WO2011118009A1 - HIGH-PURITY Cu BONDING WIRE - Google Patents

HIGH-PURITY Cu BONDING WIRE Download PDF

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Publication number
WO2011118009A1
WO2011118009A1 PCT/JP2010/055281 JP2010055281W WO2011118009A1 WO 2011118009 A1 WO2011118009 A1 WO 2011118009A1 JP 2010055281 W JP2010055281 W JP 2010055281W WO 2011118009 A1 WO2011118009 A1 WO 2011118009A1
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WIPO (PCT)
Prior art keywords
copper
phosphorus
purity
wire
copper alloy
Prior art date
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PCT/JP2010/055281
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French (fr)
Japanese (ja)
Inventor
山下　勉
岳 桑原
純一 岡崎
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田中電子工業株式会社
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Publication date
Application filed by 田中電子工業株式会社 filed Critical 田中電子工業株式会社
Priority to MYPI2012700686A priority Critical patent/MY166908A/en
Priority to CN201080065756.4A priority patent/CN102859672B/en
Priority to PCT/JP2010/055281 priority patent/WO2011118009A1/en
Priority to KR1020127024832A priority patent/KR101280053B1/en
Priority to SG2012070769A priority patent/SG184233A1/en
Publication of WO2011118009A1 publication Critical patent/WO2011118009A1/en

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C9/00—Alloys based on copper
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Definitions

  • the present invention relates to a copper alloy wire that connects an IC chip electrode and a substrate such as a lead by a ball bonding method using a wire bonder, and more particularly to a bonding wire in which the initial ball (FAB) has a soft room temperature hardness.
  • the high-purity copper alloy wire drawn out from the reel is introduced into a capillary as a bonding tool, and then the tip of the copper alloy wire led out to the outlet side of the tool is inactivated.
  • An initial ball (FAB) is formed by melting with a micro discharge between the electrode torch under an atmosphere or a reducing atmosphere, and then the molten ball is ultrasonically vibrated on the electrode of the heated IC chip. Crimp.
  • the capillary is moved in the XYZ directions (front and rear, left and right, up and down directions) to form a copper alloy wire attached on the electrode of the IC chip in a predetermined shape, and after wedge bonding to the external wiring lead frame, A method of wire bonding by cutting a high purity copper alloy wire has been adopted.
  • high-purity copper alloy wires are easily oxidized by oxygen present in the atmosphere, so when forming the above-mentioned initial ball (FAB), the surface is covered with an oxide film in the atmosphere and diffuses inside the ball. Impurities present in the molten copper metal are also oxidized by the oxygen. For this reason, the molten ball of high-purity copper alloy wire becomes hard in an atmosphere where oxygen is present, and when thermocompression bonding is performed on the electrodes of the IC chip, the bondability is deteriorated and the IC chip is cracked at the same time. Was a problem.
  • IC chip cracking is thought to be caused by oxide films of high-purity copper alloys so far, and in order to prevent the formation of such oxide films, a completely sealed atmosphere using only an inert gas or an inert gas atmosphere can be used.
  • the initial ball (FAB) is formed by using a gas mixed with hydrogen having a reducing effect to prevent oxidation of the initial ball (FAB) of the copper alloy wire ball (Patent Documents 1, 2, 3). ).
  • Patent Documents 1, 2, and 3 As these measures, several high purity copper alloy wires in which various trace elements are added to high purity copper metal wires have been reported (Patent Documents 1, 2, and 3).
  • the initial ball (FAB) does not become spherical even if it is a high-purity copper alloy wire, or the initial ball (FAB) becomes too hard, and the semiconductor IC chip. Cracks occurred. For this reason, it is impossible to perform thermocompression bonding with a satisfactory initial ball (FAB) with high bonding strength, or a satisfactory loop shape cannot be drawn. It could not be tolerated.
  • the present invention has been made in view of the above circumstances, and the object thereof is a copper alloy wire having a high recrystallization temperature and made of a high-purity copper alloy that can be drawn.
  • An object of the present invention is to provide a bonding wire having an alloy wire initial ball (FAB) or a molten ball having a room temperature hardness lower than that of a copper metal wire made of high-purity copper metal to which a slight amount is not added.
  • FAB alloy wire initial ball
  • molten ball having a room temperature hardness lower than that of a copper metal wire made of high-purity copper metal to which a slight amount is not added.
  • it is a high purity copper alloy wire having a high recrystallization temperature by adding a small amount of phosphorus (P) to high purity copper metal. When a small amount of phosphorus (P) is added, the recrystallization temperature of high-purity copper metal rises rapidly.
  • the copper alloy wire can be drawn by die drawing at room temperature.
  • the purity of the copper (Cu) metal and the amount of phosphorus (P) added are moderate, the room temperature hardness of the initial ball (FAB) of the copper alloy wire to which phosphorus (P) is added does not add phosphorus (P).
  • FAB room temperature hardness of the initial ball
  • the present inventors searched for an additive element that lowers the room temperature hardness of the initial ball (FAB) or molten ball. As a result, it was found that a predetermined amount of phosphorus (P) lowers the room temperature hardness of high purity copper metal initial balls (FAB) or molten balls.
  • the addition effect of phosphorus (P) on high-purity copper metal becomes more apparent as copper (Cu) becomes higher purity, but also depends on the impurity element contained in the copper (Cu) metal.
  • the present inventors have not added phosphorus (P) to a copper alloy wire obtained by adding a small amount of phosphorus (P) to a high-purity copper metal wire of about 99.9999% by mass, although the recrystallization temperature rises. It has been discovered that the room temperature hardness of initial balls (FAB) or molten balls is lower than high purity copper metal wires. Until now, when a small amount of some elements are added to a high-purity copper metal wire of 99.999% by mass or more, the recrystallization temperature of the copper alloy wire rises and the room temperature hardness of the copper alloy wire itself increases. That was known. That is, the knowledge that the room temperature hardness of the high purity copper alloy wire increases was considered to increase with the addition amount of the trace amount of additive element.
  • Patent Document 1 In the phosphorous (P) content in the range of 40 to 400 ppm by mass, the formation of oxides during the formation of molten balls is prevented, the hardness of the balls is reduced and chip cracking is prevented,
  • Patent Document 2 is a bonding wire containing at least one of Mg and P in a total amount of 10 to 700 ppm by mass and oxygen in a range of 6 to 20 ppm by mass, Although addition of Mg and phosphorus (P) can avoid chip damage as long as it is within the above range, its action is an element that improves hardness.
  • Patent Document 3 examples are Ti, Hf, V, Nb, Ta, Ni, Pd, Pt, Au, Cd, B, Al, In, Si, Ge, P, Sb, Bi, Se, and Te.
  • a bonding wire containing 0.001 to 2% by weight of one or more elements selected from the above, with the balance being substantially copper is described, but these component elements improve the hardness. Conceivable.
  • 1 is a graph of data showing these relationships, in which the vertical axis indicates the hardness with respect to the P content after formation of the molten ball, and the phosphorus (P) content is around 200 ppm by mass. It is a generally known phenomenon that the hardness increases as the phosphorus (P) content increases, but here the hardness increases in the region where the phosphorus (P) content is lower than around 150 ppm, and once reaches 100 mN It can be seen that there is a region where the hardness suddenly decreases after rising. That is the enlarged area in the figure, and the hardness is less than or equal to that of high-purity copper metal with a phosphorus (P) content of 0 when the P content is near 0.5 to 15 ppm by mass. .
  • the effect of reducing the room temperature hardness of phosphorus (P) on a high-purity Cu alloy is considered to be based on the following phenomenon. That is, when the copper alloy wire as the bonding wire is melted by spark discharge, oxygen is taken into the molten copper (Cu) from the atmosphere, but the oxide film on the copper alloy wire surface is partially cut by phosphorus (P), It seems to be evaporated. Then, in the case of a high-purity copper alloy wire of about 99.998% by mass or more, since the metal elements excluding phosphorus (P) are only about 10 ppm by mass, the absolute amount of impurity elements associated with oxygen is reduced, and hard oxidation This is consistent with the low room temperature hardness of the high purity copper alloy wire because no film is formed.
  • the chip damage of the IC chip caused by the copper alloy wire is reduced if the initial temperature (FAB) of the copper alloy wire is low. Should be able to.
  • the recrystallization temperature of the copper alloy wire which is indispensable for wire drawing under the same conditions, rises, and the aging softening of the copper alloy wire itself is relaxed, The strength required for the drawing process is maintained. From such knowledge, the present inventors have completed the present invention.
  • the initial temperature (FAB) of the copper alloy wire to which phosphorus (P) is added does not add phosphorus (P).
  • a copper alloy wire for high-purity ball bonding is provided which is characterized by being lower than that of a copper metal wire.
  • (2) In a copper alloy bonding wire made of phosphorus (P) and copper (Cu), the initial hardness (FAB) of the copper alloy wire to which phosphorus (P) is added does not add phosphorus (P).
  • Copper alloy for high-purity ball bonding characterized in that the total amount of metal elements other than phosphorus (P) in copper (Cu) is less than the content of phosphorus (P) and lower than that of copper metal wire A wire is provided.
  • phosphorus (P) is made of 0.5 to 15 mass ppm and the balance is made of copper (Cu) having a purity of 99.9985 mass% or more.
  • the room temperature hardness of the initial ball (FAB) of the copper alloy wire is lower than that of a copper metal wire having a purity of 99.99985% by mass or more without adding phosphorus (P).
  • a copper alloy wire for high-purity ball bonding is provided.
  • a copper alloy wire made of copper (Cu) having a phosphorus (P) content of 0.5 to 10 mass ppm and the balance of 99.9985 mass% or more is preferable because the room temperature hardness of the initial ball (FAB) is further reduced.
  • phosphorus (P) is made of 0.5 to 15 mass ppm and the balance is made of copper (Cu) having a purity of 99.9985 mass% or more.
  • the total amount of metal elements other than phosphorus (P) in copper (Cu) is not more than the content of phosphorus (P), the room temperature of the initial ball (FAB) of the copper alloy wire
  • a copper alloy wire for ball bonding characterized in that the hardness is lower than that of a copper metal wire having a purity of 99.9985% by mass or more without adding phosphorus (P).
  • the copper alloy wire for ball bonding according to the present invention does not form a hard oxide film on the surface of the initial ball (FAB) of copper (Cu) due to the deoxidizing action of a small amount of phosphorus (P). There is an effect that can be reduced.
  • the breaking load of the bonding wire in the pull strength measurement is improved by the deoxidizing action of phosphorus (P).
  • the breaking ratio at the wire portion where the loop is formed is larger than the breaking ratio at the crimped portion of the second bond, and these characteristics are improved.
  • the metal elements contained in copper (Cu) having a purity of 99.999% by mass or more are Ag, Ca, Fe, Mn, Mg, Ni, Al, Pb and Si. Is preferred. This is because even if these metal elements coexist with phosphorus (P), the room temperature hardness of the initial ball (FAB) of copper (Cu) is not increased as long as it is a certain amount or less. In addition, when these metal elements are contained in copper (Cu), any metal element has an effect of increasing the recrystallization temperature of copper (Cu) as is known so far.
  • the metal elements contained in copper (Cu) having a purity of 99.999 mass% or more are more preferably less than 10 mass ppm excluding phosphorus (P). This is because the deoxidation action of phosphorus (P), which lowers the room temperature hardness of the initial ball (FAB) of copper (Cu), is better exhibited.
  • FIG. 1 shows the relationship between the phosphorus (P) content of the high-purity Cu alloy bonding wire of the present invention and the breaking strength indicating hardness.
  • the bonding wire of the present invention is specifically manufactured as follows, and the confirmation of the aging softening action, the confirmation of the recrystallization temperature, the room temperature hardness of the molten ball, and the confirmation of the number of chip cracks are as follows. Implemented.
  • a method for producing a copper alloy wire for ball bonding according to the present invention will be described. 99.9999 mass% or more of high purity copper (Cu) metal (referred to as Cu ingot “A”) and 99.999 mass% or more of high purity copper (Cu) metal (Cu ingot “B”) And a copper alloy wire composition shown in Table 1 to which a predetermined amount of phosphorus (P) is added. Those having these compositions are processed into bonding wires in the same manner as in the method of producing a high purity gold wire. First, a predetermined amount of raw material is melted in a vacuum melting furnace and then cast into an ingot. The ingot was subjected to groove roll rolling, and then subjected to annealing treatment, rust prevention treatment, etc., to produce a high purity copper alloy wire having a diameter of 25 ⁇ m.
  • ball bonding on the IC chip side was performed in a 95% nitrogen + 5% hydrogen atmosphere under the conditions of a ball bonding load of 0.2 N, a ball bonding time of 10 milliseconds, and a ball bonding power of 0.30 watts.
  • the second bonding on the external wiring side was performed under the conditions of a load of 0.3 N, a ball bonding time of 10 milliseconds, and a ball bonding power of 0.40 watts.
  • the second bonding on the external wiring side was performed under the conditions of a load of 0.3 N, a ball bonding time of 10 milliseconds, and a ball bonding power of 0.40 watts.
  • the number of non-pressure bonding due to peeling of the Al film in the first bonding was counted.
  • the measurement results are shown in the right column of Table 3.
  • the copper alloy wires added with a predetermined amount of phosphorus (P) in Examples Nos. 1 to 9 at the recrystallization temperature shown in Table 2 were high-purity copper wires in which no phosphorus (P) was added in Comparative Example 10 and Comparative Example 11 It can be seen that the recrystallization temperature is higher than that of a high-purity copper wire to which a slight amount of phosphorus (P) is added.
  • the high-purity copper alloy wire of about 99.999 mass% to which a predetermined amount of phosphorus (P) of Examples No. 6 and 7 was added has the initial room temperature hardness of the phosphorus (P) of Comparative Example 10 at all. It is lower than the high-purity copper metal wire not added and the copper alloy wire added with a large amount of phosphorus (P) in Comparative Example 15, and the number of peeling of the aluminum film in Table 2 is small (the 30,000 times test value is zero). .
  • the bonding wire of the present invention has a low recrystallization temperature
  • the initial ball (FAB) has a low room temperature hardness, and in all cases, the aluminum film peels off significantly after 30,000 bondings. It was done. Therefore, the bonding wire of the present invention has a high recrystallization temperature and a small aging softening action, so that the wire drawing characteristics are maintained.
  • the initial ball has a low room temperature hardness, so that chip cracking is effective. Prevent it.
  • the copper alloy wire of the present invention to which a predetermined amount of phosphorus (P) is added, is excellent in preventing chip cracking by the initial ball (FAB), and in the same manner as the conventional bonding wires. It can be drawn and exhibits an excellent effect in improving the reliability of the semiconductor device.

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Abstract

Provided is a ball bonding wire of a high-purity copper alloy, the wire having a high recrystallization temperature and being easily produced through wiredrawing with a die at room temperature. The ball bonding wire has a low initial ball hardness and causes no breakage of IC chips. Phosphorus (P) is added in an amount as slight as 0.5-15 mass ppm to high-purity copper having a purity of 99.9985 mass% or higher to thereby produce a copper alloy which has a higher recrystallization temperature than high-purity copper having a purity of 99.9999 mass% or higher and which has a lowered initial ball hardness in ball bonding. Those characteristics are thus achieved. Alternatively, phosphorus (P) is added in an amount as slight as 0.5-15 mass ppm to high-purity copper having a purity of 99.9985 mass% or higher, and the total amount of any other impurities contained in the copper is reduced to a value lower than the phosphorus (P) content. Those characteristics are thereby achieved.

Description

高純度ＣｕボンディングワイヤHigh purity Cu bonding wire
　本発明は、ワイヤボンダを用いたボールボンディング法によってＩＣチップ電極とリード等の基板を接続する銅合金ワイヤに関し、特にイニシャルボール（ＦＡＢ）の室温硬さが軟らかいボンディングワイヤに関する。 The present invention relates to a copper alloy wire that connects an IC chip electrode and a substrate such as a lead by a ball bonding method using a wire bonder, and more particularly to a bonding wire in which the initial ball (FAB) has a soft room temperature hardness.
　従来、ＩＣチップの電極と基板上のリード等を接続する方法として金線の代わりに高純度の銅合金ワイヤを用いてボールボンディング法により配線する方法が知られている。 Conventionally, as a method for connecting an electrode of an IC chip and a lead on a substrate, a method of wiring by a ball bonding method using a high purity copper alloy wire instead of a gold wire is known.
　ボールボンディング法により配線する方法においては、リールから繰り出された高純度の銅合金ワイヤは、ボンディングツールとしてのキャピラリに導入され、次いでそのツールの出口側に導出された銅合金ワイヤの先端を不活性雰囲気または還元性雰囲気のもとで電極トーチとの間の微小放電により溶融してイニシャルボール（ＦＡＢ）を形成した後、加熱されたＩＣチップの電極上にこの溶融ボールを超音波振動させながら熱圧着する。その後、キャピラリをＸＹＺ方向（前後、左右、上下方向）に移動させてＩＣチップの電極上に取り付けられた銅合金ワイヤを所定の形状にループを形成し、外部配線リードフレームにウェッジボンディングした後、高純度の銅合金ワイヤを切断してワイヤボンディングする方法が採られている。 In the method of wiring by the ball bonding method, the high-purity copper alloy wire drawn out from the reel is introduced into a capillary as a bonding tool, and then the tip of the copper alloy wire led out to the outlet side of the tool is inactivated. An initial ball (FAB) is formed by melting with a micro discharge between the electrode torch under an atmosphere or a reducing atmosphere, and then the molten ball is ultrasonically vibrated on the electrode of the heated IC chip. Crimp. Thereafter, the capillary is moved in the XYZ directions (front and rear, left and right, up and down directions) to form a copper alloy wire attached on the electrode of the IC chip in a predetermined shape, and after wedge bonding to the external wiring lead frame, A method of wire bonding by cutting a high purity copper alloy wire has been adopted.
　しかしながら、高純度銅合金ワイヤは大気中に存在する酸素によって酸化しやすいため、前述のイニシャルボール（ＦＡＢ）を形成する際、大気中ではその表面が酸化膜に覆われ、かつ、ボール内部に拡散した酸素によって溶融銅金属中に存在する不純物も酸化してしまう。このため、酸素が存在する雰囲気中では高純度銅合金ワイヤの溶融ボールが硬くなり、前記ＩＣチップの電極上に熱圧着する際、接合性が悪くなると同時にＩＣチップに割れが生じるようになることが問題であった。ＩＣチップの割れは、これまで高純度銅合金の酸化膜に起因すると考えられ、このような酸化膜の形成を防ぐため不活性ガスのみを用いた完全密閉雰囲気にしたり、不活性ガス雰囲気中に還元効果のある水素を混入したガスを用いたりして前記イニシャルボール（ＦＡＢ）の形成を行い、銅合金ワイヤのボールのイニシャルボール（ＦＡＢ）の酸化を防止してきた（特許文献１、２、３）。 However, high-purity copper alloy wires are easily oxidized by oxygen present in the atmosphere, so when forming the above-mentioned initial ball (FAB), the surface is covered with an oxide film in the atmosphere and diffuses inside the ball. Impurities present in the molten copper metal are also oxidized by the oxygen. For this reason, the molten ball of high-purity copper alloy wire becomes hard in an atmosphere where oxygen is present, and when thermocompression bonding is performed on the electrodes of the IC chip, the bondability is deteriorated and the IC chip is cracked at the same time. Was a problem. IC chip cracking is thought to be caused by oxide films of high-purity copper alloys so far, and in order to prevent the formation of such oxide films, a completely sealed atmosphere using only an inert gas or an inert gas atmosphere can be used. The initial ball (FAB) is formed by using a gas mixed with hydrogen having a reducing effect to prevent oxidation of the initial ball (FAB) of the copper alloy wire ball (Patent Documents 1, 2, 3). ).
　他方、銅金属ワイヤの純度を９９．９９質量％から９９．９９９質量％ないし９９．９９９９質量％まで高めることにより、できるだけ不純物または酸化物となる元素を減らすことを目指す学術的な研究も行なわれた。銅金属ワイヤの純度が高くなればなるほど、溶融ボールを形成したときのボール形状が真球に近くなっていき、真球になればなるほど熱圧着による接合面での変形が真円形になっていくからである。
しかし、銅金属ワイヤの純度が高純度になればなるほど、再結晶温度が低くなり、銅金属ワイヤ自体が軟らかくなる。そのため、あらかじめ加工硬化させておいても時効軟化してしまい、軟らかくなった高純度の銅金属ワイヤの取扱いはきわめて困難となる。特に、ボンディングワイヤ用の銅金属ワイヤは伸線加工によって大量生産されているため、銅金属ワイヤの純度を高くしていくと、伸線加工中に銅金属ワイヤと伸線ダイスとの摩擦熱によって高純度の銅金属ワイヤ自体が軟化してワイヤが切断してしまう。また、手間暇をかければ、このような高純度の銅金属ワイヤも試作することができるが、このような高純度の銅金属ワイヤを用いて前記ＩＣチップの電極上に超音波併用熱圧着しても、ＩＣチップの電極上に接合された銅金属ワイヤから所定のループを形成しようとすると、９９．９９９質量％程度以上の高純度銅金属ワイヤはへたってしまう。 On the other hand, academic studies aiming to reduce impurities or oxides as much as possible by increasing the purity of copper metal wires from 99.99 mass% to 99.999 mass% to 99.9999 mass% have been conducted. It was. The higher the purity of the copper metal wire, the closer the ball shape when the molten ball is formed becomes to a true sphere, and the more the ball becomes a true sphere, the more the deformation at the joint surface due to thermocompression bonding becomes a true circle. Because.
However, the higher the purity of the copper metal wire, the lower the recrystallization temperature and the softer the copper metal wire itself. For this reason, aging softens even if work-hardened in advance, and it becomes extremely difficult to handle soft copper metal wires that have become soft. In particular, since copper metal wires for bonding wires are mass-produced by wire drawing, if the purity of the copper metal wires is increased, frictional heat between the copper metal wires and the wire drawing dies will be generated during wire drawing. The high purity copper metal wire itself is softened and the wire is cut. Moreover, such a high-purity copper metal wire can be prototyped if time is required, but using such a high-purity copper metal wire, thermocompression bonding with ultrasonic waves is applied onto the electrodes of the IC chip. However, when a predetermined loop is formed from the copper metal wire bonded on the electrode of the IC chip, a high-purity copper metal wire of about 99.999 mass% or more is lost.
これらの対策として、高純度の銅金属ワイヤにさまざまな微量元素を添加した高純度の銅合金ワイヤがいくつか報告されている（特許文献１、２、３）。しかし、ボールボンディングの雰囲気中に酸素が存在すると、高純度の銅合金ワイヤであってもイニシャルボール（ＦＡＢ）が真球状にならなかったり、イニシャルボール（ＦＡＢ）が硬くなりすぎて半導体のICチップに割れが生じたりした。このため接合強度の高い、満足のいくイニシャルボール（ＦＡＢ）による熱圧着を行なうことができず、あるいは、満足のいくループ形状を描くことができず、これまで高純度の銅合金ワイヤでは実用的に耐えうるものとはならなかった。 As these measures, several high purity copper alloy wires in which various trace elements are added to high purity copper metal wires have been reported (Patent Documents 1, 2, and 3). However, if oxygen is present in the ball bonding atmosphere, the initial ball (FAB) does not become spherical even if it is a high-purity copper alloy wire, or the initial ball (FAB) becomes too hard, and the semiconductor IC chip. Cracks occurred. For this reason, it is impossible to perform thermocompression bonding with a satisfactory initial ball (FAB) with high bonding strength, or a satisfactory loop shape cannot be drawn. It could not be tolerated.
特開２００３－１３３３６４号公報JP 2003-133364 A 特開２００８－０８５３２０号公報JP 2008-085320 A 特公平０５－２０４９３号公報Japanese Patent Publication No. 05-20493
このため、高純度の銅合金からなるボールボンディング用銅合金ワイヤでありながら、室温での伸線ダイス加工が容易にでき、かつ、イニシャルボール（ＦＡＢ）によるＩＣチップ割れが生じないようなボンディングワイヤが求められていた。 For this reason, it is a copper alloy wire for ball bonding made of a high-purity copper alloy, but it can be easily drawn at room temperature and does not cause cracking of the IC chip due to the initial ball (FAB). Was demanded.
本発明は上記の事情に鑑みてなされたものであり、その目的とするところは、再結晶温度が高く、伸線加工することができる高純度の銅合金からなる銅合金ワイヤでありながら、銅合金ワイヤのイニシャルボール（ＦＡＢ）ないし溶融ボールの室温硬さが微量添加しない高純度銅金属からなる銅金属ワイヤのものよりも低いボンディングワイヤを提供することにある。具体的には、リン（Ｐ）を高純度の銅金属に微量添加することにより再結晶温度を高くした高純度銅合金ワイヤである。リン（Ｐ）を微量添加していくと、高純度の銅金属の再結晶温度は急激に上昇する。このためリン（Ｐ）が微量であっても、銅合金ワイヤは室温下でダイス伸線による伸線加工が可能になる。しかも、銅（Ｃｕ）金属の純度とリン（Ｐ）の添加量を適度にすると、リン（Ｐ）を添加した銅合金ワイヤのイニシャルボール（ＦＡＢ）の室温硬さがリン（Ｐ）を添加しない銅金属ワイヤのものよりも低くなる領域がある。本発明の目的は、このような高純度の銅合金ワイヤを提供することにある。 The present invention has been made in view of the above circumstances, and the object thereof is a copper alloy wire having a high recrystallization temperature and made of a high-purity copper alloy that can be drawn. An object of the present invention is to provide a bonding wire having an alloy wire initial ball (FAB) or a molten ball having a room temperature hardness lower than that of a copper metal wire made of high-purity copper metal to which a slight amount is not added. Specifically, it is a high purity copper alloy wire having a high recrystallization temperature by adding a small amount of phosphorus (P) to high purity copper metal. When a small amount of phosphorus (P) is added, the recrystallization temperature of high-purity copper metal rises rapidly. For this reason, even if phosphorus (P) is a very small amount, the copper alloy wire can be drawn by die drawing at room temperature. Moreover, when the purity of the copper (Cu) metal and the amount of phosphorus (P) added are moderate, the room temperature hardness of the initial ball (FAB) of the copper alloy wire to which phosphorus (P) is added does not add phosphorus (P). There are areas that are lower than those of copper metal wires. An object of the present invention is to provide such a high purity copper alloy wire.
本発明者らは、イニシャルボール（ＦＡＢ）ないし溶融ボールの室温硬さがＩＣチップ割れの原因であることから、イニシャルボール（ＦＡＢ）ないし溶融ボールの室温硬さを低くする添加元素を探索した。その結果、所定量のリン（Ｐ）が高純度銅金属のイニシャルボール（ＦＡＢ）ないし溶融ボールの室温硬さを低くすることがわかった。高純度銅金属に及ぼすリン（Ｐ）の添加効果は、銅（Ｃｕ）が高純度になればなるほど顕在化してくるが、銅（Ｃｕ）金属中に含まれる不純物元素によっても左右される。本発明者らは、９９．９９９９質量％程度の高純度銅金属ワイヤにリン（Ｐ）を微量添加した銅合金ワイヤは、再結晶温度が上昇するにもかかわらず、リン（P）を添加しない高純度の銅金属ワイヤよりもイニシャルボール（ＦＡＢ）ないし溶融ボールの室温硬さが低下することを発見した。
これまでも９９．９９９質量％以上の高純度銅金属ワイヤにいくつかの元素を微量添加していくと、銅合金ワイヤの再結晶温度が上昇し、銅合金ワイヤ自体の室温硬さが増加することは知られていた。すなわち、高純度銅合金ワイヤの室温硬さが増加するという知見は、微量添加元素の添加量とともに増加していくものと考えられていた。事実、リン（Ｐ）の場合も、９９．９９９９質量％以上の高純度銅金属ワイヤに０質量ｐｐｍから２０質量ｐｐｍ、５０質量ｐｐｍ、１００質量ｐｐｍ、２００質量ｐｐｍおよび４００質量ｐｐｍと添加量を増加するにつれ、高純度銅金属ワイヤの結晶粒が微細化していき、一見すると再結晶温度が上昇するとともに材料強度そのものが上がって室温硬さも増加しているようにみえる。このため学術的には、リン（Ｐ）を１０質量ｐｐｍ程度添加した銅合金ワイヤの室温硬さは、リン（Ｐ）を添加しない高純度銅金属ワイヤのものと大差なく、この程度の硬さの相違は実験による誤差範囲内のものと片付けられていた。
これらの事情について前述の特許文献１によれば、
リン（Ｐ）含有量４０～４００質量ｐｐｍの範囲において溶融ボール形成時の酸化物の形成を防止して、ボールの硬さを低減してチップ割れを防止するというものであり、
特許文献２記載のものは、Ｍｇ及びＰの少なくとも１種を総計で１０～７００質量ｐｐｍ、酸素を６～２０質量ｐｐｍの範囲で含有するボンディングワイヤであって、
Ｍｇ及びリン（Ｐ）の添加は、上記範囲内であればチップ損傷は回避できるというものの、その作用は硬さを向上する元素としている。
また、特許文献３記載のものは、Ｔｉ，Ｈｆ，Ｖ，Ｎｂ，Ｔａ，Ｎｉ，Ｐｄ，Ｐｔ，Ａｕ，Ｃｄ，Ｂ，Ａｌ，Ｉｎ，Ｓｉ，Ｇｅ，Ｐ，Ｓｂ，Ｂｉ，Ｓｅ，及びＴｅから選択された１種又は２種以上の元素を０．００１～２重量％含有し、残部が実質的に銅であるボンディングワイヤが記載されているが、これらの成分元素は硬さを向上すると考えられる。 Since the room temperature hardness of the initial ball (FAB) or molten ball is the cause of IC chip cracking, the present inventors searched for an additive element that lowers the room temperature hardness of the initial ball (FAB) or molten ball. As a result, it was found that a predetermined amount of phosphorus (P) lowers the room temperature hardness of high purity copper metal initial balls (FAB) or molten balls. The addition effect of phosphorus (P) on high-purity copper metal becomes more apparent as copper (Cu) becomes higher purity, but also depends on the impurity element contained in the copper (Cu) metal. The present inventors have not added phosphorus (P) to a copper alloy wire obtained by adding a small amount of phosphorus (P) to a high-purity copper metal wire of about 99.9999% by mass, although the recrystallization temperature rises. It has been discovered that the room temperature hardness of initial balls (FAB) or molten balls is lower than high purity copper metal wires.
Until now, when a small amount of some elements are added to a high-purity copper metal wire of 99.999% by mass or more, the recrystallization temperature of the copper alloy wire rises and the room temperature hardness of the copper alloy wire itself increases. That was known. That is, the knowledge that the room temperature hardness of the high purity copper alloy wire increases was considered to increase with the addition amount of the trace amount of additive element. In fact, even in the case of phosphorus (P), an addition amount of 0 to 20 mass ppm, 50 mass ppm, 100 mass ppm, 200 mass ppm and 400 mass ppm is added to a high-purity copper metal wire of 99.9999 mass% or more. As it increases, the crystal grains of the high-purity copper metal wire become finer. At first glance, it seems that the recrystallization temperature increases, the material strength itself increases, and the room temperature hardness also increases. Therefore, academically, the room temperature hardness of a copper alloy wire to which about 10 ppm by mass of phosphorus (P) is added is not much different from that of a high-purity copper metal wire to which no phosphorus (P) is added. This difference was cleared from the experimental error range.
According to the aforementioned Patent Document 1 regarding these circumstances,
In the phosphorous (P) content in the range of 40 to 400 ppm by mass, the formation of oxides during the formation of molten balls is prevented, the hardness of the balls is reduced and chip cracking is prevented,
The one described in Patent Document 2 is a bonding wire containing at least one of Mg and P in a total amount of 10 to 700 ppm by mass and oxygen in a range of 6 to 20 ppm by mass,
Although addition of Mg and phosphorus (P) can avoid chip damage as long as it is within the above range, its action is an element that improves hardness.
Further, those described in Patent Document 3 are Ti, Hf, V, Nb, Ta, Ni, Pd, Pt, Au, Cd, B, Al, In, Si, Ge, P, Sb, Bi, Se, and Te. A bonding wire containing 0.001 to 2% by weight of one or more elements selected from the above, with the balance being substantially copper is described, but these component elements improve the hardness. Conceivable.
ところが、本発明者らの研究によれば、２０質量ｐｐｍ以下の範囲でリン（Ｐ）の含有量を細かく分けて高純度銅（Ｃｕ）に添加していったところ、高純度の銅合金ワイヤの再結晶温度が上昇しているにもかかわらず、銅合金ワイヤのイニシャルボール（ＦＡＢ）ないし溶融ボール形成後の室温硬さがリン（Ｐ）を含まない高純度銅金属ワイヤの室温硬さよりも低くなる領域のあることがわかった。そこで、これらの範囲および２０質量ｐｐｍを超えてリン（Ｐ）を高純度銅（Ｃｕ）に添加して正確に調べてみたところ、銅合金ワイヤの再結晶温度はリン（Ｐ）の増加とともに上昇するが、銅合金ワイヤのイニシャルボール（ＦＡＢ）ないし溶融ボール形成後の室温硬さはリン（Ｐ）の増加とともに上昇するわけではなく、リン（Ｐ）を含有する銅合金ワイヤであっても高純度銅金属ワイヤの室温硬さより低くなる領域のあることがわかった。このような領域は、高純度銅金属ワイヤに含まれる金属元素が少なくなればなるほど顕著に現れた。また、銅（Ｃｕ）に及ぼすリン（Ｐ）の硬さ低減効果は、銅（Ｃｕ）中にＡｇ，Ｃａ，Ｆｅ，Ｍｎ，Ｍｇ，Ｎｉ，Ａｌ，ＰｂおよびＳｉが存在していてもあまり影響されないことがわかった。（図１）
図１は、これらの関係を示すデータをグラフ化したものであって、溶融ボール形成後のＰ含有量に対する硬さを縦軸に採ったもので、リン（Ｐ）含有量が２００質量ｐｐｍ付近からリン（Ｐ）含有量の増加につれて硬さが向上することは一般に知られた現象であるが、ここでリン（P）含有量が１５０ｐｐｍ近傍より低い領域で硬さが高くなり、一旦１００ｍＮまで上昇してから急激に硬さが低下する領域があることがわかる。
図中で拡大した領域がそれで、Ｐ含有量がほぼ０．５～１５質量ｐｐｍ近傍の間で、その硬さはリン（P）含有量が０の高純度銅金属と同等以下となるのである。
リン（Ｐ）の高純度Ｃｕ合金に対する室温硬さの低減効果は、次のような現象に基づいているものと考えられる。すなわち、ボンディングワイヤとしての銅合金ワイヤが火花放電によって溶融すると、大気中から酸素を溶融銅（Ｃｕ）中に取り込むが、銅合金ワイヤ表面の酸化物の膜はリン（Ｐ）によって一部分断され、蒸発されるものと思われる。そうすると、９９．９９８質量％程度以上の高純度銅合金ワイヤの場合は、リン（Ｐ）を除く金属元素が１０質量ｐｐｍ程度しかないので酸素と結びつく不純物元素の絶対量が少なくなり、硬質の酸化膜が形成されないため高純度銅合金ワイヤの室温硬さが低くなることとつじつまが合う。 However, according to the study by the present inventors, when the content of phosphorus (P) is finely divided and added to high purity copper (Cu) within a range of 20 mass ppm or less, a high purity copper alloy wire is obtained. Although the recrystallization temperature of the copper alloy wire is increased, the room temperature hardness of the copper alloy wire after forming the initial ball (FAB) or molten ball is higher than the room temperature hardness of the high-purity copper metal wire containing no phosphorus (P). It was found that there was a region that became lower. Therefore, when phosphorus (P) was added to high-purity copper (Cu) beyond these ranges and 20 ppm by mass, the recrystallization temperature of the copper alloy wire increased with an increase in phosphorus (P). However, the room temperature hardness of the copper alloy wire after forming the initial ball (FAB) or molten ball does not increase with the increase of phosphorus (P), and even if the copper alloy wire containing phosphorus (P) is high It was found that there is a region that is lower than the room temperature hardness of the pure copper metal wire. Such a region becomes more prominent as the amount of metal elements contained in the high-purity copper metal wire decreases. In addition, the hardness reduction effect of phosphorus (P) on copper (Cu) is not much affected even if Ag, Ca, Fe, Mn, Mg, Ni, Al, Pb and Si are present in copper (Cu). I found out that it was not. (Figure 1)
FIG. 1 is a graph of data showing these relationships, in which the vertical axis indicates the hardness with respect to the P content after formation of the molten ball, and the phosphorus (P) content is around 200 ppm by mass. It is a generally known phenomenon that the hardness increases as the phosphorus (P) content increases, but here the hardness increases in the region where the phosphorus (P) content is lower than around 150 ppm, and once reaches 100 mN It can be seen that there is a region where the hardness suddenly decreases after rising.
That is the enlarged area in the figure, and the hardness is less than or equal to that of high-purity copper metal with a phosphorus (P) content of 0 when the P content is near 0.5 to 15 ppm by mass. .
The effect of reducing the room temperature hardness of phosphorus (P) on a high-purity Cu alloy is considered to be based on the following phenomenon. That is, when the copper alloy wire as the bonding wire is melted by spark discharge, oxygen is taken into the molten copper (Cu) from the atmosphere, but the oxide film on the copper alloy wire surface is partially cut by phosphorus (P), It seems to be evaporated. Then, in the case of a high-purity copper alloy wire of about 99.998% by mass or more, since the metal elements excluding phosphorus (P) are only about 10 ppm by mass, the absolute amount of impurity elements associated with oxygen is reduced, and hard oxidation This is consistent with the low room temperature hardness of the high purity copper alloy wire because no film is formed.
すなわち、ＩＣチップの電極上に銅合金ワイヤを超音波併用で熱圧着する際、銅合金ワイヤのイニシャルボール（ＦＡＢ）の室温硬さが低ければ、銅合金ワイヤが与えるＩＣチップのチップダメージを軽減することができるはずである。
しかも上記したように、これらワイヤボンディングにおいて求められる特と共に、同じ条件下でワイヤの線引き加工に欠かせない銅合金ワイヤの再結晶温度が上昇し、銅合金ワイヤ自体の時効軟化が緩和されて、線引き加工に求められる強度が維持されるのである。
このような知見から本発明者らは本発明を完成するに至ったのである。 In other words, when the copper alloy wire is thermocompression bonded to the IC chip electrode with ultrasonic waves, the chip damage of the IC chip caused by the copper alloy wire is reduced if the initial temperature (FAB) of the copper alloy wire is low. Should be able to.
Moreover, as described above, along with the characteristics required in these wire bonding, the recrystallization temperature of the copper alloy wire, which is indispensable for wire drawing under the same conditions, rises, and the aging softening of the copper alloy wire itself is relaxed, The strength required for the drawing process is maintained.
From such knowledge, the present inventors have completed the present invention.
具体的には、本発明によれば、
（１）リン（Ｐ）と銅（Ｃｕ）とからなる銅合金のボンディングワイヤにおいて、リン（Ｐ）を添加した銅合金ワイヤのイニシャルボール（ＦＡＢ）の室温硬さがリン（Ｐ）を添加しない銅金属ワイヤのものよりも低いことを特徴とする高純度ボールボンディング用銅合金ワイヤが提供される。
また、本発明によれば、
（２）リン（Ｐ）と銅（Ｃｕ）とからなる銅合金のボンディングワイヤにおいて、リン（Ｐ）を添加した銅合金ワイヤのイニシャルボール（ＦＡＢ）の室温硬さがリン（Ｐ）を添加しない銅金属ワイヤのものよりも低く、かつ、銅（Ｃｕ）中のリン（Ｐ）以外の金属元素の総量がリン（Ｐ）の含有量以下であることを特徴とする高純度ボールボンディング用銅合金ワイヤが提供される。
また、本発明によれば、
（３）リン（Ｐ）と銅（Ｃｕ）とからなる銅合金のボンディングワイヤにおいて、リン（Ｐ）を０．５～１５質量ｐｐｍおよび残部が純度９９．９９８５質量%以上の銅（Ｃｕ）からなる銅合金ワイヤであり、かつ、当該銅合金ワイヤのイニシャルボール（ＦＡＢ）の室温硬さがリン（Ｐ）を添加しない純度９９．９９８５質量%以上の銅金属ワイヤのものよりも低いことを特徴とする高純度ボールボンディング用銅合金ワイヤが提供される。リン（Ｐ）を０．５～１０質量ｐｐｍおよび残部が純度９９．９９８５質量%以上の銅（Ｃｕ）からなる銅合金ワイヤであれば更にイニシャルボール（ＦＡＢ）の室温硬さが低下するので好ましい。
また、本発明によれば、
（４）リン（Ｐ）と銅（Ｃｕ）とからなる銅合金のボンディングワイヤにおいて、リン（Ｐ）を０．５～１５質量ｐｐｍおよび残部が純度９９．９９８５質量%以上の銅（Ｃｕ）からなる高純度銅合金ワイヤであり、かつ、銅（Ｃｕ）中のリン（Ｐ）以外の金属元素の総量がリン（Ｐ）の含有量以下で、当該銅合金ワイヤのイニシャルボール（ＦＡＢ）の室温硬さがリン（Ｐ）を添加しない純度９９．９９８５質量%以上の銅金属ワイヤのものよりも低いことを特徴とするボールボンディング用銅合金ワイヤが提供される。 Specifically, according to the present invention,
(1) In a copper alloy bonding wire composed of phosphorus (P) and copper (Cu), the initial temperature (FAB) of the copper alloy wire to which phosphorus (P) is added does not add phosphorus (P). A copper alloy wire for high-purity ball bonding is provided which is characterized by being lower than that of a copper metal wire.
Moreover, according to the present invention,
(2) In a copper alloy bonding wire made of phosphorus (P) and copper (Cu), the initial hardness (FAB) of the copper alloy wire to which phosphorus (P) is added does not add phosphorus (P). Copper alloy for high-purity ball bonding, characterized in that the total amount of metal elements other than phosphorus (P) in copper (Cu) is less than the content of phosphorus (P) and lower than that of copper metal wire A wire is provided.
Moreover, according to the present invention,
(3) In a copper alloy bonding wire composed of phosphorus (P) and copper (Cu), phosphorus (P) is made of 0.5 to 15 mass ppm and the balance is made of copper (Cu) having a purity of 99.9985 mass% or more. And the room temperature hardness of the initial ball (FAB) of the copper alloy wire is lower than that of a copper metal wire having a purity of 99.99985% by mass or more without adding phosphorus (P). A copper alloy wire for high-purity ball bonding is provided. A copper alloy wire made of copper (Cu) having a phosphorus (P) content of 0.5 to 10 mass ppm and the balance of 99.9985 mass% or more is preferable because the room temperature hardness of the initial ball (FAB) is further reduced. .
Moreover, according to the present invention,
(4) In a copper alloy bonding wire made of phosphorus (P) and copper (Cu), phosphorus (P) is made of 0.5 to 15 mass ppm and the balance is made of copper (Cu) having a purity of 99.9985 mass% or more. And the total amount of metal elements other than phosphorus (P) in copper (Cu) is not more than the content of phosphorus (P), the room temperature of the initial ball (FAB) of the copper alloy wire There is provided a copper alloy wire for ball bonding characterized in that the hardness is lower than that of a copper metal wire having a purity of 99.9985% by mass or more without adding phosphorus (P).
本発明のボールボンディング用銅合金ワイヤは、微量のリン（Ｐ）の脱酸素作用によって銅（Ｃｕ）のイニシャルボール（ＦＡＢ）の表面に硬質の酸化膜が形成されないので、Ｓｉチップのチップダメージを軽減することができる効果がある。また、同様にリードに第二ボンディングしたときもリン（Ｐ）の脱酸素作用によってプル強度測定におけるボンディングワイヤの破断荷重が向上する。この場合、ボンディング強度試験装置を用いてプル強度を測定すると、第二ボンドの圧着部での破断比率よりもループが形成されたワイヤ部分での破断比率の方が多くなり、これらの特性が向上したことがわかる。 The copper alloy wire for ball bonding according to the present invention does not form a hard oxide film on the surface of the initial ball (FAB) of copper (Cu) due to the deoxidizing action of a small amount of phosphorus (P). There is an effect that can be reduced. Similarly, when the second bonding is performed to the lead, the breaking load of the bonding wire in the pull strength measurement is improved by the deoxidizing action of phosphorus (P). In this case, when the pull strength is measured using a bonding strength test device, the breaking ratio at the wire portion where the loop is formed is larger than the breaking ratio at the crimped portion of the second bond, and these characteristics are improved. You can see that
本発明のボールボンディング用銅合金ワイヤにおいて、純度９９．９９９質量%以上の銅（Cu）に含まれる金属元素は、Ａｇ，Ｃａ，Ｆｅ，Ｍｎ，Ｍｇ，Ｎｉ，Ａｌ，ＰｂおよびＳｉであることが好ましい。これらの金属元素がリン（Ｐ）と共存しても、一定量以下であれば銅（Ｃｕ）のイニシャルボール（ＦＡＢ）の室温硬さを高くすることはないからである。なお、銅（Ｃｕ）にこれらの金属元素が含有されていると、これまで知られているとおり、いずれの金属元素も銅（Ｃｕ）の再結晶温度を高くする効果はある。 In the copper alloy wire for ball bonding of the present invention, the metal elements contained in copper (Cu) having a purity of 99.999% by mass or more are Ag, Ca, Fe, Mn, Mg, Ni, Al, Pb and Si. Is preferred. This is because even if these metal elements coexist with phosphorus (P), the room temperature hardness of the initial ball (FAB) of copper (Cu) is not increased as long as it is a certain amount or less. In addition, when these metal elements are contained in copper (Cu), any metal element has an effect of increasing the recrystallization temperature of copper (Cu) as is known so far.
本発明のボールボンディング用銅合金ワイヤにおいて、純度９９．９９９質量%以上の銅（Ｃｕ）に含まれる金属元素は、リン（Ｐ）を除いて１０質量ｐｐｍ未満であることがより好ましい。銅（Ｃｕ）のイニシャルボール（ＦＡＢ）の室温硬さを低くするというリン（Ｐ）の脱酸素作用をより良く発揮させるためである。 In the copper alloy wire for ball bonding of the present invention, the metal elements contained in copper (Cu) having a purity of 99.999 mass% or more are more preferably less than 10 mass ppm excluding phosphorus (P). This is because the deoxidation action of phosphorus (P), which lowers the room temperature hardness of the initial ball (FAB) of copper (Cu), is better exhibited.
図１は、本発明の高純度Ｃｕ合金ボンディングワイヤのリン（Ｐ）含有量と硬さを示す破断強度との関係を示す。FIG. 1 shows the relationship between the phosphorus (P) content of the high-purity Cu alloy bonding wire of the present invention and the breaking strength indicating hardness.
本発明のボンディングワイヤは次のようにして具体的に製造し、時効軟化作用の確認、再結晶温度の確認、溶融ボールの室温硬さ、およびチップ割れ個数の確認は次のようにして具体的に実施した。 The bonding wire of the present invention is specifically manufactured as follows, and the confirmation of the aging softening action, the confirmation of the recrystallization temperature, the room temperature hardness of the molten ball, and the confirmation of the number of chip cracks are as follows. Implemented.
〔ボールボンディング用銅ワイヤの製造方法〕
本発明に係るボールボンディング用銅合金ワイヤの製造方法を説明する。９９．９９９９質量％以上の高純度銅（Ｃｕ）金属（Ｃｕの地金「Ａ」とする。）および９９．９９９質量％以上の高純度銅（Ｃｕ）金属（Ｃｕの地金「Ｂ」とする。）を原料として、リン（Ｐ）を所定量添加した、表１に示す銅合金ワイヤ組成のものを準備する。これらの組成のものを高純度金ワイヤの製造方法の場合と同様にしてボンディングワイヤに加工する。まず、所定量の原料を真空溶解炉で溶解した後インゴットに鋳造する。このインゴットに溝ロール圧延をした後、アニール処理、防錆処理等を施して直径２５μｍの高純度銅合金ワイヤを作製した。 [Method of manufacturing copper wire for ball bonding]
A method for producing a copper alloy wire for ball bonding according to the present invention will be described. 99.9999 mass% or more of high purity copper (Cu) metal (referred to as Cu ingot “A”) and 99.999 mass% or more of high purity copper (Cu) metal (Cu ingot “B”) And a copper alloy wire composition shown in Table 1 to which a predetermined amount of phosphorus (P) is added. Those having these compositions are processed into bonding wires in the same manner as in the method of producing a high purity gold wire. First, a predetermined amount of raw material is melted in a vacuum melting furnace and then cast into an ingot. The ingot was subjected to groove roll rolling, and then subjected to annealing treatment, rust prevention treatment, etc., to produce a high purity copper alloy wire having a diameter of 25 μm.
〔時効軟化作用の確認〕
９９．９９９９質量％以上の高純度銅およびこの高純度銅にリン（Ｐ）を所定量添加した、表１に示す高純度銅ワイヤ(φ200μｍ)の時効軟化作用を確認した。その結果を表２に示す。 [Confirmation of aging softening effect]
99.9999% by mass or more of high-purity copper and the aging softening action of the high-purity copper wire (φ200 μm) shown in Table 1 in which a predetermined amount of phosphorus (P) was added to this high-purity copper were confirmed. The results are shown in Table 2.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　表１に示す高純度銅合金ワイヤを用いてボールボンディング法による超音波併用熱圧着試験を行った。ボールボンディング法は、ＩＣチップの電極、特にＡｌ金属またはＡｌ合金からなるＡｌ電極と外部リードとをボンディングワイヤで配線する際、第一ボンディングでは溶融した銅（Ｃｕ）のイニシャルボール（ＦＡＢ）と２００℃程度に加熱したＡｌ電極との接合となり、第二ボンディングでは溶融ボールを形成することなく、ワイヤ側面を超音波圧着して２００℃程度に加熱した銀（Ａｇ）メッキリードフレームへ接合する方法である。この時、ＩＣチップ側のボールボンディングは９５％窒素＋5%水素雰囲気中でボールボンディング荷重を０．２Ｎ、ボールボンディング時間を１０ミリ秒、ボールボンディングパワーを０．３０ワットの条件で行った。また、外部配線側の第二ボンディングは荷重を０．３Ｎ、ボールボンディング時間を１０ミリ秒、ボールボンディングパワーを０．４０ワットの条件で行った。 Using a high-purity copper alloy wire shown in Table 1, an ultrasonic combined thermocompression test by a ball bonding method was performed. In the ball bonding method, when an electrode of an IC chip, in particular, an Al electrode made of Al metal or an Al alloy and an external lead are wired with a bonding wire, in the first bonding, a molten copper (Cu) initial ball (FAB) and 200 are used. In the second bonding, the side surface of the wire is ultrasonically pressure-bonded and bonded to a silver (Ag) plated lead frame heated to about 200 ° C. without forming a molten ball. is there. At this time, ball bonding on the IC chip side was performed in a 95% nitrogen + 5% hydrogen atmosphere under the conditions of a ball bonding load of 0.2 N, a ball bonding time of 10 milliseconds, and a ball bonding power of 0.30 watts. The second bonding on the external wiring side was performed under the conditions of a load of 0.3 N, a ball bonding time of 10 milliseconds, and a ball bonding power of 0.40 watts.
〔３万回試験〕
この高純度銅合金ワイヤをボールボンディング装置（株式会社新川製の商品名「ＵＴＣ－１０００」）を用いて、それぞれ２００℃程度に加熱したＩＣチップのＡｌ電極上及び２００℃程度に加熱した銀（Ａｇ）メッキリードフレームの外部配線上に超音波併用ボールボンディングを連続して３万回行った。この時、ＩＣチップ側のボールボンディングは９５％窒素＋５％水素の雰囲気中でボールボンディング荷重を０．２Ｎ、ボールボンディング時間を１０ミリ秒、ボールボンディングパワーを０．３０ワットの条件で行った。また、外部配線側の第二ボンディングは荷重を０．３Ｎ、ボールボンディング時間を1０ミリ秒、ボールボンディングパワーを０．４０ワットの条件で行った。
この試験で第一ボンディングのAl膜はがれを起因とする不圧着の回数を数えた。その測定結果を表３右欄に示す。 [30,000 test]
This high-purity copper alloy wire was heated on an Al electrode of an IC chip heated to about 200 ° C. and silver (about 200 ° C.) using a ball bonding apparatus (trade name “UTC-1000” manufactured by Shinkawa Co., Ltd.). Ag) Ball bonding with ultrasonic waves was continuously performed 30,000 times on the external wiring of the plated lead frame. At this time, ball bonding on the IC chip side was performed in an atmosphere of 95% nitrogen + 5% hydrogen under the conditions of a ball bonding load of 0.2 N, a ball bonding time of 10 milliseconds, and a ball bonding power of 0.30 watts. The second bonding on the external wiring side was performed under the conditions of a load of 0.3 N, a ball bonding time of 10 milliseconds, and a ball bonding power of 0.40 watts.
In this test, the number of non-pressure bonding due to peeling of the Al film in the first bonding was counted. The measurement results are shown in the right column of Table 3.
〔ワイヤの再結晶温度およびイニシャルボール（ＦＡＢ）の室温硬さ〕
ワイヤの再結晶温度は伸線加工後の状態から材料が完全に軟化する温度を調べ、その温度を再結晶温度として表２に記した。
第一ボンディングで溶融凝固した銅合金ワイヤのイニシャルボール（ＦＡＢ）ないし溶融ボールの室温硬さに関する評価は、3万回ボンディングした試料から任意に１０個のボールボンディングされた資料を選び、株式会社明石製作所製のマイクロビッカース硬度計（型式「DMH-1」）で測定し、その平均値を算出した。測定結果を表３に示す。 [Recrystallization temperature of wire and room temperature hardness of initial ball (FAB)]
Regarding the recrystallization temperature of the wire, the temperature at which the material was completely softened was examined from the state after the wire drawing process, and the temperature was shown in Table 2 as the recrystallization temperature.
To evaluate the initial hardness (FAB) of copper alloy wire melted and solidified in the first bonding or room temperature hardness of the molten ball, select 10 ball-bonded materials from 30,000 bonded samples, and Akashi Co., Ltd. The average value was calculated using a micro Vickers hardness meter (model “DMH-1”) manufactured by Seisakusho. Table 3 shows the measurement results.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
表２の再結晶温度において、実施例No.１～９のリン（Ｐ）を所定量添加した銅合金ワイヤは、比較例１０のリン（Ｐ）をまったく添加しない高純度銅ワイヤおよび比較例１１のリン（Ｐ）をごくわずか添加した高純度銅ワイヤにくらべて、再結晶温度が高いことがわかる。 The copper alloy wires added with a predetermined amount of phosphorus (P) in Examples Nos. 1 to 9 at the recrystallization temperature shown in Table 2 were high-purity copper wires in which no phosphorus (P) was added in Comparative Example 10 and Comparative Example 11 It can be seen that the recrystallization temperature is higher than that of a high-purity copper wire to which a slight amount of phosphorus (P) is added.
他方、実施例No.６、７のリン（Ｐ）を所定量添加した９９．９９９質量％程度の高純度銅合金ワイヤは、イニシャルボールの室温硬さが比較例１０のリン（Ｐ）をまったく添加しない高純度銅金属ワイヤおよび比較例１５のリン（Ｐ）を多量に添加した銅合金ワイヤよりも低く、表2のアルミ膜はがれの個数も少ない（３万回試験値は零）ことがわかる。 On the other hand, the high-purity copper alloy wire of about 99.999 mass% to which a predetermined amount of phosphorus (P) of Examples No. 6 and 7 was added has the initial room temperature hardness of the phosphorus (P) of Comparative Example 10 at all. It is lower than the high-purity copper metal wire not added and the copper alloy wire added with a large amount of phosphorus (P) in Comparative Example 15, and the number of peeling of the aluminum film in Table 2 is small (the 30,000 times test value is zero). .
　以上のとおり、本発明のボンディングワイヤは、再結晶温度が高いにもかかわらず、イニシャルボール（ＦＡＢ）の室温硬さが低く、いずれも3万回のボンディング回数においてアルミ膜はがれ不良が大幅に低減された。
　したがって、本発明のボンディングワイヤは、再結晶温度が高く、時効軟化作用が小さいため、ワイヤ伸線加工特性を維持し、また、ボールボンディングにおいてはイニシャルボールの室温硬さが低いためチップ割れを効果的に防止する。 As described above, although the bonding wire of the present invention has a low recrystallization temperature, the initial ball (FAB) has a low room temperature hardness, and in all cases, the aluminum film peels off significantly after 30,000 bondings. It was done.
Therefore, the bonding wire of the present invention has a high recrystallization temperature and a small aging softening action, so that the wire drawing characteristics are maintained. In ball bonding, the initial ball has a low room temperature hardness, so that chip cracking is effective. Prevent it.
　本発明によるボンディングワイヤによれば、リン（Ｐ）を所定量添加した、本発明の銅合金ワイヤは、イニシャルボール（ＦＡＢ）によるチップ割れ防止に優れており、しかもこれまでのボンディングワイヤと同様に伸線加工することができ、半導体装置の信頼性向上に優れた効果を発揮する。
  According to the bonding wire according to the present invention, the copper alloy wire of the present invention, to which a predetermined amount of phosphorus (P) is added, is excellent in preventing chip cracking by the initial ball (FAB), and in the same manner as the conventional bonding wires. It can be drawn and exhibits an excellent effect in improving the reliability of the semiconductor device.

Claims (3)

  1. リン（Ｐ）の含有量が０．５～１５質量ｐｐｍ、および残部が純度９９．９９８５質量%以上の銅（Ｃｕ）からなる銅合金ワイヤであり、
    かつ、その銅合金ワイヤのイニシャルボール（ＦＡＢ）の室温硬さをリン（Ｐ）を添加しない純度９９．９９９９質量%以上の銅金属ワイヤのものよりも低下させたことを特徴とするボールボンディング用銅合金ワイヤ。     A copper alloy wire made of copper (Cu) having a phosphorus (P) content of 0.5 to 15 ppm by mass and the balance being 99.9985% by mass or more,
    In addition, the room temperature hardness of the initial ball (FAB) of the copper alloy wire is lower than that of a copper metal wire having a purity of 99.9999% by mass or more without adding phosphorus (P). Copper alloy wire.
  2. リン（Ｐ）が０．５～１５質量ｐｐｍ、および残部が純度９９．９９８５質量%以上の銅（Ｃｕ）からなる銅合金ワイヤであり、
    かつ、銅（Ｃｕ）中のリン（Ｐ）以外の金属元素の総量がリン（Ｐ）の含有量以下であって、当該銅合金ワイヤのイニシャルボール（ＦＡＢ）の室温硬さをリン（Ｐ）を添加しない純度９９．９９９９質量%以上の銅金属ワイヤのものよりも低下させたことを特徴とする高純度ボールボンディング用銅合金ワイヤ。     A copper alloy wire made of copper (Cu) having a phosphorus (P) content of 0.5 to 15 ppm by mass and the balance of 99.9985% by mass or more,
    And the total amount of metal elements other than phosphorus (P) in copper (Cu) is less than or equal to the content of phosphorus (P), and the room temperature hardness of the initial ball (FAB) of the copper alloy wire is phosphorus (P). A copper alloy wire for high-purity ball bonding, wherein the copper alloy wire has a purity lower than that of a copper metal wire having a purity of 99.9999% by mass or more to which no copper is added.
  3.   銅（Ｃｕ）中のリン（Ｐ）以外の金属元素がＰｔ，Ａｕ，Ａｇ，Pｄ，Ｃａ，Ｆｅ，Ｍｎ，Ｍｇ，Ｎｉ，Ａｌ，ＰｂおよびＳｉの内のいずれか1種または2種以上であることを特徴とする請求項２に記載の高純度ボールボンディング用銅合金ワイヤ。

          Metal elements other than phosphorus (P) in copper (Cu) are any one or more of Pt, Au, Ag, Pd, Ca, Fe, Mn, Mg, Ni, Al, Pb and Si. The copper alloy wire for high-purity ball bonding according to claim 2, wherein the copper alloy wire is used.

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