【０００１】
【発明の属する技術分野】
本発明は、炭化ケイ素（ＳｉＣ）とアルミニウム（Ａｌ）の複合体（Ａｌ−ＳｉＣ系複合体）に関し、特に主に炭化ケイ素からなる多孔体に、アルミニウムを主成分とする金属を含浸して形成したＡｌ−ＳｉＣ系複合体に関する。本発明のＡｌ−ＳｉＣ系複合体は、低熱膨張、高熱伝導特性を有し、放熱基板、ヒートシンク、パッケージなど半導体装置に用いられる放熱部品に好適なものである。
【０００２】
【従来の技術】
近年、産業機器の分野では、半導体スイッチングデバイスを用いて大きな電力を最適な電力に効率よく交換制御する大電力モジュール装置の開発が進んでいる。例えば、電動車輌用インバータとして高電圧、大電流動作が可能なＩＧＢＴモジュールがある。このような大電力モジュール化に伴い、半導体チップから発生する熱も増大している。半導体チップは熱に弱く、発熱が大きくなれば半導体回路の誤動作や破壊を招くことになる。そこで、半導体チップなど電子部品を搭載するための回路基板の裏面にヒートシンクなどの放熱部品を設けて、放熱部品を介して半導体チップから発生した熱を外部に発散させ、半導体回路の動作を安定にすることが行われている。半導体チップなどの電子部品を搭載するための半導体基板としては、窒化ケイ素（Ｓｉ３Ｎ４）、窒化アルミニウム（ＡｌＮ）、酸化アルミニウム（Ａｌ２Ｏ３）などのセラミックス基板が主に用いられている。
【０００３】
従来の放熱部品用材料として、銅、モリブデン、タングステンなどがある。モリブデンやタングステンからなる放熱部品は高価であり、また金属の比重が大きいため放熱部品の重量が重くなり、放熱部品の軽量化が望まれる用途には好ましくない。
【０００４】
また、銅からなる放熱部品は、放熱部品と接合されるセラミックス基板との熱膨張係数の差が大きいので、放熱部品とセラミックス基板との加熱接合時や、使用中の熱サイクルにより、はんだ層の破壊、熱流路の遮断、セラミックス基板の割れを生じやすい。つまり、放熱部品と接合されるセラミックス基板との熱膨張係数の差が大き過ぎる場合、互いの接合部には熱応力および熱歪みが残留する。そして、モジュール装置の使用時に熱ストレスが繰り返し与えられ、残留熱応力および熱歪みに重畳されると、はんだ層の疲労破壊による熱流路の遮断と、機械的に脆い性質を持つセラミックス基板の割れを生じる。
【０００５】
銅などの従来材に替わる放熱部品用材料として、アルミニウムまたはアルミニウム合金中に炭化ケイ素を分散させた低熱膨張・高熱伝導特性を有するＡｌ−ＳｉＣ系複合体が注目されている（特公平７−２６１７４号、特開昭６４−８３６３４号等参照）。Ａｌ−ＳｉＣ系複合体の製法としては、炭化ケイ素粉末あるいは炭化ケイ素繊維で形成された多孔体（プリフォーム）を用い、この多孔体を型内の空間に配置し、アルミニウムインゴットを接触させて、窒素雰囲気中で加圧もしくは非加圧で加熱溶融したアルミニウムを型内の空間に流し込むことによって、炭化ケイ素の多孔体に含浸させ、冷却して作製する溶融金属含浸法などがある。この製造方法によれば、炭化ケイ素の含有量を２０〜９０体積％の範囲で選択できる。また、炭化ケイ素多孔体の形状の自由度が高く、複雑な形状の製品をネットシェイプ成形できる利点を有する。
【０００６】
【発明が解決しようとする課題】
一般に、放熱部品とセラミックス基板とは、はんだによりろう付けされており、ろう材の融点以上に加熱した後、室温まで冷却される。その際、ろう材の凝固点で互いに固定され、その後は固定されたまま放熱部品とセラミックス基板がそれぞれ固有の熱膨張係数に従って収縮し、放熱部品全体に反りなどの変形を生じる。
【０００７】
板形状の放熱部品を半導体モジュール装置に組立てる場合、放熱部品に固定用穴を数箇所設け、固定用穴にボルト、ワッシャなどの固定部材を装着し、モジュール装置を構成するヒートシンクなどの支持部材にグリースなどの緩衝剤を介して放熱部品を固定することが一般に行われる。その際、放熱部品に反りなどの変形がある場合、放熱部品と支持部材の間に隙間が生じ、半導体チップから発生した熱の外部への放熱が阻害され、半導体回路の誤動作や破壊を招くことになる。
【０００８】
これを図面に基づいて説明する。図５は、従来のＡｌ−ＳｉＣ系複合体からなる放熱部品を具備する半導体モジュール装置の一例を示す。図５において、上側は平面図、下側は縦断面図である。半導体モジュール装置は、複数個の半導体チップ７を搭載した半導体基板２と、Ａｌ−ＳｉＣ系複合体からなる板形状の放熱部品１と、ヒートシンクなどの支持部材５とから主に構成される。
【０００９】
放熱部品１の上面には半導体基板２がはんだ付けなどにより接合される。この放熱部品１と支持部材５の間にグリースなどの緩衝剤を介在させて、放熱部品１の底面に支持部材５を配置する。そして、放熱部品１および支持部材５の所定の位置に数箇所設けた固定用穴３にボルトなどの固定部材４を装着して締め付けることにより、放熱部品１を支持部材５に固定する。
【００１０】
このような組立てを行なう場合、半導体基板２を放熱部品１にはんだ付けにより接合する際、ろう材の融点以上に加熱させた後、室温まで冷却される。そのとき、ろう材の凝固点で互いに固定され、その後は固定されたまま放熱部品１と半導体基板２がそれぞれ固有の熱膨張係数に従って収縮するため、放熱部品１全体に反りなどの変形を生じる。
【００１１】
反りが生じた状態で放熱部品１を支持部材５に締め付け固定すると、放熱部品１と支持部材５の接合面間の中央部にわずかな隙間６が生じ、両部材が十分に接触しないため半導体チップ７から発生した熱の外部への放熱が阻害されるという問題がある。
【００１２】
本発明は、上記の事情に鑑みなされたものであって、放熱部品と支持部材の間に隙間が生じることなく半導体チップから発生した熱を外部へ十分に発散でき得るＡｌ−ＳｉＣ系複合体、そのＡｌ−ＳｉＣ系複合体を用いた放熱部品および半導体モジュール装置を提供することを目的とする。
【００１３】
【課題を解決するための手段】
本発明のＡｌ−ＳｉＣ系複合体は、半導体基板が接合される側の主面と反対側の主面が、端部から中央部に向かって凸状に突出し、その突出量が１５０〜５００μｍである板状体のＡｌ−ＳｉＣ系複合体であって、半導体基板を接合後、該半導体基板が接合される側の主面と反対側の主面の突出量が４０〜１２０μｍになることを特徴とする。
【００１４】
また、本発明の第１態様のＡｌ−ＳｉＣ系複合体は、半導体基板が接合される側の主面と反対側の主面が、端部から中央部に向かって凸状に突出し、その突出量が１５０〜５００μｍであるとともに、半導体基板が接合される側の主面が平坦状であることを特徴とする。
【００１５】
また、本発明の第２態様のＡｌ−ＳｉＣ系複合体は、半導体基板が接合される側の主面と反対側の主面が、端部から中央部に向かって凸状に突出し、その突出量が１５０〜５００μｍであり、その突出は加熱しながら負荷を与えて塑性変形により付与されたことを特徴とする。
【００１６】
さらに、本発明の第３態様のＡｌ−ＳｉＣ系複合体は、半導体基板が接合される側の主面と反対側の主面が、端部から中央部に向かって凸状に突出し、その突出量が１５０〜５００μｍであり、その突出は半導体基板が接合される側の主面に形成されるアルミニウム被覆層の厚みを、反対側の主面に形成されるそれより厚くすることにより付与されたことを特徴とする。
【００１７】
前記本発明において、Ａｌ−ＳｉＣ系複合体が主に炭化ケイ素からなる多孔体にアルミニウムを主成分とする金属を含浸して形成されたことを特徴とする。また本発明は、前記本発明のＡｌ−ＳｉＣ系複合体からなる放熱部品であることを特徴とする。さらに、前記本発明のＡｌ−ＳｉＣ系複合体からなる放熱部品を具備する半導体モジュール装置であることを特徴とする。
【００１８】
【発明の実施の形態】
Ａｌ−ＳｉＣ系複合体からなる放熱部品において、半導体基板が接合される側の主面と反対側の主面すなわち放熱部品の底面の突出量を種々変化させて、半導体基板が接合される側の主面に半導体基板をはんだ付けにより接合したときの放熱性の良否を検討した。その結果、半導体基板を接合後の放熱部品の底面の突出量が４０〜１２０μｍ（より好ましくは７０〜１２０μｍ）の範囲であれば、放熱部品と支持部材の接合面間の中央部に空洞状の隙間が見られず、放熱部品と支持部材とが密接に接触して、半導体チップから発生した熱の外部への放熱が良好であった。放熱部品に半導体基板をはんだ付けにより接合したとき、放熱部品全体に反りを生じるため、半導体基板を接合後の放熱部品の底面の突出量を４０〜１２０μｍとするには、半導体基板を接合前の放熱部品の底面の突出量を１５０〜５００μｍの範囲にしておく必要がある。
【００１９】
（実施例１）
図１は、本発明実施例１（本発明の第１態様）のＡｌ−ＳｉＣ系複合体からなる放熱部品の縦断面図を示す。図１において、放熱部品１は板形状のＡｌ−ＳｉＣ系複合体からなり、主に炭化ケイ素からなる多孔体にアルミニウムを主成分とする金属を含浸して形成されたＡｌ−ＳｉＣ複合本体部１０と、Ａｌ−ＳｉＣ複合本体部１０の表面全体にわたって形成された実質的にアルミニウムまたはアルミニウム合金からなるアルミニウム被覆層１１を有する。ただし、実施例１はアルミニウム被覆層１１の有無にかかわらず、本発明の効果を得ることができる。
【００２０】
本発明実施例１の放熱部品１は板状体であり、半導体基板が接合される側の主面８（上面）と反対側の主面９（底面）が、端部１３から中央部１２に向かって凸状に突出し特定の突出量で反っているとともに、半導体基板が接合される側の主面８が平坦状であることを特徴とする。主面８が平坦状とは表面にわずかな凹凸、好ましくは１００μｍ以下の凹凸があっても構わない。放熱部品１の底面９全体が球面形状でもよいし、一方の板幅方向のみが凸状に突出した所謂かまぼこ形状でもよい。
【００２１】
実施例１の放熱部品を以下のように製造した。まず、平均粒径６０μｍ、純度９８％以上の炭化ケイ素粉末に結合剤、保形剤の溶媒を加え、これを攪拌機で混合して炭化ケイ素のスラリーを得た。このスラリーを、一方の主面のみが球面形状に凹んだ空間を有する金型内に注入して成形後、冷却して脱型した。これを乾燥して炭化ケイ素の多孔体を作製した。
【００２２】
ついで、得られた炭化ケイ素の多孔体と型の内壁との間に所定の隙間を確保した状態で、炭化ケイ素の多孔体を型内に装入した。その後、炭化ケイ素の多孔体を装入した型内に加熱溶融したアルミニウム合金を圧入し含浸させた。含浸完了、冷却後、型を解体し、Ａｌ−ＳｉＣ系複合体からなる板状の放熱部品を作製した。
【００２３】
このようにして、板状体の寸法および底面の突出量が異なる数種類のＡｌ−ＳｉＣ系複合体を作製した。
【００２４】
そして、これらのＡｌ−ＳｉＣ系複合体の上面に、それぞれ半導体基板をはんだ付けにより接合した。ここで、半導体基板を接合する前および接合した後における、Ａｌ−ＳｉＣ系複合体の底面の突出量を測定した。Ａｌ−ＳｉＣ系複合体の底面の高さを突出した板幅方向の一端部から他端部までの全長にわたって測定して、その最大高低差を突出量とした。
【００２５】
表１に、Ａｌ−ＳｉＣ系複合体の寸法（縦×横×厚み）、半導体基板の接合前後のＡｌ−ＳｉＣ系複合体の底面の突出量を示す。表１において、Ａｌ−ＳｉＣ系複合体底面の突出量の符号が＋は凸状、−は凹状に反っていることを表わす。また、Ｎｏ．１１〜１４は本発明例、Ｎｏ．１５〜１６は比較例である。
【００２６】
【００２７】
（実施例２）
図２は、本発明実施例２（本発明の第２態様）のＡｌ−ＳｉＣ系複合体からなる放熱部品の縦断面図を示す。図２において、放熱部品１は板形状のＡｌ−ＳｉＣ系複合体からなり、主に炭化ケイ素からなる多孔体にアルミニウムを主成分とする金属を含浸して形成されたＡｌ−ＳｉＣ複合本体部１０と、Ａｌ−ＳｉＣ複合本体部１０の表面全体にわたって形成された実質的にアルミニウムまたはアルミニウム合金からなるアルミニウム被覆層１１を有する。ただし、実施例２はアルミニウム被覆層１１の有無にかかわらず、本発明の効果を得ることができる。
【００２８】
本発明実施例２の放熱部品１は板状体であり、半導体基板が接合される側の主面８（上面）と反対側の主面９（底面）が、端部１３から中央部１２に向かって凸状に突出し特定の突出量で反っているとともに、上面８も底面９と同じ方向に反っていることを特徴とする。放熱部品１の底面９全体が球面形状でもよいし、一方の板幅方向のみが凸状に突出した所謂かまぼこ形状でもよい。
【００２９】
実施例２の放熱部品を以下のように製造した。まず、平均粒径６０μｍ、純度９８％以上の炭化ケイ素粉末に結合剤、保形剤の溶媒を加え、これを攪拌機で混合して炭化ケイ素のスラリーを得た。このスラリーを所望の形状の金型内に注入して成形後、冷却して脱型した。これを乾燥して炭化ケイ素の多孔体を作製した。
【００３０】
ついで、得られた炭化ケイ素の多孔体と型の内壁との間に所定の隙間を確保した状態で、炭化ケイ素の多孔体を型内に装入した。その後、炭化ケイ素の多孔体を装入した型内に加熱溶融したアルミニウム合金を圧入し含浸させた。含浸完了、冷却後、型を解体し、Ａｌ−ＳｉＣ系複合体からなる板状の放熱部品を作製した。
【００３１】
次に、このＡｌ−ＳｉＣ系複合体の外周縁部の下面に、薄いシム板を敷いた状態で、Ａｌ−ＳｉＣ系複合体を加熱炉の中に入れた。そして、Ａｌ−ＳｉＣ系複合体の半導体基板が接合される側の主面の中央部に錘を載せて、全体を加熱しながらＡｌ−ＳｉＣ系複合体全体に反りを付与し底面を突出させた。
【００３２】
このようにして、板状体の寸法および底面の突出量が異なる数種類のＡｌ−ＳｉＣ系複合体を作製した。
【００３３】
そして、実施例１同様、半導体基板を接合する前および接合した後における、Ａｌ−ＳｉＣ系複合体の底面の突出量を測定した。
【００３４】
表２に、Ａｌ−ＳｉＣ系複合体の寸法（縦×横×厚み）、半導体基板の接合前後のＡｌ−ＳｉＣ系複合体の底面の突出量を示す。表２において、Ｎｏ．２１〜２４は本発明例、Ｎｏ．２５〜２６は比較例である。
【００３５】
【００３６】
（実施例３）
図３は、本発明実施例３（本発明の第３態様）のＡｌ−ＳｉＣ系複合体からなる放熱部品の縦断面図を示す。図３において、放熱部品１は板形状のＡｌ−ＳｉＣ系複合体からなり、主に炭化ケイ素からなる多孔体にアルミニウムを主成分とする金属を含浸して形成されたＡｌ−ＳｉＣ複合本体部１０と、Ａｌ−ＳｉＣ複合本体部１０の表面全体にわたって形成された実質的にアルミニウムまたはアルミニウム合金からなるアルミニウム被覆層１１を有する。実施例３は、後述するように、アルミニウム被覆層１１の存在により本発明の効果を得ることができるものである。
【００３７】
本発明実施例３の放熱部品１は板状体であり、半導体基板が接合される側の主面８（上面）と反対側の主面９（底面）が、端部１３から中央部１２に向かって凸状に突出し特定の突出量で反っているとともに、上面８も底面９と同じ方向に反っている。さらには、上面８に形成されたアルミニウム被覆層１１ａの厚みが、底面９に形成されたアルミニウム被覆層１１ｂのそれより厚いことを特徴とする。放熱部品１の底面９全体が球面形状でもよいし、一方の板幅方向のみが凸状に突出した所謂かまぼこ形状でもよい。
【００３８】
実施例３の放熱部品を以下のように製造した。まず、平均粒径６０μｍ、純度９８％以上の炭化ケイ素粉末に結合剤、保形剤の溶媒を加え、これを攪拌機で混合して炭化ケイ素のスラリーを得た。このスラリーを所望の形状の金型内に注入して成形後、冷却して脱型した。これを乾燥して炭化ケイ素の多孔体を作製した。
【００３９】
ついで、得られた炭化ケイ素の多孔体と型の内壁との間に所定の隙間を確保した状態で、炭化ケイ素の多孔体を型内に装入した。ここで、アルミニウムの含浸によって形成されるアルミニウム被覆層について、半導体基板が接合される側の主面に形成されるアルミニウム被覆層の厚みを、反対側の主面に形成されるそれより厚くするため、半導体基板が接合される側の主面と型の内壁との間の隙間が、反対側の主面と型の内壁との間の隙間より大きくなるようにした。その後、炭化ケイ素の多孔体を装入した型内に加熱溶融したアルミニウム合金を圧入し含浸させた。含浸時、溶融したアルミニウムが炭化ケイ素の多孔体と型の内壁との隙間を通り、アルミニウム被覆層が形成された。含浸完了、冷却後、型を解体し、Ａｌ−ＳｉＣ系複合体からなる板状の放熱部品を作製した。
【００４０】
Ａｌ−ＳｉＣ系複合体の上面に形成されたアルミニウム被覆層の厚みを、底面に形成されたアルミニウム被覆層のそれより厚くして、凝固時の収縮差を著しくすることにより、底面が端部近傍から中央部に向かって凸状に突出するようにＡｌ−ＳｉＣ系複合体全体に反りを付与し底面を突出させた。
【００４１】
このようにして、板状体の寸法および底面の突出量が異なる数種類のＡｌ−ＳｉＣ系複合体を作製した。
【００４２】
そして、実施例１同様、半導体基板を接合する前および接合した後における、Ａｌ−ＳｉＣ系複合体の底面の突出量を測定した。
【００４３】
また、Ａｌ−ＳｉＣ系複合体を破断して、半導体基板が接合される側の上面に形成されたアルミニウム被覆層と、底面に形成されたアルミニウム被覆層の厚みを測定した。
【００４４】
表３に、Ａｌ−ＳｉＣ系複合体の寸法（縦×横×厚み）、半導体基板の接合前後のＡｌ−ＳｉＣ系複合体の底面の突出量、上面および底面のアルミニウム被覆層の厚みを示す。表３において、Ｎｏ．３１〜３４は本発明例、Ｎｏ．３５〜３６は比較例である。
【００４５】
【００４６】
ここで、実施例１〜実施例３で得た本発明例および比較例のＡｌ−ＳｉＣ系複合体からなる放熱部品を用いて、半導体モジュール装置を組立て、両者の放熱性能を比較した。
【００４７】
図４は、本発明例のＡｌ−ＳｉＣ系複合体からなる放熱部品を具備する半導体モジュール装置の一例を示す。図４において、上側は平面図、下側は縦断面図である。図４は本発明の最も特徴とするところを除いて図５と同様の構成である。半導体モジュール装置は、複数個の半導体チップ７を搭載した半導体基板２と、Ａｌ−ＳｉＣ系複合体からなる板形状の放熱部品１と、ヒートシンクなどの支持部材５とから主に構成される。なお、図４ではアルミニウム被覆層１１の図示を省略した。
【００４８】
放熱部品１の半導体基板２が接合される側の主面８に半導体基板２をはんだ付けにより接合したとき、放熱部品１全体に中央部１２ほど半導体基板２側に反る形で反りが発生した。本発明例の放熱部品１の場合、放熱部品１の底面が予め適度な突出量１５０〜５００μｍで凸状に突出しているため、半導体基板２の接合後は、放熱部品１の底面が突出量４０〜１２０μｍでわずかに凸状に反った形の平坦に近い状態になる。
【００４９】
そして、この放熱部品１の底面と支持部材５の上面との間にグリースなどの緩衝剤を介在させた後、放熱部品１および支持部材５の所定の位置に数箇所設けた固定用穴３にボルトなどの固定部材４を装着して締め付けることにより、放熱部品１を支持部材５に固定した。
【００５０】
半導体基板２を接合した後の放熱部品１の底面はわずかに凸状に反った形で平坦に近いため、放熱部品１と支持部材５の接合面間の中央部には空洞状の隙間が見られず、放熱部品１と支持部材５とが密接に接触して、半導体チップ７から発生した熱の外部への放熱を十分に行なえることを確認できた。
【００５１】
一方、比較例の放熱部品の場合、半導体基板を接合した後の放熱部品の底面が逆に凹状に反ったため、放熱部品と支持部材の接合面間の中央部には空洞状の隙間が見られ、本発明例に比べて半導体チップから発生した熱の外部への放熱が不十分であった。
【００５２】
【発明の効果】
本発明のＡｌ−ＳｉＣ系複合体によれば、Ａｌ−ＳｉＣ系複合体からなる放熱部品と支持部材の間に隙間が生じることなく、半導体チップから発生した熱の外部への放熱が阻害されることなく、十分に放熱できる。
【図面の簡単な説明】
【図１】本発明実施例１のＡｌ−ＳｉＣ系複合体からなる放熱部品の縦断面図を示す。
【図２】本発明実施例２のＡｌ−ＳｉＣ系複合体からなる放熱部品の縦断面図を示す。
【図３】本発明実施例３のＡｌ−ＳｉＣ系複合体からなる放熱部品の縦断面図を示す。
【図４】本発明例のＡｌ−ＳｉＣ系複合体からなる放熱部品を具備する半導体モジュール装置の一例を示す。
【図５】従来のＡｌ−ＳｉＣ系複合体からなる放熱部品を具備する半導体モジュール装置の一例を示す。
【符号の説明】
１ 放熱部品、 ２ 半導体基板、 ３ 固定用穴、 ４ 固定部材、 ５ 支持部材、
６ 隙間、 ７ 半導体チップ、 ８ 半導体基板が接合される側の主面、
９ 半導体基板が接合される側の主面と反対側の主面、
１０ Ａｌ−ＳｉＣ複合本体部、 １１ アルミニウム被覆層、
１１ａ 上面に形成されたアルミニウム被覆層、
１１ｂ 底面に形成されたアルミニウム被覆層、
１２ 中央部、 １３ 端部[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a composite of silicon carbide (SiC) and aluminum (Al) (Al-SiC-based composite), and particularly to a porous body mainly composed of silicon carbide formed by impregnating a metal containing aluminum as a main component. Related to an Al-SiC-based composite. The Al-SiC-based composite of the present invention has low thermal expansion and high thermal conductivity, and is suitable for a heat radiating component used for a semiconductor device such as a heat radiating substrate, a heat sink, and a package.
[0002]
[Prior art]
2. Description of the Related Art In recent years, in the field of industrial equipment, the development of large power module devices that efficiently exchange control large power to optimal power using semiconductor switching devices has been progressing. For example, there is an IGBT module capable of operating at a high voltage and a large current as an inverter for an electric vehicle. With such a large power module, heat generated from a semiconductor chip is also increasing. Semiconductor chips are susceptible to heat, and large heat generation may cause malfunction or destruction of semiconductor circuits. Therefore, a heat radiating component such as a heat sink is provided on the back of the circuit board for mounting electronic components such as semiconductor chips, and the heat generated from the semiconductor chip is radiated to the outside through the heat radiating component to stably operate the semiconductor circuit. That is being done. As a semiconductor substrate for mounting an electronic component such as a semiconductor chip, a ceramic substrate such as silicon nitride (Si 3 N 4 ), aluminum nitride (AlN), and aluminum oxide (Al 2 O 3 ) is mainly used. .
[0003]
Conventional heat dissipating component materials include copper, molybdenum, and tungsten. A heat dissipating component made of molybdenum or tungsten is expensive, and the specific gravity of the metal is large, so that the heat dissipating component becomes heavy, which is not preferable for applications in which it is desired to reduce the weight of the heat dissipating component.
[0004]
In addition, the heat dissipating component made of copper has a large difference in thermal expansion coefficient between the heat dissipating component and the ceramic substrate to be joined. It is easy to break, block the heat flow path, and crack the ceramic substrate. That is, if the difference between the thermal expansion coefficients of the heat radiating component and the ceramic substrate to be joined is too large, thermal stress and thermal strain remain at the joints. When the thermal stress is repeatedly applied during the use of the module device and superimposed on the residual thermal stress and thermal strain, the thermal flow path is cut off due to the fatigue destruction of the solder layer, and the crack of the mechanically brittle ceramic substrate is caused. Occurs.
[0005]
As a material for heat dissipating parts that replaces conventional materials such as copper, an Al—SiC-based composite having low thermal expansion and high thermal conductivity in which silicon carbide is dispersed in aluminum or an aluminum alloy has attracted attention (Japanese Patent Publication No. 7-26174). And JP-A-64-83634. As a method for producing an Al-SiC-based composite, a porous body (preform) formed of silicon carbide powder or silicon carbide fiber is used, and the porous body is arranged in a space in a mold, and an aluminum ingot is brought into contact with the porous body. There is a molten metal impregnation method in which aluminum heated and melted under pressure or non-pressure in a nitrogen atmosphere is poured into a space in a mold to impregnate a porous body of silicon carbide, and then cooled. According to this production method, the content of silicon carbide can be selected in the range of 20 to 90% by volume. In addition, there is an advantage that the shape of the porous silicon carbide body is high and a product having a complicated shape can be formed into a net shape.
[0006]
[Problems to be solved by the invention]
Generally, the heat dissipating component and the ceramic substrate are brazed by solder, and after being heated to a temperature equal to or higher than the melting point of the brazing material, are cooled to room temperature. At that time, the heat-dissipating component and the ceramic substrate are fixed to each other at the solidification point of the brazing material, and then shrink in accordance with their respective thermal expansion coefficients while being fixed, causing deformation such as warping of the entire heat-dissipating component.
[0007]
When assembling a plate-shaped heat radiating component into a semiconductor module device, provide several fixing holes in the heat radiating component, attach fixing members such as bolts and washers to the fixing holes, and attach them to support members such as heat sinks that constitute the module device. It is common practice to fix the heat radiating component via a buffer such as grease. At this time, if the heat dissipating component is deformed such as warpage, a gap is generated between the heat dissipating component and the support member, and the heat generated from the semiconductor chip is dissipated to the outside, resulting in malfunction or destruction of the semiconductor circuit. become.
[0008]
This will be described with reference to the drawings. FIG. 5 shows an example of a conventional semiconductor module device provided with a heat-dissipating component made of an Al-SiC-based composite. In FIG. 5, the upper side is a plan view, and the lower side is a longitudinal sectional view. The semiconductor module device mainly includes a semiconductor substrate 2 on which a plurality of semiconductor chips 7 are mounted, a plate-shaped heat dissipating component 1 made of an Al-SiC-based composite, and a support member 5 such as a heat sink.
[0009]
The semiconductor substrate 2 is joined to the upper surface of the heat radiating component 1 by soldering or the like. The support member 5 is disposed on the bottom surface of the heat radiating component 1 with a buffer such as grease interposed between the heat radiating component 1 and the support member 5. Then, the heat radiating component 1 is fixed to the support member 5 by mounting and tightening a fixing member 4 such as a bolt in fixing holes 3 provided at predetermined positions of the heat radiating component 1 and the support member 5.
[0010]
In performing such assembling, when the semiconductor substrate 2 is joined to the heat radiating component 1 by soldering, the semiconductor substrate 2 is heated to a temperature equal to or higher than the melting point of the brazing material and then cooled to room temperature. At that time, the heat radiating component 1 and the semiconductor substrate 2 are fixed to each other at the solidification point of the brazing material, and then contracted according to their respective thermal expansion coefficients while being fixed, so that the entire heat radiating component 1 is deformed such as warping.
[0011]
When the heat dissipating component 1 is tightened and fixed to the support member 5 in a warped state, a slight gap 6 is formed at the center between the joining surfaces of the heat dissipating component 1 and the support member 5, and the two members do not sufficiently contact each other. There is a problem in that the heat generated from 7 is dissipated to the outside.
[0012]
The present invention has been made in view of the above circumstances, and is an Al-SiC-based composite that can sufficiently radiate heat generated from a semiconductor chip to the outside without generating a gap between a heat radiating component and a supporting member; It is an object of the present invention to provide a heat dissipation component and a semiconductor module device using the Al-SiC-based composite.
[0013]
[Means for Solving the Problems]
In the Al-SiC-based composite of the present invention, the main surface on the side opposite to the side to which the semiconductor substrate is bonded protrudes from the end toward the center, and the protrusion amount is 150 to 500 μm. An Al-SiC-based composite of a plate-like body, wherein after a semiconductor substrate is bonded, a protrusion amount of a main surface opposite to a side to which the semiconductor substrate is bonded is 40 to 120 μm. And
[0014]
Further, in the Al-SiC-based composite according to the first aspect of the present invention, the main surface on the side opposite to the side to which the semiconductor substrate is bonded protrudes from the end toward the center, and the protrusion is formed. The amount is 150 to 500 μm, and the main surface on the side to which the semiconductor substrate is bonded is flat.
[0015]
In the Al-SiC-based composite according to the second aspect of the present invention, the main surface on the side opposite to the side to which the semiconductor substrate is bonded protrudes from the end toward the center, and the protrusion is formed. The amount is 150 to 500 μm, and the protrusion is characterized by being applied by plastic deformation by applying a load while heating.
[0016]
Further, in the Al-SiC-based composite according to the third aspect of the present invention, the main surface on the side opposite to the side to which the semiconductor substrate is bonded protrudes from the end toward the center, and the protrusion is formed. The protrusion amount was 150 to 500 μm, and the protrusion was given by making the thickness of the aluminum coating layer formed on the main surface on the side to which the semiconductor substrate was bonded thicker than that formed on the opposite main surface. It is characterized by the following.
[0017]
In the present invention, the Al-SiC composite is formed by impregnating a metal mainly composed of aluminum into a porous body mainly composed of silicon carbide. Further, the present invention is characterized in that the heat radiating component is made of the Al-SiC-based composite of the present invention. Further, the present invention is characterized in that it is a semiconductor module device provided with a heat-dissipating component comprising the Al-SiC-based composite of the present invention.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
In the heat-dissipating component made of the Al-SiC-based composite, the amount of protrusion of the main surface opposite to the main surface on the side to which the semiconductor substrate is bonded, that is, the bottom surface of the heat-dissipating component, is changed variously, and The quality of heat dissipation when the semiconductor substrate was joined to the main surface by soldering was examined. As a result, if the protrusion amount of the bottom surface of the heat radiating component after bonding the semiconductor substrate is in the range of 40 to 120 μm (more preferably, 70 to 120 μm), a hollow shape is formed at the center between the bonding surfaces of the heat radiating component and the support member. No gap was observed, and the heat dissipating component and the supporting member were in close contact with each other, so that the heat generated from the semiconductor chip was well radiated to the outside. When the semiconductor substrate is joined to the heat dissipating component by soldering, the entire heat dissipating component is warped. Therefore, in order to set the protrusion amount of the bottom surface of the heat dissipating component after joining the semiconductor substrate to 40 to 120 μm, the semiconductor substrate before joining is required. It is necessary to keep the protrusion amount of the bottom surface of the heat radiating component in the range of 150 to 500 μm.
[0019]
(Example 1)
FIG. 1 is a longitudinal sectional view of a heat-dissipating component made of an Al—SiC-based composite according to Example 1 of the present invention (first embodiment of the present invention). In FIG. 1, a heat radiation component 1 is made of a plate-shaped Al-SiC-based composite, and an Al-SiC composite main body 10 formed by impregnating a metal mainly composed of aluminum into a porous body mainly composed of silicon carbide. And an aluminum coating layer 11 substantially made of aluminum or an aluminum alloy formed over the entire surface of the Al-SiC composite main body 10. However, in Example 1, the effects of the present invention can be obtained regardless of the presence or absence of the aluminum coating layer 11.
[0020]
The heat radiating component 1 according to the first embodiment of the present invention is a plate-like body, and the main surface 9 (bottom surface) opposite to the main surface 8 (top surface) to which the semiconductor substrate is bonded is connected from the end 13 to the center 12. The semiconductor device is characterized in that it protrudes in a convex shape and is warped by a specific amount of protrusion, and the main surface 8 on the side to which the semiconductor substrate is bonded is flat. When the main surface 8 is flat, the surface may have slight irregularities, preferably irregularities of 100 μm or less. The entire bottom surface 9 of the heat radiating component 1 may have a spherical shape, or may have a so-called kamaboko shape in which only one of the plate width directions protrudes in a convex shape.
[0021]
The heat dissipation component of Example 1 was manufactured as follows. First, a solvent for a binder and a shape-retaining agent was added to silicon carbide powder having an average particle diameter of 60 μm and a purity of 98% or more, and the mixture was mixed with a stirrer to obtain a silicon carbide slurry. This slurry was poured into a mold having a space in which only one main surface was concave in a spherical shape, molded, cooled, and demolded. This was dried to produce a silicon carbide porous body.
[0022]
Then, the silicon carbide porous body was charged into the mold with a predetermined gap secured between the obtained silicon carbide porous body and the inner wall of the mold. Thereafter, an aluminum alloy that had been heated and melted was pressed into a mold in which a porous body of silicon carbide was charged, and impregnated. After completion of the impregnation and cooling, the mold was disassembled to produce a plate-shaped heat-dissipating component made of an Al-SiC-based composite.
[0023]
In this way, several types of Al—SiC-based composites having different dimensions of the plate-like body and different amounts of protrusion of the bottom surface were produced.
[0024]
Then, semiconductor substrates were joined to the upper surfaces of these Al-SiC-based composites by soldering. Here, the amount of protrusion of the bottom surface of the Al—SiC-based composite before and after joining the semiconductor substrates was measured. The height of the bottom surface of the Al-SiC-based composite was measured over the entire length from one end to the other end in the protruding plate width direction, and the maximum height difference was defined as the amount of protrusion.
[0025]
Table 1 shows the dimensions (length × width × thickness) of the Al—SiC composite and the amount of protrusion of the bottom surface of the Al—SiC composite before and after bonding the semiconductor substrate. In Table 1, the sign of the amount of protrusion of the bottom surface of the Al—SiC-based composite indicates that the protrusion is warped in a convex shape, and that the sign of the protrusion amount is in a concave shape. No. Nos. 11 to 14 are examples of the present invention. 15 and 16 are comparative examples.
[0026]
[0027]
(Example 2)
FIG. 2 is a longitudinal sectional view of a heat-dissipating component made of an Al—SiC-based composite according to a second embodiment of the present invention (a second embodiment of the present invention). In FIG. 2, a heat radiation component 1 is made of a plate-shaped Al-SiC-based composite, and an Al-SiC composite main body 10 formed by impregnating a porous body mainly composed of silicon carbide with a metal containing aluminum as a main component. And an aluminum coating layer 11 substantially made of aluminum or an aluminum alloy formed over the entire surface of the Al-SiC composite main body 10. However, in Example 2, the effects of the present invention can be obtained regardless of the presence or absence of the aluminum coating layer 11.
[0028]
The heat dissipating component 1 according to the second embodiment of the present invention is a plate-like body, and the main surface 9 (bottom surface) opposite to the main surface 8 (upper surface) on the side to which the semiconductor substrate is bonded extends from the end 13 to the center 12. It is characterized in that it projects in a convex shape and warps by a specific amount of protrusion, and the upper surface 8 also warps in the same direction as the bottom surface 9. The entire bottom surface 9 of the heat radiating component 1 may have a spherical shape, or may have a so-called kamaboko shape in which only one of the plate width directions protrudes in a convex shape.
[0029]
The heat dissipation component of Example 2 was manufactured as follows. First, a solvent for a binder and a shape-retaining agent was added to silicon carbide powder having an average particle diameter of 60 μm and a purity of 98% or more, and the mixture was mixed with a stirrer to obtain a silicon carbide slurry. The slurry was poured into a mold having a desired shape, molded, cooled, and demolded. This was dried to produce a silicon carbide porous body.
[0030]
Then, the silicon carbide porous body was charged into the mold with a predetermined gap secured between the obtained silicon carbide porous body and the inner wall of the mold. Thereafter, an aluminum alloy that had been heated and melted was pressed into a mold in which a porous body of silicon carbide was charged, and impregnated. After completion of the impregnation and cooling, the mold was disassembled to produce a plate-shaped heat-dissipating component made of an Al-SiC-based composite.
[0031]
Next, the Al-SiC-based composite was placed in a heating furnace with a thin shim plate laid on the lower surface of the outer peripheral edge of the Al-SiC-based composite. Then, a weight was placed on the center of the main surface of the Al-SiC-based composite to which the semiconductor substrate was bonded, and the entire Al-SiC-based composite was warped while the whole was heated, so that the bottom surface was protruded. .
[0032]
In this way, several types of Al—SiC-based composites having different dimensions of the plate-like body and different amounts of protrusion of the bottom surface were produced.
[0033]
Then, as in Example 1, the amount of protrusion of the bottom surface of the Al—SiC-based composite before and after joining the semiconductor substrates was measured.
[0034]
Table 2 shows the dimensions (length × width × thickness) of the Al—SiC-based composite and the amount of protrusion of the bottom surface of the Al—SiC-based composite before and after joining the semiconductor substrate. In Table 2, No. Nos. 21 to 24 are examples of the present invention. 25 to 26 are comparative examples.
[0035]
[0036]
(Example 3)
FIG. 3 is a longitudinal sectional view of a heat-dissipating component made of an Al—SiC-based composite according to Example 3 of the present invention (third embodiment of the present invention). In FIG. 3, a heat radiation component 1 is made of a plate-shaped Al-SiC-based composite, and an Al-SiC composite main body 10 formed by impregnating a metal mainly composed of aluminum into a porous body mainly made of silicon carbide. And an aluminum coating layer 11 substantially made of aluminum or an aluminum alloy formed over the entire surface of the Al-SiC composite main body 10. In Example 3, the effect of the present invention can be obtained by the presence of the aluminum coating layer 11, as described later.
[0037]
The heat radiating component 1 according to the third embodiment of the present invention is a plate-like body, and the main surface 9 (bottom surface) opposite to the main surface 8 (upper surface) on the side to which the semiconductor substrate is joined is connected from the end 13 to the center 12. It projects in a convex shape and warps by a specific amount of protrusion, and the upper surface 8 also warps in the same direction as the bottom surface 9. Further, the thickness of the aluminum coating layer 11a formed on the upper surface 8 is larger than that of the aluminum coating layer 11b formed on the bottom surface 9. The entire bottom surface 9 of the heat radiating component 1 may have a spherical shape, or may have a so-called kamaboko shape in which only one of the plate width directions protrudes in a convex shape.
[0038]
The heat dissipation component of Example 3 was manufactured as follows. First, a solvent for a binder and a shape-retaining agent was added to silicon carbide powder having an average particle diameter of 60 μm and a purity of 98% or more, and the mixture was mixed with a stirrer to obtain a silicon carbide slurry. The slurry was poured into a mold having a desired shape, molded, cooled, and demolded. This was dried to produce a silicon carbide porous body.
[0039]
Then, the silicon carbide porous body was charged into the mold with a predetermined gap secured between the obtained silicon carbide porous body and the inner wall of the mold. Here, for the aluminum coating layer formed by impregnation with aluminum, the thickness of the aluminum coating layer formed on the main surface on the side to which the semiconductor substrate is bonded is made larger than that formed on the opposite main surface. The gap between the main surface on the side where the semiconductor substrate is bonded and the inner wall of the mold is made larger than the gap between the opposite main surface and the inner wall of the mold. Thereafter, an aluminum alloy that had been heated and melted was pressed into a mold in which a porous body of silicon carbide was charged, and impregnated. During the impregnation, the molten aluminum passed through the gap between the porous silicon carbide body and the inner wall of the mold, forming an aluminum coating layer. After completion of the impregnation and cooling, the mold was disassembled to produce a plate-shaped heat-dissipating component made of an Al-SiC-based composite.
[0040]
The thickness of the aluminum coating layer formed on the upper surface of the Al-SiC-based composite is made thicker than that of the aluminum coating layer formed on the bottom surface, so that the difference in shrinkage during solidification is remarkable. The entire Al-SiC-based composite was warped so as to protrude from the center toward the center, and the bottom surface was protruded.
[0041]
In this way, several types of Al—SiC-based composites having different dimensions of the plate-like body and different amounts of protrusion of the bottom surface were produced.
[0042]
Then, as in Example 1, the amount of protrusion of the bottom surface of the Al—SiC-based composite before and after joining the semiconductor substrates was measured.
[0043]
Further, the Al—SiC-based composite was broken, and the thicknesses of the aluminum coating layer formed on the upper surface on the side to which the semiconductor substrate was bonded and the aluminum coating layer formed on the bottom surface were measured.
[0044]
Table 3 shows the dimensions (length × width × thickness) of the Al—SiC-based composite, the amount of protrusion of the bottom surface of the Al—SiC-based composite before and after the bonding of the semiconductor substrate, and the thickness of the aluminum coating layer on the top and bottom surfaces. In Table 3, no. Nos. 31 to 34 are examples of the present invention. 35 to 36 are comparative examples.
[0045]
[0046]
Here, the semiconductor module device was assembled using the heat-radiating components made of the Al-SiC-based composites of the present invention example and the comparative example obtained in Examples 1 to 3, and the heat radiation performance of both was compared.
[0047]
FIG. 4 shows an example of a semiconductor module device provided with a heat-dissipating component made of the Al-SiC-based composite of the present invention. 4, the upper side is a plan view, and the lower side is a longitudinal sectional view. FIG. 4 has the same configuration as that of FIG. 5 except for the most characteristic feature of the present invention. The semiconductor module device mainly includes a semiconductor substrate 2 on which a plurality of semiconductor chips 7 are mounted, a plate-shaped heat dissipating component 1 made of an Al-SiC-based composite, and a support member 5 such as a heat sink. In FIG. 4, the illustration of the aluminum coating layer 11 is omitted.
[0048]
When the semiconductor substrate 2 is joined by soldering to the main surface 8 of the heat dissipating component 1 on the side to which the semiconductor substrate 2 is joined, warping occurs in the entire heat dissipating component 1 such that the central portion 12 is warped toward the semiconductor substrate 2 side. . In the case of the heat dissipating component 1 of the present invention, the bottom surface of the heat dissipating component 1 has a protrusion amount of 40 to 500 μm, so that the bottom surface of the heat dissipating component 1 has a protrusion amount of 40 after the semiconductor substrate 2 is joined. When the thickness is about 120 μm, the shape becomes slightly flat and slightly flat.
[0049]
Then, after interposing a buffer such as grease between the bottom surface of the heat radiating component 1 and the upper surface of the support member 5, the fixing holes 3 are provided at predetermined positions of the heat radiating component 1 and the support member 5. The heat radiating component 1 was fixed to the support member 5 by mounting and tightening the fixing member 4 such as a bolt.
[0050]
Since the bottom surface of the heat dissipating component 1 after bonding the semiconductor substrate 2 is slightly flat and warped to be nearly flat, a hollow gap is observed at the center between the joining surface of the heat dissipating component 1 and the support member 5. However, it was confirmed that the heat radiating component 1 and the supporting member 5 were in close contact with each other, and the heat generated from the semiconductor chip 7 could be sufficiently radiated to the outside.
[0051]
On the other hand, in the case of the heat dissipating component of the comparative example, since the bottom surface of the heat dissipating component after joining the semiconductor substrate was warped in a concave shape, a hollow gap was observed at the center between the joining surfaces of the heat dissipating component and the support member. In addition, the heat generated from the semiconductor chip to the outside was insufficiently radiated as compared with the example of the present invention.
[0052]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the Al-SiC-based composite of the present invention, there is no gap between the heat-dissipating component made of the Al-SiC-based composite and the support member, and the heat radiation from the semiconductor chip to the outside is inhibited. Without heat, heat can be radiated sufficiently.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a heat-dissipating component made of an Al—SiC-based composite of Example 1 of the present invention.
FIG. 2 is a longitudinal sectional view of a heat-dissipating component comprising an Al—SiC-based composite according to a second embodiment of the present invention.
FIG. 3 is a longitudinal sectional view of a heat-dissipating component made of an Al—SiC-based composite according to a third embodiment of the present invention.
FIG. 4 shows an example of a semiconductor module device provided with a heat-dissipating component made of the Al—SiC-based composite of the present invention.
FIG. 5 shows an example of a conventional semiconductor module device provided with a heat radiating component made of an Al—SiC-based composite.
[Explanation of symbols]
Reference Signs List 1 heat dissipation component, 2 semiconductor substrate, 3 fixing hole, 4 fixing member, 5 supporting member,
6 gap, 7 semiconductor chip, 8 main surface on the side where the semiconductor substrate is bonded,
9 A main surface opposite to the main surface on which the semiconductor substrate is bonded,
10 Al-SiC composite main body, 11 aluminum coating layer,
11a an aluminum coating layer formed on the upper surface,
11b Aluminum coating layer formed on the bottom surface,
12 center, 13 end
