及び可動側金属材料２の材質が共に銅である場合を例にとって説明する。
同図（ａ）は超音波接合前の材料の状態を示したものである。まず、同図（ａ）に示すように、固定側金属材料１の表面に、銅からなる微粒子４を散布する。
次に、 同図（ｂ）は超音波接合時の材料の状態を示したものである。固定側金属材料１の上面に可動側金属材料２を所定加圧力で押し当て、可動側金属材料２に超音波振動を印加し、固定側金属材料１と可動側金属材料２とを図1（ｂ）に矢印で示すように左右（あるいは紙面に対して前後）に相対変位させる。 FIG. 1 shows an embodiment of the present invention. FIG. 2A shows the state of the metal material before ultrasonic bonding, and an oxide film 3 is formed on the surfaces of the fixed side metal material 1 and the movable side metal material 2.
In the following, description will be given by taking as an example a case where both the fixed-side metal material 1 and the movable-side metal material 2 are copper.
FIG. 4A shows the state of the material before ultrasonic bonding. First, as shown in FIG. 2A, fine particles 4 made of copper are dispersed on the surface of the fixed metal material 1.
Next, FIG. 5B shows the state of the material during ultrasonic bonding. The movable metal material 2 is pressed against the upper surface of the fixed metal material 1 with a predetermined pressure, and ultrasonic vibration is applied to the movable metal material 2 so that the fixed metal material 1 and the movable metal material 2 are shown in FIG. As shown by arrows in b), they are displaced relative to the left and right (or back and forth with respect to the paper surface).

可動側金属材料２を図示しない加圧機構により固定側金属材料１に押し当てた状態で超音波振動を与える。加圧力は0.08Ｎ/ｍｍ２〜2.5Ｎ/ｍｍ２，超音波周波数は10〜30ｋＨｚの範囲で強固な接合を得るに適切な条件とする。このようにして銅微粒子４を固定側金属材料１と可動側金属材料２の間に挟みこみ、加圧力及び超音波振動を負荷すると、銅微粒子４により固定側金属材料１及び可動側金属材料２表面に形成された酸化膜３が破られ、酸化膜３が破られた部分から金属の新生面が露出する。
これらの作業は大気中で行うが、固定側金属材料１と可動側金属材料２は加圧機構により加圧され、密着状態にあるので、超音波振動により新生面が露出しても直ちに酸化されることがない。
図１（ｃ）は接合後の状態を示すものであり、固定側金属材料１と可動側金属材料２間に挿入された銅微粒子４は、固定側金属材料１と可動側金属材料２との界面に残存している。同図（ｄ）は接合後の状態の別の例を示すものであり、銅微粒子４がそれぞれの金属材料に溶け込んでいる。これは、超音波接合における金属材料の摺動面が状況によっては数百度付近に上昇し、固定側金属材料１及び可動側金属材料２と4銅微粒子が原子間距離まで近接し、前述した金属学的結合を形成するためである。この金属学的結合は金属の融点の1/3付近、あるいはそれ以下の温度でも形成され得る。銅の場合、融点は1083℃であるので金属学的結合は360℃付近となる。同図（ｃ）（ｄ）のいずれの状態であっても、両金属資料の接合面の酸化膜を破り強固な接合を得ることできる。 Ultrasonic vibration is applied in a state where the movable metal material 2 is pressed against the fixed metal material 1 by a pressure mechanism (not shown). Pressure is 0.08N / mm 2 ~2.5N / mm 2 , the ultrasonic frequency is set to appropriate conditions to obtain a strong bonding in the range of 10～30KHz. When the copper fine particles 4 are sandwiched between the fixed metal material 1 and the movable metal material 2 in this way and a pressure force and ultrasonic vibration are applied, the fixed metal material 1 and the movable metal material 2 are applied by the copper fine particles 4. The oxide film 3 formed on the surface is broken, and a new metal surface is exposed from the portion where the oxide film 3 is broken.
Although these operations are performed in the atmosphere, the fixed-side metal material 1 and the movable-side metal material 2 are pressurized by the pressurizing mechanism and are in a close contact state, so that they are immediately oxidized even if the new surface is exposed by ultrasonic vibration. There is nothing.
FIG. 1C shows a state after joining. The copper fine particles 4 inserted between the fixed-side metal material 1 and the movable-side metal material 2 are formed between the fixed-side metal material 1 and the movable-side metal material 2. It remains at the interface. FIG. 4D shows another example of the state after joining, in which the copper fine particles 4 are dissolved in the respective metal materials. This is because the sliding surface of the metal material in ultrasonic bonding rises to several hundred degrees depending on the situation, and the fixed side metal material 1 and the movable side metal material 2 and the 4 copper fine particles are close to the interatomic distance. This is to form a chemical bond. This metallurgical bond can be formed at temperatures near 1/3 of the melting point of the metal or lower. In the case of copper, the melting point is 1083 ° C, so the metallurgical bond is around 360 ° C. In any of the states shown in FIGS. 3C and 3D, the oxide film on the joint surface of both metal materials can be broken to obtain a strong joint.

本実施例のように、固定側金属材料１及び可動側金属材料２と微粒子４の材質が同一の場合において、超音波振動により酸化膜が充分に排除され、摺動による温度上昇により、微粒子４は固定側金属材料１及び可動側金属材料２と一体となり、強固な接合が得られる。
なお、微粒子の大きさは、固定側金属材料１及び可動側金属材料２の表面に形成される酸化膜の厚さに応じて選択され、各金属材料の表面酸化膜厚と同程度か若干大きいことが望ましい。微粒子が酸化膜厚より小さいと、加圧により銅微粒子が酸化膜に埋没してしまって酸化膜破壊につながりにくくなるためである。本実施例では、固定側金属材料１及び可動側金属材料２が銅であり、半導体回路基板に使用される銅材の自然酸化膜厚は数ｎｍ〜数十ｎｍであるので、銅微粒子４の大きさは数十ｎｍ以上とすればよい。 In the case where the fixed side metal material 1 and the movable side metal material 2 are the same as the material of the fine particles 4 as in this embodiment, the oxide film is sufficiently eliminated by ultrasonic vibration, and the temperature rises due to sliding, so that the fine particles 4 Is integrated with the fixed-side metal material 1 and the movable-side metal material 2, and a strong bond is obtained.
The size of the fine particles is selected according to the thickness of the oxide film formed on the surfaces of the fixed-side metal material 1 and the movable-side metal material 2, and is the same as or slightly larger than the surface oxide film thickness of each metal material. It is desirable. This is because if the fine particles are smaller than the oxide film thickness, the copper fine particles are buried in the oxide film by pressurization, and the oxide film is not easily destroyed. In the present embodiment, the fixed metal material 1 and the movable metal material 2 are copper, and the natural oxide film thickness of the copper material used for the semiconductor circuit board is several nm to several tens of nm. The size may be several tens of nm or more.

また、微粒子は、固定側金属材料１及び可動側金属材料２のうち、硬度の高い材料と同じかそれ以上の硬度を有することが望ましい。微粒子の硬度が高いと、２つの接合材料間に挟んで加圧しても微粒子が変形しにくいため、より酸化膜を破壊しやすくなる。
ここで、微粒子の形状は球形とするよりも、多面体や微小突起を有する形状が望ましい。球形のものに比して加圧によって酸化膜に効果的に突き刺さり、その後の超音波振動によって酸化膜を破壊しやすいためである。
上記の微粒子の製造方法としては機械的粉砕法，アトマイズ法，気相還元法，電解法等が周知である。上述の如く微粒子を球形とするよりは、多角形もしくは微小突起を有する形状とすることが望ましいため、例えば機械的粉砕法，アトマイズ法等によって製造すればよい。 Further, it is desirable that the fine particles have a hardness equal to or higher than that of the high-hardness material among the fixed-side metal material 1 and the movable-side metal material 2. If the hardness of the fine particles is high, the fine particles are not easily deformed even if they are sandwiched between two bonding materials and pressed, so that the oxide film is more easily broken.
Here, the shape of the fine particles is preferably a shape having a polyhedron or minute protrusions rather than a spherical shape. This is because the oxide film is effectively pierced by pressurization as compared with a spherical one, and the oxide film is easily destroyed by the subsequent ultrasonic vibration.
As a method for producing the above fine particles, a mechanical pulverization method, an atomization method, a gas phase reduction method, an electrolysis method and the like are well known. As described above, it is desirable that the fine particles have a polygonal shape or a shape having minute protrusions, rather than a spherical shape, and may be manufactured by, for example, a mechanical pulverization method, an atomization method, or the like.

また、固定側金属材料に散布した際に、多角形であると転がりにくいため、散布の際に不要な個所への付着を防ぐことができ作業性が良い。
なお、微粒子を固定側金属材料と可動側金属材料との間への配置は次のように行うと良い。所望の個所を開口させた金属製あるいは樹脂製のマスクを用意する。前記マスクの開口部を固定側金属材料の接合個所に併せて設置し、微粒子を散布する。
このとき、微粒子を溶剤と混ぜて所望個所に塗布しても良い。このようにすると、不必要な個所への微粒子の付着を防ぐことができる。散布・塗布いずれの方法においても、接合個所に微粒子を均一に配置することが望ましい。
前記マスクを取り外し、微粒子が散布された接合個所に可動側金属材料を押し当る。可動側金属材料を説工個所に加圧して超音波振動を印加し、両金属材料を接合する。接合後、超音波洗浄等の洗浄手段によって洗浄し、接合面に取り込まれなかった微粒子や他の部位に付着した微粒子を洗浄除去する。 Moreover, since it is hard to roll if it is a polygon when it spreads to a stationary-side metal material, adhesion to an unnecessary part can be prevented at the time of spreading, and workability | operativity is good.
The fine particles are preferably arranged between the fixed side metal material and the movable side metal material as follows. A metal or resin mask having an opening at a desired location is prepared. The opening of the mask is installed at the joint of the fixed metal material, and fine particles are dispersed.
At this time, the fine particles may be mixed with a solvent and applied to a desired location. In this way, it is possible to prevent fine particles from adhering to unnecessary portions. In any of the spraying and coating methods, it is desirable to uniformly dispose the fine particles at the joints.
The mask is removed, and the movable side metal material is pressed against the joint where the fine particles are dispersed. The metal material on the movable side is pressed against the prescription site and ultrasonic vibration is applied to join the two metal materials. After the bonding, the particles are cleaned by a cleaning means such as ultrasonic cleaning, and the fine particles that have not been taken into the bonding surface and the fine particles attached to other parts are cleaned and removed.

あるいは、硬質の作業台上に微粒子を散布もしくは塗布し、ここに可動側金属材料の接合面を一旦押し当てて、微粒子を可動側金属材料の接合面に食い込ませた状態とし、この状態で固定側金属材料の接合面に押し当てて可動側金属材料を接合個所に加圧して超音波振動を印加し、両金属材料を接合してもよい。超音波洗浄等の洗浄手段によって洗浄し、接合面に取り込まれなかった微粒子や他の部位に付着した微粒子を洗浄除去する。微粒子を固定側金属材料上に散布する方法に比べて余分な微粒子の付着を防ぐことができる。
上記実施例では固定側金属材料１及び可動側金属材料２を銅材とし、微粒子４も同じ銅材の場合について説明したが、微粒子に銅に換えて銀や金の微粒子を使用しても良い。銀及び金の融点はそれぞれ962℃及び1064℃であり、固定側金属材料１及び可動側金属材料２に銅を用いる場合、銅の融点に近く、金属学的結合が起こりやすい。 Alternatively, fine particles are sprayed or applied onto a hard work table, and the joint surface of the movable metal material is pressed once to make the fine particles bite into the joint surface of the movable metal material and fixed in this state. The two metal materials may be bonded by pressing the movable metal material against the bonding surface of the side metal material and pressurizing the movable metal material to the bonding portion to apply ultrasonic vibration. Cleaning is performed by a cleaning means such as ultrasonic cleaning, and the fine particles that have not been taken into the bonding surface and the fine particles attached to other parts are cleaned and removed. Compared with the method in which the fine particles are dispersed on the stationary metal material, it is possible to prevent the extra fine particles from adhering.
In the above embodiment, the fixed side metal material 1 and the movable side metal material 2 are made of copper, and the fine particles 4 are the same copper material. However, fine particles of silver or gold may be used instead of copper. . The melting points of silver and gold are 962 ° C. and 1064 ° C., respectively, and when copper is used for the fixed side metal material 1 and the movable side metal material 2, it is close to the melting point of copper and metallurgical bonding is likely to occur.

また、接合する金属材料の硬度に応じて、微粒子を焼きなまして所望の硬度としても良い。
これまで、微粒子に銅，銀及び金を用いた場合について説明したが、微粒子を固定側金属材料及び可動側金属材料間に挟み、加圧並びに超音波振動を印加することにより、前記金属材料表面に形成された酸化膜を破壊可能な粒径並びに硬度を有するものであれば、微粒子に他の無機材料を用いても良い。例えば、アルミナ、窒化アルミ、窒化珪素、炭化珪素などが適用可能である。
上記の実施例では固定側金属材料１及び可動側金属材料２は銅材としたが、銅材に限られることはなく、熱移動体として用いることのできる金属、例えばアルミニウム材などを用いてもよい。このとき、微粒子には同材料であるアルミニウムが好適である。 Further, depending on the hardness of the metal material to be joined, the fine particles may be annealed to obtain a desired hardness.
So far, the case where copper, silver and gold are used for the fine particles has been described. However, the surface of the metal material is obtained by sandwiching the fine particles between the fixed-side metal material and the movable-side metal material, and applying pressure and ultrasonic vibration. Other inorganic materials may be used for the fine particles as long as they have a particle diameter and hardness capable of breaking the oxide film formed on the surface. For example, alumina, aluminum nitride, silicon nitride, silicon carbide, or the like is applicable.
In the above embodiment, the fixed-side metal material 1 and the movable-side metal material 2 are copper materials. However, the present invention is not limited to copper materials, and a metal that can be used as a heat transfer body, such as an aluminum material, may be used. Good. At this time, aluminum which is the same material is suitable for the fine particles.

上記の接合方法を図３に示す半導体装置の製造に適用することができる。即ち、半導体装置１０において、固定側金属材料１が、半導体素子１１の電極パッド部や絶縁基板１３上の回路パターン１１などに相当し、同様に、可動側金属材料２が、半導体素子１１，絶縁基板上の配線パターン１１，外部導出端子（図示せず）などを相互に接続する金属導体板（リードフレームなど）１２に相当する。これらの部材間の接合に上記のとおり、微粒子を介在させて超音波接合を行うことにより、強固な接合を得ることができる。
大容量の電力変換装置のように、半導体素子１１にパワー半導体素子を用いて、熱サイクル，パワーサイクルが印加されるような使用条件においても、部材間が強固に接合されているため、高い信頼性を得ることができる。 The above bonding method can be applied to the manufacture of the semiconductor device shown in FIG. That is, in the semiconductor device 10, the fixed-side metal material 1 corresponds to the electrode pad portion of the semiconductor element 11, the circuit pattern 11 on the insulating substrate 13, and the like. This corresponds to a metal conductor plate (such as a lead frame) 12 that interconnects the wiring pattern 11 on the substrate, external lead-out terminals (not shown), and the like. As described above, strong bonding can be obtained by performing ultrasonic bonding by interposing fine particles in the bonding between these members.
As in a large-capacity power conversion device, a power semiconductor element is used as the semiconductor element 11, and the members are firmly joined to each other even under use conditions where a thermal cycle and a power cycle are applied. Sex can be obtained.

実施例を示す図である。It is a figure which shows an Example. 従来例を示す図である。It is a figure which shows a prior art example. 半導体装置の要部を示す図The figure which shows the principal part of a semiconductor device

符号の説明Explanation of symbols

１ 固定側金属材料
２ 可動側金属材料
３ 酸化膜
４ 微粒子 DESCRIPTION OF SYMBOLS 1 Fixed side metal material 2 Movable side metal material 3 Oxide film 4 Fine particle

Claims (8)

２つの金属部材の接合表面に微粒子を介装し、前記金属部材の少なくとも一方に超音波振動を印加して、前記２つの金属部材を接合することを特徴とする接合方法。   A joining method characterized in that fine particles are interposed on the joining surfaces of two metal members, and ultrasonic vibration is applied to at least one of the metal members to join the two metal members. 前記２つの金属部材の接合表面に形成される自然酸化膜のうち、厚い方の酸化膜厚以上の粒径を有する微粒子を用いたことを特徴とする請求項１に記載の接合方法。   The bonding method according to claim 1, wherein fine particles having a particle diameter equal to or larger than a thicker oxide film thickness among natural oxide films formed on the bonding surfaces of the two metal members are used. 前記２つの金属部材の硬度以上の硬度を有する微粒子を用いたことを特徴とする請求項１に記載の接合方法。   The joining method according to claim 1, wherein fine particles having a hardness equal to or higher than the hardness of the two metal members are used. 前記微粒子は無機材料であることを特徴とする請求項２または請求項３に記載の接合方法。   The bonding method according to claim 2, wherein the fine particles are an inorganic material. 前記微粒子は、前記２つの金属部材のうちの少なくとも一方を構成する材料からなることを特徴とする請求項２または請求項３に記載の接合方法。   The joining method according to claim 2 or 3, wherein the fine particles are made of a material constituting at least one of the two metal members. 前記２つの金属部材のうち、少なくとも一方は銅であって、前記微粒子は、金，銀，銅からなる群のうち少なくとも１つを選択して用いることを特徴とする請求項１に記載の接合方法。   2. The bonding according to claim 1, wherein at least one of the two metal members is copper, and the fine particles are selected from at least one selected from the group consisting of gold, silver, and copper. Method. 前記２つの金属部材のうち、一方は半導体素子の電極パッドもしくは該半導体素子が搭載された基板上の回路パターンであり、他方は前記半導体素子の電極パッドもしくは該半導体素子が搭載された基板上の回路パターンを接続する金属導体であって、両者を請求項１〜請求項６に記載の接合方法によって接合することを特徴とする半導体装置の製造方法。   Of the two metal members, one is an electrode pad of a semiconductor element or a circuit pattern on a substrate on which the semiconductor element is mounted, and the other is an electrode pad on the semiconductor element or on a substrate on which the semiconductor element is mounted. A method of manufacturing a semiconductor device, comprising: a metal conductor for connecting circuit patterns, wherein the two are joined by the joining method according to claim 1. 半導体素子と、該半導体素子が搭載された基板上の回路パターンと、前記半導体素子の電極パッドもしくは該半導体素子が搭載された基板上の回路パターンを接続する金属導体とを備えた半導体装置であって、前記半導体素子の電極パッドもしくは該半導体素子が搭載された基板上の回路パターンと前記金属導体との間を請求項１〜請求項６に記載の接合方法によって接合したことを特徴とする半導体装置。   A semiconductor device comprising: a semiconductor element; a circuit pattern on a substrate on which the semiconductor element is mounted; and a metal conductor that connects an electrode pad of the semiconductor element or a circuit pattern on the substrate on which the semiconductor element is mounted. A semiconductor device characterized in that an electrode pad of the semiconductor element or a circuit pattern on a substrate on which the semiconductor element is mounted and the metal conductor are joined by the joining method according to claim 1. apparatus.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009105267A (en) * 2007-10-24 2009-05-14 Fuji Electric Device Technology Co Ltd Semiconductor apparatus, and method of manufacturing the same

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009105267A (en) * 2007-10-24 2009-05-14 Fuji Electric Device Technology Co Ltd Semiconductor apparatus, and method of manufacturing the same

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