JP2014222725A - Bonding wire for high-speed signal - Google Patents
Bonding wire for high-speed signal Download PDFInfo
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- JP2014222725A JP2014222725A JP2013102191A JP2013102191A JP2014222725A JP 2014222725 A JP2014222725 A JP 2014222725A JP 2013102191 A JP2013102191 A JP 2013102191A JP 2013102191 A JP2013102191 A JP 2013102191A JP 2014222725 A JP2014222725 A JP 2014222725A
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Abstract
Description
本発明は、半導体素子のパッド電極と配線基板上のリード電極とを接続する高速信号線用ボンディングワイヤに関し、特に１〜１５ギガＨｚの周波数を用いる高速信号線用ボンディングワイヤに関する。 The present invention relates to a high-speed signal line bonding wire for connecting a pad electrode of a semiconductor element and a lead electrode on a wiring board, and more particularly to a high-speed signal line bonding wire using a frequency of 1 to 15 GHz.
近年、半導体装置の製造技術の発展に伴い、数ギガＨｚ帯を超える超高周波を用いる高速信号線用の半導体集積回路装置を携帯電話機等に組み込むことが増えてきた。高周波伝送には、従来から純度９９．９９質量％以上の高純度金ボンディングワイヤが一般的に使用されてきた。しかし、数ギガないし十数ギガＨｚ帯に通常のボンディングワイヤを使用して超高周波を用いる高速・超高速信号線用の半導体素子と配線電極等を接続すると、超高周波信号がボンディングワイヤの表皮層を流れるので、超高周波信号による高周波抵抗が一段と大きくなる。よって、高純度金ボンディングワイヤを用いたのでは、受信感度や送信出力等を低下させる原因となる。 2. Description of the Related Art In recent years, with the development of semiconductor device manufacturing technology, a semiconductor integrated circuit device for a high-speed signal line using an ultra-high frequency exceeding several gigahertz band has been incorporated into a cellular phone or the like. Conventionally, high-purity gold bonding wires having a purity of 99.99% by mass or more have been generally used for high-frequency transmission. However, if a semiconductor element for a high-speed / ultra-high-speed signal line using a normal bonding wire in the several gigahertz to tens of gigahertz band is connected to a wiring electrode or the like, the super-high frequency signal is applied to the skin layer of the bonding wire. Therefore, the high frequency resistance due to the super high frequency signal is further increased. Therefore, using a high-purity gold bonding wire causes a decrease in reception sensitivity, transmission output, and the like.
このため電気比抵抗値が高純度金（Ａｕ）の２．４μΩｃｍに対し、電気比抵抗値が１．６μΩcmの純度９９．９９％の高純度銀（Ａｇ）などのワイヤが検討された。しかし、溶解・鋳造後洗浄してから連続伸線を経てボンディングワイヤが製造される過程において、バルクの高純度銀（Ａｇ）ワイヤは軟らかすぎて実用化に適さない。また、大気中で銀（Ａｇ）が硫化してボンディングワイヤの表皮層に硫化銀（Ａｇ２Ｓ）膜が形成され、溶融ボールを硬くしてしまうので、フリー・エアー・ボール（ＦＡＢ）によるボールボンディング特性を損なってしまうという欠点がある。よって、純銀ボンディングワイヤが直接数μｍの表皮層を流れる高周波伝送用に使用されることはなく、特開昭５７−２１８３０号公報でＡｇ−Ｐｄ合金ワイヤが提案されたものの、特開２００３−５９９６３号公報（後述する特許文献１）に見られるように、純金メッキをした純銀ボンディングワイヤが実用化されているにすぎなかった。このように、純銀ボンディングワイヤが実用化されなかったのは、超高周波を用いる高速信号線として用いる以前に、安定した溶融ボールを形成することができなかったからである。すなわち、フリー・エアー・ボール（ＦＡＢ）によるボールボンディングに用いようとして溶融ボールを形成したとき、ワイヤ表面に形成された強固な硫化銀（Ａｇ２Ｓ）が溶融ボールを硬くするため、第一ボンディングにおいてチップ割れ等を生じていた。 For this reason, wires such as high-purity silver (Ag) having a purity of 99.99% with an electrical resistivity of 1.6 μΩcm and an electrical resistivity of 2.4 μΩcm were investigated. However, in a process in which a bonding wire is manufactured through continuous drawing after being melted and cast and washed, bulk high-purity silver (Ag) wire is too soft to be suitable for practical use. In addition, since silver (Ag) is sulfided in the atmosphere and a silver sulfide (Ag 2 S) film is formed on the skin layer of the bonding wire, which hardens the molten ball, a ball made of free air ball (FAB) There is a disadvantage that bonding characteristics are impaired. Therefore, a pure silver bonding wire is not used for high-frequency transmission directly flowing through a skin layer of several μm, and an Ag—Pd alloy wire was proposed in Japanese Patent Laid-Open No. 57-21830, but Japanese Patent Laid-Open No. 2003-59963. As can be seen in Japanese Patent Publication (Patent Document 1 described later), a pure silver bonding wire plated with pure gold has only been put into practical use. The reason why the pure silver bonding wire was not put to practical use in this way was that a stable molten ball could not be formed before it was used as a high-speed signal line using ultra-high frequency. That is, when a molten ball is formed for use in ball bonding with a free air ball (FAB), the strong silver sulfide (Ag 2 S) formed on the surface of the wire hardens the molten ball. Chip cracking and the like occurred.
他方、電気伝導性の高いＡｇの電気比抵抗を利用することを目的として、現在広く使用されている純度９９％のＡｕワイヤ並の３．１μΩｃｍ以下とさほど低下させることなく、Ａｇに１００００〜５５０００質量ｐｐｍ（１〜５．５質量％）のＡｕおよび１〜１００質量ｐｐｍのＢｉを添加するＡｇ−Ａｕ二元系合金のボンディングワイヤが開発され、さらに、このワイヤにＰｄを２００００質量ｐｐｍ以下添加したＡｇ−Ａｕ−Ｐｄ三元系合金のボンディングワイヤも開発されている（特開２０１２−４９１９８号公報（後述する特許文献２））。ここで、Ｐｄの添加量を２００００質量ｐｐｍ（２質量％）以下とするのは、「２００００質量ｐｐｍを超えて添加するとボールの硬度が高くなってボールボンディング時のパッドダメージが発生する（同公報００２１段落参照）」からであるとされる。 On the other hand, for the purpose of utilizing the electrical resistivity of Ag having high electrical conductivity, it is not less than 3.1 μΩcm, which is comparable to that of 99% purity Au wire, which is currently widely used. A bonding wire of Ag-Au binary alloy to which Au of mass ppm (1 to 5.5 mass%) and Bi of 1 to 100 massppm is added was developed, and Pd was added to this wire in an amount of 20000 ppm by mass or less. An Ag—Au—Pd ternary alloy bonding wire has also been developed (Japanese Patent Laid-Open No. 2012-49198 (Patent Document 2 described later)). Here, the amount of Pd to be added is 20000 ppm by mass (2% by mass) or less because “when it exceeds 20000 ppm by mass, the hardness of the ball increases and pad damage occurs during ball bonding (the same publication). (See paragraph 0021).
また、Ｃａ、Ｃｕ、Ｇｄ、Ｓｍから選ばれる２種以上の元素を合計で５〜５００重量ｐｐｍ含み、Ｐｄ、Ａｕから選ばれる１種以上の元素を合計で０．５〜５．０重量％含んで、それ以外がＡｇ及び不可避不純物からなることを特徴とするボールボンディング用ワイヤ（特開２０１２−１５１３５０号公報（後述する特許文献３））も開示されている。しかしながら、このボンディングワイヤは、半導体素子のＮｉ／Ｐｄ／Ａｕ被覆された電極と回路配線基板の導体配線をボールボンディング法によって接続するためのボンディング用ワイヤ（Ｗ）であって、Ａｌ合金(Ａｌ−Ｓｉ−Ｃｕ等）パッド電極を接合するものではない。「ＡｌとＡｇとの接合個所は腐食し易い（特開２０１２−１５１３５０号公報（後述する特許文献３）００１５段落参照）」とされるからである。 Further, it contains 5 to 500 ppm by weight in total of two or more elements selected from Ca, Cu, Gd, and Sm, and 0.5 to 5.0% by weight in total of one or more elements selected from Pd and Au. In addition, a ball bonding wire (Japanese Patent Laid-Open No. 2012-151350 (Patent Document 3 to be described later)) characterized in that the other is composed of Ag and inevitable impurities is also disclosed. However, this bonding wire is a bonding wire (W) for connecting a Ni / Pd / Au coated electrode of a semiconductor element and a conductor wiring of a circuit wiring board by a ball bonding method, and is an Al alloy (Al-- Si-Cu etc.) Pad electrodes are not joined. This is because “the joint between Al and Ag is easily corroded (see Japanese Patent Laid-Open No. 2012-151350 (Patent Document 3 described later) paragraph 0015)”.
さらに、「銀（Ａｇ）を主成分とし、１００００〜９００００質量ｐｐｍの金（Ａｕ）、１００００〜５００００質量ｐｐｍのパラジウム（Ｐｄ）、１００００〜３００００質量ｐｐｍの銅（Ｃｕ）、１００００〜２００００質量ｐｐｍのニッケル（Ｎｉ）から選ばれた少なくとも１種以上の成分を含み、塩素（Ｃｌ）含有量が１質量ｐｐｍ未満」のボンディングワイヤも開示されている（特開２０１２−９９５７７号公報（後述する特許文献４））。しかしながら、このボンディングワイヤは、「波長３８０〜５６０ｎｍの光の反射率が９５％以上であるため、青色系の発光を使用する白色ＬＥＤにも有効である（同公報００１０段落参照）」とあるように、ＬＥＤ用であり、高速信号線用ボンディングワイヤとは目的・効果が異なる。 Furthermore, “mainly composed of silver (Ag), 10,000 to 90000 mass ppm of gold (Au), 10,000 to 50000 mass ppm of palladium (Pd), 10,000 to 30000 mass ppm of copper (Cu), 10,000 to 20000 mass ppm Also disclosed is a bonding wire that contains at least one component selected from nickel (Ni) and has a chlorine (Cl) content of less than 1 ppm by mass (Japanese Patent Laid-Open No. 2012-99777 (patents to be described later)). Reference 4)). However, this bonding wire is said to be “effective for white LEDs using blue light emission because the reflectance of light with a wavelength of 380 to 560 nm is 95% or more (see paragraph 0010 of the same publication)”. Furthermore, it is for LED and has a different purpose and effect from the bonding wire for high-speed signal lines.
本発明は、Ａｇ−Ｐｄ−Ａｕ基合金のボンディングワイヤの表面に、高濃度の純銀層および低濃度の金合金化層（以下、「高濃度純銀層」と略す）を偏析させることにより、その偏析した均一な厚さの高濃度純銀層の形成によってフリー・エアー・ボール（ＦＡＢ）によるボンディング特性を良好にすると同時に、大気中に放置しても一定期間硫化銀の形成ないし内部進行を阻止し、安定した数ギガＨｚ帯等の超高周波信号を送ることができるＡｇ−Ｐｄ−Ａｕ基合金の高速信号線用ボンディングワイヤを提供することを目的とする。 The present invention segregates a high-concentration pure silver layer and a low-concentration gold alloyed layer (hereinafter abbreviated as “high-concentration pure silver layer”) on the surface of a bonding wire of an Ag—Pd—Au-based alloy. By forming a segregated and uniform high-concentration pure silver layer, the bonding characteristics of the free air ball (FAB) are improved, and at the same time, the formation of silver sulfide or internal progress is prevented even if left in the atmosphere. Another object of the present invention is to provide a bonding wire for high-speed signal lines of an Ag—Pd—Au base alloy capable of sending a stable ultra-high frequency signal such as several gigahertz band.
本発明の課題を解決するための高速信号線用ボンディングワイヤの一つは、 半導体素子のパッド電極と配線基板上のリード電極とをフリー・エアー・ボール（ＦＡＢ）により接続するための微量添加元素を含有するＡｇ−Ｐｄ−Ａｕ基合金ボンディングワイヤであって、当該ボンディングワイヤはパラジウム（Ｐｄ）を２．５〜４．０質量％、金（Ａｕ）を１．５〜２．５質量％および残部が純度９９．９９質量％以上の銀（Ａｇ）からなる三元合金であって、そのボンディングワイヤの表面は連続鋳造後に縮径された連鋳面からなり、そのボンディングワイヤの断面は表面偏析層と芯材とからなり、その表面偏析層は、芯材よりも銀（Ａｇ）の含有量が漸増し、かつ、金（Ａｕ）の含有量が漸減している合金領域からなる高濃度純銀層である。 One of the high-speed signal line bonding wires for solving the problems of the present invention is a trace additive element for connecting a pad electrode of a semiconductor element and a lead electrode on a wiring board by a free air ball (FAB). An Ag—Pd—Au based alloy bonding wire containing, wherein the bonding wire is 2.5 to 4.0 mass% of palladium (Pd), 1.5 to 2.5 mass% of gold (Au) and The balance is a ternary alloy composed of silver (Ag) with a purity of 99.99% by mass or more, and the surface of the bonding wire is a continuous cast surface whose diameter is reduced after continuous casting. A high-concentration pure silver consisting of an alloy region in which the content of silver (Ag) is gradually increased and the content of gold (Au) is gradually decreased. In layers That.
また、本発明の課題を解決するための高速信号線用ボンディングワイヤの一つは、半導体素子のパッド電極と配線基板上のリード電極とをフリー・エアー・ボール（ＦＡＢ）により接続するための微量添加元素を含有するＡｇ−Ｐｄ−Ａｕ基合金ボンディングワイヤであって、当該ボンディングワイヤはパラジウム（Ｐｄ）を２．５〜４．０質量％、金（Ａｕ）を１．５〜２．５質量％、並びに、ロジウム（Ｒｈ）、イリジウム（Ｉｒ）、ルテニウム（Ｒｕ）、銅（Ｃｕ）、ニッケル（Ｎｉ）、鉄（Ｆｅ）、マグネシウム（Ｍｇ）、亜鉛（Ｚｎ）、アルミニウム（Ａｌ）、インジウム（Ｉｎ）、シリコン（Ｓｉ）、ゲルマニウム（Ｇe）、ベリリウム（Ｂｅ）、ビスマス（Ｂi）、セレン（Ｓｅ）、セリウム（Ｃｅ）、イットリウム（Ｙ）、ランタン（Ｌａ）、カルシウム（Ｃａ）またはユーロピウム（Ｅｕ）のうちの少なくとも１種以上の加微量元素をその合計で５〜３００質量ｐｐｍ、および残部が純度９９．９９質量％以上の銀（Ａｇ）からなる三元系合金であって、そのボンディングワイヤの表面は連続鋳造後に縮径された連鋳面からなり、そのボンディングワイヤの断面は表面偏析層と芯材とからなり、その表面偏析層は、芯材よりも銀（Ａｇ）の含有量が漸増し、かつ、金（Ａｕ）の含有量が漸減している合金領域からなる高濃度純銀層である。 One of the high-speed signal line bonding wires for solving the problems of the present invention is a small amount for connecting a pad electrode of a semiconductor element and a lead electrode on a wiring board by a free air ball (FAB). An Ag—Pd—Au based alloy bonding wire containing an additive element, the bonding wire containing 2.5 to 4.0 mass% of palladium (Pd) and 1.5 to 2.5 mass of gold (Au). , Rhodium (Rh), iridium (Ir), ruthenium (Ru), copper (Cu), nickel (Ni), iron (Fe), magnesium (Mg), zinc (Zn), aluminum (Al), indium (In), silicon (Si), germanium (Ge), beryllium (Be), bismuth (Bi), selenium (Se), cerium (Ce), yttrium (Y), La Silver (Ag) having a total of 5 to 300 mass ppm of at least one trace element of tan (La), calcium (Ca) or europium (Eu) and the balance being 99.99 mass% or more The surface of the bonding wire consists of a continuous casting surface that has been reduced in diameter after continuous casting, and the bonding wire has a cross-section consisting of a surface segregation layer and a core material. The high-concentration pure silver layer is composed of an alloy region in which the content of silver (Ag) is gradually increased and the content of gold (Au) is gradually decreased as compared with the core material.
また、本発明の課題を解決するための高速信号線用Ａｇ−Ｐｄ−Ａｕ基合金ボンディングワイヤの好ましい態様の一つは、上記高速信号が１〜１５ギガＨｚの周波数であることである。 Moreover, one of the preferable aspects of the Ag-Pd-Au base alloy bonding wire for high-speed signal lines for solving the problems of the present invention is that the high-speed signal has a frequency of 1 to 15 GHz.
また、本発明の課題を解決するための高速信号線用Ａｇ−Ｐｄ−Ａｕ基合金ボンディングワイヤの好ましい態様の一つは、上記パッド電極が純度９９．９質量％以上のアルミニウム（Ａｌ）金属または０．５〜２．０質量％のシリコン（Ｓｉ）または銅（Ｃｕ）および残部純度９９．９質量％以上のアルミニウム（Ａｌ）合金であることである。 One of the preferred embodiments of the Ag—Pd—Au base alloy bonding wire for high-speed signal lines for solving the problems of the present invention is that the pad electrode is an aluminum (Al) metal having a purity of 99.9% by mass or more. It is an aluminum (Al) alloy of 0.5 to 2.0% by mass of silicon (Si) or copper (Cu) and the balance purity of 99.9% by mass or more.
また、本発明の課題を解決するための高速信号線用Ａｇ−Ｐｄ−Ａｕ基合金ボンディングワイヤの好ましい態様の一つは、上記パッド電極が金（Ａｕ）、パラジウム（Ｐｄ）または白金（Ｐｔ）の表層からなる電極パッドであることである。 One of the preferred embodiments of the Ag—Pd—Au based alloy bonding wire for high-speed signal lines for solving the problems of the present invention is that the pad electrode is gold (Au), palladium (Pd) or platinum (Pt). It is that it is an electrode pad which consists of a surface layer.
なお、本発明の課題を解決するための高速信号線用Ａｇ−Ｐｄ−Ａｕ基合金ボンディングワイヤは、純金ボンディングワイヤと同様に、ダイヤモンドダイスにより断面減少率が９９％以上縮径され、連続して冷間伸線加工され、その後、調質熱処理によってボンディングワイヤの機械的特性が調えられる。この調質熱処理は、温度が低く、処理時間も短いので、高濃度純銀層の表面偏析層は消滅しない。 Note that the Ag—Pd—Au base alloy bonding wire for high-speed signal lines for solving the problems of the present invention is continuously reduced in diameter by 99% or more by a diamond die, like a pure gold bonding wire, and continuously. After cold drawing, the mechanical properties of the bonding wire are adjusted by tempering heat treatment. Since this tempering heat treatment has a low temperature and a short treatment time, the surface segregation layer of the high concentration pure silver layer does not disappear.
（主添加元素）
本発明において、残部の銀（Ａｇ）に純度９９．９９質量％以上のものを用いるのは、銀（Ａｇ）の含有量が多い合金の表面偏析層をワイヤの全周縁に均一に生じさせるためである。純度が低いと、不純物の影響により銀（Ａｇ）の含有量が多い合金の表面偏析層の厚さがばらつくおそれがあるからである。
(Main additive element)
In the present invention, the remaining silver (Ag) having a purity of 99.99% by mass or more is used to uniformly generate a surface segregation layer of an alloy having a high silver (Ag) content on the entire periphery of the wire. It is. This is because if the purity is low, the thickness of the surface segregation layer of the alloy having a high silver (Ag) content may vary due to impurities.
純銀ボンディングワイヤの場合、硫化物が酸化物より安定するので、この硫化物が形成されるのを嫌う。これまでの純銀ボンディングワイヤでは、大気中の高純度銀（Ａｇ）表面で表面の銀（Ａｇ）がイオンとなり、大気中の硫化水素と結合して硫化物となる。この硫化物は、最初は純銀ワイヤ表面で不安定な硫化銀層が形成されるものの、この硫化銀層が純銀ボンディングワイヤの内部へ進んでいき、やがて硫化銀層が成長して数ｎｍ程度の強固な硫化銀（Ａｇ２Ｓ）膜が純銀ボンディングワイヤの表面に確保されてしまう。しかも、この表皮層に存在するイオウ化合物は、結晶粒界を伝って更に純銀ボンディングワイヤの内部へ入り込んで強固な硫化銀（Ａｇ２Ｓ）膜が拡がるものと考えられる。 In the case of a pure silver bonding wire, the sulfide is more stable than the oxide, and therefore it is not desirable to form this sulfide. In conventional pure silver bonding wires, surface silver (Ag) becomes ions on the surface of high-purity silver (Ag) in the atmosphere, and combines with hydrogen sulfide in the atmosphere to form sulfide. Although this sulfide initially forms an unstable silver sulfide layer on the surface of the pure silver wire, the silver sulfide layer advances into the pure silver bonding wire, and eventually the silver sulfide layer grows to about several nanometers. A strong silver sulfide (Ag 2 S) film is secured on the surface of the pure silver bonding wire. Moreover, it is considered that the sulfur compound existing in the skin layer further penetrates into the inside of the pure silver bonding wire through the crystal grain boundary, and the strong silver sulfide (Ag 2 S) film expands.
純銀（Ａｇ）にパラジウム（Ｐｄ）および金（Ａｕ）を合金化したバルクのＡｇ−Ｐｄ−Ａｕ合金の場合、高濃度純銀層の硫化銀層の形成は純銀ボンディングワイヤよりも弱くなる。しかも、本発明のＡｇ−Ｐｄ−Ａｕ基合金の場合、金（Ａｕ）濃度が表層から芯材内部に行くほど漸増し、芯材のほうはパラジウム（Ｐｄ）および金（Ａｕ）が４．０〜６．５質量％の含有量があるので、表面に形成された硫化銀（Ａｇ２Ｓ）膜を内部へ入り込んでいくのを時間的に遅延させることができる。 In the case of a bulk Ag-Pd-Au alloy obtained by alloying pure silver (Ag) with palladium (Pd) and gold (Au), the formation of the silver sulfide layer of the high concentration pure silver layer is weaker than that of the pure silver bonding wire. Moreover, in the case of the Ag—Pd—Au base alloy of the present invention, the gold (Au) concentration gradually increases from the surface layer to the inside of the core material, and the core material is composed of palladium (Pd) and gold (Au) of 4.0. Since there is content of ˜6.5% by mass, it is possible to delay the time for the silver sulfide (Ag 2 S) film formed on the surface to enter the inside.
Ａｇ−Ｐｄ−Ａｕ基合金からなるボンディングワイヤのパラジウム（Ｐｄ）含有量を金（Ａｕ）の含有量よりも多くしたのは、銀（Ａｇ）マトリックスよりも耐硫化性に対して貴なＡｇ−Ｐｄマトリックスを構成し、そのＡｇ−Ｐｄマトリックス中にさらに貴な金（Ａｕ）による表面偏析層を形成するためである。 The reason why the palladium (Pd) content of the bonding wire made of an Ag—Pd—Au-based alloy is made larger than the content of gold (Au) is that Ag— which is more precious against sulfidation resistance than the silver (Ag) matrix. This is because a Pd matrix is formed, and a surface segregation layer made of noble gold (Au) is formed in the Ag-Pd matrix.
本発明において、パラジウム（Ｐｄ）を所定量添加するのは、硫化の進行を遅らせるためである。湿気が多い環境下でボンディングワイヤを使用する場合などは、ボンディングワイヤ表面が硫化しやすくなるので、ワイヤ自体に耐硫化性のあるＡｇ−Ｐｄ−Ａｕ基合金からなるワイヤが必要になる。パラジウム（Ｐｄ）含有量が２．５質量％あれば、純銀ボンディングワイヤの表面に強固な硫化銀（Ａｇ２Ｓ）膜が形成されてしまうのを遅延させることができる。他方、パラジウム（Ｐｄ）が２．５質量％を超えていくと、銀濃度が低下するため高周波特性は多少悪くなり、超高周波信号線としては不適当になるが、高濃度純銀層が形成されているので、実用上４．０質量％までは差支えがない。 In the present invention, the predetermined amount of palladium (Pd) is added to delay the progress of sulfidation. When the bonding wire is used in a humid environment, the surface of the bonding wire is likely to be sulfided, and thus a wire made of an Ag—Pd—Au base alloy having resistance to sulfur is necessary for the wire itself. If the palladium (Pd) content is 2.5 mass%, it is possible to delay the formation of a strong silver sulfide (Ag 2 S) film on the surface of the pure silver bonding wire. On the other hand, when palladium (Pd) exceeds 2.5 mass%, the silver concentration decreases, so the high-frequency characteristics are somewhat deteriorated and become unsuitable as an ultra-high frequency signal line, but a high-concentration pure silver layer is formed. Therefore, there is no problem up to 4.0% by mass in practical use.
また、パラジウム（Ｐｄ）は著しく硬さを増す合金化元素であり、パラジウム（Ｐｄ）含有量が２．５質量％以上存在すると、フリー・エアー・ボール（ＦＡＢ）を形成したとき、溶融ボールの硬度が高くなってボールボンディング時のチップ割れが懸念される（特許文献２第００２１段落参照）が、金（Ａｕ）の含有量を多くして低融点の高濃度純銀層を設けることで、パラジウム（Ｐｄ）含有量が４．０質量％以内の範囲であれば、この問題は解決できた。なお、パラジウム（Ｐｄ）の濃度は、高濃度純銀層中も芯材中もほぼ一定である。 Palladium (Pd) is an alloying element that remarkably increases the hardness. When the palladium (Pd) content is 2.5% by mass or more, when a free air ball (FAB) is formed, There is concern about chip cracking during ball bonding due to high hardness (see Patent Document 2, paragraph 0021), but by increasing the content of gold (Au) and providing a high-concentration pure silver layer with a low melting point, palladium If the (Pd) content was within a range of 4.0% by mass, this problem could be solved. The concentration of palladium (Pd) is substantially constant both in the high concentration pure silver layer and in the core material.
本発明において金（Ａｕ）の合金化元素は、銀（Ａｇ）およびパラジウム（Ｐｄ）よりも比重が高く、Ａｇ−Ｐｄ基合金マトリックスに対して表面偏析効果を発揮する。表面偏析した高濃度純銀層は、希薄合金の固相・気相間の表面現象を利用するものなので、この高濃度純銀層は一定の幅の層をボンディングワイヤの全周にわたって均一に形成することができる。この高濃度純銀層において、ワイヤの表面から中心をみた場合、銀（Ａｇ）濃度が漸減して低くなると（図１の上側の曲線）、逆に金（Ａｕ）の合金化元素の濃度は漸増して高くなる（図１の下側の曲線）。そして、ワイヤ内には銀（Ａｇ）が相対的に高濃度の高濃度純銀層の領域と相対的に低濃度の芯材の領域の二領域が存在することになる。このため、高濃度のワイヤ表面で不安定な硫化銀層が形成されても、銀（Ａｇ）よりも貴な合金化元素（パラジウム（Ｐｄ）および金（Ａｕ））が存在することと相まって、室温大気中でボンディングワイヤが製造後信号線として使用されるまでの放置期間中は、銀合金表面のイオウ化合物が内部へ進行するのを遅延させるとともに、銀合金表面で強固な硫化銀（Ａｇ２Ｓ）膜が形成されるのも遅延させることができる。 In the present invention, the alloying element of gold (Au) has a higher specific gravity than silver (Ag) and palladium (Pd), and exhibits a surface segregation effect on the Ag—Pd based alloy matrix. Since the surface-segregated high-concentration pure silver layer uses the surface phenomenon between the solid phase and the gas phase of a dilute alloy, this high-concentration pure silver layer can form a uniform width layer uniformly around the entire circumference of the bonding wire. it can. In this high-concentration pure silver layer, when the center is viewed from the surface of the wire, if the silver (Ag) concentration is gradually decreased and lowered (the upper curve in FIG. 1), conversely, the concentration of the alloying element of gold (Au) gradually increases. (The lower curve in FIG. 1). In the wire, there are two regions, a region of a high concentration pure silver layer having a relatively high concentration of silver (Ag) and a region of a core material having a relatively low concentration. For this reason, even if an unstable silver sulfide layer is formed on the surface of a high concentration of wire, coupled with the presence of alloying elements (palladium (Pd) and gold (Au)) that are nobler than silver (Ag), During the standing period until the bonding wire is used as a signal wire after manufacturing in the air at room temperature, the sulfur compound on the surface of the silver alloy is delayed from progressing to the inside, and the silver sulfide (Ag 2) is strong on the surface of the silver alloy. S) The formation of the film can also be delayed.
高純度のＡｇ−Ｐｄ合金マトリックスに対し高純度の金（Ａｕ）は表面偏析するので、パラジウム（Ｐｄ）と金（Ａｕ）を高純度の銀（Ａｇ）に添加して連続鋳造すると、表皮層近傍に銀（Ａｇ）の高濃度領域と金（Ａｕ）の低濃度領域の高濃度純銀層がドーナッツ状に形成される。ボンディングワイヤの製造工程において、この高濃度層を保持したまま、水で冷却などして冷間で連続伸線すれば、この高濃度層は細線の線径に比例して縮径される。よって、この高濃度純銀層は、数ギガヘルツ（Ｈｚ）以上の高周波信号用に利用することができる。 Since the high purity gold (Au) is segregated on the surface of the high purity Ag-Pd alloy matrix, when the continuous casting is performed by adding palladium (Pd) and gold (Au) to the high purity silver (Ag), the skin layer In the vicinity, a high concentration pure silver layer of a high concentration region of silver (Ag) and a low concentration region of gold (Au) is formed in a donut shape. In the manufacturing process of the bonding wire, if the high-concentration layer is retained and then cooled with water and continuously drawn cold, the high-concentration layer is reduced in proportion to the wire diameter of the thin wire. Therefore, this high concentration pure silver layer can be used for high frequency signals of several gigahertz (Hz) or more.
直径８ｍｍの連続鋳造ワイヤを２０μｍのボンディングワイヤまで縮径する場合（断面減少率９９．９％以上）、ボンディングワイヤの表皮には理論的には表面から数ｎｍ以下の銀（Ａｇ）の高濃度層が残り、実際に直径８ｍｍの連続鋳造ワイヤから直径２０μｍのワイヤの伸線段階で、図１のような銀（Ａｇ）の高濃度領域（図１の上側の曲線）と金（Ａｕ）の低濃度領域（図１の下側の曲線）の高濃度純銀層が観察された。 When a continuous casting wire with a diameter of 8 mm is reduced to a bonding wire with a diameter of 20 μm (cross-sectional reduction rate of 99.9% or more), the surface of the bonding wire theoretically has a high concentration of silver (Ag) of several nm or less from the surface. The layer remains, and in the wire drawing stage of a continuous casting wire having a diameter of 8 mm to a wire having a diameter of 20 μm, a high concentration region of silver (Ag) as shown in FIG. 1 (upper curve in FIG. 1) and gold (Au) A high concentration pure silver layer in a low concentration region (lower curve in FIG. 1) was observed.
一般的に数ギガＨｚの高周波信号は１μｍ程度の表層を流れ、周波数が高くなればなるほどより表面近傍を流れるとされているので、高濃度の銀（Ａｇ）層が表層に存在すれば、高濃度層が無い従来のボンディングワイヤに比べて、信号量が増え、なおかつ、信号波形を安定させることができる。
Generally, a high frequency signal of several gigahertz flows on the surface layer of about 1 μm, and it is said that the higher the frequency, the closer to the surface, so if a high concentration silver (Ag) layer exists on the surface layer, Compared to a conventional bonding wire without a concentration layer, the signal amount is increased and the signal waveform can be stabilized.
パラジウム（Ｐｄ）の範囲が２．５〜４．０質量％のとき、金（Ａｕ）の範囲が１．５〜２．５質量％であれば、ＦＡＢの溶融ボールがチップ割れを起こすこともなく、安定したボンディング特性を得ることができる。 When the range of palladium (Pd) is 2.5 to 4.0% by mass, the molten ball of FAB may cause chip cracking if the range of gold (Au) is 1.5 to 2.5% by mass. And stable bonding characteristics can be obtained.
（微量添加元素）
本発明のＡｇ−Ｐｄ−Ａｕ基合金は、ロジウム（Ｒｈ）、ルテニウム（Ｒｕ）、イリジウム（Ｉｒ）、銅（Ｃｕ）、ニッケル（Ｎｉ）、鉄（Ｆｅ）、マグネシウム（Ｍｇ）、亜鉛（Ｚｎ）、アルミニウム（Ａｌ）、マンガン（Ｍｎ）、インジウム（Ｉｎ）、ケイ素（Ｓｉ）、ゲルマニウム（Ｇe）、スズ（Ｓｎ）、ベリリウム（Ｂｅ）、ビスマス（Ｂi）、セレン（Ｓｅ）、セリウム（Ｃｅ）、チタン（Ｔｉ）、イットリウム（Ｙ）、カルシウム（Ｃａ）、ランタン（Ｌａ）、ユーロピウム（Ｅｕ）またはアンチモン（Ｓｂ）の少なくとも１種が合計で５〜３００質量ｐｐｍ添加することができる。これらの微量添加元素は、Ａｇ−Ｐｄ−Ａｕ基合金の表面偏析層を変化させることはないが、高濃度純銀層の無いＡｇ−Ｐｄ−Ａｕ基合金ボンディングワイヤにおいてボンディング特性に効果があるので、本発明のＡ−Ｐｄ−Ａｕ基合金ボンディングワイヤにおいても採択した。具体的には、溶融ボールとアルミニウム（Ａｌ）金属またはアルミニウム（Ａｌ）合金のパッド電極との接合性、特に長期間の安定性に効果がある。また、Ａｇ−Ｐｄ−Ａｕ基合金にロジウム（Ｒｈ）、ルテニウム（Ｒｕ）、イリジウム（Ｉｒ）、銅（Ｃｕ）、ニッケル（Ｎｉ）、鉄（Ｆｅ）、マグネシウム（Ｍｇ）、亜鉛（Ｚｎ）、アルミニウム（Ａｌ）、マンガン（Ｍｎ）、インジウム（Ｉｎ）、ケイ素（Ｓｉ）、ゲルマニウム（Ｇe）、スズ（Ｓｎ）、ベリリウム（Ｂｅ）、ビスマス（Ｂi）、セレン（Ｓｅ）、セリウム（Ｃｅ）、チタン（Ｔｉ）、イットリウム（Ｙ）、カルシウム（Ｃａ）、ランタン（Ｌａ）、ユーロピウム（Ｅｕ）またはアンチモン（Ｓｂ）の元素を所定範囲内で添加すると、ＦＡＢの形状を損なうことなくボンディングワイヤのしなやかさを増す。しかし、これらの元素の合計が５質量ｐｐｍ未満では添加効果が無く、３００質量ｐｐｍを超えるとＦＡＢを形成したときの溶融ボールの結晶粒が硬くなりすぎ、チップ割れを起こす。よって、ロジウム（Ｒｈ）、ルテニウム（Ｒｕ）、イリジウム（Ｉｒ）、銅（Ｃｕ）、ニッケル（Ｎｉ）、鉄（Ｆｅ）、マグネシウム（Ｍｇ）、亜鉛（Ｚｎ）、アルミニウム（Ａｌ）、マンガン（Ｍｎ）、インジウム（Ｉｎ）、ケイ素（Ｓｉ）、ゲルマニウム（Ｇe）、スズ（Ｓｎ）、ベリリウム（Ｂｅ）、ビスマス（Ｂi）、セレン（Ｓｅ）、セリウム（Ｃｅ）、チタン（Ｔｉ）、イットリウム（Ｙ）、カルシウム（Ｃａ）、ランタン（Ｌａ）、ユーロピウム（Ｅｕ）またはアンチモン（Ｓｂ）のうちの少なくとも１種が合計で５〜３００質量ｐｐｍの範囲とした。通常のボンディングワイヤは、これらの微量添加元素は合計で１００質量ｐｐｍ以下で使用されることが多いので、これらの微量添加元素は５〜１００質量ｐｐｍが好ましい。
(Trace addition element)
The Ag—Pd—Au base alloy of the present invention is composed of rhodium (Rh), ruthenium (Ru), iridium (Ir), copper (Cu), nickel (Ni), iron (Fe), magnesium (Mg), zinc (Zn ), Aluminum (Al), manganese (Mn), indium (In), silicon (Si), germanium (Ge), tin (Sn), beryllium (Be), bismuth (Bi), selenium (Se), cerium (Ce) ), Titanium (Ti), yttrium (Y), calcium (Ca), lanthanum (La), europium (Eu) or antimony (Sb) can be added in a total amount of 5 to 300 ppm by mass. These trace additive elements do not change the surface segregation layer of the Ag—Pd—Au base alloy, but have an effect on bonding characteristics in an Ag—Pd—Au base alloy bonding wire without a high-concentration pure silver layer. It was also adopted in the A-Pd-Au base alloy bonding wire of the present invention. Specifically, it has an effect on the bondability between a molten ball and a pad electrode made of aluminum (Al) metal or aluminum (Al) alloy, in particular, long-term stability. Moreover, rhodium (Rh), ruthenium (Ru), iridium (Ir), copper (Cu), nickel (Ni), iron (Fe), magnesium (Mg), zinc (Zn), Ag—Pd—Au base alloy, Aluminum (Al), manganese (Mn), indium (In), silicon (Si), germanium (Ge), tin (Sn), beryllium (Be), bismuth (Bi), selenium (Se), cerium (Ce), Addition of titanium (Ti), yttrium (Y), calcium (Ca), lanthanum (La), europium (Eu) or antimony (Sb) within a predetermined range makes the bonding wire flexible without damaging the FAB shape. Increase the size. However, if the total of these elements is less than 5 ppm by mass, there is no effect of addition, and if it exceeds 300 ppm by mass, the crystal grains of the molten ball when FAB is formed become too hard and chip cracking occurs. Therefore, rhodium (Rh), ruthenium (Ru), iridium (Ir), copper (Cu), nickel (Ni), iron (Fe), magnesium (Mg), zinc (Zn), aluminum (Al), manganese (Mn ), Indium (In), silicon (Si), germanium (Ge), tin (Sn), beryllium (Be), bismuth (Bi), selenium (Se), cerium (Ce), titanium (Ti), yttrium (Y) ), Calcium (Ca), lanthanum (La), europium (Eu) or antimony (Sb) in a total range of 5 to 300 ppm by mass. In ordinary bonding wires, these trace additive elements are often used in a total amount of 100 ppm by mass or less, and therefore these trace additive elements are preferably 5 to 100 ppm by mass.
なお、パッド電極は、金（Ａｕ）、パラジウム（Ｐｄ）または金（Ａｕ）または白金（Ｐｔ）の表層からなる電極パッドであることが好ましい。本発明のＡｇ−Ｐｄ−Ａｕ三元合金およびＡｇ−Ｐｄ−Ａｕ三元系合金のボンディングワイヤは、低融点の高濃度純銀層があるためこれらの電極パッドとＦＡＢによる接合性が良いからである。 The pad electrode is preferably an electrode pad made of a surface layer of gold (Au), palladium (Pd), gold (Au), or platinum (Pt). This is because the bonding wires of the Ag—Pd—Au ternary alloy and the Ag—Pd—Au ternary alloy according to the present invention have a high-concentration pure silver layer having a low melting point, so that these electrode pads and FAB have good bondability. .
本発明のＡｇ−Ｐｄ−Ａｕ三元合金およびＡｇ−Ｐｄ−Ａｕ三元系合金のＡｇ−Ｐｄ−Ａｕ基合金ボンディングワイヤは、高速信号の伝達に適した高濃度の銀（Ａｇ）の高濃度純銀層を確実に形成することができ、高濃度純銀層および低濃度金（Ａｕ）層がＡｇ−Ｐｄ−Ａｕ三元合金およびＡｇ−Ｐｄ−Ａｕ三元系合金の芯材に付加されているので、従来のボンディングワイヤよりもパッドとの接合性も良く、数ギガないし十数ギガＨｚの高周波信号の伝送に適した安定した富銀合金の信号層が形成できる。
また、本発明のＡｇ−Ｐｄ−Ａｕ基合金ボンディングワイヤは、高濃度純銀層の厚さが薄いので、ワイヤ自体のバルクの機械的強度があり、これまでのボンディングワイヤと同様の優れたループ特性を有する。
また、ＦＡＢ特性やなどのボンディング特性は、低融点の高濃度純銀層が表層にあるので、溶融ボールとパッド電極との接合性およびセカンド接合性については高濃度純銀層が無いボンディングワイヤよりも優れているという追加的効果がある。特に、パッド電極の表層が、金（Ａｕ）、パラジウム（Ｐｄ）または金（Ａｕ）または白金（Ｐｔ）からなる電極パッドの場合は接合強度が安定している。
The Ag—Pd—Au ternary alloy and the Ag—Pd—Au ternary alloy Ag—Pd—Au based alloy bonding wire of the present invention have a high concentration of silver (Ag) suitable for high-speed signal transmission. A pure silver layer can be reliably formed, and a high-concentration pure silver layer and a low-concentration gold (Au) layer are added to the core material of an Ag—Pd—Au ternary alloy and an Ag—Pd—Au ternary alloy. Therefore, the bonding property to the pad is better than that of the conventional bonding wire, and a stable silver-rich alloy signal layer suitable for transmitting a high frequency signal of several giga to several tens of gigahertz can be formed.
In addition, the Ag—Pd—Au based alloy bonding wire of the present invention has a bulk mechanical strength of the wire itself because the high-concentration pure silver layer is thin, and has excellent loop characteristics similar to those of conventional bonding wires. Have
Also, the bonding characteristics such as FAB characteristics and the like have a low melting point high-concentration pure silver layer on the surface layer, so that the bonding property between the molten ball and the pad electrode and the second bonding property are superior to the bonding wire without the high-concentration pure silver layer. There is an additional effect. In particular, when the surface layer of the pad electrode is an electrode pad made of gold (Au), palladium (Pd), gold (Au), or platinum (Pt), the bonding strength is stable.
また、本発明のＡｇ−Ｐｄ−Ａｕ基合金ボンディングワイヤは、ボンディングワイヤの機械的強度に影響を与えるパラジウム（Ｐｄ）の添加量が４．０質量％以下および金（Ａｕ）の添加量が２．５質量％以下なので、低融点の表面偏析層によってＦＡＢを形成したときの溶融ボールの結晶粒が硬くなりすぎることも無い。また、本発明のＡｇ−Ｐｄ−Ａｕ基合金ボンディングワイヤは、純度９９．９質量％以上のアルミニウム（Ａｌ）金属または０．５〜２．０質量％のシリコン（Ｓｉ）または銅（Ｃｕ）および残部純度９９．９質量％以上のアルミニウム（Ａｌ）合金からなるやわらかいアルミパッドを用いた場合でも、低融点の表面偏析層によってチップ割れやパッドめくれが生じることは無い。この結果、一定期間室温大気中で放置しても、接合界面にマイグレーションが発生せず、高周波信号を安定して伝送できる効果がある。 Further, the Ag—Pd—Au based alloy bonding wire of the present invention has an addition amount of palladium (Pd) that affects the mechanical strength of the bonding wire of 4.0% by mass or less and an addition amount of gold (Au) of 2. Since it is 5 mass% or less, the crystal grains of the molten ball when the FAB is formed by the low melting point surface segregation layer will not be too hard. In addition, the Ag—Pd—Au based alloy bonding wire of the present invention includes an aluminum (Al) metal having a purity of 99.9% by mass or more, silicon (Si) or copper (Cu) having a purity of 0.5 to 2.0% by mass, and Even when a soft aluminum pad made of an aluminum (Al) alloy having a remaining purity of 99.9% by mass or more is used, chip cracking and pad turn-up do not occur due to a low melting point surface segregation layer. As a result, even if left for a certain period of time in the air at room temperature, no migration occurs at the bonding interface, and there is an effect that a high-frequency signal can be transmitted stably.
表１に示す成分組成を有するＡｇ−Ｐｄ−Ａｕ三元合金およびＡｇ−Ｐｄ−Ａｕ三元系合金（いずれも、パラジウム（Ｐｄ）および金（Ａｕ）の純度は９９．９９質量％以上とし、銀（Ａｇ）の純度は９９．９９９質量％以上とし、 微量添加元素として、ロジウム（Ｒｈ）、ルテニウム（Ｒu）、イリジウム（Ｉｒ）、銅（Ｃｕ）、ニッケル（Ｎｉ）、鉄（Ｆｅ）、マグネシウム（Ｍｇ）、亜鉛（Ｚｎ）、アルミニウム（Ａｌ）、マンガン（Ｍｎ）、インジウム（Ｉｎ）、ケイ素（Ｓｉ）、ゲルマニウム（Ｇｅ）、スズ（Ｓｎ）、ベリリウム（Ｂｅ）、ビスマス（Ｂｉ）、セレン（Ｓｅ）、セリウム（Ｃｅ）、チタン（Ｔｉ）、イットリウム（Ｙ）、カルシウム（Ｃａ）、ランタン（Ｌａ）、ユーロピウム（Ｅｕ）、アンチモン（Ｓｂ）の合計を５〜３００ｐｐｍとした。また、その製造方法は、通常の純金ボンディングワイヤと同様に溶解し、不活性雰囲気中で８ｍｍ径まで連続鋳造した。引き続き、この連続鋳造した太線をダイヤモンドダイスにより連続して２０μｍの最終線径まで湿式で断面減少率が９９．９９％以上の連続冷間伸線をし、所定の調質熱処理を施して、２０μｍの線径を有する本発明に係るボンディングワイヤ（以下、「実施品」という）１〜２１を製造した。
実施例１〜９が請求項１に係る実施品および実施例１０〜２１が請求項２に係る実施品である。
Ag-Pd-Au ternary alloy and Ag-Pd-Au ternary alloy having the composition shown in Table 1 (both the purity of palladium (Pd) and gold (Au) is 99.99 mass% or more, The purity of silver (Ag) is 99.999% by mass or more, and rhodium (Rh), ruthenium (Ru), iridium (Ir), copper (Cu), nickel (Ni), iron (Fe), Magnesium (Mg), zinc (Zn), aluminum (Al), manganese (Mn), indium (In), silicon (Si), germanium (Ge), tin (Sn), beryllium (Be), bismuth (Bi), Combination of selenium (Se), cerium (Ce), titanium (Ti), yttrium (Y), calcium (Ca), lanthanum (La), europium (Eu), antimony (Sb) In addition, the manufacturing method was dissolved in the same manner as a normal pure gold bonding wire, and was continuously cast up to a diameter of 8 mm in an inert atmosphere. The bonding wire according to the present invention having a wire diameter of 20 μm (hereinafter referred to as “the wire”) having a wire diameter of 20 μm is subjected to continuous cold drawing with a cross-section reduction rate of 99.99% or more by wet treatment up to a final wire diameter of 20 μm and a predetermined tempering heat treatment. 1 to 21).
Examples 1 to 9 are products according to claim 1 and Examples 10 to 21 are products according to claim 2.
実施例と同様にして、本発明の組成範囲に入らない表１に示す成分組成の比較品のボンディングワイヤ２２〜２５（以下、「比較品」という）を製造した。
なお、比較品２５は、実施例と同様にして連続鋳造した８ｍｍφの太線を８０℃の希硝酸で酸洗いした素線を連続伸線（縮径）し、表層に表面偏析層がないボンディングワイヤを形成したものである。よって、比較品２５は、組成範囲は本発明の範囲内にあるが、酸洗いされている点で実施品と異なっている。
In the same manner as in the examples, comparative bonding wires 22 to 25 (hereinafter referred to as “comparative products”) having the composition shown in Table 1 that do not fall within the composition range of the present invention were manufactured.
The comparative product 25 is a bonding wire in which a 8 mmφ thick wire continuously cast in the same manner as in the Examples is continuously drawn (reduced) by pickling with 80 ° C. diluted nitric acid, and the surface layer does not have a surface segregation layer. Is formed. Therefore, the comparative product 25 has a composition range within the range of the present invention, but is different from the actual product in that it is pickled.
なお、本発明および比較例における調質熱処理は、金線の場合と同様に、管状炉において、温度およびスピードを調整の上、引張り破断試験機による測定で伸びが所定の値となるように調整するための熱処理であり、この調質熱処理では実施品の表面に偏析したドーナッツ状の高濃度純銀層が消失することは無かった。
[高濃度純銀層の確認]
The tempering heat treatment in the present invention and the comparative example is adjusted so that the elongation becomes a predetermined value as measured by a tensile fracture tester in a tubular furnace after adjusting the temperature and speed in the same manner as in the case of a gold wire. In this tempering heat treatment, the donut-like high concentration pure silver layer segregated on the surface of the product was not lost.
[Confirmation of high-concentration pure silver layer]
実施品１の組成を有するＡｇ−Ｐｄ−Ａｕ基合金を不活性雰囲気下で直径８ｍｍの太線に連続鋳造した。この太線を水冷で連続伸線し、伸び率が４％となるように調質熱処理して直径２０μｍのボンディングワイヤを得た。このボンディングワイヤの銀（Ａｇ）および金（Ａｕ）元素について表層から中心方向への深さ方向のオージェ分析をした。その結果は図１上側の模式図で示す曲線および下側の曲線のようになった。
図１の模式図で示す通り、実施品は表面から１０ｎｍ近辺まで高濃度の銀（Ａｇ）の漸減層が存在し、対照的に、金（Ａｕ）の合金化元素は逆の低濃度の漸増層が存在する。なお、パラジウム（Ｐｄ）の濃度は、図示していないが、高濃度純銀層中も芯材中もほぼ一定であった。
［硫化銀の確認］
An Ag—Pd—Au base alloy having the composition of Example 1 was continuously cast into a thick wire having a diameter of 8 mm under an inert atmosphere. The thick wire was continuously drawn with water cooling, and tempered and heat-treated so that the elongation was 4% to obtain a bonding wire having a diameter of 20 μm. Auger analysis in the depth direction from the surface layer toward the center was performed on the silver (Ag) and gold (Au) elements of the bonding wire. As a result, the curve shown in the schematic diagram on the upper side of FIG. 1 and the curve on the lower side were obtained.
As shown in the schematic diagram of FIG. 1, the product has a gradually decreasing layer of silver (Ag) with a high concentration from the surface to around 10 nm, and in contrast, the alloying element of gold (Au) has an increasing concentration at the opposite low concentration. There is a layer. Although the concentration of palladium (Pd) is not shown, it was almost constant both in the high concentration pure silver layer and in the core material.
[Confirmation of silver sulfide]
実施品１のボンディングワイヤを室温の大気中に３０日間放置して、硫化膜厚測定機（サーマトロニクス社製ＱＣ−２００）を用いて、最表面を連続電気化学還元法による硫化銀（Ａｇ２Ｓ）の膜厚を測定した。その結果、硫化銀（Ａｇ２Ｓ）膜は検出されなかった。これを図２の赤線（Ｌ字状曲線）に示す。 The bonding wire of the product 1 was left in the atmosphere at room temperature for 30 days, and the outermost surface was silver sulfide (Ag 2) by a continuous electrochemical reduction method using a sulfide film thickness measuring machine (QC-200 manufactured by Thermatronics). The film thickness of S) was measured. As a result, a silver sulfide (Ag 2 S) film was not detected. This is shown in the red line (L-shaped curve) in FIG.
比較品２２のボンディングワイヤを実施品１と同様に、室温の大気中に３０日間放置して、硫化銀（Ａｇ２Ｓ）の膜厚を測定した。その結果、硫化銀（Ａｇ２Ｓ）膜が検出された。これを図２の緑線（階段状曲線）に示す。 The bonding wire of the comparative product 22 was left in the air at room temperature for 30 days in the same manner as the working product 1, and the film thickness of silver sulfide (Ag 2 S) was measured. As a result, a silver sulfide (Ag 2 S) film was detected. This is shown by the green line (stepped curve) in FIG.
詳述すると、図２は時間に伴う電圧変化をグラフ化したものである。硫化銀（Ａｇ２Ｓ）を形成した比較品２２の場合、電圧が−０．２５〜−０．８０Ｖの区間において時間が変化した場合でも、図２の緑線（階段状曲線）に示すように、硫化銀（Ａｇ２Ｓ）膜が存在する範囲で、電圧は変化しない現象が生じる。一方、実施品１のボンディングワイヤは、上述した電圧の区間において、上述した階段状現象はみられず、図２の赤線（Ｌ字状曲線）に示すように、時間の経過に伴って電圧が変化した。電圧が変化しなかった領域がなかったことから、実施品１のボンディングワイヤの最表面は、硫化銀（Ａｇ２Ｓ）膜を形成していないことがわかる。 More specifically, FIG. 2 is a graph showing voltage changes with time. In the case of the comparative product 22 in which silver sulfide (Ag 2 S) is formed, even when the time changes in the section where the voltage is −0.25 to −0.80 V, as shown by the green line (stepped curve) in FIG. In addition, a phenomenon in which the voltage does not change occurs in the range where the silver sulfide (Ag 2 S) film exists. On the other hand, the bonding wire of the product 1 does not show the above-mentioned step-like phenomenon in the above-described voltage section, and the voltage with time elapses as shown by the red line (L-shaped curve) in FIG. Changed. Since there was no region where the voltage did not change, it can be seen that the outermost surface of the bonding wire of the product 1 did not form a silver sulfide (Ag 2 S) film.
また、実施品１の最表面を走査型オージェ分析装置（ＶＧ社製ＭＩＣＲＯＬＡＢ-３１０Ｄ）によって定性分析したところ、イオウ（Ｓ）が検出された。この定性分析結果を図３に示す。
図３に示すように、実施品１のボンディングワイヤの最表面にはイオウ（Ｓ）が存在していることがわかる。しかし、図２の結果から硫化銀（Ａｇ２Ｓ）膜が検出されなかったことから、実施品１のボンディングワイヤのイオウ（Ｓ）は最表面に存在する銀（Ａｇ）と反応しているものの、強固な硫化銀（Ａｇ２Ｓ）膜を形成していないことから、物理的に吸着した不安定な硫化銀の結合状態であることがわかる。また、図３から明らかな通り、実施品１のボンディングワイヤの最表面の金属元素には、銀（Ａｇ）以外のパラジウム（Ｐｄ）と金（Ａｕ）が検出されず、実質的に高濃度の銀（Ａｇ）層だけなので、高速信号層として最適な構成であることがわかる。
［アルミスプラッシュ試験］
Moreover, when the outermost surface of the implementation product 1 was qualitatively analyzed with a scanning Auger analyzer (MICROLAB-310D manufactured by VG), sulfur (S) was detected. The qualitative analysis results are shown in FIG.
As shown in FIG. 3, it can be seen that sulfur (S) is present on the outermost surface of the bonding wire of the product 1. However, since no silver sulfide (Ag 2 S) film was detected from the results of FIG. 2, the sulfur (S) of the bonding wire of Example 1 reacted with silver (Ag) present on the outermost surface. From the fact that a strong silver sulfide (Ag 2 S) film is not formed, it can be understood that the bonded state is unstable silver sulfide physically adsorbed. Further, as is apparent from FIG. 3, palladium (Pd) and gold (Au) other than silver (Ag) are not detected in the metal element on the outermost surface of the bonding wire of the product 1, and the concentration is substantially high. Since it is only a silver (Ag) layer, it turns out that it is the optimal structure as a high-speed signal layer.
[Aluminum splash test]
これらの実施品１〜２１および比較品２２〜２５を汎用のワイヤボンダーにセットし、ダミーの半導体ＩＣ（テストパターンをウェーハに埋め込んだもの、略称「ＴＥＧ」）表面のＡｌ−１．０質量％Ｓｉ−０．５質量％Ｃｕ合金からなる７０μｍ角アルミパッド（表面に２０ｎｍの金（Ａｕ）層を蒸着したもの）に、吹付け窒素雰囲気下にて３８μｍ狙いでフリー・エアー・ボール（ＦＡＢ）を作製し、基材の加熱温度：２００℃、ループ長さ：５ｍｍ、ループ高さ：２２０μｍ、圧着ボール径：５０μｍ、圧着ボール高さ：１０μｍ、の条件でボールボンディングをおこなった。アルミスプラッシュ量の測定方法は、汎用の走査型電子顕微鏡（ＳＥＭ）を用いて各ワイヤの圧着ボールを直上から観察し、圧着ボールの外周部を基点とし、圧着ボールから最もはみ出したアルミニウムの位置を計測した。はみだしたアルミニウム量が２μｍ未満の場合を○とし、２μｍ以上４μ未満の場合を△、４μｍ以上を×と判定した。このアルミスプラッシュ試験について評価結果を表２に示す。 These products 1 to 21 and comparative products 22 to 25 are set in a general-purpose wire bonder, and Al-1.0 mass% on the surface of a dummy semiconductor IC (a test pattern embedded in a wafer, abbreviated as “TEG”) Free air ball (FAB) aiming at 38 μm in a spraying nitrogen atmosphere on a 70 μm square aluminum pad (with a 20 nm gold (Au) layer deposited on the surface) made of Si-0.5 mass% Cu alloy The substrate was heated under the conditions of 200 ° C., loop length: 5 mm, loop height: 220 μm, pressure ball diameter: 50 μm, pressure ball height: 10 μm. The method of measuring the amount of aluminum splash is to observe the pressure-bonded ball of each wire from directly above using a general-purpose scanning electron microscope (SEM), and use the outer periphery of the pressure-bonded ball as the base point to determine the position of the aluminum that protrudes most from the pressure-bonded ball. Measured. The case where the amount of protruding aluminum was less than 2 μm was evaluated as “◯”, the case where it was 2 μm or more and less than 4 μm was evaluated as Δ, and the case where it was 4 μm or more was determined as ×. The evaluation results for this aluminum splash test are shown in Table 2.
さらに、この試料についてチップダメージをみた。チップダメージ試験は、水酸化ナトリウム水溶液で上記の基材のアルミパッドを溶かした後にチップを実体顕微鏡で観察した結果である。表２中の「チップダメージ試験」は、、傷やクラックが少しでも入っている場合は×とし、傷やクラックがまったくない場合を○として、それぞれ。表２に示す。
［信号波形の劣化試験］
Furthermore, chip damage was observed for this sample. The chip damage test is a result of observing the chip with a stereomicroscope after dissolving the aluminum pad of the base material with an aqueous sodium hydroxide solution. “Chip damage test” in Table 2 is indicated as “x” when any scratches or cracks are present, and “◯” when no scratches or cracks are present. It shows in Table 2.
[Deterioration test of signal waveform]
次に、信号波形の劣化試験は四端子法を用いて測定した。試料は実施品・比較品のワイヤ（それぞれ、線径２０μｍ、長さ１００ｍｍ）を使用した。測定には汎用性ファンクションジェネレーターを用いて１０ＧＨｚ、２Ｖのパルス波形を実施品ワイヤおよび比較品ワイヤへ伝播させ、１０ＧＨｚ帯域のパルス波形が測定可能な所定の汎用のデジタルオシロスコープおよびプローブを用いて信号波形を測定した。測定用プローブ間隔は５０ｍｍとした。信号波形の劣化の度合いはワイヤへ伝播する出力信号波形が入力電圧値に達するまでの遅延時間を測定した。ここで、実験結果より従来の純金ワイヤ（Ｃａ１５ｐｐｍ、Ｅｕ２０ｐｐｍおよび残部９９．９９９質量％Ａｕ）の信号遅延時間は２０％であることを確認した。したがって、信号遅延時間の判定は、遅延時間が従来のワイヤと比較して２０％未満の場合は○、２０％より遅延が大きい場合は×とした。この信号波形の劣化試験について実施品・比較品のワイヤの評価結果を表２に示す。
［圧着ボールのシェア強度試験］
Next, the signal waveform degradation test was measured using the four probe method. As the sample, the wire of the implemented product / comparative product (wire diameter 20 μm,
[Pressure ball shear strength test]
アルミスプラッシュ試験と同様の部材および評価装置を用いて、実施品ワイヤおよび比較品ワイヤに対し、専用のＩＣチップにワイヤボンダーでボンディングを行い、１００点について、デイジ社製の製品名「万能ボンドテスター（ＢＴ）（型式４０００）」を用い、ボールボンディング時の圧着ボールのシェア強度評価を行った。この圧着ボールのシェア評価結果を表２に示す。 Using the same members and evaluation equipment as in the aluminum splash test, bonding was performed on the product wire and the comparative product wire on a dedicated IC chip with a wire bonder. About 100 points, the product name “Universal Bond Tester” (BT) (model 4000) "was used to evaluate the shear strength of the press-bonded ball during ball bonding. Table 2 shows the result of the shear evaluation of this press-bonded ball.
表２中、「ボールシェア」は、第一ボンドにおけるシェア荷重値を示し、○は１２ｋｇ／ｍｍ２以上、△は１０ｋｇ／ｍｍ２以上１２ｋｇ／ｍｍ２未満、そして、×は１０ｋｇ／ｍｍ２未満もしくはボール剥がれが発生した場合を示す。 In Table 2, “Ball share” indicates the shear load value in the first bond, ○ is 12 kg / mm 2 or more, Δ is 10 kg / mm 2 or more and less than 12 kg / mm 2 , and × is less than 10 kg / mm 2 Or it shows the case where the ball peeling occurs.
表２の結果から明らかな通り、信号波形の劣化試験について、本発明の実施品１〜２１はすべて劣化が見られないのに対し、比較品２２〜２５はいずれも劣っていることがわかる。
また、アルミスプラッシュ試験、チップダメージ試験および圧着ボールのシェア強度試験については、本発明の実施品１〜２１はすべて良好であるのに対し、比較品２２は圧着ボールのシェア強度試験が劣っており、比較品２３と２４はアルミスプラッシュ試験およびチップダメージ試験が劣っていることがわかる。
As is clear from the results of Table 2, it can be seen that in the deterioration test of the signal waveform, all the products 1 to 21 of the present invention are not deteriorated, whereas the comparison products 22 to 25 are all inferior.
In addition, regarding the aluminum splash test, chip damage test, and shear strength test of the press-bonded ball, all of the products 1 to 21 of the present invention are good, whereas the comparative product 22 is inferior in the shear strength test of the press-bonded ball. It can be seen that Comparative products 23 and 24 are inferior in the aluminum splash test and the chip damage test.
本発明のボンディングワイヤは、数ギガないし十数ギガヘルツの超高周波信号の伝送に最適なボンディングワイヤであり、広く高周波信号の伝送に適した信号用ボンディングワイヤの用途がある。
The bonding wire of the present invention is an optimum bonding wire for transmission of ultra high frequency signals of several gigahertz to several tens of gigahertz, and is widely used as a signal bonding wire suitable for transmission of high frequency signals.
Claims (6)
3. The high-speed signal line bonding wire according to claim 1, wherein the pad electrode is an electrode pad made of a surface layer of gold (Au), palladium (Pd), or platinum (Pt). .
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2013102191A JP5399581B1 (en) | 2013-05-14 | 2013-05-14 | High speed signal bonding wire |
| KR1020130138234A KR101568479B1 (en) | 2013-05-14 | 2013-11-14 | Bonding wire for high speed signal |
| SG2013094669A SG2013094669A (en) | 2013-05-14 | 2013-12-20 | Bonding wire for high speed signal |
| TW103101755A TWI508204B (en) | 2013-05-14 | 2014-01-17 | High-speed signal line with bonding wire |
| CN201410108092.5A CN104157625B (en) | 2013-05-14 | 2014-03-21 | HW High Way closing line |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2013102191A JP5399581B1 (en) | 2013-05-14 | 2013-05-14 | High speed signal bonding wire |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP5399581B1 JP5399581B1 (en) | 2014-01-29 |
| JP2014222725A true JP2014222725A (en) | 2014-11-27 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2013102191A Expired - Fee Related JP5399581B1 (en) | 2013-05-14 | 2013-05-14 | High speed signal bonding wire |
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| Country | Link |
|---|---|
| JP (1) | JP5399581B1 (en) |
| KR (1) | KR101568479B1 (en) |
| CN (1) | CN104157625B (en) |
| SG (1) | SG2013094669A (en) |
| TW (1) | TWI508204B (en) |
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| CN105296788A (en) * | 2015-11-13 | 2016-02-03 | 汕头市骏码凯撒有限公司 | Silver alloy bonding wire and manufacturing method thereof |
| JP2018530899A (en) * | 2015-09-29 | 2018-10-18 | ヘレウス マテリアルズ シンガポール ピーティーイー． リミテッド | Silver alloy wire |
| EP3549715A1 (en) * | 2015-11-23 | 2019-10-09 | Heraeus Materials Singapore Pte. Ltd. | Coated wire |
| WO2021065036A1 (en) * | 2019-10-01 | 2021-04-08 | 田中電子工業株式会社 | Wire joining structure, bonding wire used in same, and semiconductor device |
| WO2022085365A1 (en) * | 2020-10-20 | 2022-04-28 | 日鉄マイクロメタル株式会社 | Ag ALLOY BONDING WIRE FOR SEMICONDUCTOR DEVICE |
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| MY168617A (en) | 2014-04-21 | 2018-11-14 | Nippon Micrometal Corp | Bonding wire for semiconductor device |
| JP6343197B2 (en) * | 2014-07-16 | 2018-06-13 | タツタ電線株式会社 | Bonding wire |
| JP2016029691A (en) * | 2014-07-25 | 2016-03-03 | 田中電子工業株式会社 | Structure of surface property-modified silver palladium alloy wire |
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| EP3086362B1 (en) | 2015-02-26 | 2023-11-22 | Nippon Micrometal Corporation | Bonding wire for semiconductor devices |
| WO2016203659A1 (en) | 2015-06-15 | 2016-12-22 | 日鉄住金マイクロメタル株式会社 | Bonding wire for semiconductor device |
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| JPH11288962A (en) * | 1998-04-01 | 1999-10-19 | Sumitomo Metal Mining Co Ltd | Bonding wire |
| US7969021B2 (en) * | 2000-09-18 | 2011-06-28 | Nippon Steel Corporation | Bonding wire for semiconductor device and method for producing the same |
| JP2003059963A (en) * | 2001-08-01 | 2003-02-28 | Doko Cho | Gold wire for package and high-frequency transmission, and manufacturing method thereof |
| JP5116101B2 (en) * | 2007-06-28 | 2013-01-09 | 新日鉄住金マテリアルズ株式会社 | Bonding wire for semiconductor mounting and manufacturing method thereof |
| TW201028227A (en) * | 2009-01-23 | 2010-08-01 | jun-de Li | Method for manufacturing composite metal wire and product thereof |
| JP5616165B2 (en) * | 2010-08-24 | 2014-10-29 | タツタ電線株式会社 | Silver bonding wire |
| JP2012099577A (en) * | 2010-10-29 | 2012-05-24 | Sumitomo Metal Mining Co Ltd | Bonding wire |
| CN102130068B (en) * | 2011-01-07 | 2012-09-05 | 四川威纳尔特种电子材料有限公司 | Alloy-type bonding wire with composite plating on surface |
| JP5064577B2 (en) * | 2011-01-20 | 2012-10-31 | タツタ電線株式会社 | Ball bonding wire |
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| JP2013004781A (en) | 2011-06-17 | 2013-01-07 | Sanken Electric Co Ltd | Semiconductor device and semiconductor device manufacturing method |
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| JP5165810B1 (en) * | 2012-09-12 | 2013-03-21 | 田中電子工業株式会社 | Silver gold palladium alloy bump wire |
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2013
- 2013-05-14 JP JP2013102191A patent/JP5399581B1/en not_active Expired - Fee Related
- 2013-11-14 KR KR1020130138234A patent/KR101568479B1/en active IP Right Grant
- 2013-12-20 SG SG2013094669A patent/SG2013094669A/en unknown
-
2014
- 2014-01-17 TW TW103101755A patent/TWI508204B/en not_active IP Right Cessation
- 2014-03-21 CN CN201410108092.5A patent/CN104157625B/en not_active Expired - Fee Related
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2018530899A (en) * | 2015-09-29 | 2018-10-18 | ヘレウス マテリアルズ シンガポール ピーティーイー． リミテッド | Silver alloy wire |
| CN105296788A (en) * | 2015-11-13 | 2016-02-03 | 汕头市骏码凯撒有限公司 | Silver alloy bonding wire and manufacturing method thereof |
| EP3549715A1 (en) * | 2015-11-23 | 2019-10-09 | Heraeus Materials Singapore Pte. Ltd. | Coated wire |
| US10960498B2 (en) | 2015-11-23 | 2021-03-30 | Heraeus Materials Singapore Pte., Ltd. | Coated wire |
| WO2021065036A1 (en) * | 2019-10-01 | 2021-04-08 | 田中電子工業株式会社 | Wire joining structure, bonding wire used in same, and semiconductor device |
| JPWO2021065036A1 (en) * | 2019-10-01 | 2021-04-08 | ||
| JP7269361B2 (en) | 2019-10-01 | 2023-05-08 | 田中電子工業株式会社 | Wire bonding structure, bonding wire and semiconductor device used therefor |
| WO2022085365A1 (en) * | 2020-10-20 | 2022-04-28 | 日鉄マイクロメタル株式会社 | Ag ALLOY BONDING WIRE FOR SEMICONDUCTOR DEVICE |
Also Published As
| Publication number | Publication date |
|---|---|
| KR20140134593A (en) | 2014-11-24 |
| KR101568479B1 (en) | 2015-11-11 |
| CN104157625B (en) | 2017-03-01 |
| CN104157625A (en) | 2014-11-19 |
| TW201444005A (en) | 2014-11-16 |
| JP5399581B1 (en) | 2014-01-29 |
| SG2013094669A (en) | 2014-12-30 |
| TWI508204B (en) | 2015-11-11 |
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