【0001】
【発明の属する技術分野】
本発明は良好な放熱特性の放熱構造を有する半導体素子収納用パッケージおよびそれを用いた半導体装置に関するものである。
【0002】
【従来の技術】
従来、半導体素子を収容するための半導体素子収納用パッケージは、一般に酸化アルミニウム質焼結体・ムライト質焼結体・ガラスセラミックス焼結体等の電気絶縁材料から成る絶縁基体と、半導体素子が搭載されてその動作時に発生する熱を外部もしくは大気中に良好に放散させるための銅とタングステンとの合金材料または銅とモリブデンとの合金材料から成る放熱部材と蓋体とから構成されており、放熱部材の上面の半導体素子の搭載部を取り囲むように絶縁基体が配置されているとともに、これら絶縁基体および放熱部材によって形成される凹部の内側から外表面にかけて、タングステン・モリブデン・マンガン・銅・銀等から成る複数の配線導体が絶縁枠体に被着され導出されている。そして、放熱部材の上面の搭載部に半導体素子をガラス・樹脂・ロウ材等の接着剤を介して接着固定するとともにこの半導体素子の各電極をボンディングワイヤを介して配線導体に電気的に接続し、しかる後、絶縁基体と放熱部材とから成る凹部にエポキシ樹脂等の封止樹脂を注入し、半導体素子を封止することによって製品としての半導体装置となる。この半導体装置は、さらに放熱効率を向上させるために、ねじ止め等によって外部放熱板に搭載される場合もある。
【0003】
このようなタングステンと銅との合金材料等から成る放熱部材を具備した半導体素子収納用パッケージは、放熱部材の熱伝導率が高く、なおかつ放熱部材の熱膨張係数が半導体素子の構成材料であるシリコン・ガリウム砒素やパッケージの構成材料として使われるセラミック材料等と熱膨張係数が近似することから、パワーICや高周波トランジスタ等の高発熱半導体素子を搭載する半導体素子収納用パッケージとして注目されている。
【0004】
【特許文献1】
特開平9−312361号公報
【0005】
【発明が解決しようとする課題】
近年、パワーICや高周波トランジスタの高集積化に伴う発熱量の増大によって、現在では300W/m・K以上の熱伝導率を持つ放熱部材が求められている。しかしながら、前述のタングステンと銅との合金材料またはモリブデンと銅との合金材料から成る放熱部材の熱伝導率は200W/m・K程度とその要求に対して低いため、放熱特性が不十分になりつつあるという問題がある。
【0006】
これに対し、タングステンと銅とがマトリクス状に構成された複合材料から成る放熱部材を用いることが提案されている。また、銅または銅合金の高熱伝導層と、Fe−Ni系合金の低熱膨張層が交互に積層され、低熱膨張層を挟み込む高熱伝導層が低熱膨張層に形成した複数の貫通孔を介して連続している複合材料から成る伝熱基板を用いることも提案されている(例えば、特許文献1参照。)。
【0007】
しかしながら、このタングステンと銅とがマトリクス状に構成された複合材料から成る放熱部材を用いた半導体素子収納用パッケージでは、タングステンは熱伝導率・熱膨張係数が共に低く、銅は熱伝導率・熱膨張係数が共に高いため、銅の含有量を増加させるに従って放熱部材の熱伝導率・熱膨張率を共に増加させることができるものの、熱伝導率を向上させるために銅の含有量を増加させると、半導体素子と放熱部材との熱膨張係数の差が大きくなり、半導体素子を放熱部材に強固に接合することができなくなってしまうという問題が発生する。
【0008】
また、銅または銅合金の高熱伝導層とFe−Ni系合金の低熱膨張層とから成る複合材料から成る伝熱基板を用いる場合は、一般にFe−Ni系合金は熱伝導率が低く(例えばFe−42Ni合金の場合であれば約16W/m・K)、基板の厚み方向の伝熱性が低いという問題があった。
【0009】
加えて、銅または銅合金の高熱伝導層と、Fe−Ni系合金の低熱膨張層とが交互に積層され、低熱膨張層を挟み込む高熱伝導層が低熱膨張層に形成した複数の貫通孔を介して連続している複合材料の場合は、熱膨張率が異なる材料を複雑に配しているため、加熱時に基板が大きく反ってしまうという問題があった。
【0010】
また、この複合材料から成る放熱部材を用いた半導体素子収納用パッケージでは、パッケージ組み立ての際の高温時に銅が膨張しかつ塑性変形を起こすため、冷却後に元の状態に戻らず、その結果、放熱部材の表面が粗くなるという問題が発生することがある。
【0011】
一般に放熱部材の表面粗さは、半導体素子をガラス・樹脂・ロウ材等の接着剤を介して放熱部材に接着固定する際の接着剤中のボイド発生による放熱部材と半導体素子との接合強度の低下を防止するために、放熱部材の表面粗さを算術平均粗さRaでRa≦30μmにすることが必要とされる。そのため、この複合材料から成る放熱部材を用いる場合は、表面粗さを算術平均粗さRaでRa≦30μmにするために研摩によって表面を平滑にすることが行なわれるが、半導体素子の搭載部を取り囲むように絶縁枠体が取着されたパッケージでは、放熱部材の搭載部を研摩することができないという問題があった。
【0012】
本発明は上記従来の技術における問題に鑑み案出されたものであり、その目的は、半導体素子の発した熱を外部や大気中に良好に放散させることができ、かつ半導体素子を放熱部材に強固に接着させることができる半導体素子収納用パッケージおよびそれを用いた半導体装置を提供することにある。
【0013】
【課題を解決するための手段】
本発明の半導体素子収納用パッケージは、上面の中央部に半導体素子が搭載される搭載部を有する平板状の放熱部材と、この放熱部材の上面に前記搭載部を取り囲んで取着された、内側の前記搭載部周辺から外表面に導出する複数の配線導体を有する絶縁枠体とを具備し、前記放熱部材と前記絶縁枠体とからなる凹部に前記半導体素子を封止する封止樹脂が注入される半導体素子収納用パッケージであって、前記放熱部材は、タングステンまたはモリブデンと銅とのマトリクスから成る平板状の基体の前記搭載部の上面から下面にかけて銅から成る貫通金属体が埋設されているとともに、少なくともこれら貫通金属体が埋設されている部位の上下面に銅層が接合されており、前記貫通金属体は、断面積が前記基体の中心側から前記銅層との接合部に向かって漸次大きくなっていることを特徴とするものである。
【0014】
本発明の半導体素子収納用パッケージによれば、放熱部材の基体の半導体素子の搭載部に、基体の上面から下面まで貫通する銅から成る貫通金属体を埋設したことから、タングステンと銅とのマトリクスのみで形成された放熱部材に比べて、半導体素子の搭載部の下により多くの銅から成る高熱伝導部分を配置することができるので、半導体素子で発生した熱を半導体素子の搭載面に垂直な方向により多く伝えることができ、その結果、半導体素子に発生する熱をこの放熱部材を介して大気中あるいは外部放熱板に良好に放散することができる。
【0015】
さらに、放熱部材の半導体素子の搭載部の下に埋設された、基体の上面から下面まで貫通する銅から成る貫通金属体を、基体の上下面に接合されている銅層と直接接合していることから、これら銅層と貫通金属体とにより半導体素子で発生する熱の放熱部材内における伝達を極めて良好なものとすることができる。これらの結果、半導体素子の熱を良好に放散させることができ、半導体素子を長期間にわたり正常かつ安定に作動させることが可能となる。
【0016】
また、貫通金属体の断面積が、基体の中心側から銅層との接合部に向かって漸次大きくなっていることから、銅層と接触する、タングステンまたはモリブデンと銅とのマトリクスから成る平板状の基体に形成された、貫通金属体が埋設されている貫通孔の開口の周縁部が鈍角化することとなり、その結果、貫通金属体の端部と基体の貫通孔の開口部との接触摩擦抵抗が少なくなるため、半導体素子収納用パッケージの組み立て時の高温からの冷却の際に、膨張し塑性変形した銅から成る貫通金属体が元の状態へ戻りやすくなり、その結果、貫通金属体の上に位置する銅層に貫通金属体の突き上げにより発生する突起の高さを例えば30μm未満に抑えることができるようになるため、半導体素子をガラス・樹脂・ロウ材等の接着剤を介して放熱部材の搭載部に接着固定する際の接着剤中のボイド発生が無く、その結果、半導体素子を強固に接続することができることから、半導体素子で発生する熱を放熱部材へ効率良く伝達することが可能になる。
【0017】
また、本発明の半導体装置は、上記構成の本発明の半導体素子収納用パッケージの前記搭載部に半導体素子を搭載するとともにこの半導体素子の電極と前記配線導体とを電気的に接続し、前記放熱部材と前記絶縁枠体とからなる凹部に前記搭載部を覆うように前記封止樹脂を注入して成ることを特徴とするものである。
【0018】
本発明の半導体装置によれば、上記構成の本発明の半導体素子収納用パッケージの搭載部に半導体素子を搭載するとともにこの半導体素子の電極と配線導体とを電気的に接続し、放熱部材と絶縁枠体とからなる凹部に搭載部を覆うように封止樹脂を注入して成ることから、以上のような本発明の半導体素子収納用パッケージの特徴を備えた、半導体素子の放熱部材への接合が強固で、放熱特性が極めて良好な、長期にわたって安定して半導体素子を作動させることができる半導体装置を提供することができる。
【0019】
【発明の実施の形態】
次に、本発明を添付図面に基づき詳細に説明する。
【0020】
図1は本発明の半導体素子収納用パッケージおよびそれを用いた半導体装置の実施の形態の一例を示す断面図であり、1は放熱部材、2は放熱部材1の基体、3は貫通金属体、4(4a,4b)は銅層、5は絶縁枠体、6は配線導体、7はリード端子、10は封止樹脂である。これら放熱部材1と絶縁枠体5と封止樹脂10とで半導体素子11を収納する半導体素子収納用パッケージ8が構成される。また、この放熱部材1の搭載部に半導体素子11を搭載した後に、放熱部材1と絶縁枠体5とからなる凹部5aに搭載部を覆うように封止樹脂10を注入して半導体素子11を封止することにより、本発明の半導体装置14が構成される。
【0021】
絶縁枠体5は酸化アルミニウム質焼結体・ムライト質焼結体・ガラスセラミック質焼結体等から成り、ロウ材9を介して放熱部材1の上面に搭載部を取り囲んで接着固定されることにより取着される。なお、このロウ材9による接着固定に際しては、通常、ロウ付け用の金属層(図示せず)が絶縁枠体5の放熱部材1との接合部に形成される。
【0022】
また、放熱部材1には、その上面の中央部の搭載部に半導体素子11が樹脂・ガラス・ロウ材等の接着剤12を介して固定される。なお、接着剤12としてロウ材を用いる場合には、通常、ロウ付け用の金属層(図示せず)が放熱部材1の半導体素子11との接着部に形成される。ただし、放熱部材1の上面の搭載部に接合された銅層4(4a)により十分なロウ付けができる場合には、ロウ付け用の金属層は特に必要ではない。
【0023】
絶縁枠体5は、例えば、酸化アルミニウム質焼結体から成る場合であれば、酸化アルミニウム・酸化珪素・酸化マグネシウム・酸化カルシウム等の原料粉末に適当な有機バインダ・溶剤・可塑剤・分散剤等を混合添加して泥漿状となすとともに、これからドクターブレード法やカレンダーロール法を採用することによってセラミックグリーンシート(セラミック生シート)を形成し、しかる後に、このセラミックグリーンシートに適当な打ち抜き加工を施すとともに、タングステン・モリブデン・マンガン・銅・銀・ニッケル・パラジウム・金等の金属材料粉末に適当な有機バインダ・溶剤を混合してなる導電性ペーストをグリーンシートに予めスクリーン印刷法等により所定パターンに印刷塗布した後に、このグリーンシートを複数枚積層し、約1600℃の温度で焼成することによって作製される。
【0024】
また、絶縁枠体5には、放熱部材1と絶縁枠体5とで構成される凹部5aの内側の搭載部周辺から絶縁枠体5の外表面にかけて導出する配線導体6が形成されており、配線導体6の凹部5aの内側の一端には半導体素子11の各電極がボンディングワイヤ13を介して電気的に接続される。
【0025】
配線導体6はタングステン・モリブデン等の高融点金属から成り、タングステン・モリブデン等の金属粉末に適当な有機バインダ・溶剤等を添加混合して得た金属ペーストを絶縁枠体5となるセラミックグリーンシートに予めスクリーン印刷法等によって所定のパターンに印刷塗布しておくことによって、放熱部材1および絶縁枠体5による凹部5aの内側の搭載部周辺から絶縁枠体5の外表面にかけて被着形成される。
【0026】
また、配線導体6はその露出する表面にニッケル・金等の耐食性に優れ、かつボンディングワイヤ13のボンディング性に優れる金属を1〜20μmの厚みにメッキ法によって被着させておくと、配線導体6の酸化腐食を有効に防止できるとともに配線導体6へのボンディングワイヤ13の接続を強固となすことができる。従って、配線導体6は、その露出する表面にニッケル・金等の耐食性に優れ、かつボンディング性に優れる金属を1〜20μmの厚みに被着させておくことが望ましい。
【0027】
放熱部材1は、半導体素子11の作動に伴い発生する熱を吸収するとともに大気中に放散させる、あるいは外部放熱板に伝導させる機能を有する。例えば、平均粒径が5〜40μmのタングステン粉末またはモリブデン粉末を、半導体素子11の搭載部に貫通穴が形成されるように加圧成形し、これを1300〜1600℃の雰囲気中で焼結することによって得られる、半導体素子11の搭載部に上面から下面にかけて形成された貫通穴を持つ多孔体をあらかじめ作製し、この多孔体に水素雰囲気下において約1200℃で10〜50質量%の銅を含浸させることにより、タングステンまたはモリブデンと銅とのマトリクスから成る平板状の基体2を作製する。この基体2の中央の搭載部に形成された貫通穴に、基体2の搭載部の上面から下面にかけて銅から成る貫通金属体3を埋設し、これに基体2および貫通金属体3の上面を覆って銅層4aならびに基体2および貫通金属体3の下面を覆って銅層4bを接合することによって形成される。
【0028】
貫通金属体3の断面積が銅層4(4a・4b)との接合部に向かって漸次大きくなる形状は、階段状あるいは傾斜状のどちらでもかまわない。
【0029】
貫通金属体3の断面積を基体2の中心側から銅層4(4a・4b)との接合部に向かって漸次大きくするためには、基体2となる多孔体を形成し、この多孔体に貫通金属体3が埋設される貫通孔を形成した後、エンドミル加工機等でこの貫通孔の開口の周縁部を所定形状に削除すればよく、これによって、階段状あるいは傾斜状のどちらでも作製できる。
【0030】
また、タングステン粉末またはモリブデン粉末を加圧形成して基体2となる多孔体を形成する際に、貫通金属体3が埋設される貫通孔を形成するジグピンの形状を貫通孔の開口に向けて階段状あるいは傾斜状としておくことによっても作製できる。
【0031】
銅層4の内、半導体素子11の搭載部となる基体2の上面の銅層4aは、その上面の算術平均粗さRaがRa>30(μm)の場合は、半導体素子11をガラス・樹脂・ロウ材等の接着剤12を介して接着固定する際に、接着剤12中にボイドが発生することがあり、接着剤12中に発生したボイドは半導体素子11と放熱部材1との接合強度を低下させるだけでなく、半導体素子11と放熱部材1との間の熱伝達を阻害し、半導体素子収納用パッケージ8および半導体装置14の熱放散性を低下させるおそれがある。
【0032】
貫通金属体3は、その断面積が、基体2の中心側から銅層4(4a・4b)との接合部に向かって漸次大きくなるように形成されている。通常の貫通金属体のように断面積が一様であれば、半導体素子収納用パッケージの組み立ての際の高温時に、貫通金属体は膨張して基体の上下面の銅層をそれぞれ押し上げ、その後、冷却の際に貫通金属体は収縮を始めるが、銅が塑性変形を起こしているため完全に元の状態には戻らず、その結果、銅層の表面粗さが大きくなる。これに対し、貫通金属体3の断面積を基体2の中心側から銅層4(4a・4b)との接合部に向かって漸次大きくなるように形成することにより、銅層4(4a・4b)と接触する、タングステンまたはモリブデンと銅とのマトリクスから成る平板状の基体2に形成された、貫通金属体3が埋設されている貫通孔の開口の周縁部が鈍角化することとなり、その結果、貫通金属体3と基体2との接触摩擦抵抗が少なくなるため、半導体素子収納用パッケージ8の組み立て時等の高温状態時に膨張し塑性変形した貫通金属体3が冷却の際に元の状態へ戻りやすくなり、その結果、貫通金属体3の上下に位置する銅層4(4a・4b)が突き上げられ、また引き戻されて、その表面粗さが大きくなることを防止することができる。
【0033】
このように貫通金属体3の断面積を基体2の中心側から銅層4(4a・4b)との接合部に向かって漸次大きくする場合は、銅層4(4a・4b)との接合部における貫通金属体3の断面積は、基体2の中心部に位置する部分の断面積より10%以上大きいことが望ましい。また、この貫通金属体3の断面積は、隣接する貫通金属体3との間隔の中間点に達するまでの大きさで大きくすることが可能である。
【0034】
一方、半導体素子11が搭載される上面とは反対側の基体2の下面に接合された銅層4bの下面の算術平均粗さRaは、Ra≦30(μm)であることが好ましい。通常、半導体素子収納用パッケージ8は、アルミニウムや銅等の金属体あるいは、高熱伝導を有するセラミック体から成る支持基板へネジ止めにより、またははんだ等の溶融金属・ロウ材を用いて接続される。このとき、基体2の下面の銅層4bの下面の算術平均粗さRaがRa>30(μm)の場合には、半導体素子収納用パッケージ8と支持基板とを十分に密着させることが困難となり、両者の間に空隙やボイドが発生してしまい、その結果、半導体素子7で発生した熱を半導体素子収納用パッケージ8からこの支持基板へ効率良く伝達させることができなくなるおそれがある。したがって、下面の銅層4bの外側表面となる下面は、支持基板との良好な密着性が得られるように平滑であることが望ましい。
【0035】
よって、半導体素子11が搭載される上面とは反対側の、基体2の貫通金属体3が埋設されている部位の下面に接合された銅層4bの下面の算術平均粗さRaは、Ra≦30(μm)で表面が平滑であることが好ましい。
【0036】
銅層4(4a,4b)の厚みは、それぞれ800μmより厚くなると基体2と銅層4(4a,4b)との熱膨張差によって発生する応力が大きくなり十分な接合強度が得られない傾向があることから、800μm以下としておくことが望ましい。また、銅層4(4a,4b)の厚みが50μm以上であれば、半導体素子11の作動に伴い発生する熱が銅層4(4a,4b)の平面方向に十分広がるので、放熱部材1の熱放散性はさらに向上する。
【0037】
なお、放熱部材1の基体2の上下面に接合される銅層4(4a,4b)の材料は、純銅に限られるものではなく、熱伝導性が良好でタングステンまたはモリブデンと銅とのマトリックスである基体2と十分な接合強度が得られるものであれば、銅を主成分とする各種の銅合金であっても構わない。これは、銅から成る貫通金属体3についても同様である。
【0038】
また、放熱部材1の基体2の上下面に接合される銅層4(4a,4b)は、少なくとも複数の貫通金属体3が埋設されている部位の上下面のうち、例えば半導体素子11の搭載部および外部放熱板との接合部に形成されれば十分であり、必ずしも図1に示すように放熱部材1の上下面の全面を覆うように形成される必要はない。
【0039】
かくして、上述の半導体素子収納用パッケージ8によれば、放熱部材1の搭載部上に半導体素子11をガラス・樹脂・ロウ材等から成る接着剤12を介して接着固定するとともに、半導体素子11の各電極をボンディングワイヤ13を介して所定の配線導体6に電気的に接続し、しかる後に、放熱部材1と絶縁枠体5とからなる凹部5aに搭載部を覆うように封止樹脂10を注入して凹部5a内に半導体素子11を封止することによって、製品としての半導体装置14となる。
【0040】
なお、本発明は以上の実施の形態の例に限定されるものではなく、本発明の要旨を逸脱しない範囲であれば種々の変更が可能である。例えば、半導体素子11で発生した熱を放熱部材1から大気中に効率良く放散させるために、放熱部材1の基体2および貫通金属体3の下面に接合された銅層4bに、放熱フィンを接続したり、放熱フィンをロウ付け等で接合して放熱フィンが放熱部材1と一体化した形状としたりしてもよく、これによって、半導体素子11の作動に伴い発生する熱を放熱部材1により吸収するとともに大気中に放散させる作用をさらに向上することができる。
【0041】
【発明の効果】
本発明の半導体素子収納用パッケージによれば、放熱部材の基体の半導体素子の搭載部に、基体の上面から下面まで貫通する銅から成る貫通金属体を埋設したことから、タングステンと銅とのマトリクスのみで形成された放熱部材に比べて、半導体素子の搭載部の下により多くの銅から成る高熱伝導部分を配置することができるので、半導体素子で発生した熱を半導体素子の搭載面に垂直な方向により多く伝えることができ、その結果、半導体素子に発生する熱をこの放熱部材を介して大気中あるいは外部放熱板に良好に放散することができる。
【0042】
さらに、放熱部材の半導体素子の搭載部の下に埋設された、基体の上面から下面まで貫通する銅から成る貫通金属体を、基体の上下面に接合されている銅層と直接接合していることから、これら銅層と貫通金属体とにより半導体素子で発生する熱の放熱部材内における伝達を極めて良好なものとすることができる。これらの結果、半導体素子の熱を良好に放散させることができ、半導体素子を長期間にわたり正常かつ安定に作動させることが可能となる。
【0043】
また、貫通金属体の断面積が、基体の中心側から銅層との接合部に向かって漸次大きくなっていることから、銅層と接触する、タングステンまたはモリブデンと銅とのマトリクスから成る平板状の基体に形成された、貫通金属体が埋設されている貫通孔の開口の周縁部が鈍角化することとなり、その結果、貫通金属体の端部と基体の貫通孔の開口部との接触摩擦抵抗が少なくなるため、半導体素子収納用パッケージの組み立て時の高温からの冷却の際に、膨張し塑性変形した銅から成る貫通金属体が元の状態へ戻りやすくなり、その結果、貫通金属体の上に位置する銅層に貫通金属体の突き上げにより発生する突起の高さを例えば30μm未満に抑えることができるようになるため、半導体素子をガラス・樹脂・ロウ材等の接着剤を介して放熱部材の搭載部に接着固定する際の接着剤中のボイド発生が無く、その結果、半導体素子を強固に接続することができることから、半導体素子で発生する熱を放熱部材へ効率良く伝達することが可能になる。
【0044】
また、本発明の半導体装置によれば、上記構成の本発明の半導体素子収納用パッケージの搭載部に半導体素子を搭載するとともにこの半導体素子の電極と配線導体とを電気的に接続し、放熱部材と絶縁枠体とからなる凹部に搭載部を覆うように封止樹脂を注入して成ることから、以上のような本発明の半導体素子収納用パッケージの特徴を備えた、半導体素子の放熱部材への接合が強固で、放熱特性が極めて良好な、長期にわたって安定して半導体素子を作動させることができる半導体装置を提供することができる。
【0045】
以上により、本発明によれば、半導体素子の発した熱を外部や大気中に良好に放散させることができ、かつ半導体素子を放熱部材に強固に接着させることができる半導体素子収納用パッケージおよびそれを用いた半導体装置を提供することができた。
【図面の簡単な説明】
【図1】本発明の半導体素子収納用パッケージおよびそれを用いた本発明の半導体装置の実施の形態の一例を示す断面図である。
【符号の説明】
1・・・・・放熱部材
2・・・・・基体
3・・・・・貫通金属体
4、4a、4b・・・・・銅層
5・・・・・絶縁枠体
5a・・・・・凹部
6・・・・・配線導体
7・・・・・端子
8・・・・・半導体素子収納用パッケージ
10・・・・・封止樹脂
11・・・・・半導体素子
14・・・・・半導体装置[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a semiconductor element storage package having a heat radiation structure with good heat radiation characteristics and a semiconductor device using the same.
[0002]
[Prior art]
Conventionally, a semiconductor element housing package for housing a semiconductor element generally includes an insulating base made of an electrically insulating material such as an aluminum oxide sintered body, a mullite sintered body, a glass ceramic sintered body, and a semiconductor element. It is composed of a heat dissipating member and a lid made of an alloy material of copper and tungsten or an alloy material of copper and molybdenum for dissipating heat generated during the operation to the outside or the atmosphere. An insulating base is arranged so as to surround the mounting portion of the semiconductor element on the upper surface of the member, and tungsten, molybdenum, manganese, copper, silver, etc. are formed from the inside to the outer surface of the recess formed by the insulating base and the heat radiating member. Are attached to the insulating frame and led out. The semiconductor element is bonded and fixed to the mounting portion on the upper surface of the heat radiating member via an adhesive such as glass, resin, brazing material, and each electrode of the semiconductor element is electrically connected to a wiring conductor via a bonding wire. Thereafter, a sealing resin such as an epoxy resin is injected into the concave portion formed by the insulating base and the heat radiating member, and the semiconductor element is sealed, thereby obtaining a semiconductor device as a product. This semiconductor device may be mounted on an external heat radiating plate by screwing or the like in order to further improve the heat radiation efficiency.
[0003]
The semiconductor element housing package provided with such a heat dissipating member made of an alloy material of tungsten and copper, etc., has a high heat conductivity of the heat dissipating member, and has a thermal expansion coefficient of silicon which is a constituent material of the semiconductor element. Since the thermal expansion coefficient is close to that of gallium arsenide or a ceramic material used as a constituent material of the package, the package is attracting attention as a semiconductor element housing package for mounting a high heat generating semiconductor element such as a power IC or a high-frequency transistor.
[0004]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 9-312361
[Problems to be solved by the invention]
In recent years, due to an increase in the amount of heat generated due to high integration of power ICs and high-frequency transistors, a heat dissipating member having a thermal conductivity of 300 W / m · K or more is now required. However, the thermal conductivity of the above-described heat-dissipating member made of the alloy material of tungsten and copper or the alloy material of molybdenum and copper is about 200 W / m · K, which is low for the requirement, so that the heat-dissipating characteristics become insufficient. There is a problem that is going on.
[0006]
On the other hand, it has been proposed to use a heat radiation member made of a composite material in which tungsten and copper are arranged in a matrix. In addition, a high thermal conductive layer of copper or a copper alloy and a low thermal expansion layer of an Fe-Ni alloy are alternately laminated, and a high thermal conductive layer sandwiching the low thermal expansion layer is continuously formed through a plurality of through holes formed in the low thermal expansion layer. It has also been proposed to use a heat transfer substrate made of a composite material (see, for example, Patent Document 1).
[0007]
However, in a semiconductor element housing package using a heat dissipating member made of a composite material in which tungsten and copper are arranged in a matrix, tungsten has low thermal conductivity and thermal expansion coefficient, and copper has thermal conductivity and thermal expansion coefficient. Since both expansion coefficients are high, the thermal conductivity and thermal expansion coefficient of the heat dissipating member can both be increased as the copper content is increased, but when the copper content is increased to improve the thermal conductivity, In addition, the difference in the thermal expansion coefficient between the semiconductor element and the heat radiating member increases, which causes a problem that the semiconductor element cannot be firmly joined to the heat radiating member.
[0008]
In addition, when a heat transfer substrate made of a composite material including a high thermal conductive layer of copper or a copper alloy and a low thermal expansion layer of an Fe—Ni alloy is used, the Fe—Ni alloy generally has a low thermal conductivity (eg, Fe In the case of a -42Ni alloy, about 16 W / mK), there is a problem that the heat conductivity in the thickness direction of the substrate is low.
[0009]
In addition, a high thermal conductive layer of copper or a copper alloy and a low thermal expansion layer of an Fe-Ni alloy are alternately laminated, and a high thermal conductive layer sandwiching the low thermal expansion layer is formed through a plurality of through holes formed in the low thermal expansion layer. In the case of a composite material that is continuously continuous, materials having different coefficients of thermal expansion are arranged in a complicated manner, so that there is a problem that the substrate is greatly warped during heating.
[0010]
Also, in a semiconductor element housing package using a heat dissipating member made of this composite material, copper expands and undergoes plastic deformation at high temperatures during package assembly, so that it does not return to its original state after cooling. There may be a problem that the surface of the member becomes rough.
[0011]
Generally, the surface roughness of the heat dissipating member is determined by the bonding strength between the heat dissipating member and the semiconductor element due to generation of voids in the adhesive when the semiconductor element is bonded and fixed to the heat dissipating member via an adhesive such as glass, resin, brazing material, or the like. In order to prevent the reduction, it is necessary that the surface roughness of the heat radiating member be Ra ≦ 30 μm in arithmetic average roughness Ra. Therefore, when a heat dissipating member made of this composite material is used, the surface is smoothed by polishing to make the surface roughness Ra ≦ 30 μm with the arithmetic average roughness Ra. In a package in which an insulating frame is attached so as to surround it, there is a problem that the mounting portion of the heat radiating member cannot be polished.
[0012]
The present invention has been devised in view of the above-mentioned problems in the related art, and has as its object to dissipate the heat generated by a semiconductor element to the outside or the atmosphere in a favorable manner, and to use the semiconductor element as a heat dissipation member. An object of the present invention is to provide a semiconductor element housing package that can be firmly bonded and a semiconductor device using the same.
[0013]
[Means for Solving the Problems]
The semiconductor element housing package of the present invention has a flat heat dissipating member having a mounting portion on which a semiconductor element is mounted at the center of the upper surface, and an inner surface mounted on the upper surface of the heat dissipating member so as to surround the mounting portion. An insulating frame having a plurality of wiring conductors extending from the periphery of the mounting portion to the outer surface, and a sealing resin for sealing the semiconductor element is injected into a concave portion formed by the heat radiating member and the insulating frame. Wherein the heat radiating member has a through metal body made of copper buried from the upper surface to the lower surface of the mounting portion of a flat substrate made of a matrix of tungsten or molybdenum and copper. At the same time, a copper layer is bonded to at least the upper and lower surfaces of the portion where the penetrating metal body is buried, and the cross-sectional area of the penetrating metal body is in contact with the copper layer from the center side of the base. And it is characterized in that it gradually becomes larger toward the part.
[0014]
According to the semiconductor element housing package of the present invention, since the through metal body made of copper penetrating from the upper surface to the lower surface of the substrate is embedded in the mounting portion of the semiconductor element of the substrate of the heat radiation member, the matrix of tungsten and copper Compared with the heat dissipating member formed only by the semiconductor element, a high heat conducting portion made of copper can be arranged below the mounting portion of the semiconductor element, so that the heat generated in the semiconductor element is perpendicular to the mounting surface of the semiconductor element. More heat can be transmitted in the direction, and as a result, heat generated in the semiconductor element can be satisfactorily dissipated to the air or an external heat radiating plate via the heat radiating member.
[0015]
Further, a penetrating metal body made of copper penetrating from the upper surface to the lower surface of the base and buried under the mounting portion of the semiconductor element of the heat dissipation member is directly bonded to the copper layer bonded to the upper and lower surfaces of the base. Therefore, the transmission of heat generated in the semiconductor element in the heat radiating member can be made extremely good by the copper layer and the penetrating metal body. As a result, the heat of the semiconductor element can be satisfactorily dissipated, and the semiconductor element can be normally and stably operated for a long period of time.
[0016]
In addition, since the cross-sectional area of the penetrating metal body gradually increases from the center side of the base toward the junction with the copper layer, the cross-sectional area of the tungsten or molybdenum-copper matrix is in contact with the copper layer. The peripheral edge of the opening of the through-hole in which the through-metal body is buried formed in the base body becomes obtuse, and as a result, the contact friction between the end of the through-metal body and the opening of the through-hole in the base body Since the resistance is reduced, the through metal body made of expanded and plastically deformed copper tends to return to its original state when cooled from a high temperature at the time of assembling the package for housing the semiconductor element, and as a result, the through metal body Since the height of the protrusion generated by pushing up the penetrating metal body on the upper copper layer can be suppressed to, for example, less than 30 μm, the semiconductor element is released via an adhesive such as glass, resin, or brazing material. Since there is no void in the adhesive when the adhesive is fixed to the mounting portion of the member, and as a result, the semiconductor element can be firmly connected, so that the heat generated in the semiconductor element can be efficiently transmitted to the heat radiating member. Will be possible.
[0017]
In the semiconductor device of the present invention, a semiconductor element is mounted on the mounting portion of the semiconductor element housing package of the present invention having the above-described configuration, and the electrodes of the semiconductor element are electrically connected to the wiring conductors. The sealing resin is injected into a recess formed by a member and the insulating frame so as to cover the mounting portion.
[0018]
According to the semiconductor device of the present invention, the semiconductor element is mounted on the mounting portion of the semiconductor element housing package of the present invention having the above configuration, and the electrodes of the semiconductor element and the wiring conductors are electrically connected to each other to insulate the heat radiating member. Since the sealing resin is injected so as to cover the mounting portion in the recess formed by the frame, the bonding of the semiconductor element to the heat radiating member having the characteristics of the semiconductor element housing package of the present invention as described above is provided. And a semiconductor device which is strong, has extremely good heat radiation characteristics, and can operate the semiconductor element stably for a long period of time.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the present invention will be described in detail with reference to the accompanying drawings.
[0020]
FIG. 1 is a cross-sectional view showing an embodiment of a semiconductor element housing package of the present invention and a semiconductor device using the same, wherein 1 is a heat radiating member, 2 is a base of the heat radiating member 1, 3 is a penetrating metal body, 4 (4a, 4b) is a copper layer, 5 is an insulating frame, 6 is a wiring conductor, 7 is a lead terminal, and 10 is a sealing resin. The heat dissipation member 1, the insulating frame 5 and the sealing resin 10 constitute a semiconductor element housing package 8 for housing the semiconductor element 11. After the semiconductor element 11 is mounted on the mounting portion of the heat radiating member 1, a sealing resin 10 is injected into the concave portion 5a formed by the heat radiating member 1 and the insulating frame 5 so as to cover the mounting portion, and the semiconductor element 11 is mounted. The sealing forms the semiconductor device 14 of the present invention.
[0021]
The insulating frame 5 is made of an aluminum oxide sintered body, a mullite sintered body, a glass ceramic sintered body, or the like, and is bonded and fixed to the upper surface of the heat radiating member 1 via the brazing material 9 so as to surround the mounting portion. Attached by At the time of bonding and fixing with the brazing material 9, usually, a metal layer (not shown) for brazing is formed at the joint of the insulating frame 5 and the heat radiating member 1.
[0022]
Further, the semiconductor element 11 is fixed to the mounting portion at the center of the upper surface of the heat dissipating member 1 via an adhesive 12 such as resin, glass, brazing material or the like. In the case where a brazing material is used as the adhesive 12, a metal layer (not shown) for brazing is usually formed at a bonding portion between the heat dissipation member 1 and the semiconductor element 11. However, when sufficient brazing can be performed by the copper layer 4 (4a) joined to the mounting portion on the upper surface of the heat radiating member 1, the metal layer for brazing is not particularly necessary.
[0023]
When the insulating frame 5 is made of, for example, an aluminum oxide sintered body, an organic binder, a solvent, a plasticizer, a dispersant, etc., suitable for a raw material powder such as aluminum oxide, silicon oxide, magnesium oxide, and calcium oxide. Is mixed and added to form a slurry, and a ceramic green sheet (ceramic green sheet) is formed by employing a doctor blade method or a calender roll method, and thereafter, the ceramic green sheet is subjected to an appropriate punching process. At the same time, a conductive paste made by mixing an appropriate organic binder and solvent into a metal material powder such as tungsten, molybdenum, manganese, copper, silver, nickel, palladium, gold, etc. is formed in a predetermined pattern on a green sheet in advance by a screen printing method or the like. After printing and coating, multiple green sheets are laminated , It is produced by firing at a temperature of about 1600 ° C..
[0024]
In addition, a wiring conductor 6 is formed on the insulating frame 5 so as to extend from the periphery of the mounting portion inside the concave portion 5 a formed by the heat radiating member 1 and the insulating frame 5 to the outer surface of the insulating frame 5. Each electrode of the semiconductor element 11 is electrically connected to one end inside the recess 5 a of the wiring conductor 6 via a bonding wire 13.
[0025]
The wiring conductor 6 is made of a metal having a high melting point such as tungsten or molybdenum. A metal paste obtained by adding a suitable organic binder or solvent to a metal powder such as tungsten or molybdenum is mixed into a ceramic green sheet to be the insulating frame 5. By printing and applying a predetermined pattern in advance by a screen printing method or the like, the heat radiation member 1 and the insulating frame 5 are attached and formed from around the mounting portion inside the concave portion 5 a to the outer surface of the insulating frame 5.
[0026]
When the wiring conductor 6 is coated with a metal having excellent corrosion resistance such as nickel and gold and excellent bonding properties of the bonding wire 13 to a thickness of 1 to 20 μm on the exposed surface by plating, the wiring conductor 6 Can be effectively prevented, and the connection of the bonding wire 13 to the wiring conductor 6 can be strengthened. Therefore, it is desirable that the wiring conductor 6 be coated with a metal having excellent corrosion resistance and excellent bonding properties such as nickel and gold to a thickness of 1 to 20 μm on the exposed surface.
[0027]
The heat dissipating member 1 has a function of absorbing heat generated by the operation of the semiconductor element 11 and dissipating it into the atmosphere, or conducting the heat to an external heat sink. For example, tungsten powder or molybdenum powder having an average particle size of 5 to 40 μm is pressure-formed so that a through-hole is formed in the mounting portion of the semiconductor element 11, and this is sintered in an atmosphere of 1300 to 1600 ° C. A porous body having a through hole formed from the upper surface to the lower surface of the mounting portion of the semiconductor element 11 is prepared in advance, and 10 to 50% by mass of copper is added to the porous body at about 1200 ° C. in a hydrogen atmosphere. The impregnation produces a flat substrate 2 made of a matrix of tungsten or molybdenum and copper. A through metal body 3 made of copper is buried in a through hole formed in the center mounting portion of the base 2 from the upper surface to the lower surface of the mounting portion of the base 2, and covers the upper surfaces of the base 2 and the through metal member 3. And is formed by joining the copper layer 4b covering the lower surfaces of the copper layer 4a and the base 2 and the penetrating metal body 3.
[0028]
The shape in which the cross-sectional area of the penetrating metal body 3 gradually increases toward the junction with the copper layer 4 (4a, 4b) may be either stepped or inclined.
[0029]
In order to gradually increase the cross-sectional area of the penetrating metal body 3 from the center side of the base body 2 toward the joint with the copper layer 4 (4a, 4b), a porous body serving as the base body 2 is formed. After forming the through-hole in which the through-metal body 3 is embedded, the peripheral portion of the opening of the through-hole may be deleted into a predetermined shape by an end mill processing machine or the like. .
[0030]
Further, when forming a porous body to be the base 2 by pressing and forming tungsten powder or molybdenum powder, the shape of a jig pin forming a through hole in which the through metal body 3 is buried is stepped toward the opening of the through hole. It can also be produced by making the shape or inclined shape.
[0031]
When the arithmetic average roughness Ra of the upper surface of the copper layer 4a on the upper surface of the base 2 to be the mounting portion of the semiconductor element 11 is Ra> 30 (μm), the semiconductor element 11 is made of glass / resin. When the adhesive is fixed via the adhesive 12 such as a brazing material, voids may be generated in the adhesive 12, and the voids generated in the adhesive 12 are bonding strength between the semiconductor element 11 and the heat radiation member 1. In addition, the heat transfer between the semiconductor element 11 and the heat radiating member 1 may be hindered, and the heat dissipation of the semiconductor element housing package 8 and the semiconductor device 14 may be reduced.
[0032]
The penetrating metal body 3 is formed such that its cross-sectional area gradually increases from the center side of the base 2 toward the joint with the copper layer 4 (4a, 4b). If the cross-sectional area is uniform like a normal penetrating metal body, at a high temperature at the time of assembling the package for housing the semiconductor element, the penetrating metal body expands and pushes up the copper layers on the upper and lower surfaces of the base, respectively, During cooling, the penetrating metal body begins to shrink, but does not completely return to the original state due to the plastic deformation of the copper, and as a result, the surface roughness of the copper layer increases. On the other hand, by forming the cross-sectional area of the penetrating metal body 3 so as to gradually increase from the center side of the base 2 toward the joint with the copper layer 4 (4a, 4b), the copper layer 4 (4a, 4b) is formed. ), The peripheral edge of the opening of the through-hole in which the through-metal body 3 is buried formed in the plate-shaped base 2 made of a matrix of tungsten or molybdenum and copper becomes obtuse, as a result. Since the contact frictional resistance between the penetrating metal body 3 and the base 2 is reduced, the penetrating metal body 3 which has expanded and plastically deformed in a high temperature state such as when assembling the semiconductor element housing package 8 returns to its original state upon cooling. As a result, it is possible to prevent the copper layers 4 (4a and 4b) located above and below the through metal body 3 from being pushed up and pulled back, thereby preventing the surface roughness from being increased.
[0033]
When the cross-sectional area of the penetrating metal body 3 is gradually increased from the center of the base 2 toward the joint with the copper layer 4 (4a, 4b), the joint with the copper layer 4 (4a, 4b) is required. Is preferably 10% or more larger than the cross-sectional area of the portion located at the center of the base 2. Further, the cross-sectional area of the penetrating metal body 3 can be increased by a size until reaching the intermediate point of the interval between the adjacent penetrating metal bodies 3.
[0034]
On the other hand, the arithmetic average roughness Ra of the lower surface of the copper layer 4b joined to the lower surface of the base 2 opposite to the upper surface on which the semiconductor element 11 is mounted is preferably Ra ≦ 30 (μm). Normally, the semiconductor element housing package 8 is connected to a supporting substrate made of a metal body such as aluminum or copper or a ceramic body having high thermal conductivity by screwing or using a molten metal or brazing material such as solder. At this time, when the arithmetic average roughness Ra of the lower surface of the copper layer 4b on the lower surface of the base 2 is Ra> 30 (μm), it becomes difficult to sufficiently adhere the semiconductor element housing package 8 to the support substrate. In addition, voids and voids are generated between the two, and as a result, heat generated in the semiconductor element 7 may not be efficiently transmitted from the semiconductor element housing package 8 to the support substrate. Therefore, it is desirable that the lower surface, which is the outer surface of the lower copper layer 4b, be smooth so that good adhesion to the support substrate can be obtained.
[0035]
Therefore, the arithmetic average roughness Ra of the lower surface of the copper layer 4b joined to the lower surface of the portion of the base 2 where the penetrating metal body 3 is buried, which is opposite to the upper surface on which the semiconductor element 11 is mounted, is Ra ≦ The surface is preferably smooth at 30 (μm).
[0036]
When the thickness of each of the copper layers 4 (4a, 4b) is more than 800 μm, the stress generated due to the difference in thermal expansion between the substrate 2 and the copper layers 4 (4a, 4b) tends to increase, and sufficient bonding strength tends not to be obtained. For this reason, it is desirable to set the thickness to 800 μm or less. If the thickness of the copper layer 4 (4a, 4b) is 50 μm or more, the heat generated by the operation of the semiconductor element 11 spreads sufficiently in the plane direction of the copper layer 4 (4a, 4b). The heat dissipation is further improved.
[0037]
The material of the copper layers 4 (4a, 4b) joined to the upper and lower surfaces of the base 2 of the heat radiating member 1 is not limited to pure copper, but has a good thermal conductivity and is a matrix of tungsten or molybdenum and copper. Various copper alloys containing copper as a main component may be used as long as sufficient bonding strength with a certain base 2 can be obtained. This is the same for the through metal body 3 made of copper.
[0038]
The copper layers 4 (4 a, 4 b) joined to the upper and lower surfaces of the base 2 of the heat radiating member 1 are, for example, mounted on the upper and lower surfaces of at least the plurality of penetrating metal bodies 3, for mounting the semiconductor element 11. It is sufficient if the heat radiating member 1 is formed at the joint between the heat radiating member and the external heat radiating plate, and does not necessarily need to be formed so as to cover the entire upper and lower surfaces of the heat radiating member 1 as shown in FIG.
[0039]
Thus, according to the semiconductor element housing package 8 described above, the semiconductor element 11 is bonded and fixed on the mounting portion of the heat radiation member 1 via the adhesive 12 made of glass, resin, brazing material, or the like. Each electrode is electrically connected to a predetermined wiring conductor 6 via a bonding wire 13, and thereafter, a sealing resin 10 is injected so as to cover the mounting portion in a concave portion 5 a formed by the heat radiating member 1 and the insulating frame 5. Then, the semiconductor element 11 is sealed in the concave portion 5a, thereby forming the semiconductor device 14 as a product.
[0040]
It should be noted that the present invention is not limited to the above embodiments, and various changes can be made without departing from the scope of the present invention. For example, in order to efficiently dissipate the heat generated in the semiconductor element 11 from the heat radiating member 1 to the atmosphere, heat radiating fins are connected to the copper layer 4b joined to the base 2 of the heat radiating member 1 and the lower surface of the penetrating metal body 3. Alternatively, the heat radiation fins may be joined by brazing or the like so that the heat radiation fins are integrated with the heat radiation member 1, whereby the heat generated by the operation of the semiconductor element 11 is absorbed by the heat radiation member 1. At the same time, the effect of dissipating into the atmosphere can be further improved.
[0041]
【The invention's effect】
According to the semiconductor element housing package of the present invention, since the through metal body made of copper penetrating from the upper surface to the lower surface of the substrate is embedded in the mounting portion of the semiconductor element of the substrate of the heat radiation member, the matrix of tungsten and copper Compared with the heat dissipating member formed only by the semiconductor element, a high heat conducting portion made of copper can be arranged below the mounting portion of the semiconductor element, so that the heat generated in the semiconductor element is perpendicular to the mounting surface of the semiconductor element. More heat can be transmitted in the direction, and as a result, heat generated in the semiconductor element can be satisfactorily dissipated to the air or an external heat radiating plate via the heat radiating member.
[0042]
Further, a penetrating metal body made of copper penetrating from the upper surface to the lower surface of the base and buried under the mounting portion of the semiconductor element of the heat dissipation member is directly bonded to the copper layer bonded to the upper and lower surfaces of the base. Therefore, the transmission of heat generated in the semiconductor element in the heat radiating member can be made extremely good by the copper layer and the penetrating metal body. As a result, the heat of the semiconductor element can be satisfactorily dissipated, and the semiconductor element can be normally and stably operated for a long period of time.
[0043]
In addition, since the cross-sectional area of the penetrating metal body gradually increases from the center side of the base toward the junction with the copper layer, the cross-sectional area of the tungsten or molybdenum-copper matrix is in contact with the copper layer. The peripheral edge of the opening of the through-hole in which the through-metal body is buried formed in the base body becomes obtuse, and as a result, the contact friction between the end of the through-metal body and the opening of the through-hole in the base body Since the resistance is reduced, the through metal body made of expanded and plastically deformed copper tends to return to its original state when cooled from a high temperature at the time of assembling the package for housing the semiconductor element, and as a result, the through metal body Since the height of the protrusion generated by pushing up the penetrating metal body on the upper copper layer can be suppressed to, for example, less than 30 μm, the semiconductor element is released via an adhesive such as glass, resin, or brazing material. Since there is no void in the adhesive when the adhesive is fixed to the mounting portion of the member, and as a result, the semiconductor element can be firmly connected, so that the heat generated in the semiconductor element can be efficiently transmitted to the heat radiating member. Will be possible.
[0044]
Further, according to the semiconductor device of the present invention, the semiconductor element is mounted on the mounting portion of the semiconductor element housing package of the present invention having the above configuration, and the electrode of the semiconductor element and the wiring conductor are electrically connected to each other. Since the sealing resin is injected so as to cover the mounting portion in the concave portion formed of the semiconductor element and the insulating frame, the heat radiating member of the semiconductor element having the features of the semiconductor element housing package of the present invention as described above is provided. The semiconductor device can be provided that has a strong junction and extremely good heat radiation characteristics and can operate the semiconductor element stably for a long period of time.
[0045]
As described above, according to the present invention, a package for housing a semiconductor element, which can satisfactorily dissipate the heat generated by the semiconductor element to the outside and the atmosphere, and can firmly adhere the semiconductor element to the heat dissipation member, and Was able to provide a semiconductor device using the same.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of an embodiment of a semiconductor element housing package of the present invention and a semiconductor device of the present invention using the same.
[Explanation of symbols]
1 heat-dissipating member 2 base 3 penetrating metal body 4, 4a, 4b copper layer 5 insulating frame 5a Recess 6 wiring conductor 7 terminal 8 semiconductor device housing package 10 sealing resin 11 semiconductor element 14・ Semiconductor device