JP2004063533A

JP2004063533A - Package for housing semiconductor element

Info

Publication number: JP2004063533A
Application number: JP2002216143A
Authority: JP
Inventors: Seigo Matsuzono; 松園　清吾
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2002-07-25
Filing date: 2002-07-25
Publication date: 2004-02-26
Anticipated expiration: 2022-07-25
Also published as: JP3872391B2

Abstract

<P>PROBLEM TO BE SOLVED: To conduct a good heat dissipation by forming copper layers on both surfaces by an impinging method of a heat sink base to a copper-silicon carbide. <P>SOLUTION: A package for housing a semiconductor element includes the heat sink base 3 having a placing part for placing the semiconductor element 4 on an upper surface, an insulating film 1 mounted on the upper surface of the base 3 and having a wiring layer 8, and a cover 2 mounted on the upper surface of the frame 1. The frame 1 is formed of a glass ceramic sintered material having a specific permittivity of 7 or less. The layer 8 is formed of a metal material having an electric resistivity of 2.5 μΩcm or less. The base 3 is formed of a composite material layer 3a formed by impregnating a porous material of the silicon carbide with copper and copper layers 3b formed on upper and lower surfaces of the layer 3a, and satisfies 30 μm≤t2≤300 μm and t2≤0.15×t1. The reference t1 is a thickness of the layer 3a, and t2 is a thickness of the layer 3b. Thus, the heat of the element 4 can be efficiently dissipated, and the base 3 can be connected to the frame 1 with high reliability. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は半導体素子収納用パッケージに関し、特にガリウム砒素（ＧａＡｓ）・インジウム燐（ＩｎＰ）・シリコン（Ｓｉ）等の高発熱の半導体素子が搭載される、放熱特性に優れた高信頼性用途の半導体素子収納用パッケージ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り、上面に半導体素子を収容するための凹部を有する絶縁基体と、この絶縁基体の凹部から外表面にかけて被着導出されたタングステン・モリブデン・マンガン・銅・銀等の金属粉末から成る複数個の配線層と、蓋体とから構成されており、絶縁基体の凹部底面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層に電気的に接続し、しかる後、絶縁基体に蓋体をガラス・樹脂・ロウ材等から成る封止材を介して接合させ、絶縁基体と蓋体とから成る容器内部に半導体素子等の発熱部品を収容することによって製品としての半導体装置となる。
【０００３】
この従来の半導体素子収納用パッケージは、絶縁基体を構成する酸化アルミニウム質焼結体の熱伝導率が低い（約１５Ｗ／ｍＫ）ため、絶縁基体に収容される半導体素子が作動時に多量の熱を発生した場合、その熱を大気中に良好に放散させることができず、その結果、半導体素子はその発生する熱によって高温となリ、半導体素子に熱破壊を起こさせたり、特性に熱変化を与え誤動作を生じるという欠点を有していた。
【０００４】
そこで、高発熱の半導体素子を収容する半導体素子収納用パッケージにおいては、絶縁基体を介して半導体素子の熱を良好に放散させるために、銅−タングステン・銅−モリブデンといった複合金属材料から成る放熱部品が半導体素子の真下に位置するように設けられている。
【０００５】
例えば、銅−タングステン複合材料から成る放熱部品はタングステンと銅がマトリクス状に構成されており、銅−タングステン複合材料の熱伝導率は、比率により異なるが、一般的に１５０乃至２００Ｗ／ｍＫ程度である。
【０００６】
しかしながら、パワーＩＣや高周波トランジスタ等の大電流を必要とする半導体素子の発展に伴って、半導体素子の発熱量は年々増加する傾向にあり、現在では２５０Ｗ／ｍＫ以上の熱伝導率を持つ放熱部品が求められている。
【０００７】
この問題を解決するために、特開平６−２６８１１５号公報には、半導体装置用放熱基板として、モリブデンから成る第１の部材（基材）と銅から成る第２の部材とのクラッド材でＣ．Ｍ．Ｃ．（Ｃｕ／Ｍｏ／Ｃｕ）構造のものが開示されている。このＣ．Ｍ．Ｃ．構造のクラッド材から成る半導体装置用放熱基板の熱伝導率は２００Ｗ／ｍＫ以上と非常に高い。
【０００８】
また、特開平６−２６８１１７号公報には、タングステン−銅合金およびモリブデン−銅合金から成る群より選ばれた少なくとも一種の金属材料から成る第１の部材（基材）の両主面に銅を主材料とする金属材料から成る第２の部材が熱間一軸加圧法または圧延法のいずれかで接合された半導体装置用放熱基板が提案されており、この半導体装置用放熱基板では２５０Ｗ／ｍＫ以上の熱伝導率を達成している。
【０００９】
【発明が解決しようとする課題】
しかしながら、特開平６−２６８１１５号公報や特開平６−２６８１１７号公報に開示された半導体装置用放熱基板は、熱伝導率が約２５０Ｗ／ｍＫと非常に高いが、製造方法として圧延法や熱間一軸加工法により基材層と銅層とを貼り合わせているため、これを半導体素子収納用パッケージの放熱基体として絶縁枠体を接合すると、接合時の熱応力により基材層と銅層との界面にクラックが発生し易いという問題点がある。
【００１０】
また、銅層と基材層との間に界面が存在するために、両層の接触抵抗により、熱伝導率が低下することとなるといった問題点がある。
【００１１】
また、従来の半導体収納用パッケージにおいては、絶縁枠体を形成する酸化アルミニウム質焼結体の比誘電率９〜１０（室温、１ＭＨｚ）と高いことから絶縁枠体に設けた配線層を伝わる電気信号の伝搬速度が遅く、そのため信号の高速伝搬を要求する半導体素子は収容が不可となるという問題点を有していた。
【００１２】
さらに、この従来の半導体収納用パッケージにおいては、絶縁枠体に形成される配線層はタングステンやモリブデン・マンガン等の高融点金属材料により形成されており、これらタングステン等はその比電気抵抗が５．４μΩ・ｃｍ（２００℃）以上と高いことから、配線層に電気信号を伝搬させた場合、電気信号に大きな減衰が生じ、電気信号を正確、かつ確実に伝搬させることができないという問題点を有していた。
【００１３】
本発明は上記従来の技術における問題点に鑑み案出されたものであり、その目的は、放熱基体を銅−炭化珪素に対して溶浸法により両面に銅層を形成したものとすることにより、半導体素子の発生した熱を絶縁体に良好に放散させることができるとともに、銅層を熱間一軸法や圧延等の貼り合わせではない溶浸法により形成しているために、絶縁体と放熱基体とを強固に信頼性よく接合させることが可能で、かつ内部に高速駆動を行なう半導体素子を収容することができる半導体素子収納用パッケージを提供することにある。
【００１４】
【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、上面に半導体素子が載置される載置部を有する放熱基体と、この放熱基体の上面に前記載置部を囲繞するように取着され、前記半導体素子の電極が電気的に接続される半導体素子を有する絶縁枠体と、この絶縁枠体の上面に取着される蓋体とから成る半導体素子収納用パッケージであって、前記絶縁枠体は比誘電率が７以下のガラスセラミックス焼結体で、前記配線層は電気抵抗率が２．５μΩ・ｃｍ以下の金属材料で形成されており、前記放熱基体は、炭化珪素の多孔質体に銅を含浸させて成る複合材料層とその上下面に形成された銅層とから成るとともに、前記複合材料層の厚みをｔ１、前記銅層の厚みをｔ２としたとき、３０μｍ≦ｔ２≦３００μｍかつｔ２≦０．１５×ｔ１であることを特徴とするものである。
【００１５】
また、本発明の半導体素子収納用パッケージは、上記構成において、前記複合材料層は、タングステンまたはモリブデンの多孔質体に２０乃至３５質量％の銅を含浸させて成ることを特徴とするものである。
【００１６】
また、本発明の半導体素子収納用パッケージは、上記構成において、前記絶縁枠体の前記ガラスセラミックス焼結体は、熱膨張係数が６乃至８×１０^−６／℃（室温〜８００℃）であることを特徴とするものである。
【００１７】
本発明の半導体素子収納用パッケージによれば、放熱基体が、炭化珪素の多孔質体に銅を含浸させて成る複合材料層とその上下面に形成された銅層とから成るとともに、複合材料層の厚みをｔ１、銅層の厚みをｔ２としたとき、３０μｍ≦ｔ２≦３００μｍかつｔ２≦０．１５×ｔ１であることから、炭化珪素の多孔質体に銅を含浸させて成る複合材料層のみで構成された放熱基体に比べて、これに載置される半導体素子で発生した熱を、まず表面近傍で銅層によって面内の水平方向により多く逃がすことができるとともに、銅層と複合材料層中の銅とは連続的につながっているため熱伝導の損失が小さくなり、その結果、複合材料層内により多く熱を逃がすことができる。また、複合材料層内は、銅−炭化珪素材料であるので２３０Ｗ／ｍＫ以上の熱伝導率が確保されている。これによって、放熱基体の熱伝導率を２５０Ｗ／ｍＫ以上と極めて高いものとすることが可能となる。
【００１８】
また、複合材料層の上下面に形成された銅層は、複合材料層を炭化珪素に銅を溶浸法で含浸させる際に同時に形成することができることから、熱間一軸法や圧延法で貼り合わせた銅層と異なり、放熱基体に絶縁枠体を接合する時の熱応力により銅層と複合材料層との界面にクラックが発生することはほとんどなく、その結果、放熱基体に載置されてパッケージ内部に収容される半導体素子を長期にわたり正常に、かつ安定に作動させることが可能となる。
【００１９】
また、放熱基体が、炭化珪素の多孔質体に銅を含浸させて成る複合材料層とその上下面に形成された銅層とから成るとともに、複合材料層の厚みをｔ１、銅層の厚みをｔ２としたとき、３０μｍ≦ｔ２≦３００μｍかつｔ２≦０．１５×ｔ１であることから、放熱基体の上面に設けられた半導体素子の載置部では熱伝導率とともに熱膨張係数も大きい銅の占める割合が多いにもかかわらず、放熱基体の熱膨張係数を絶縁枠体の熱膨張係数に近づけることが可能となる。
【００２０】
特に、複合材料層を炭化珪素の多孔質体に２０乃至３５質量％の銅を含浸させて成るものとしたときには、放熱基体の熱膨張係数は９×１０^−６／℃以下の値になるため、放熱基体と絶縁枠体とを長期間にわたり良好に、かつ安定に接合させることが可能となる。
【００２１】
また、絶縁枠体のガラスセラミックス焼結体を熱膨張係数が６乃至８×１０^−６／℃（室温〜８００℃）であるものとしたときには、放熱基体の熱膨張係数をその絶縁枠体の熱膨張係数の近傍の値にすることが可能となるので、放熱基体と絶縁枠体とを長期間にわたり良好に、かつ安定に接合させることが可能となる。
【００２２】
また本発明の半導体素子収納用パッケージによれば、絶縁枠体を比誘電率が７以下のガラスセラミックス焼結体で形成したことから、絶縁枠体に設けた配線層を伝わる電気信号の伝搬速度を速いものとすることができて、信号の高速伝搬を要求する半導体素子の収納が可能となる。
【００２３】
また本発明の半導体素子収納用パッケージによれば、絶縁枠体を低温焼成（約８００℃〜９００℃）が可能なガラスセラミックス焼結体で形成するとともに、絶縁枠体と同時焼成により形成される配線層を比電気抵抗が２．５μΩ・ｃｍ以下と低い銅や銀・金で形成したことから、配線層に電気信号を伝搬させた場合に、電気信号に大きな減衰が生じることはなく、電気信号を正確、かつ確実に伝搬させることが可能となる。
【００２４】
【発明の実施の形態】
以下、本発明を添付図面に基づき詳細に説明する。
【００２５】
図１は本発明の半導体素子収納用パッケージの実施の形態の一例を示す断面図であり、１は絶縁枠体、２は蓋体、３は放熱基体であり、４は半導体素子である。放熱基体３は上面の中央部に半導体素子４が載置される載置部を有しており、絶縁枠体１は放熱基体３の上面に載置部を囲繞するように取着されており、これら絶縁枠体１と蓋体２と放熱基体３とで半導体素子４を収納する容器が構成される。
【００２６】
絶縁枠体１は比誘電率が７以下のガラスセラミックス焼結体（線熱膨張係数：６乃至８×１０^−６／℃）から成り、具体的には、
１）ホウケイ酸ガラスにアルミナもしくはムライトを添加して成る原料粉末より製作されるガラスセラミックス焼結体（比誘電率５〜６）
２）コージェライト系結晶化ガラスにアルミナもしくはムライトを添加して成る原料粉末より製作されるガラスセラミックス焼結体（比誘電率５〜６）
３）ムライト系結晶化ガラスにアルミナもしくはムライトを添加して成る原料粉末より製作されるガラスセラミックス焼結体（比誘電率５〜６）
等で形成されている。
【００２７】
絶縁枠体１は放熱基体３とロウ材６を介して接着固定される。なお、絶縁枠体１の放熱基体３との接合部にはロウ付け用の金属層（非図示）が形成される。
【００２８】
絶縁枠体１は、例えばホウケイ酸ガラスにアルミナもしくはムライトを添加して成る原料粉末より製作されるガラスセラミックス焼結体から成る場合、原料粉末の組成が質量比で７２〜７６％のシリカ・１５〜１７％の酸化ホウ素・２〜４％の酸化アルミニウム・酸化ナトリウム・酸化カリウムおよび酸化チタンの合計量２〜３％から成るホウケイ酸粉末に、アルミナ・石英およびコージェライトの各粉末と有機バインダや溶剤等を添加混合して泥漿物を作るとともに、この泥漿物を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）となし、しかる後に、これら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これを複数枚積層し、約９００℃の温度で焼成することによって作製される。
【００２９】
また、絶縁枠体１には、その内側の半導体素子４の載置部を取り囲む部位から外表面にかけて導出する配線層８が形成されており、絶縁枠体１の内側に露出する配線層８の一端には半導体素子４の各電極がボンディングワイヤ５を介して電気的に接続され、また、絶縁枠体１の上面に導出された部位には、外部電気回路と接続される外部リードピン９が銀ロウ等のロウ材を介してロウ付け取着されている。
【００３０】
この配線層８は、半導体素子４の各電極を外部電気回路に接続する際の導電路として機能し、銅・銀・金等の金属粉末により形成されている。
【００３１】
配線層８は、銅・銀・金等の金属粉末に適当な有機バインダや溶剤等を添加混合して得た金属ペーストを絶縁枠体１となるセラミックグリーンシートに予め従来周知の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、絶縁枠体１の内側から外表面にかけて被着形成される。
【００３２】
配線層８を形成する銅・銀・金等はその融点が約１０００℃と低いものの、絶縁枠体１を構成するガラスセラミックス焼結体の焼成温度が低いことから、絶縁枠体１に所定パターンに被着形成することが可能となる。
【００３３】
また、配線層８を形成する銅や銀・金等は、その電気抵抗率が２．５μΩ・ｃｍ以下と低いことから、配線層８を介して容器内部に収容する半導体素子４と外部電気回路との間に電極信号の出し入れをしたとしても、配線層８において電気信号が大きく減衰することはなく、その結果、半導体素子４を正確、かつ確実に動作させることができる。
【００３４】
さらに、配線層８は、この配線層８が被着されている絶縁枠体１の比誘電率が７以下（室温、１ＭＨｚ）、好適には５．５〜６と低いことから、配線層８を伝わる電気信号の伝搬速度が速いものとなり、その結果、配線層８を介して容器内部に収容する半導体素子４と外部電気回路との間に電気信号の出し入れをしたとしても、電気信号の伝搬に遅延を生じることがなく、半導体素子４に正確、かつ確実に電気信号を出し入れすることができる。
【００３５】
なお、配線層８は、銅や銀から成る場合、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５のボンディング性に優れる金属を１乃至２０μｍの厚みにメッキ法によって被着させておくと、配線層８の酸化腐食を有効に防止できるとともに配線層８へのボンディングワイヤ５の接続を強固となすことができる。従って、配線層８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乃至２０μｍの厚みに被着させておくことが望ましい。
【００３６】
また、絶縁枠体１に被着した配線層８にロウ付けされる外部リードピン９は、鉄−ニッケル−コバルト合金や鉄−ニッケル合金等の金属材料から成り、半導体素子４の各電極を外部電気回路に電気的に接続する機能を有する。
【００３７】
外部リードピン９は、例えば、鉄−ニッケル−コバルト合金等の金属から成るインゴット（塊）に圧延加工法や打ち抜き加工法等、従来周知の貴族加工法を施すことによって所定形状に形成される。
【００３８】
放熱基体３は、その上面に半導体素子４の載置部を有しており、この載置部には半導体素子４が樹脂・ガラス・ロウ材等の接着材７を介して固定される。なお、接着材７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（非図示）が放熱基体３の半導体素子４との接合部に形成される。また、絶縁枠体１と放熱基体３とは、銀−銅合金等から成るロウ材６を用い、ロウ材６を６００℃から９００℃の還元雰囲気中で溶融させた後に冷却固化させることで接合される。
【００３９】
放熱基体３は、図２にその概略構成を断面図で示すように、炭化珪素の多孔質体に銅を含浸させて成る複合材料層３ａとその上下面に形成された銅層３ｂとから成る。放熱基体３は、半導体素子４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機能を有する。
【００４０】
放熱基体３の作製は、予め形成された炭化珪素の多孔質体に溶浸法により上下面から銅を溶融含浸させて複合材料層３ａを形成し、その際に複合材料層３ａの上下面に残った銅が銅層３ｂとなって上下面を被覆しているため、この銅層３ｂを３０乃至２００μｍの厚さで残すように研磨することによって行なわれる。その後、必要に応じて、銅層３ｂの表面の耐食性を高め、またロウ材６や接着材７との濡れ性を高める等の目的で、露出する表面にニッケル等のメッキ層（非図示）を施す。
【００４１】
放熱基体３において、複合材料層３ａを構成する炭化珪素の多孔質体は、例えば中心粒径が数μｍ乃至１００μｍの炭化珪素粉末に適量のバインダを混合した後、約１０ｋＮ／ｃｍ^３程度の圧力でプレス体を成形し、このプレス成形体を約１５００℃程度の温度で焼成して焼結させることによって得ることができる。
【００４２】
そして、この多孔質体に銅を含浸させて複合材料層３ａが形成されるとともに、その上下面に銅層３ｂが形成されている。この銅層３ｂは、通常は、複合材料層３ａに多孔質体の上下面から含浸させた銅のうち内部に含浸されきれずに残った分が複合材料層３ａの上下面に配置されて形成される。
【００４３】
そして、この放熱基体３においては、図２中に示すように、上下面のそれぞれの銅層３ｂの厚みをｔ２、複合材料層３ａの厚みをｔ１としたとき、３０μｍ≦ｔ２≦３００μｍかつｔ２≦０．１５×ｔ１とすることが重要である。ｔ２＜３０μｍとなると、表面近傍で銅層３ｂによって面内の水平方向により多く熱を逃がすことができなくなるために、半導体素子４が発生する熱を大気中に良好に放散することが困難になり、半導体素子４の熱破壊が起きたり、特性に熱変化を与え誤動作を生じさせる傾向がある。他方、ｔ２＞３００μｍとなると、半導体素子４の載置部における銅の占める割合が大きくなり過ぎ、熱膨張係数が大きくなり、半導体素子４および放熱基体３と接合材７との間および絶縁枠体１および放熱基体３と接合材６との間で破壊や剥離が生じやすくなる傾向がある。
【００４４】
また、ｔ２＞０．１５×ｔ１となると、上記と同様に、半導体素子４の載置部における銅の占める割合が大きくなり過ぎ、熱膨張係数が大きくなり、半導体素子４および放熱基体３と接合材７との間および絶縁枠体１および放熱基体３と接合材６との間で破壊や剥離が生じやすくなる傾向がある。
【００４５】
また、複合材料層３ａにおいて炭化珪素の多孔質体に含浸させる銅の含有量は、放熱基体３の熱膨張係数を６．５乃至９×１０^−６／℃と、ガラスセラミックス焼結体から成る絶縁枠体１の熱膨張係数の近傍の値にするために、２０乃至３５質量％としておくことが好ましい。この銅の含有量が１０質量％未満となると、放熱基体３の熱膨張係数が６×１０^−６／℃以下になるために、半導体素子４および放熱基体３と接合材７との間および絶縁枠体１および放熱基体３と接合材７との間で破壊や剥離が生じやすくなる傾向がある。他方、２５質量％を超えると、放熱基体３の熱膨張係数が９×１０^−６／℃以上になるために、半導体素子４および放熱基体３と接合材７との間および絶縁枠体１および放熱基体３と接合材７との間で破壊や剥離が生じやすくなる傾向がある。
【００４６】
なお、このような放熱基体３に対し、絶縁枠体１としては、放熱基体３の熱膨張係数をその絶縁枠体１の熱膨張係数の近傍の値にする観点からは、熱膨張係数が６乃至８×１０^−６／℃（室温〜８００℃）の。ガラスセラミックス焼結体から成ることが好ましい。
【００４７】
かくして上述の本発明の半導体素子収納用パッケージによれば、放熱基体３の上面の載置部に半導体素子４をガラス・樹脂・ロウ材等から成る接着材７を介して接着固定して載置するとともにこの半導体素子４の各電極をボンディングワイヤ５を介して所定の配線層８に接続させ、しかる後に、絶縁枠体１の上面に蓋体２をガラス・樹脂・ロウ材等から成る封止材を介して接合させ、絶縁枠体１と放熱基体３と蓋体２とから成る容器内部に半導体素子４を気密に収容することによって、製品としての半導体装置となる。
【００４８】
【実施例】
（実施例１）
まず、中心粒径が数μｍ乃至１００μｍの炭化珪素粉末に適量のバインダを混合した後、約１０ｋＮ／ｃｍ^３の圧力でプレス体を成形し、このプレス成形体を約１５００℃の温度で焼成して得た炭化珪素から成る焼結多孔質体を準備した。次に、この多孔質体に１２００℃の温度で１５質量％の銅の溶浸を行なって含浸させ、上下面のそれぞれの銅層の厚みが０，０．０１５，０．０３０，０．０５０，０．１０，０．２０，０．３０，０．５０ｍｍになるようにして、評価用の放熱基体試料の作製を行なった。
【００４９】
そして、これら評価用放熱基体試料につき、ＪＩＳ　Ｒ１６１１に規定のファインセラミックスのレーザーフラッシュ法により熱拡散・比熱容量・熱伝導率試験方法に基づき評価用放熱基体試料の熱伝導率（Ｗ／ｍＫ）を測定し、またＴＭＡ（Ｔｈｅｒｍｏｍｅｃｈａｎｉｃａｌ　Ａｎａｌｙｓｉｓ）法により評価用放熱基体試料を昇温させながら各温度に対する評価用放熱基体試料の伸び量を測定し、その値を温度上昇幅の値で除算することによって熱膨張係数（×１０^−６／℃）を測定した。また、接合界面について、倍率が４０倍の顕微鏡にて界面観察を行なった。その後、超音波探傷装置にて同様の観察を行なった。
【００５０】
その結果について、表１にこれら炭化珪素および銅から成る複合材料層とその上下面の銅層との厚み比率を変化させた場合の放熱基体の熱膨張係数および熱伝導率の物性値と、温度サイクル試験（ＴＣＴ：−６５／＋１５０℃、１０００サイクル）後のサイズが１０ｍｍ□で、厚みが０．６ｍｍのシリコン製の半導体素子と放熱基体との接合界面状態と、外形サイズが２０ｍｍ□、キャビティサイズが１２ｍｍ□で、厚みが１ｍｍの絶縁枠体と放熱基体との接合界面状態とを示す。
【００５１】
【表１】

【００５２】
表１に示す結果より分かるように、Ｎｏ．１乃至Ｎｏ．８の放熱基体では、複合材料層の厚みを２ｍｍに固定して銅層の厚みを０乃至０．５０ｍｍで変更した場合に、複合材料層／銅層厚み比率（ｔ２／ｔ１比率）は０乃至０．２５と大きくなり、これに伴い熱伝導率および熱膨張係数も大きい値を示している。特に、ｔ２／ｔ１＝０．０１５以上で２５０Ｗ／ｍＫ以上の値を示した。しかし、銅層厚みが０．３０ｍｍ以上では熱伝導率は大きく変化しないが、ｔ２／ｔ１＝０．１５を超えると放熱基体と絶縁体との接合界面でクラックが発生することが確認できた。放熱基体として、２５０Ｗ／ｍＫ以上の高放熱性があり絶縁体との信頼性が確保できる複合材料層と銅層との厚み比率は、０．１５以下が好適である。
【００５３】
また、Ｎｏ．９乃至Ｎｏ．１０の放熱基体では、複合材料層の厚みを１ｍｍと３ｍｍに変更し、銅層の厚みを０．１０ｍｍと０．３０ｍｍに変更した場合でも、熱伝導率が２５０Ｗ／ｍＫ以上で熱膨張係数も８．０×１０^−６／℃以下の値を示すことが分かる。
【００５４】
（実施例２）
中心粒径が数μｍ乃至１００μｍの炭化珪素粉末に適量のバインダを混合した後、約１０ｋＮ／ｃｍ^３の圧力でプレス体を成形し、このプレス成形体を約１５００℃の温度で焼成して得た炭化珪素から成る焼結多孔質体を準備した。次に、この多孔質体に１２００℃の温度で銅をそれぞれ２０乃至７０質量％の含有量（炭化珪素の量が３０乃至８０質量％）となるように溶浸させて含浸させ、上下面のそれぞれの銅層の厚みは０．１０ｍｍになるようにして評価用の放熱基体試料を作製した。そして、実施例１と同様の評価を行なった。
【００５５】
その結果について、表２に複合材料層とその上下面の銅層との厚み比率が０．０５での複合材料層の銅量を２０質量％乃至７０質量％の間で変化させた場合の放熱基体の熱膨張係数と熱伝導率の物性値と、温度サイクル試験（ＴＣＴ：−６５／１５０℃、１０００サイクル）後の半導体素子と放熱基体との接合界面状態および絶縁体と放熱基体との接合界面状態を示す。
【００５６】
【表２】

【００５７】
表２に示す結果より分かるように、Ｎｏ．１乃至Ｎｏ．８の放熱基体では、銅−炭化珪素複合材料層の銅含有率は２０乃至７０質量％の範囲で変更を行なっており、複合材料層の銅量の比率を上げることで熱膨張係数は徐々に増加する。また、特に銅比率が４０質量％以上では熱膨張係数が９×１０^−６／℃以上となり、放熱基体と絶縁体との界面でクラック等が発生する。よって信頼性が確保できる複合材料層の銅料の比率は、２０乃至３５質量％が好適である。
【００５８】
なお、本発明は上述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種々の変更を加えることは何ら差し支えない。
【００５９】
【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、放熱基体が、炭化珪素の多孔質体に銅を含浸させて成る複合材料層とその上下面に形成された銅層とから成るとともに、複合材料層の厚みをｔ１、銅層の厚みをｔ２としたとき、３０μｍ≦ｔ２≦３００μｍかつｔ２≦０．１５×ｔ１であることから、炭化珪素の多孔質体に銅を含浸させて成る複合材料層のみで構成された放熱基体に比べて、これに載置される半導体素子で発生した熱を、まず表面近傍で銅層によって面内の水平方向により多く逃がすことができるとともに、銅層と複合材料層中の銅とは連続的につながっているため熱伝導の損失が小さくなり、その結果、複合材料層内により多く熱を逃がすことができる。また、複合材料層内は、銅−炭化珪素材料であるので２３０Ｗ／ｍＫ以上の熱伝導率が確保されている。これによって、放熱基体の熱伝導率を２５０Ｗ／ｍＫ以上と極めて高いものとすることが可能となる。
【００６０】
また、複合材料層の上下面に形成された銅層は、複合材料層を炭化珪素に銅を溶浸法で含浸させる際に同時に形成することができることから、熱間一軸法や圧延法で貼り合わせた銅層と異なり、放熱基体に絶縁枠体を接合する時の熱応力により銅層と複合材料層との界面にクラックが発生することはほとんどなく、その結果、放熱基体に載置されてパッケージ内部に収容される半導体素子を長期にわたり正常に、かつ安定に作動させることが可能となる。
【００６１】
また、放熱基体が、炭化珪素の多孔質体に銅を含浸させて成る複合材料層とその上下面に形成された銅層とから成るとともに、複合材料層の厚みをｔ１、銅層の厚みをｔ２としたとき、３０μｍ≦ｔ２≦３００μｍかつｔ２≦０．１５×ｔ１であることから、放熱基体の上面に設けられた半導体素子の載置部では熱伝導率とともに熱膨張係数も大きい銅の占める割合が多いにもかかわらず、放熱基体の熱膨張係数を絶縁枠体の熱膨張係数に近づけることが可能となる。
【００６２】
特に、複合材料層を炭化珪素の多孔質体に２０乃至３５質量％の銅を含浸させて成るものとしたときには、放熱基体の熱膨張係数は９×１０^−６／℃以下の値になるため、放熱基体と絶縁枠体とを長期間にわたり良好に、かつ安定に接合させることが可能となる。
【００６３】
また、絶縁枠体のガラスセラミックス焼結体の熱膨張係数が６乃至８×１０^−６／℃（室温〜８００℃）であるものとしたときには、放熱基体の熱膨張係数をその絶縁枠体の熱膨張係数の近傍の値にすることが可能となるので、放熱基体と絶縁枠体とを長期間にわたり良好に、かつ安定に接合させることが可能となる。
【００６４】
また本発明の半導体素子収納用パッケージによれば、絶縁枠体を比誘電率が７以下のガラスセラミックス焼結体で形成したことから、絶縁枠体に設けた配線層を伝える電気信号の伝搬速度を速いものとでき、信号の高速伝搬を要求する半導体素子を収納することが可能となる。
【００６５】
また本発明の半導体素子収納用パッケージによれば、絶縁枠体を低温焼成（約８００℃〜９００℃）が可能なガラスセラミックス焼結体で形成するとともに、絶縁枠体と同時焼成により形成される配線層を比電気抵抗が２．５μΩ・ｃｍ以下と低い銅や銀・金で形成したことから、配線層に電気信号を伝搬させた場合に、電気信号に大きな減衰が生じることはなく、電気信号を正確、かつ確実に伝搬させることが可能となる。
【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の実施の形態の一例を示す断面図である。
【図２】本発明の半導体素子収納用パッケージにおける放熱基体の概略構成を示す断面図である。
【符号の説明】
１・・・・・絶縁枠体
２・・・・・蓋体
３・・・・・放熱基体
３ａ・・・・・複合材料層
３ｂ・・・・・銅層
４・・・・・半導体素子
８・・・・・配線層[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a package for housing a semiconductor element, and more particularly to a semiconductor for high reliability use having excellent heat radiation characteristics, on which a semiconductor element having high heat generation such as gallium arsenide (GaAs), indium phosphide (InP), silicon (Si) is mounted. The present invention relates to an element storage package.
[0002]
[Prior art]
Conventionally, a semiconductor element housing package for housing a semiconductor element is generally made of an electrically insulating material such as an aluminum oxide sintered body, a mullite sintered body, or a glass ceramic sintered body, and accommodates the semiconductor element on an upper surface. An insulating substrate having a concave portion for forming the insulating substrate, a plurality of wiring layers made of a metal powder such as tungsten, molybdenum, manganese, copper, silver, etc., which are attached and derived from the concave portion of the insulating substrate to the outer surface, and a lid. The semiconductor element is bonded and fixed to the bottom surface of the concave portion of the insulating base via an adhesive such as glass, resin or brazing material, and each electrode of the semiconductor element is electrically connected to a wiring layer via a bonding wire. Thereafter, the lid is bonded to the insulating base via a sealing material made of glass, resin, brazing material, or the like, and the semiconductor element or the like is placed inside the container including the insulating base and the lid. A semiconductor device as a product by housing the heat component.
[0003]
In this conventional package for housing semiconductor elements, since the thermal conductivity of the aluminum oxide sintered body constituting the insulating base is low (about 15 W / mK), the semiconductor elements housed in the insulating base generate a large amount of heat during operation. If this occurs, the heat cannot be satisfactorily dissipated into the atmosphere.As a result, the heat generated by the semiconductor element will be heated to a high temperature, causing the semiconductor element to undergo thermal destruction or change in characteristics. There is a drawback that a given malfunction occurs.
[0004]
Therefore, in a semiconductor device housing package for housing a semiconductor device with high heat generation, a heat dissipating component made of a composite metal material such as copper-tungsten / copper-molybdenum in order to satisfactorily dissipate the heat of the semiconductor device via the insulating base. Are provided immediately below the semiconductor element.
[0005]
For example, in a heat-dissipating component made of a copper-tungsten composite material, tungsten and copper are configured in a matrix, and the thermal conductivity of the copper-tungsten composite material varies depending on the ratio, but is generally about 150 to 200 W / mK. is there.
[0006]
However, with the development of semiconductor devices that require a large current, such as power ICs and high-frequency transistors, the amount of heat generated by the semiconductor devices tends to increase year by year. At present, heat dissipating components having a thermal conductivity of 250 W / mK or more are present. Is required.
[0007]
In order to solve this problem, Japanese Patent Application Laid-Open No. 6-268115 discloses a heat dissipation board for a semiconductor device in which a first member (base material) made of molybdenum and a second member made of copper are clad with a clad material. . M. C. A (Cu / Mo / Cu) structure is disclosed. This C. M. C. The thermal conductivity of the heat dissipation substrate for a semiconductor device made of a clad material having a structure is as high as 200 W / mK or more.
[0008]
Japanese Patent Application Laid-Open No. 6-268117 discloses that copper is coated on both main surfaces of a first member (base material) made of at least one metal material selected from the group consisting of a tungsten-copper alloy and a molybdenum-copper alloy. There has been proposed a heat dissipation board for a semiconductor device in which a second member made of a metal material as a main material is joined by either a hot uniaxial pressing method or a rolling method. In this heat dissipation board for a semiconductor device, 250 W / mK or more is proposed. Of thermal conductivity.
[0009]
[Problems to be solved by the invention]
However, the heat dissipation board for a semiconductor device disclosed in JP-A-6-268115 or JP-A-6-268117 has a very high thermal conductivity of about 250 W / mK. Since the base layer and the copper layer are bonded by the uniaxial processing method, when this is joined to the insulating frame as a heat dissipation base of the package for housing the semiconductor element, the base layer and the copper layer are bonded by thermal stress at the time of joining. There is a problem that cracks easily occur at the interface.
[0010]
In addition, since an interface exists between the copper layer and the base material layer, there is a problem that the thermal conductivity is reduced due to the contact resistance between the two layers.
[0011]
In the conventional semiconductor housing package, since the relative permittivity of the aluminum oxide sintered body forming the insulating frame is as high as 9 to 10 (room temperature, 1 MHz), the electric power transmitted through the wiring layer provided on the insulating frame is required. There has been a problem that the propagation speed of a signal is low, and therefore, a semiconductor element that requires high-speed propagation of a signal cannot be accommodated.
[0012]
Further, in this conventional semiconductor storage package, the wiring layer formed on the insulating frame is formed of a high melting point metal material such as tungsten or molybdenum / manganese, and the specific electrical resistance of the tungsten or the like is 5. Since it is as high as 4 μΩ · cm (200 ° C.) or more, when an electric signal is propagated through the wiring layer, a large attenuation occurs in the electric signal, and the electric signal cannot be propagated accurately and reliably. Was.
[0013]
The present invention has been devised in view of the above-mentioned problems in the conventional technology, and an object of the present invention is to form a heat dissipation base on a copper-silicon carbide substrate by forming copper layers on both surfaces by an infiltration method. In addition, the heat generated by the semiconductor element can be satisfactorily dissipated to the insulator, and the copper layer is formed by a hot uniaxial method or an infiltration method other than bonding such as rolling. It is an object of the present invention to provide a semiconductor element housing package that can firmly and reliably join a base and a semiconductor element that operates at high speed inside.
[0014]
[Means for Solving the Problems]
The semiconductor element housing package of the present invention is provided with a heat radiating base having a mounting portion on which a semiconductor element is mounted on an upper surface, and attached to the upper surface of the heat radiating base so as to surround the mounting portion. A semiconductor device housing package comprising: an insulating frame having a semiconductor element to which the electrodes are electrically connected; and a lid attached to an upper surface of the insulating frame, wherein the insulating frame has a relative dielectric constant. The wiring layer is formed of a metal material having an electrical resistivity of 2.5 μΩ · cm or less, and the heat dissipation base is formed by impregnating a porous body of silicon carbide with copper. When the thickness of the composite material layer is t1 and the thickness of the copper layer is t2, 30 μm ≦ t2 ≦ 300 μm and t2 ≦ 0 .15 × t1 Is what you do.
[0015]
Further, in the package for housing a semiconductor element of the present invention, in the above structure, the composite material layer is formed by impregnating a porous body of tungsten or molybdenum with 20 to 35% by mass of copper. .
[0016]
In the semiconductor device housing package according to the present invention, the glass ceramic sintered body of the insulating frame may have a coefficient of thermal expansion of 6 to 8 × 10. ^-6 / ° C (room temperature to 800 ° C).
[0017]
According to the package for housing a semiconductor element of the present invention, the heat dissipation base is composed of a composite material layer formed by impregnating a porous body of silicon carbide with copper and copper layers formed on upper and lower surfaces of the composite material layer. When the thickness of the copper layer is t1 and the thickness of the copper layer is t2, 30 μm ≦ t2 ≦ 300 μm and t2 ≦ 0.15 × t1, so that only the composite material layer obtained by impregnating the porous body of silicon carbide with copper is used. The heat generated by the semiconductor element mounted on the heat dissipation base can be dissipated more in the horizontal direction in the plane by the copper layer near the surface, and the copper layer and the composite material layer can be released. Because of the continuous connection with the copper inside, the loss of heat conduction is reduced, and as a result, more heat can be dissipated in the composite material layer. Further, since the inside of the composite material layer is a copper-silicon carbide material, a thermal conductivity of 230 W / mK or more is secured. This makes it possible to make the thermal conductivity of the heat dissipation base extremely high, such as 250 W / mK or more.
[0018]
In addition, the copper layers formed on the upper and lower surfaces of the composite material layer can be formed at the same time that the composite material layer is impregnated with copper by infiltration into silicon carbide, so that the copper layers are bonded by a hot uniaxial method or a rolling method. Unlike the combined copper layer, cracks hardly occur at the interface between the copper layer and the composite material layer due to thermal stress when the insulating frame is joined to the heat dissipation base, and as a result, it is placed on the heat dissipation base. The semiconductor element housed in the package can be normally and stably operated for a long time.
[0019]
Further, the heat dissipation base is composed of a composite material layer obtained by impregnating a porous body of silicon carbide with copper, and copper layers formed on the upper and lower surfaces thereof, and the thickness of the composite material layer is t1, and the thickness of the copper layer is Assuming that t2 is 30 μm ≦ t2 ≦ 300 μm and t2 ≦ 0.15 × t1, the mounting portion of the semiconductor element provided on the upper surface of the heat dissipation base is occupied by copper having a large thermal conductivity and a large thermal expansion coefficient. Despite the high ratio, the thermal expansion coefficient of the heat dissipation base can be made closer to the thermal expansion coefficient of the insulating frame.
[0020]
In particular, when the composite material layer is formed by impregnating a porous body of silicon carbide with 20 to 35% by mass of copper, the thermal expansion coefficient of the heat dissipation base is 9 × 10 ^-6 / ° C. or less, it is possible to bond the heat dissipation base and the insulating frame body satisfactorily and stably over a long period of time.
[0021]
Further, the glass-ceramic sintered body of the insulating frame is made to have a coefficient of thermal expansion of 6 to 8 × 10 ^-6 /.Degree. C. (room temperature to 800.degree. C.), the thermal expansion coefficient of the heat radiating base can be set to a value near the thermal expansion coefficient of the insulating frame. Can be bonded satisfactorily and stably over a long period of time.
[0022]
According to the package for housing a semiconductor element of the present invention, since the insulating frame is formed of a glass ceramic sintered body having a relative permittivity of 7 or less, the propagation speed of an electric signal transmitted through the wiring layer provided on the insulating frame is increased. And a semiconductor element requiring high-speed signal propagation can be accommodated.
[0023]
According to the package for housing a semiconductor element of the present invention, the insulating frame is formed of a glass ceramic sintered body that can be fired at a low temperature (about 800 ° C. to 900 ° C.), and is formed by simultaneous firing with the insulating frame. Since the wiring layer is formed of copper, silver, or gold having a specific electric resistance of as low as 2.5 μΩ · cm or less, when an electric signal is propagated through the wiring layer, the electric signal does not greatly attenuate. Signals can be accurately and reliably propagated.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
[0025]
FIG. 1 is a sectional view showing an example of an embodiment of a semiconductor element storage package according to the present invention, wherein 1 is an insulating frame, 2 is a lid, 3 is a heat dissipation base, and 4 is a semiconductor element. The heat radiating base 3 has a mounting portion on which the semiconductor element 4 is mounted at the center of the upper surface. The insulating frame 1 is attached to the upper surface of the heat radiating base 3 so as to surround the mounting portion. The insulating frame 1, the lid 2, and the heat dissipation base 3 constitute a container for housing the semiconductor element 4.
[0026]
The insulating frame 1 is a glass ceramic sintered body having a relative dielectric constant of 7 or less (linear thermal expansion coefficient: 6 to 8 × 10 ^-6 / ° C), specifically,
1) A glass ceramic sintered body (relative permittivity 5 to 6) manufactured from raw material powder obtained by adding alumina or mullite to borosilicate glass
2) Glass-ceramic sintered body (relative permittivity 5-6) manufactured from raw material powder obtained by adding alumina or mullite to cordierite-based crystallized glass
3) Glass ceramic sintered body (relative permittivity 5-6) manufactured from raw material powder obtained by adding alumina or mullite to mullite crystallized glass
And so on.
[0027]
The insulating frame 1 is bonded and fixed to the heat dissipation base 3 via the brazing material 6. In addition, a metal layer (not shown) for brazing is formed at a joint of the insulating frame 1 and the heat dissipation base 3.
[0028]
When the insulating frame 1 is made of a glass-ceramic sintered body made of a raw material powder obtained by adding alumina or mullite to borosilicate glass, for example, the composition of the raw material powder is silica. Borosilicate powder comprising a total of 2 to 3% of boron oxide of 2% to 17% of boron oxide, 2% to 4% of aluminum oxide, sodium oxide, potassium oxide and titanium oxide, powder of alumina, quartz and cordierite, and an organic binder, A solvent or the like is added and mixed to produce a slurry, and the slurry is formed into a ceramic green sheet (green ceramic sheet) by employing a doctor blade method or a calender roll method. Punching and laminating a plurality of them and firing at a temperature of about 900 ° C It is produced by Rukoto.
[0029]
The insulating frame 1 is formed with a wiring layer 8 extending from a portion surrounding the mounting portion of the semiconductor element 4 on the inner side to the outer surface, and the wiring layer 8 exposed inside the insulating frame 1 is formed. Each electrode of the semiconductor element 4 is electrically connected to one end via a bonding wire 5, and an external lead pin 9 connected to an external electric circuit is provided at a portion led out on the upper surface of the insulating frame 1. It is brazed and attached via brazing material such as brazing.
[0030]
The wiring layer 8 functions as a conductive path when connecting each electrode of the semiconductor element 4 to an external electric circuit, and is formed of a metal powder such as copper, silver, and gold.
[0031]
The wiring layer 8 is formed by adding a suitable organic binder or a solvent to a metal powder of copper, silver, gold or the like and mixing the metal paste with a ceramic green sheet serving as the insulating frame 1 in advance by a screen printing method known in the art. By printing and applying a predetermined pattern on the insulating frame 1, the insulating frame 1 is adhered and formed from the inside to the outer surface.
[0032]
Although the melting point of copper, silver, gold and the like forming the wiring layer 8 is as low as about 1000 ° C., since the firing temperature of the glass ceramic sintered body constituting the insulating frame 1 is low, a predetermined pattern is formed on the insulating frame 1. Can be formed.
[0033]
Further, since the electrical resistivity of copper, silver, gold and the like forming the wiring layer 8 is as low as 2.5 μΩ · cm or less, the semiconductor element 4 housed inside the container via the wiring layer 8 and the external electric circuit Even if an electrode signal is put in and taken out between them, the electric signal is not greatly attenuated in the wiring layer 8, and as a result, the semiconductor element 4 can be operated accurately and reliably.
[0034]
Further, since the relative dielectric constant of the insulating frame 1 on which the wiring layer 8 is adhered is as low as 7 or less (room temperature, 1 MHz), preferably 5.5 to 6, the wiring layer 8 is formed. As a result, even if the electric signal is transferred between the semiconductor element 4 housed in the container and the external electric circuit via the wiring layer 8, the electric signal propagates at a high speed. Therefore, electric signals can be accurately and reliably input to and output from the semiconductor element 4 without delay.
[0035]
When the wiring layer 8 is made of copper or silver, a metal having excellent corrosion resistance such as nickel and gold and excellent bonding property of the bonding wire 5 is applied to the exposed surface to a thickness of 1 to 20 μm by plating. By doing so, the oxidative corrosion of the wiring layer 8 can be effectively prevented, and the connection of the bonding wire 5 to the wiring layer 8 can be made firm. Therefore, it is desirable that the wiring layer 8 is 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.
[0036]
The external lead pins 9 brazed to the wiring layer 8 attached to the insulating frame 1 are made of a metal material such as an iron-nickel-cobalt alloy or an iron-nickel alloy. It has a function of being electrically connected to a circuit.
[0037]
The external lead pins 9 are formed in a predetermined shape by subjecting an ingot (a lump) made of a metal such as an iron-nickel-cobalt alloy to a conventionally known noble processing method such as a rolling method or a punching method.
[0038]
The heat dissipation base 3 has a mounting portion for the semiconductor element 4 on its upper surface, and the semiconductor element 4 is fixed to this mounting portion via an adhesive 7 such as resin, glass, brazing material or the like. When a brazing material is used as the adhesive 7, a metal layer (not shown) for brazing is usually formed at a joint between the heat dissipation base 3 and the semiconductor element 4. The insulating frame 1 and the heat dissipation base 3 are joined by using a brazing material 6 made of a silver-copper alloy or the like, melting the brazing material 6 in a reducing atmosphere at 600 ° C. to 900 ° C., and then cooling and solidifying. Is done.
[0039]
The heat dissipating substrate 3 is composed of a composite material layer 3a formed by impregnating a porous body of silicon carbide with copper and copper layers 3b formed on the upper and lower surfaces thereof, as schematically shown in a sectional view of FIG. . The heat radiation base 3 has a function of absorbing heat generated by the operation of the semiconductor element 4 and dissipating it into the atmosphere.
[0040]
The heat radiating substrate 3 is formed by melting and impregnating copper from the upper and lower surfaces of a previously formed porous body of silicon carbide by an infiltration method to form a composite material layer 3a. Since the remaining copper forms the copper layer 3b and covers the upper and lower surfaces, the copper layer 3b is polished so as to leave a thickness of 30 to 200 μm. Thereafter, if necessary, a plating layer (not shown) of nickel or the like is formed on the exposed surface for the purpose of increasing the corrosion resistance of the surface of the copper layer 3b and increasing the wettability with the brazing material 6 or the adhesive 7. Apply.
[0041]
In the heat dissipation base 3, the porous body of silicon carbide constituting the composite material layer 3a is formed by mixing an appropriate amount of a binder with a silicon carbide powder having a center particle diameter of several μm to 100 μm, for example, to about 10 kN / cm 2. ³ It can be obtained by molding a pressed body at a pressure of about 1, sintering and sintering the pressed body at a temperature of about 1500 ° C.
[0042]
The porous body is impregnated with copper to form a composite material layer 3a, and copper layers 3b are formed on upper and lower surfaces thereof. The copper layer 3b is usually formed by arranging the copper material impregnated into the composite material layer 3a from the upper and lower surfaces of the porous body and remaining on the upper and lower surfaces of the composite material layer 3a without being completely impregnated. Is done.
[0043]
As shown in FIG. 2, in the heat dissipation base 3, when the thickness of each of the upper and lower copper layers 3b is t2 and the thickness of the composite material layer 3a is t1, 30 μm ≦ t2 ≦ 300 μm and t2 ≦ It is important to set 0.15 × t1. When t2 <30 μm, it becomes difficult to dissipate more heat in the horizontal direction in the plane by the copper layer 3b near the surface, so that it is difficult to satisfactorily dissipate the heat generated by the semiconductor element 4 into the atmosphere. In addition, there is a tendency that the semiconductor element 4 is thermally broken or a characteristic is changed by heat to cause a malfunction. On the other hand, when t2> 300 μm, the proportion of copper in the mounting portion of the semiconductor element 4 becomes too large, the coefficient of thermal expansion becomes large, and the space between the semiconductor element 4 and the heat dissipation base 3 and the bonding material 7 and the insulating frame body 1 and the heat dissipation base 3 and the bonding material 6 tend to be easily broken or peeled off.
[0044]
If t2> 0.15 × t1, the proportion of copper in the mounting portion of the semiconductor element 4 becomes too large, the thermal expansion coefficient becomes too large, and the semiconductor element 4 and the heat radiating base 3 are bonded. There is a tendency that destruction or peeling is likely to occur between the material 7 and the insulating frame 1 and the heat dissipation base 3 and the bonding material 6.
[0045]
The content of copper impregnated in the porous body of silicon carbide in the composite material layer 3a is determined by adjusting the thermal expansion coefficient of the heat dissipation base 3 to 6.5 to 9 × 10 4. ^-6 / ° C. and a value close to the coefficient of thermal expansion of the insulating frame 1 made of a glass ceramic sintered body, the content is preferably set to 20 to 35% by mass. When the content of copper is less than 10% by mass, the thermal expansion coefficient of the heat dissipation base 3 is 6 × 10 ^-6 / ° C. or less, there is a tendency that destruction or peeling is likely to occur between the semiconductor element 4 and the heat dissipation base 3 and the bonding material 7 and between the insulating frame 1 and the heat dissipation base 3 and the bonding material 7. On the other hand, if it exceeds 25% by mass, the thermal expansion coefficient of the heat dissipation base 3 is 9 × 10 ^-6 / ° C. or more, there is a tendency that destruction or peeling is likely to occur between the semiconductor element 4 and the heat dissipation base 3 and the joining material 7 and between the insulating frame 1 and the heat dissipation base 3 and the joining material 7.
[0046]
In addition, from the viewpoint of setting the thermal expansion coefficient of the heat radiating base 3 to a value near the thermal expansion coefficient of the insulating frame 1, the thermal expansion coefficient of the insulating frame 1 is 6 in comparison with the heat radiating base 3. ~ 8 × 10 ^-6 / ° C (room temperature to 800 ° C). It is preferable to be made of a glass ceramic sintered body.
[0047]
Thus, according to the semiconductor element storage package of the present invention described above, the semiconductor element 4 is mounted and fixed on the mounting portion on the upper surface of the heat dissipation base 3 via the adhesive 7 made of glass, resin, brazing material or the like. At the same time, each electrode of the semiconductor element 4 is connected to a predetermined wiring layer 8 via a bonding wire 5. Thereafter, the lid 2 is sealed on the upper surface of the insulating frame 1 with glass, resin, brazing material or the like. A semiconductor device as a product is obtained by joining the semiconductor element 4 in a container including the insulating frame 1, the heat dissipation base 3, and the lid 2 in an airtight manner.
[0048]
【Example】
(Example 1)
First, an appropriate amount of a binder is mixed with a silicon carbide powder having a center particle size of several μm to 100 μm, and then mixed at about 10 kN / cm. ³ And a sintered porous body made of silicon carbide obtained by firing this pressed body at a temperature of about 1500 ° C. Next, the porous body is impregnated with 15% by mass of copper at a temperature of 1200 ° C. to be impregnated, and the thickness of each of the upper and lower copper layers is 0, 0.015, 0.030, 0.050. , 0.10, 0.20, 0.30, and 0.50 mm, and a heat radiation base sample for evaluation was produced.
[0049]
The thermal conductivity (W / mK) of the heat-dissipating substrate sample for evaluation was determined by the laser flash method for fine ceramics specified in JIS R1611 based on the thermal diffusion, specific heat capacity, and thermal conductivity test methods. The elongation of the heat-dissipating substrate sample for each temperature is measured while increasing the temperature of the heat-dissipating substrate sample for evaluation by the TMA (Thermomechanical Analysis) method, and the value is divided by the value of the temperature rise. Expansion coefficient (× 10 ^-6 / ° C) was measured. The interface of the bonded interface was observed with a microscope having a magnification of 40 times. After that, the same observation was performed with an ultrasonic flaw detector.
[0050]
Table 1 shows the physical properties of the thermal expansion coefficient and thermal conductivity of the heat dissipation base when the thickness ratio between the composite material layer made of silicon carbide and copper and the upper and lower copper layers was changed. After the cycle test (TCT: -65 / + 150 ° C., 1000 cycles), the size of the bonding interface between the silicon semiconductor element having a thickness of 0.6 mm and the heat-radiating substrate having a thickness of 0.6 mm and the outer size of 20 mm square, and the cavity The figure shows the bonding interface state between the insulating frame body having a size of 12 mm square and the thickness of 1 mm and the heat dissipation base.
[0051]
[Table 1]

[0052]
As can be seen from the results shown in Table 1, 1 to No. 8, when the thickness of the composite material layer is fixed at 2 mm and the thickness of the copper layer is changed from 0 to 0.50 mm, the composite material layer / copper layer thickness ratio (t2 / t1 ratio) is from 0 to As a result, the thermal conductivity and the thermal expansion coefficient also show large values. In particular, a value of 250 W / mK or more was exhibited when t2 / t1 was 0.015 or more. However, when the thickness of the copper layer was 0.30 mm or more, the thermal conductivity did not change significantly. However, when t2 / t1 exceeded 0.15, it was confirmed that cracks occurred at the joint interface between the heat dissipation base and the insulator. The thickness ratio between the composite material layer and the copper layer, which have a high heat dissipation of 250 W / mK or more and can ensure the reliability with the insulator, is preferably 0.15 or less.
[0053]
No. 9 to No. 9 In the heat dissipation base of No. 10, even when the thickness of the composite material layer is changed to 1 mm and 3 mm and the thickness of the copper layer is changed to 0.10 mm and 0.30 mm, the thermal conductivity is 250 W / mK or more and the thermal expansion coefficient is also 8.0 × 10 ^-6 It can be seen that the value is not more than / ° C.
[0054]
(Example 2)
After mixing an appropriate amount of a binder with silicon carbide powder having a center particle size of several μm to 100 μm, the mixture is mixed to about 10 kN / cm ³ And a sintered porous body made of silicon carbide obtained by firing this pressed body at a temperature of about 1500 ° C. Next, this porous body is infiltrated with copper at a temperature of 1200 ° C. so as to have a content of 20 to 70% by mass (the amount of silicon carbide is 30 to 80% by mass). Heat dissipation base samples for evaluation were prepared so that the thickness of each copper layer was 0.10 mm. Then, the same evaluation as in Example 1 was performed.
[0055]
The results are shown in Table 2. The heat radiation when the thickness of the composite material layer and the upper and lower copper layers is 0.05 and the amount of copper in the composite material layer is changed between 20% by mass and 70% by mass. Thermal expansion coefficient and thermal conductivity of the substrate, physical properties of the substrate, state of bonding interface between semiconductor element and heat radiating substrate after temperature cycle test (TCT: -65 / 150 ° C., 1000 cycles), bonding of insulator to heat radiating substrate This shows the interface state.
[0056]
[Table 2]

[0057]
As can be seen from the results shown in Table 2, 1 to No. In the heat dissipation base of No. 8, the copper content of the copper-silicon carbide composite material layer was changed in the range of 20 to 70% by mass, and the coefficient of thermal expansion gradually increased by increasing the ratio of the copper content of the composite material layer. To increase. In particular, when the copper ratio is 40% by mass or more, the coefficient of thermal expansion is 9 × 10 ^-6 / ° C or more, cracks and the like occur at the interface between the heat dissipation base and the insulator. Therefore, the proportion of the copper material in the composite material layer that can ensure reliability is preferably 20 to 35% by mass.
[0058]
It should be noted that the present invention is not limited to the above-described embodiment, and various changes may be made without departing from the spirit of the present invention.
[0059]
【The invention's effect】
According to the package for housing a semiconductor element of the present invention, the heat dissipation base is composed of a composite material layer formed by impregnating a porous body of silicon carbide with copper and copper layers formed on upper and lower surfaces of the composite material layer. When the thickness of the copper layer is t1 and the thickness of the copper layer is t2, 30 μm ≦ t2 ≦ 300 μm and t2 ≦ 0.15 × t1, so that only the composite material layer obtained by impregnating the porous body of silicon carbide with copper is used. The heat generated by the semiconductor element mounted on the heat dissipation base can be dissipated more in the horizontal direction in the plane by the copper layer near the surface, and the copper layer and the composite material layer can be released. Because of the continuous connection with the copper inside, the loss of heat conduction is reduced, and as a result, more heat can be dissipated in the composite material layer. Further, since the inside of the composite material layer is a copper-silicon carbide material, a thermal conductivity of 230 W / mK or more is secured. This makes it possible to make the thermal conductivity of the heat dissipation base extremely high, such as 250 W / mK or more.
[0060]
In addition, the copper layers formed on the upper and lower surfaces of the composite material layer can be formed at the same time that the composite material layer is impregnated with copper by infiltration into silicon carbide, so that the copper layers are bonded by a hot uniaxial method or a rolling method. Unlike the combined copper layer, cracks hardly occur at the interface between the copper layer and the composite material layer due to thermal stress when the insulating frame is joined to the heat dissipation base, and as a result, it is placed on the heat dissipation base. The semiconductor element housed in the package can be normally and stably operated for a long time.
[0061]
Further, the heat dissipation base is composed of a composite material layer obtained by impregnating a porous body of silicon carbide with copper, and copper layers formed on the upper and lower surfaces thereof, and the thickness of the composite material layer is t1, and the thickness of the copper layer is Assuming that t2 is 30 μm ≦ t2 ≦ 300 μm and t2 ≦ 0.15 × t1, the mounting portion of the semiconductor element provided on the upper surface of the heat dissipation base is occupied by copper having a large thermal conductivity and a large thermal expansion coefficient. Despite the high ratio, the thermal expansion coefficient of the heat dissipation base can be made closer to the thermal expansion coefficient of the insulating frame.
[0062]
In particular, when the composite material layer is formed by impregnating a porous body of silicon carbide with 20 to 35% by mass of copper, the thermal expansion coefficient of the heat dissipation base is 9 × 10 ^-6 / ° C. or less, it is possible to bond the heat dissipation base and the insulating frame body satisfactorily and stably over a long period of time.
[0063]
The glass-ceramic sintered body of the insulating frame has a coefficient of thermal expansion of 6 to 8 × 10 ^-6 /.Degree. C. (room temperature to 800.degree. C.), the thermal expansion coefficient of the heat radiating base can be set to a value near the thermal expansion coefficient of the insulating frame. Can be bonded satisfactorily and stably over a long period of time.
[0064]
Further, according to the package for housing a semiconductor element of the present invention, since the insulating frame is formed of a glass ceramic sintered body having a relative dielectric constant of 7 or less, the propagation speed of an electric signal transmitted through the wiring layer provided on the insulating frame is , And semiconductor devices that require high-speed signal propagation can be accommodated.
[0065]
According to the package for housing a semiconductor element of the present invention, the insulating frame is formed of a glass ceramic sintered body that can be fired at a low temperature (about 800 ° C. to 900 ° C.), and is formed by simultaneous firing with the insulating frame. Since the wiring layer is formed of copper, silver, or gold having a specific electric resistance of as low as 2.5 μΩ · cm or less, when an electric signal is propagated through the wiring layer, the electric signal does not greatly attenuate. Signals can be accurately and reliably propagated.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of an embodiment of a semiconductor device housing package according to the present invention.
FIG. 2 is a cross-sectional view showing a schematic configuration of a heat dissipation base in the package for housing a semiconductor element of the present invention.
[Explanation of symbols]
1 ... Insulating frame
2 .... Lid
3 .... radiation base
3a ... Composite material layer
3b ····· Copper layer
4 ... Semiconductor element
8 Wiring layer

Claims

A heat dissipating base having a mounting part on which a semiconductor element is mounted on an upper surface, and wiring attached to the upper surface of the heat dissipating base so as to surround the mounting part and electrically connecting electrodes of the semiconductor element A package for housing a semiconductor element, comprising: an insulating frame having a layer; and a lid attached to an upper surface of the insulating frame, wherein the insulating frame has a relative dielectric constant of 7 or less. The wiring layer is formed of a metal material having an electrical resistivity of 2.5 μΩ · cm or less, and the heat dissipation base is composed of a composite material layer formed by impregnating a porous body of silicon carbide with copper and upper and lower surfaces thereof. And the thickness of the composite material layer is t1, and the thickness of the copper layer is t2, where 30 μm ≦ t2 ≦ 300 μm and t2 ≦ 0.15 × t1. Package for storing semiconductor elements.

2. The package according to claim 1, wherein the composite material layer is formed by impregnating a porous body of silicon carbide with copper in an amount of 20 to 35% by mass.

2. The package according to claim 1, wherein the glass-ceramic sintered body of the insulating frame has a coefficient of thermal expansion of 6 to 8 × 10 ⁻⁶ / ° C. (room temperature to 800 ° C.).