【発明の詳細な説明】[Detailed description of the invention]
〔産業上の利用分野〕
本発明は、LSIやICなどの半導体装置のワイヤ
ボンデイングに使用するキヤピラリーに関するも
のである。
〔従来の技術〕
半導体装置において、半導体チツプの電極とパ
ツケージのリード電極との接続には金またはアル
ミニウムよりなる直径0.015〜0.1mm程度の細い導
線を用いているが、この接続工程（ワイヤボンデ
イング）には、第３図に先端部を示すように導線
を先端に送出する直径0.025〜0.1mm程度の細孔１
ａを備えたキヤピラリー１を使用していた。
このキヤピラリー１は、全体を純度98％程度の
アルミナ多結晶セラミツクスまたはルビー、サフ
アイアなどのアルミナ単結晶で形成したものが広
く用いられていた。
〔従来技術の問題点〕
ところが、従来のアルミナ多結晶セラミツクス
製キヤピラリーの場合、表面に存在する1μm以上
のボイドやピンホール等のため、先端部に導線や
電極の粉が付着しやすく、この付着部が多くたま
ると細孔１ａの穴詰まりや導線切れ、ループ異常
等を引き起こしていた。さらに、このキヤピラリ
ー先端部は常に300℃程度となつており、１秒間
に14回程度の高速で導線を電極上に圧着する際
に、電極に打ちつけられた瞬間的に約1000℃の高
温に達することがあるため、ヒートシヨツクによ
る先端部の欠けや摩耗が激しく、比較的短期間で
使用不能となつていた。
また、ルビー、サフアイア等のアルミナ単結晶
で形成したキヤピラリーの場合は、先端部への導
線や電極粉の付着や摩耗は少ないが、キヤピラリ
ー自体を製造する加工工程中に発生したマイクロ
クラツクに基づき、キヤピラリーをボンデイング
装置に取り着ける際などの取り扱い中に欠けや折
れが発生することが多く、ボンデイングにより寿
命を全うするものに対し途中で使用不能となるも
のが約50％あつた。さらにルビーやサフアイア
は、アルミナ多結晶セラミツクスに比べコストが
高いという問題点もあつた。
〔問題点を解決するための手段〕
上記に鑑みて、本発明はワイヤボンデイング用
キヤピラリーの少なくとも先端部を、純度99.9％
以上で、かつ平均気孔径が1μm以下のアルミナ多
結晶セラミツクスにより形成したものである。
〔実施例〕
本発明に係るキヤピラリー１は、第１図に示す
ように、導線を先端に送出する細孔１ａを備えて
いる。このキヤピラリー１は、全体を純度99.9％
以上のアルミナ多結晶セラミツクスにより形成し
ており、また平均気孔径が1μm以下となつてい
る。
このようなキヤピラリー１の実施例として、ア
ルミナ純度が99.90％のものと、アルミナ純度が
99.93％のものを試作した。従来のアルミナ純度
が98％で平均気孔径が1μm以上であるキヤピラリ
ーとの特性の比較は、第１表の通りである。
[Industrial Application Field] The present invention relates to a capillary used for wire bonding of semiconductor devices such as LSIs and ICs. [Prior Art] In semiconductor devices, thin conductive wires made of gold or aluminum with a diameter of about 0.015 to 0.1 mm are used to connect the electrodes of the semiconductor chip and the lead electrodes of the package, and this connection process (wire bonding) As shown in Figure 3, there is a pore 1 with a diameter of about 0.025 to 0.1 mm through which the conductor is sent to the tip.
Capillary 1 with a was used. This capillary 1 has been widely used which is made entirely of alumina polycrystalline ceramics with a purity of about 98% or alumina single crystal such as ruby or sapphire. [Problems with conventional technology] However, in the case of conventional capillaries made of alumina polycrystalline ceramics, powder from conductive wires and electrodes easily adheres to the tip due to voids and pinholes of 1 μm or more existing on the surface. If a large amount of this amount accumulates, it causes clogging of the pores 1a, breakage of the conductor, loop abnormalities, etc. Furthermore, the tip of this capillary is always at about 300℃, and when the conductor is crimped onto the electrode at a high speed of about 14 times per second, it instantly reaches a high temperature of about 1000℃ when it hits the electrode. As a result, the tip was severely chipped and worn due to the heat shock, making it unusable in a relatively short period of time. In addition, in the case of capillaries made of alumina single crystals such as ruby and sapphire, there is less adhesion of conductive wires and electrode powder to the tip and less wear, but microcracks that occur during the manufacturing process of the capillary itself Chips and bends often occur during handling, such as when attaching the capillary to a bonding device, and approximately 50% of the capillary capillaries become unusable mid-way through bonding, compared to those that could complete their lifespans. Another problem was that ruby and sapphire were more expensive than alumina polycrystalline ceramics. [Means for Solving the Problems] In view of the above, the present invention provides at least the tip of a capillary for wire bonding with a purity of 99.9%.
It is made of alumina polycrystalline ceramic having the above properties and an average pore diameter of 1 μm or less. [Example] As shown in FIG. 1, a capillary 1 according to the present invention is provided with a pore 1a through which a conducting wire is delivered to the tip. This capillary 1 has a total purity of 99.9%.
It is formed from the above alumina polycrystalline ceramics, and the average pore diameter is 1 μm or less. Examples of such capillary 1 include one with alumina purity of 99.90% and one with alumina purity of 99.90%.
We made a prototype of 99.93%. Table 1 shows a comparison of the characteristics with a conventional capillary that has alumina purity of 98% and an average pore diameter of 1 μm or more.
【表】
第１表から明らかなように、本発明実施例であ
るNo.１，No.２のキヤピラリーは、従来例であるNo.
３のキヤピラリーに比べ、ビツカース硬度、抗折
強度が大きく、また熱伝導率も高いことがわか
る。さらに、アルミナ純度が最も高いNo.１のキヤ
ピラリーは、かさ比重が3.98とアルミナ単結晶
（かさ比重3.99）により近く、性質的にもアルミ
ナ単結晶に近いものである。
次に、これらのキヤピラリーおよび他の材質に
より形成したキヤピラリーを用いてワイヤボンデ
イング試験を行なつた。それぞれのキヤピラリー
を10個用意し、同一条件のもとに金線でボンデイ
ングを行ない、ボンデイング回数と導線の接続状
態の関係を調べた結果、それぞれの平均値は第２
表の通りであつた。[Table] As is clear from Table 1, capillaries No. 1 and No. 2, which are examples of the present invention, are different from capillaries No. 1 and No. 2, which are examples of the present invention.
It can be seen that compared to capillary No. 3, the Vickers hardness and bending strength are greater, and the thermal conductivity is also higher. Furthermore, the No. 1 capillary with the highest alumina purity has a bulk specific gravity of 3.98, which is closer to an alumina single crystal (bulk specific gravity of 3.99), and is also closer in properties to an alumina single crystal. Next, a wire bonding test was conducted using these capillaries and capillaries made of other materials. We prepared 10 of each type of capillary, bonded them with gold wire under the same conditions, and investigated the relationship between the number of bonding cycles and the connection state of the conductor wires.
It was as shown in the table.
【表】
△…ワイヤの接続不良が若干発生
×…ワイヤの接続不良が多発し、使用不能
この第２表からわかるように、No.１の超硬質材
よりなるキヤピラリーは30万回適度で、またNo.２
のアルミナ多結晶セラミツクス（純度98％）より
なるキヤピラリーは60万回程度のボンデイング
で、それぞれワイヤの接続不良が多く発生し、使
用不能となつた。No.２のアルミナ多結晶セラミツ
クス（純度98％）よりなるキヤピラリーは、付着
部による穴詰まりが多く、途中で付着部を洗浄し
てやると再使用できるが、それでも100万回程度
で、摩耗のため完全に使用不能となつた。また、
No.３のルビーよりなるキヤピラリーは、400万回
程度のボンデイングを行うことができるが、ボン
デイング装置に取り付けるときに欠けや折れが発
生して使用不能となつたものが３本あつた。それ
に対し、本発明の実施例であるNo.４のアルミナ多
結晶セラミツクス（純度99.9％）よりなるキヤピ
ラリーおよびNo.５のアルミナ多結晶セラミツクス
（純度99.3％）よりなるキヤピラリーおよびNo.５
のアルミナ多結晶セラミツクス（純度99、93％）
よりなるキヤピラリーは、それぞれ240万回、400
万回程度迄ボンデイングを行うことができ、しか
もボンデイング装置に取り付けるときに欠けや折
れが発生するものはなかつた。
このように本発明に係るキヤピラリーは、導線
や電極粉の付着が少なく、また硬度、耐摩耗性が
大きく放熱特性が良いため、ヒートシヨツクによ
る欠けや摩耗が少なく、寿命が長い。さらにルビ
ーのような単結晶構造でないために、マイクロク
ラツクがあつてもある程度以上大きくならず、取
り扱い中に折れや欠けが発生する恐れが少ない。
上記実施例におけるキヤピラリーは、99.9％以
上のアルミナにMgO等の焼結助剤を加えたもの
を成形し、ホツトプレス法、HIP（熱間静水圧加
圧）処理、真空焼成等のうちのいずれかを行うこ
とによつて非常に緻密な構造となり、平均気孔径
を1μm以下とすることができる。この他、アルミ
ナ純度が平均気孔径の大きさをさまざまに変化さ
せたアルミナ多結晶セラミツクスよりなるキヤピ
ラリーを試作し、上記と同様のボンデイング試験
を行つた結果、アルミナ純度が99.9％より低いも
のは先端部の欠けや摩耗が大きく、また平均気孔
径が1μmより大きいものでは導線が電極粉の付着
が大きく、いずれも寿命が短いものであつた。
また、上記実施例においては、キヤピラリー全
体を純度が99.9％以上でかつ平均気孔径が1μm以
下のアルミナ多結晶セラミツクスにより形成した
ものを示したが、これに限らず第２図に示すよう
に先端部分Ｓのみを純度が99.9％以上で、かつ平
均気孔径が1μm以下のアルミナ多結晶セラミツク
スにより形成し、他の部分は別の材質としたもの
であつてもよい。
〔発明の効果〕
叙上のように、本発明によれば、ワイヤボンデ
イング用キヤピラリーの少なくとも先端部を純度
が99.9％以上で、かつ平均気孔径が1μm以下のア
ルミナ多結晶セラミツクスにより形成したことに
よつて、先端部への導線や電極粉の付着が少ない
ため、ワイヤの接続不良が起こりにくく、また強
度、耐摩耗性が大きく放熱特性が良いため先端の
欠けや摩耗が少なく、寿命が長くなるだけでな
く、安定したワイヤボンデイングを行うことがで
き、半導体装置の品質を安定させることができ
る。
さらに、ルビー、サフアイアにくらべてコスト
を低くできるなどの多くの特長を有したワイヤボ
ンデイング用キヤピラリーを提供することができ
る。[Table] △... Some wire connection failures occur. ×... Wire connection failures occur frequently, making it unusable. As can be seen from this second table, the capillary made of No. 1 ultra-hard material can withstand a reasonable 300,000 cycles. Also No.2
The capillary made of alumina polycrystalline ceramics (98% purity) was bonded approximately 600,000 times, but many wire connections occurred and it became unusable. Capillaries made of No. 2 alumina polycrystalline ceramics (98% purity) often have holes clogged by adhesive parts, and although they can be reused by cleaning the adhesive parts midway through, they still only last about 1 million times before being completely worn out due to wear. became unusable. Also,
The capillary made of No. 3 ruby can be bonded about 4 million times, but three capillaries were unusable due to chipping or bending when attached to the bonding device. In contrast, the capillary made of alumina polycrystalline ceramics (purity 99.9%) of No. 4 and the capillary made of alumina polycrystalline ceramics (purity 99.3%) of No. 5, which are examples of the present invention.
Alumina polycrystalline ceramics (purity 99, 93%)
The capillaries are 2.4 million times and 400 times, respectively.
Bonding could be performed up to about 10,000 times, and none of them were chipped or bent when attached to a bonding device. As described above, the capillary according to the present invention has less adhesion of conducting wires and electrode powder, has high hardness and wear resistance, and has good heat dissipation characteristics, so it is less likely to chip or wear due to heat shock and has a long life. Furthermore, since it does not have a single crystal structure like ruby, even if it does have microcracks, they will not grow beyond a certain level, and there is less risk of breakage or chipping during handling. The capillary in the above embodiment is formed by molding 99.9% or more alumina with a sintering aid such as MgO, and is formed using one of the hot pressing method, HIP (hot isostatic pressing) treatment, vacuum firing, etc. By performing this process, a very dense structure can be obtained, and the average pore diameter can be reduced to 1 μm or less. In addition, we prototyped capillaries made of alumina polycrystalline ceramics with varying alumina purity and average pore size, and conducted bonding tests similar to those described above. In the cases where the average pore diameter was larger than 1 μm, the conductor wires had a large amount of electrode powder adhering to them, and both had short lifespans. In addition, in the above embodiment, the entire capillary was made of alumina polycrystalline ceramics with a purity of 99.9% or more and an average pore size of 1 μm or less, but the tip is not limited to this, as shown in FIG. Only the portion S may be formed of alumina polycrystalline ceramics having a purity of 99.9% or more and an average pore diameter of 1 μm or less, and the other portions may be made of a different material. [Effects of the Invention] As described above, according to the present invention, at least the tip of the wire bonding capillary is formed of alumina polycrystalline ceramics with a purity of 99.9% or more and an average pore diameter of 1 μm or less. As a result, there is less adhesion of conductor wire or electrode powder to the tip, making it less likely to cause poor wire connections.Also, due to its high strength, wear resistance, and good heat dissipation properties, there is less chance of chipping or wear on the tip, resulting in a longer life. In addition, stable wire bonding can be performed, and the quality of semiconductor devices can be stabilized. Furthermore, it is possible to provide a capillary for wire bonding that has many features such as lower cost than ruby and sapphire.
【図面の簡単な説明】[Brief explanation of the drawing]
第１図は本発明に係るワイヤボンデイング用キ
ヤピラリーを示す一部破断面図、第２図は本発明
に係るワイヤボンデイング用キヤピラリーの他の
実施例を示す一部破断面図、第３図は従来のワイ
ヤボンデイング用キヤピラリーの先端部を示す拡
大断面図である。
１：キヤピラリー、１ａ：細孔、Ｆ：付着部。
FIG. 1 is a partially cutaway cross-sectional view showing a capillary for wire bonding according to the present invention, FIG. 2 is a partially cutaway cross-sectional view showing another embodiment of the capillary for wire bonding according to the present invention, and FIG. 3 is a conventional FIG. 2 is an enlarged cross-sectional view showing the tip of the capillary for wire bonding. 1: capillary, 1a: pore, F: attachment part.