JPWO2003001612A1 - Semiconductor device and method of forming the same - Google Patents

Semiconductor device and method of forming the same Download PDF

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JPWO2003001612A1
JPWO2003001612A1 JP2003507903A JP2003507903A JPWO2003001612A1 JP WO2003001612 A1 JPWO2003001612 A1 JP WO2003001612A1 JP 2003507903 A JP2003507903 A JP 2003507903A JP 2003507903 A JP2003507903 A JP 2003507903A JP WO2003001612 A1 JPWO2003001612 A1 JP WO2003001612A1
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semiconductor device
light
diffusing agent
sealing member
semiconductor
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JP4010299B2 (en
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滋嗣 幸田
滋嗣 幸田
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Nichia Corp
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Nichia Corp
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Abstract

半導体素子と、該半導体素子が収納された凹部を有するパッケージと、前記凹部内に充填された封止部材と、を有する半導体装置であって、前記封止部材は、親水性主鎖と疎水性側鎖とを有する透光性ポリマー樹脂と、少なくとも前記ポリマー樹脂を吸収することが可能な拡散剤と、を必須成分とする硬化性組成物の硬化物であることを特徴とする。このような構成を有する半導体装置は、内部において優れた信頼性を有していると共に、外部からの影響を受けにくい形状を有している。またこのような半導体装置は、親水性主鎖と疎水性側鎖とを有する透光性ポリマー樹脂と該透光性ポリマー樹脂を吸収することが可能な拡散剤とを必須成分とする硬化性組成物液を調整する第一の工程と、前記硬化性組成物液を前記パッケージの凹部内にパッケージ上面とほぼ同一平面のラインまで注入する第二の工程と、熱処理を施し前記硬化性組成物液を硬化させる第3の工程と、とを有することを特徴とする形成方法により、歩留まり良く得ることができる。A semiconductor device comprising: a semiconductor element; a package having a concave portion in which the semiconductor element is housed; and a sealing member filled in the concave portion, wherein the sealing member has a hydrophilic main chain and a hydrophobic main chain. It is a cured product of a curable composition containing a translucent polymer resin having a side chain and a diffusing agent capable of absorbing at least the polymer resin as essential components. The semiconductor device having such a configuration has excellent reliability inside and has a shape that is hardly affected by outside. Further, such a semiconductor device has a curable composition comprising, as essential components, a light-transmitting polymer resin having a hydrophilic main chain and a hydrophobic side chain, and a diffusing agent capable of absorbing the light-transmitting polymer resin. A first step of adjusting the liquid composition, a second step of injecting the curable composition liquid into the concave portion of the package up to a line substantially flush with the upper surface of the package, and applying a heat treatment to the curable composition liquid. And a third step of curing the above, and a high yield can be obtained by the formation method.

Description

技術分野
本発明は、スイッチ内照明、フルカラーディスプレイ、液晶バックライト等の光源として用いられる半導体装置に関し、特に信頼性に優れた発光装置に関するものである。
背景技術
今日、高輝度、高出力な半導体素子や小型且つ高感度な発光装置が開発され種々の分野に利用されている。このような発光装置は小型、低消費電力や軽量などの特徴を生かして、例えば、光プリンターヘッドの光源、液晶バックライト光源、各種メータの光源や各種読み取りセンサーなどに利用されている。
このような発光装置は、例えば、半導体素子を収納可能な凹部を有し、該凹部底面から正及び負のリード電極が一方の主面が露出するように挿入され一体成形されたパッケージを用い、前記凹部底面から露出されたリード電極上に半導体素子としてLEDチップがダイボンドされ、LEDチップの各電極とパッケージに設けられたリード電極とが金線等により電気的に接続されている。また凹部内にてLEDチップ及び金線が封止部材である樹脂にて被覆されている。これにより、パッケージ内部の構成部材は水分や外力などの外部環境から保護され、極めて信頼性の高い発光装置が得られる。
現在、技術の飛躍的な進歩により、LEDチップの高出力化および短波長化が実現されている。このようなLEDチップは、大電流を投下することにより高出力の光を放出することが可能な反面、発光時に高温の発熱を伴う。これに起因して、LEDチップ近傍に配置される封止樹脂の変色劣化が生じる。特に、前記LEDチップ近傍に配置される封止部材として、熱に弱い炭素−炭素の二重結合を有する透光性有機部材を用いると、結合が切れて黄変し光学特性が損なわれる。また、各部材の熱膨張率の差により、ワイヤ断線や各部材にクラックが発生し、使用経過時間が増すにつれて急激に信頼性が低下する傾向にある。
そこで、近紫外領域の光を発光し高熱を発生する発光素子を使用する場合、近紫外領域の光に対する耐光性および耐熱性に優れ、熱応力に対して可塑性を有するシリコーン樹脂が好適に用いられている。シリコーン樹脂の主骨格は、光劣化の原因となる炭素−炭素間の2重結合を有していないため、電子遷移吸収がおこりにくく、長時間光が照射されてもほとんど劣化しない。また、柔軟性に優れているため、熱応力による半導体装置の損傷を防止することができる。
一方、シリコーン樹脂を主体とする硬化物は、柔軟性に優れている場合、降下物表面は機械的強度が弱くタック性を有している。また、シリコーン樹脂は熱に対して高い安定性を有しており、シリコーンを主体とする硬化物の形状は、硬化過程において熱収縮することはなく硬化前の充填時に決定する。このため、上述の如く凹部を有するパッケージにシリコーン樹脂からなる封止部材を設ける場合、シリコーン樹脂充填量は、表面が外部と接触しないように微調整する必要がある。具体的には、前記パッケージの端部外郭上面より一段下がった位置までシリコーン樹脂を主体とする組成物を注入し熱硬化することで、タック性を有する表面が外部と接触することを抑制している。これにより、信頼性の高い発光装置が得られる。
しかしながら、より小型化・薄型化の発光装置が望まれている現在において、上記のように凹部を有するパッケージ内にシリコーン樹脂組成物を微調整して充填することは、非常に困難であり、作業効率が悪く良好な歩留まりが得られない。
発明の開示
本発明は、上述の問題を解決するために為されたものであり、高い信頼性と良好な光学特性を有する小型化半導体装置を歩留まり良く得ることを目的とする。
本発明者は種々の実験の結果、優れた熱安定性を有し硬化前後において体積が変化しない樹脂を主体とする熱硬化性組成物の硬化物材料に、吸油量が調整可能な拡散剤を添加して硬化すると、前記熱硬化性組成物の体積を熱硬化過程において減少させることが可能であることを見いだし、本発明を成すに至った。
本発明の半導体装置は、半導体素子と、該半導体素子が収納された凹部を有するパッケージと、前記凹部内に充填された封止部材と、を有する半導体装置であって、
前記封止部材は、親水性主鎖と疎水性側鎖とを有する透光性ポリマー樹脂と、少なくとも前記ポリマー樹脂を吸収することが可能な拡散剤と、を必須成分とする硬化性組成物の硬化物であることを特徴とする。
このように構成された半導体装置は、優れた信頼性と光学特性とを有し、歩留まり良く得ることができる。
また、本発明の半導体装置において、前記封止部材の硬度は、5shore(A)〜80shore(D)であることが好ましく、これにより、大電流の投下を可能とし、高出力の半導体装置が得られる。
また、本発明の半導体装置において、前記封止部材の上面は、端部から中央部にかけて放物線状の凹みを有することが好ましく、これにより、タック性を有する前記上面が、実装時等に外部と接触することをさらに抑制することができる。また、前記封止部材が透光性である場合、一面均一に発光することが可能な発光装置が得られる。
また、本発明の半導体装置において、前記拡散剤は、針状もしくは柱状の形状を有していることが好ましく、これにより、拡散剤のポリマー樹脂吸収率が高まり、少量の拡散剤量にて所望とする封止部材形状を実現することができる。
また、本発明の半導体装置において、前記拡散剤はあられ石型結晶であることが好ましく、これにより良好に光が拡散され、均一に発光することが可能な半導体装置が得られる。
また、本発明の半導体装置において、前記拡散剤は、平均粒子径値が0.1μm〜5.0μmであることが好ましく、これにより、色むらが抑制され均一で且つ高い光度にて発光することが可能な半導体装置が得られる。
また、本発明の半導体装置において、前記拡散剤の屈折率は、前記発光素子の屈折率より低く且つ前記透光性ポリマー樹脂の屈折率より高いことが好ましく、これにより、半導体素子から発光される光を内部に密閉することなく良好に外部へ取り出すことができ、高い光度が得られる。
また、本発明の半導体装置において、前記封止部材は、前記半導体素子側から前記拡散剤の含有量の多い第一の層と前記第一の層より前記拡散剤の含有量の少ない第二の層とを有し、前記発光素子の表面は前記第一の層にてほぼ被覆されていることが好ましい。これにより、半導体素子から発光される光の取り出し効率を高くすることができる。
また、本発明の半導体装置において、前記封止部材は、半導体素子から発光される光の少なくとも一部を吸収し異なる波長を有する光を発光することが可能な蛍光物質を含有させることも可能であり、これにより発光装置間の色バラツキが少なく均一に発光することが可能な色変換型半導体装置が得られる。
また、本発明の半導体装置において、前記蛍光物質の屈折率は、前記発光素子の屈折率より低く且つ前記拡散剤の屈折率より高いことが好ましく、これにより、半導体素子から発光される光の取り出し効率を向上させることができる。
また、本発明の半導体装置において、前記蛍光物質と前記発光素子との屈折率差は、前記蛍光物質と前記拡散剤との屈折率差とほぼ等しいことが好ましく、これにより、混色性に優れた発光装置が得られる。
また、本発明の半導体装置において、透光性ポリマー樹脂、拡散剤、および蛍光物質を必須成分とする硬化性組成物を硬化させてなる封止部材は、前記半導体素子と前記第一の層との間に前記蛍光物質を含有する色変換層を有することが好ましい。つまり、前記半導体素子の表面に、蛍光物質を含有する色変換層、拡散剤の含有量の多い第一の層、そして前記第一の層より拡散剤の含有量の少ない第二の層、が順次積層されていることが好ましく、これにより、半導体素子から発光される光と、前記色変換層にて前記光の一部が吸収され変換された光とが、前記第一の層にて反射散乱され良好に混色される。次に第二の層を通過することにより混色光の指向性が改善される。この効果は、粒径が大きい蛍光物質、とくに中心粒径が15μmから50μmである蛍光物質を使用した際に顕著に現れ、高輝度で且つ均一に発光することが可能な発光装置が得られる。
また、本発明の半導体装置の形成方法は、半導体素子と、該半導体素子を収納することが可能な凹部を有するパッケージと、前記凹部内に充填された封止部材と、を有する発光装置の形成方法であって、
親水性主鎖と疎水性側鎖とを有する透光性ポリマー樹脂と該透光性ポリマー樹脂を吸収することが可能な拡散剤とを必須成分とする硬化性組成物液を調整する第一の工程と、
前記硬化性組成物液を前記パッケージの凹部内にパッケージ上面とほぼ同一平面のラインまで注入する第二の工程と、
熱処理を施し前記硬化性組成物液を硬化させる第3の工程と、
を有することを特徴とする。これにより、信頼性及び光学特性の優れた半導体装置を量産性良く得ることができる。
発明を実施するための最良の形態
以下、図面を参照にしながら、本発明に係る実施の形態について説明する。
図1は、本発明の形態であるSMD型発光ダイオードの模式的平面図および模式的断面図である。凹部を有し、該凹部底面から一対のリード電極2,3の各先端部表面が露出された樹脂製パッケージ1を用いている。前記凹部底面に発光素子4が載置され、該発光素子4の各電極と前記各リード電極先端部とがそれぞれ金線ワイヤ6にて電気的に接続されている。前記発光素子4は、サファイア基板上に窒化ガリウムであるバッファ層を介して窒化物半導体(AlGaInN、0≦X≦1、0≦Y≦1、0≦Z≦1、X+Y+Z=1)からなるpn接合が形成されてなる。このように設置された発光素子4は、親水性主鎖と疎水性側鎖とを有する透光性ポリマー樹脂に少なくとも前記ポリマー樹脂を吸収する度合いを調整することが可能な拡散剤が攪拌されて得られた硬化性組成物の硬化物8にて覆われている。以下、本発明の実施の形態における各構成について詳述する。
(半導体素子4)
本発明において半導体素子4は、特に限定されないが、本実施の形態では発光素子を用い、外部へ光を放出する発光装置を形成している。本実施の形態において、蛍光物質を共に用いる場合、該蛍光物質を効率よく励起することが可能な光を発光する発光層を有する発光素子が好ましい。このような発光素子として、ZnSeやGaNなど種々の半導体を挙げることができるが、蛍光物質を効率良く励起できる短波長を発光することが可能な窒化物半導体(InAlGa1−X−YN、0≦X、0≦Y、X+Y≦1)が好適に挙げられる。また、前記窒化物半導体に、所望に応じてボロンやリンを含有させることもできる。半導体層の構造としては、MIS接合、PIN接合やpn接合などを有するホモ構造、ヘテロ構造あるいはダブルヘテロ構成のものが挙げられる。このような半導体層は、材料やその混晶度によって発光波長を種々選択することができる。また、半導体活性層を量子効果が生ずる薄膜に形成させた単一量子井戸構造や多重量子井戸構造とすることもできる。
窒化物半導体を使用した場合、半導体用基板にはサファイア、スピネル、SiC、Si、ZnO、GaN等の材料が好適に用いられる。結晶性の良い窒化物半導体を量産性よく形成させるためにはサファイア基板を用いることが好ましい。このサファイア基板上にMOCVD法などを用いて窒化物半導体を形成させることができる。例えば、サファイア基板上にGaN、AlN、GaAIN等のバッファ層を形成し、その上にpn接合を有する窒化物半導体を形成させ、半導体素子とする。また基板上に半導層を積層した後、基板を取り除き、基板を有しない半導体素子とすることも可能である。
窒化物半導体を使用したpn接合を有する半導体素子例として、バッファ層上に、n型窒化ガリウムで形成した第1のコンタクト層、n型窒化アルミニウム・ガリウムで形成させた第1のクラッド層、窒化インジウム・ガリウムで形成した活性層、p型窒化アルミニウム・ガリウムで形成した第2のクラッド層、p型窒化ガリウムで形成した第2のコンタクト層を順に積層させたダブルヘテロ構成などが挙げられる。窒化物半導体は、不純物をドープしない状態でn型導電性を示す。発光効率を向上させるなど所望のn型窒化物半導体を形成させる場合は、n型ドーパントとしてSi、Ge、Se、Te、C等を適宜導入することが好ましい。一方、p型窒化物半導体を形成させる場合は、p型ドーパントであるZn、Mg、Be、Ca、Sr、Ba等をドープさせる。窒化物半導体は、p型ドーパントをドープしただけではp型化しにくいため、p型ドーパント導入後に炉による加熱やプラズマ照射等により低抵抗化させることが好ましい。電極形成後、半導体ウエハーからチップ状にカットさせることで窒化物半導体からなる半導体素子を形成させることができる。また、パターニングにより、各電極のボンディング部のみを露出させ素子全体を覆うようにSiO等からなる絶縁性保護膜を形成すると、小型化半導体装置を信頼性高く形成することができる。
本発明の発光装置において、白色系を発光させる場合は、蛍光物質からの発光波長との補色関係や透光性樹脂の劣化等を考慮して、半導体素子の発光波長は400nm以上530nm以下が好ましく、420nm以上490nm以下がより好ましい。さらに半導体素子の励起効率および蛍光物質の発光効率を向上させるためには、半導体素子の発光波長は450nm以上475nm以下が好ましい。
また、本発明の封止部材に用いられる樹脂は、比較的紫外線により劣化されにくく、400nmより短い紫外線領域或いは可視光の短波長領域を主発光波長とする半導体素子を用いることも可能である。また、このような近紫外線領域の波長を発光する発光素子と、その波長の一部を吸収して他の波長を発光することが可能な蛍光物質と、を組み合わせることにより、色ムラの少ない色変換型発光装置を得ることができる。このような色変換型発光装置の発光色は、蛍光物質から放出された光のみを利用するため、比較的簡単に色調整を行うことができる。特に、紫外領域の波長を発光する半導体素子を利用する場合、可視光を発光する半導体素子を用いた場合と比較して、各半導体素子間の波長などのバラツキを吸収し蛍光物質の発光色のみによって色度を決定できるため、量産性を向上させることができる。
(封止部材8)
本実施の形態において、上記の半導体素子が配置されたパッケージの凹部内に表面が発光面となる封止部材が設けられる。前記封止部材は、親水性主鎖と疎水性側鎖からなる透光性ポリマー樹脂と、該ポリマー樹脂を吸収することが可能な拡散剤と、を有する硬化性組成物の硬化物にて構成されており、前記封止部材の上面は前記パッケージの外郭上面より下方の内側に位置している。
このような封止部材は、例えば、上記ポリマー樹脂と吸油可能な拡散剤とを有する液状硬化性組成物を、例えば発光素子が配置された凹部型パッケージ内の、前記凹部の両端部上面と同一平面ライン又はそれ以上のラインまで充填させた後、熱処理により硬化させると、硬化物は硬化前と比較して体積が減少し、得られた硬化物の上面高さは前記凹部の両端部上面より下方となる。このように、本来、熱処理により硬化収縮することのない樹脂を主体とする組成物に、吸油可能な拡散剤を共存させることにより、前記組成物の体積を硬化反応中に減少させることができる。これにより、硬化物表面がタック性を有する組成物を使用した際にも、前記組成物の充填量を微調整することなく、前記表面をパッケージの外郭より内側とすることができる。これにより、内部および外部双方において信頼性の高い発光装置が得られる。
このように本発明の封止部材は、透光性ポリマー樹脂と上記拡散剤を必須成分とする硬化性組成物液を凹部パッケージの外郭上面とほぼ同一平面ラインに充填させ、熱硬化するだけで容易に得ることができ、充填量を見た目により微調整する必要がない。またパッケージの容積により封止部材の充填量が定まり、また拡散剤の表面処理の度合いおよび含有量により前記封止部材の硬化前から硬化後への体積収縮率が定まるため、各半導体装置における封止部材の体積を一定とすることができる。これにより量産性及び歩留まりが向上される。このように本発明に用いられる拡散剤は、高い信頼性を有する樹脂を用いた封止部材を、所望とする厚さに容易に形成することができる。特に本発明では、熱安定性の高いポリマー樹脂を必須成分とする熱硬化性組成物を用いることにより、信頼性の高い半導体装置を量産性良く形成することができる。
また、半導体装置の発光面となる前記封止部材の上面は、滑らかで且つ両端部から中央部にかけて放物線状に凹んだ形状とすることが好ましく、これにより、信頼性が高く且つ光学特性の優れた半導体装置が得られる。さらに前記凹みは、長軸及び短軸にてほぼ左右対称であることが好ましく、これにより、良好な指向特性を有する発光装置が得られる。このような発光面は、熱安定性の高い親水性主鎖と疎水性主鎖からなるポリマー樹脂と吸油量の調整可能な拡散剤とを必須成分とする組成物を用い、硬化過程において前記ポリマー樹脂の体積減少させることにより容易に得ることができる。
一方、前記拡散剤を用いず、熱安定性の高い親水性主鎖と疎水性主鎖からなるポリマー樹脂を必須成分とする組成物を前記パッケージ凹部内に少なめに注入し、封止部材を形成すると、各半導体装置において前記ポリマー樹脂の注入量を一定にすることは困難であり、各半導体装置間において封止部材の膜厚にバラツキが生じる。また、前記封止部材を粘度の高い樹脂組成物を硬化させて形成した場合、前記封止部材の上面は凸凹になる傾向にあり、色むらや指向特性のバラツキの原因となる。また、前記ポリマー樹脂に蛍光物質等を含有させた場合、各発光装置間において色バラツキが生じる。
このように本発明では、前記ポリマー樹脂と前記拡散剤を必須とする硬化性組成物を、常にパッケージの容積全体を封止するように注入させるため、一定量の硬化性組成物を各半導体装置に注入させることができる。これにより、蛍光物質や顔料を含有させても色バラツキが少なく歩留まりの優れた半導体装置が得られる。
ここで、本実施の形態の半導体装置における封止部材の具体的形成方法を述べる。
1.第一の工程
前記透光性ポリマー樹脂として、粘度が7000mPa・Sで且つ屈折率が1.53であるシリコーン樹脂を用い、前記シリコーン樹脂を主体とするシリコーン樹脂組成物に平均粒子径が1.0μtmで且つ吸油量が70ml/100gである軽質炭酸カルシウムを攪拌させる。
(透光性ポリマー樹脂)
本発明でもちいられる、親水性主鎖と疎水性側鎖からなる透光性ポリマー樹脂を主体とする硬化性組成物の硬化物は、前記親水性主鎖の性質により優れた耐光性、柔軟性、および熱安定性を有している。このような樹脂として、例えば、シロキサン結合を骨格としそのケイ素元素に有機基が直接結合したシロキサン系シリコーン樹脂が挙げられる。シロキサン系シリコーン樹脂に用いられる有機基は、耐熱性の観点からみてメチル基とフェニル基を用いることが好ましく、ジメチルシロキサン系シリコーン樹脂、フェニルシロキサン系シリコーン樹脂、フェニルメチルシロキサン系シリコーン樹脂を好適に用いることができ、特に窒化物系半導体素子を使用する場合、フェニルメチルシロキサン系シリコーン樹脂を用いると、良好に光を取り出すことができ好ましい。
前記透光性ポリマー樹脂の粘度は、作業性の観点からみて、2000mPa・s〜20000mPa・sが好ましく、より好ましくは3000mPa・s〜10000mPa・sである。
前記透光性ポリマー樹脂中に前記拡散剤を含有し攪拌した際、熱が生じ樹脂は熱っせられ不安定な状態となりがちであるため、樹脂は充填する前に温度が定温に戻り安定するまで一定時間放置することが好ましい。熱安定性が高く且つ前記範囲の粘度を有する樹脂を用いることにより、攪拌した後に一定時間放置しても樹脂中での前記拡散剤の分散状態を好ましい状態で維持することが可能となる。これにより、信頼性および歩留まりが向上される。
また、硬化後の硬度は、5shore(A)〜80shore(D)が好ましく、より好ましくは5shore(A)〜40shore(D)である。これにより内部応力によるワイヤ切れや各部材のクラックを防止することができる。このように熱安定性に優れ且つ柔軟性に優れた樹脂を用いることにより、大電流の投下を可能とし、高輝度に発光することが可能な半導体装置が得られる。
また、上記半導体素子(屈折率2)と共に用いることを考慮し、前記ポリマー樹脂の屈折率は1.4〜1.65であることが好ましい。本発明では、シリコーン樹脂等の親水性主鎖と疎水性主鎖からなる透光性ポリマー樹脂を使用するが、用いるポリマー樹脂は特に限定されず、エポキシ樹脂、アクリル樹脂、ウレタン樹脂、ジアリルフタレート樹脂、フッ素樹脂、等を用いることも可能である。
(拡散剤)
本発明では、上記ポリマー樹脂を主体とする硬化性組成物中に、少なくとも前記ポリマー樹脂を吸収することが可能な拡散剤として、吸油可能な拡散剤を用いている。本発明で用いられる具体的拡散剤として、軽質炭酸カルシウム、重質炭酸カルシウム、タルク、ホワイトカーボン、炭酸マグネシウム、含水硅酸アルミニウム・マグネシウム、硫酸バリウム等があげられる。
本発明で用いられる拡散剤の形状は、六方晶形等の立方形、紡錘形、破砕形、針状もしくは柱状等の棒状等、種々の構造のものを用いることができる。特に針状もしくは柱状等の棒状を有する拡散剤を用いることが好ましく、このような拡散剤をポリマー樹脂中に分散しパッケージ凹部内に充填すると、前記拡散剤は面積の広い表面が発光素子と対向した状態で沈降する。さらに小さい粒子を有する拡散剤を用いた場合、前記拡散剤はそれぞれの粒子間引力により一方の先端部が一箇所において凝集し他方の先端部間はそれぞれ離間した凝集体となる。このような凝集体は、封止部材を厚み方向において良好に収縮させることができる他、各粒子間および各凝集体間に一定の距離を設けることができるため、光取り出し効率を妨げることなく良好に光を拡散することができる。
また、拡散剤の粒径は、平均粒子径が0.1μm〜5.0μmの範囲であることが好ましく、より好ましくは1.0μm〜2.5μmであることが好ましい。このような平均粒子径値を有する拡散剤は、硬化時の熱作用により前記ポリマー樹脂を効率よく吸収することができる。
ここで、本明細書において平均粒子径とは、空気透過法を基本原理としたサブシーブサイザー法によって測定されたものである。また、拡散剤が破砕形、針状、もしくは柱状等の棒状結晶等の場合、透過型電子顕微鏡法により測定される長辺長は1.0μm〜3.0μmが好ましい。
また前記拡散剤は、前記半導体素子の屈折率よりも低く前記ポリマー樹脂よりも高い屈折率を有することが好ましく、これにより光の取り出し効率が向上され好ましい。特に、炭酸カルシウムからなる拡散剤は、あられ型(アラゴナイト型)結晶の拡散剤を用いることが好ましく、これにより拡散剤にて光を良好に屈折させることができる。
前記透光性ポリマー樹脂の体積減少率は、前記拡散剤の含有量を調整する他、前記拡散剤に施す表面処理の程度によって調整することが可能である。このような拡散剤の表面処理は、Al、Fe、Si等を用いて施すことができる。拡散剤は、表面処理を施す度合いが大きいほど吸油量が小さくなる傾向にある。また、本発明における透光性ポリマー樹脂は、表面処理を殆ど行わず用いることが好ましく、これにより少ない含有量にて前記透光性ポリマー樹脂の体積を大幅に減少させることができる。つまり、拡散剤の上記透光性ポリマー樹脂の吸収量と吸油量とは、相互関係にあると考えら、前記拡散剤の含有量を増すほど前記透光性ポリマー樹脂を主体とする封止部材の硬化前後における体積減少率は大きくなる。このように、樹脂の所望とする体積減少量に合わせて拡散剤を調整して用いるとができ、本発明はあらゆる容積サイズのパッケージを利用した半導体装置に適応することが可能である。
拡散剤の吸油量は、表面処理を施していない状態で、30ml/100g〜150ml/100gであることが好ましく、より好ましくは50ml/100g〜150ml/100gである。これにより後に表面処理を行うことで幅広い吸油量の設定が可能となる。本明細書において吸油量とは、日本工業規格(JIS K5101)の吸油量試験法により測定された値とする。
また拡散剤の封止部材中における含有量は、0.5%〜5%が好ましく、これにより、発光素子の光取り出し効率を低下させることなく発光装置の光度、信頼性、および作業性を向上させつつ、上記硬化性組成物の体積を熱処理後において減少させることができる。
2.第二および第三の工程
得られた硬化性組成物液を一定時間放置して樹脂の熱を定温に戻した後、発光措置が配置されたパッケージ凹部内に前記凹部の端部上面とほぼ同一平面ラインまで注入し(第二の工程)、加熱硬化させる(第三の工程)。この加熱硬化過程において、軽質炭酸カルシウムの何らかの作用により、充填後の前記硬化性組成物の体積が減少される。こうして得られた硬化物である封止部材の表面は、端部上面から中央部にかけて放物線状の凹部を有する形状となる。前記凹部は、長軸及び短軸においてほぼ左右対称である。
上記作用は、おそらく、軽質炭酸カルシウムの吸油量の割合が、加熱硬化過程において促進され、前記シリコーン樹脂の一部が軽質炭酸カルシウムにより吸収されていると思われる。また、軽質炭酸カルシウムの体積は、前記樹脂を吸収した後も増加することなく、ほぼ一定であると考えられる。もしくは、軽質炭酸カルシウムのシリコーン樹脂吸収による体積増加率よりも前記シリコーン樹脂の体積減少率が高いと考えられる。これにより、硬化後の封止部材の体積は充填時よりも減少し、結果、硬化収縮された封止部材表面はパッケージ凹部両端部の上面から中央部にかけて放物線状で且つ発光面からみて長軸及び短軸に対してほぼ左右対称な凹部となる。これにより、良好な発光面が得られ優れた指向特性を有する半導体装置が得られる。また前記表面は、前記パッケージ凹部両端部の上面より下方に形成されるため、前記表面が検査や実装中にて外部に接触することを抑制でき、信頼性の高い半導体装置が得られる。
(蛍光物質8)
本実施の形態の半導体装置は、封止部材中に蛍光物質8を含有させてもよい。ここで、本発明で用いられる蛍光物質について詳述する。本発明では、各構成部材に無機傾向物質や有機蛍光物質等、種々の蛍光物質を含有させることが出来る。このような蛍光物質の一例として、無機蛍光物質である希土類元素を含有する蛍光物質がある。希土類元素含有蛍光物質として、具体的には、Y、Lu,Sc、La,Gd、およびSmの群から選択される少なくとも1つの元素と、Al、Ga、およびInの群から選択される少なくとも1つの元素とを有するガーネット(ざくろ石)型蛍光体が挙げられる。
本実施の形態の半導体装置に用いた蛍光物質は、窒化物系半導体からを発光層とする半導体半導体素子から発光された光を、励起させて異なる波長の光を発光できるセリウムで付活されたイットリウム・アルミニウム酸化物系蛍光物質をベースとしたものである。具体的なイットリウム・アルミニウム酸化物系蛍光物質としては、YAlO:Ce、YAl12:Ce(YAG:Ce)やYAl:Ce、更にはこれらの混合物などが挙げられる。イットリウム・アルミニウム酸化物系蛍光物質にBa、Sr、Mg、Ca、Zn、Prの少なくとも一種が含有されていてもよい。また、Siを含有させることによって、結晶成長の反応を抑制し蛍光物質の粒子を揃えることができる。
本明細書において、Ceで付活されたイットリウム・アルミニウム酸化物系蛍光物質は特に広義に解釈するものとし、イットリウムの一部あるいは全体を、Lu、Sc、La、Gd及びSmからなる群から選ばれる少なくとも1つの元素に置換され、あるいは、アルミニウムの一部あるいは全体をBa、Tl、Ga、Inの何れが又は両方で置換され蛍光作用を有する蛍光体を含む広い意味に使用する。
更に詳しくは、一般式(YGd1−zAl12:Ce(但し、0<z≦1)で示されるフォトルミネッセンス蛍光体や一般式(Re1−aSmRe’12:Ce(但し、0≦a<1、0≦b≦1、Reは、Y、Gd、La、Scから選択される少なくとも一種、Re’は、Al、Ga、Inから選択される少なくとも一種である。)で示されるフォトルミネッセンス蛍光体である。
またフォトルミネッセンス蛍光体は、結晶中にGd(ガドリニウム)を含有することにより、460nm以上の長波長域の励起発光効率を高くすることができる。Gdの含有量の増加により、発光ピーク波長が長波長に移動し全体の発光波長も長波長側にシフトする。すなわち、赤みの強い発光色が必要な場合、Gdの置換量を多くすることで達成できる。一方、Gdが増加すると共に、青色光によるフォトルミネッセンスの発光輝度は低下する傾向にある。さらに、所望に応じてCeに加えTb、Cu、Ag、Au、Fe、Cr、Nd、Dy、Co、Ni、Ti、Eu、およびPr等を含有させることもできる。
また、ガーネット構造を持ったイットリウム・アルミニウム・ガーネット系蛍光体の組成のうち、Alの一部をGaで置換すると、発光波長は短波長側にシフトすることができる。一方、組成のYの一部をGdで置換すると、発光波長が長波長側にシフトすることができる。Yの一部をGdで置換する場合、Gdへの置換を1割未満にし、且つCeの含有(置換)を0.03から1.0にすることが好ましい。Gdへの置換が2割未満では緑色成分が大きく赤色成分が少なくなるが、Ceの含有量を増やすことで赤色成分を補え、輝度を低下させることなく所望の色調を得ることができる。このような組成にすると蛍光物質自体の温度特性が良好となり発光ダイオードの信頼性を向上させることができる。また、赤色成分を多く有するように調整されたフォトルミネッセンス蛍光体を使用すると、ピンク等の中間色を発光することが可能となり、演色性に優れた半導体装置を形成することができる。
このようなフォトルミネッセンス蛍光体は、Y、Gd、Al、及びCeの原料として酸化物、又は高温で容易に酸化物になる化合物を使用し、それらを化学量論比で十分に混合して原料を得る。又は、Y、Gd、Ceの希土類元素を化学量論比で酸に溶解した溶解液を蓚酸で共沈したものを焼成して得られる共沈酸化物と、酸化アルミニウムとを混合して混合原料を得る。これにフラックスとしてフッ化バリウムやフッ化アンモニウム等のフッ化物を適量混合して坩堝に詰め、空気中1350〜1450℃の温度範囲で2〜5時間焼成して焼成品を得、つぎに焼成品を水中でボールミルして、洗浄、分離、乾燥、最後に篩を通すことで得ることができる。
本願発明の半導体装置において、このようなフォトルミネッセンス蛍光体は、2種類以上のセリウムで付活されたイットリウム・アルミニウム・ガーネット蛍光体や他の蛍光体を混合させてもよい。
一方、半導体素子から放出される発光スペクトルが紫外領域や視感度が極めて低い可視光(例えば420nm以下)である場合、前記発光スペクトルの少なくとも一部を吸収し、2以上の発光ピークを持った発光スペクトルを発し、前記発光スペクトルは少なくとも一部が互いに補色となる蛍光である蛍光物質を用いることが好ましい。上記蛍光物質は、補色領域を含む2以上の発光スペクトルのピークを有しているため、蛍光物質自体の色調ズレが極めて小さく半導体素子のバラツキを吸収し、半導体装置の色調ズレを抑制することができる。上記2以上のピークを持った発光スペクトルは、短波長側の発光ピークの半値幅がそれよりも長波長側の発光ピークの半値幅よりも狭いことが好ましく、これにより、長波長の成分を比較的容易に取り出すことができると共に演色性の優れた半導体装置とすることができる。また、前記蛍光物質と共に、上記2以上の発光ピーク間に発光ピークをもった別の蛍光物質を用いると、白色を発光可能であると共に所望の中間色が高輝度に発光可能な半導体装置が得られる。更に、組成によって少なくとも一部が補色となる2以上の発光スペクトルの強度比が調整されていると、白色領域は少しのずれでも人間の目が敏感に感ずることができるものの、これによって、微調整が可能となる。
具体的蛍光物質として、例えば、少なくともMg、Ca、Ba、Sr、Znから選択される1種を含むMで代表される元素と、少なくともMn、Fe、Cr、Snから選択される1種を含むM’で代表される元素とを有するEuで附活されたアルカリ土類金属ハロゲンアパタイト蛍光体を用いることができ、量産性良い白色系が高輝度に発光可能な半導体装置が得られる。特に、少なくともMn及び/又はClを含むEuで附活されたアルカリ土類金属ハロゲンアパタイト蛍光体は、耐光性や、耐環境性に優れている。また、窒化物半導体から放出された発光スペクトルを効率よく吸収することができる。さらに、白色領域を発光可能であると共に組成によってその領域を調整することができる。また、長波長の紫外領域を吸収して黄色や赤色を高輝度に発光可能である。そのため、演色性に優れた半導体装置とすることができる。なお、アルカリ土類金属ハロゲンアパタイト蛍光体例としてアルカリ土類金属クロルアパタイト蛍光体が含まれることは言うまでもない。
前記アルカリ土類金属ハロゲンアパタイト蛍光体において、一般式が(M1−x−yEuM’10(POなどで表される場合(ただし、MはMg、Ca、Ba、Sr、Znから選択される少なくとも1種、M’はMn、Fe、Cr、Snから選択される少なくとも1種、Qはハロゲン元素のF、Cl、Br、およびIから選択される少なくとも1種、である。0.0001≦x≦0.5、0.0001≦y≦0.5である。)、量産性よく混色光が発光可能な半導体装置が得られる。
また、前記アルカリ土類金属ハロゲンアパタイト蛍光体に加えて、BaMgAl1627:Eu、(Sr,Ca,Ba)(POCl:Eu、SrAl:Eu、ZnS:Cu、ZnGeO:Mn、BaMgAl1627:Eu,Mn、ZnGeO:Mn、YS:Eu、LaS:Eu、GdS:Euから選択される少なくとも1種の蛍光体を含有させると、より詳細な色調を調整可能であると共に比較的簡単な構成で演色性の高い白色光を得ることができる。
上記蛍光体は、次に示す方法で得ることができる。構成元素のリン酸塩酸化物もしくは熱分解によって酸化物などになり得る各種化合物と塩化アンモニウムを所定量秤量し、ボールミル等で混合した後、坩堝に入れ、N,Hの還元雰囲気において、800℃から1200℃の温度で3〜7時間焼成する。得られた焼成品を湿式で粉砕、篩後、脱水、乾燥してアルカリ土類金属ハロゲンアパタイト蛍光体を得ることができる。
前記x値は、第一附活材Eu元素の組成比を示すもので0.0001≦x≦0.5が好ましく、xが0.0001未満では発光輝度が低下し、xが0.5を越えても濃度消光によって発光輝度が低下する傾向にある。より好ましくは、0.005≦x≦0.4、さらに好ましくは、0.01≦x≦0.2である。
また、前記y値は、Mn、Fe、Cr、Snのうちの少なくとも1種の元素の組成比を示すもので、0.0001≦y≦0.5が好ましく、より好ましくは0.005≦y≦0.4であり、さらに好ましくは0.01≦y≦0.3である。yが0.5を越えると濃度消光によって発光輝度が低下する傾向にある。
この蛍光体は紫外線から比較的短波長の可視光(たとえば、主波長が440nm以下)の励起により可視光である青色から白色系(たとえば、JIS Z8110の慣用色における白色、或いは系統色名図の基本色となる白色)、および赤色の発光色を示す。
特に、365nm程度の比較的長波長の紫外線によっても効率よく高輝度に発光可能であると共に赤色成分をも十分含むことから、平均演色性指数Raが80以上の良好な演色性を得ることもできる。
また、上記蛍光体は、その組成比を変えることで、青色系〜白色系〜赤色系に種々変化させ色調を調整することができることが分かる。即ち、MがSrの場合、450nm付近にピークを持つEu2+の発光により発光色は青色を発光するが、M‘のMnでyの値を大きくするとMnの発光により蛍光体の発光色は青色〜白色系〜赤色系の発光色を示す。MがCaの場合もEu、Mn量に同様な変化を示すが、MがBaの場合は発光色の変化は少ない。また、本発明に用いられるこの蛍光体は長波長紫外線から比較的短波長可視光(例えば、230nm乃至300nmから400nm乃至425nm)で効率よく励起され、発光色はJIS Z8110でいうところの基本色名白色の領域に含まれる。なお、この蛍光体は紫外線全域で効率よく励起されることから、短波長紫外線用途使用としても有効に利用されうるものとして期待することができる。
このような蛍光体を用いた半導体装置からは紫外線LEDや紫外線LDで励起された上述の蛍光体のうち、約460nm付近のピークと約580nm付近のピークの2つのピークを持った発光スペクトルを発光することが可能となる。この発光スペクトルは少なくともほぼ460nm付近のスペクトル成分と580nm付近のスペクトル成分を有し互いに補色となる蛍光を発している。この少なくともMn及び/又はClを含むEuで附活されたアルカリ土類金属ハロゲンアパタイト蛍光体に緑色を発光する蛍光体としてSrAl:Euを加えることによって更に演色性を高めることができる。
さらに、上述の蛍光体は所望に応じてEuに加えTb、Cu、Ag、Au、Cr、Nd、Dy、Co、Ni、Ti、およびPr等を含有させることもできる。
また、本発明で用いられる蛍光物質の粒径は1μm〜100μmの範囲が好ましく、より好ましくは10μm〜50μmの範囲が好ましく、さらに好ましくは15μm〜30μmである。15μmより小さい粒径を有する蛍光物質は、比較的凝集体を形成しやすく、液状樹脂中において密になって沈降されるため、光の透過効率を減少させてしまう。本発明では、このような蛍光物質を有しない蛍光物質を用いることにより蛍光物質による光の隠蔽を抑制し半導体装置の出力を向上させる。また本発明の粒径範囲である蛍光物質は光の吸収率及び変換効率が高く且つ励起波長の幅が広い。このように、光学的に優れた特徴を有する大粒径蛍光物質を含有させることにより、半導体素子の主波長周辺の光をも良好に変換し発光することができ、半導体装置の量産性が向上される。
ここで本発明において、蛍光物質の粒径は、体積基準粒度分布曲線により得られる値である。前記体積基準粒度分布曲線は、レーザ回折・散乱法により粒度分布を測定し得られるもので、具体的には、気温25℃、湿度70%の環境下において、濃度が0.05%であるヘキサメタリン酸ナトリウム水溶液に各物質を分散させ、レーザ回折式粒度分布測定装置(SALD−2000A)により、粒径範囲0.03μm〜700μmにて測定し得られたものである。本明細書において、この体積基準粒度分布曲線において積算値が50%のときの粒径値を中心粒径といい、本発明で用いられる蛍光物質の中心粒径は15μm〜50μmの範囲であることが好ましい。また、この中心粒径値を有する蛍光物質が頻度高く含有されていることが好ましく、頻度値は20%〜50%が好ましい。このように粒径のバラツキが小さい蛍光物質を用いることにより色ムラが抑制され良好な色調を有する半導体装置が得られる。また、蛍光物質は、本発明で用いられる拡散剤と類似の形状を有することが好ましい。本明細書において、類似の形状とは、各粒径の真円との近似程度を表す円形度(円形度=粒子の投影面積に等しい真円の周囲長さ/粒子の投影の周囲長さ)の値の差が20%未満の場合をいう。これにより、拡散剤による光の拡散と励起された蛍光体からの光が、理想的な状態で混ざり合い、より均一な発光が得られる。
実施例
以下、本発明の実施例について説明する。なお、本発明は以下に示す実施例のみに限定されるものではない。
実施例1.
本発明の半導体装置として、図1に示すような表面実装(SMD)型の半導体装置を形成する。LEDチップは、発光層として単色性発光ピークが可視光である475nmのIn0.2Ga0.8N半導体を有する窒化物半導体素子を用いる。より具体的にはLEDチップは、洗浄させたサファイア基板上にTMG(トリメチルガリウム)ガス、TMI(トリメチルインジウム)ガス、窒素ガス及びドーパントガスをキャリアガスと共に流し、MOCVD法で窒化物半導体を成膜させることにより形成させることができる。ドーパントガスとしてSiHとCpMgを切り替えることによってn型窒化物半導体やp型窒化物半導体となる層を形成させる。
LEDチップの素子構造としてはサファイア基板上に、アンドープの窒化物半導体であるn型GaN層、Siドープのn型電極が形成されn型コンタクト層となるGaN層、アンドープの窒化物半導体であるn型GaN層、次に発光層を構成するバリア層となるGaN層、井戸層を構成するInGaN層、バリア層となるGaN層を1セットとしGaN層に挟まれたInGaN層を5層積層させた多重量子井戸構造としてある。発光層上にはMgがドープされたp型クラッド層としてAlGaN層、Mgがドープされたp型コンタクト層であるGaN層を順次積層させた構成としてある。(なお、サファイア基板上には低温でGaN層を形成させバッファ層とさせてある。また、p型半導体は、成膜後400℃以上でアニールさせてある。)
エッチングによりサファイア基板上の窒化物半導体に同一面側で、pn各コンタクト層表面を露出させる。各コンタクト層上に、スパッタリング法を用いて正負各台座電極をそれぞれ形成させた。なお、p型窒化物半導体上の全面には金属薄膜を透光性電極として形成させた後に、透光性電極の一部に台座電極を形成させてある。出来上がった半導体ウエハーにスクライブラインを引いた後、外力により分割させ、発光主波長が460nmであるLEDチップ(光屈折率2.1)を形成させる。
次に、正及び負からなる一対のリード電極がインサートされて閉じられた金型内に、パッケージ成形体の下面側にあるゲートから溶融された成形用PPC樹脂を流し込み硬化してパッケージを形成する。前記パッケージは、半導体素子を収納可能な凹部を有し、該凹部底面から正及び負のリード電極が一方の主面が露出されるように一体成形されている。尚、このパッケージにおいて、正及び負のリード電極のアウタリード部は、パッケージの接合面の両端部でその接合面に沿って内側に折り曲げられてなり、その内側に折り曲げられた部分ではんだ付けされるように構成されている。
このように形成されたパッケージの凹部底面に前記LEDチップをエポキシ樹脂にてLEDチップをダイボンドする。ここでダイボンドに用いられる接合部材は特に限定されず、Au−Sn合金や導電性材料が含有された樹脂やガラス等を用いることができる。含有される導電性材料はAgが好ましく、含有量が80%〜90%であるAgペーストを用いると放熱性に優れて且つ接合後の応力が小さい半導体装置が得られる。次に、ダイボンドされたLEDチップの各電極と、パッケージ凹部底面から露出された各リード電極とをそれぞれAuワイヤにて電気的導通を取る。本実施例ではワイヤーにて電気的接続を取ったが、各電極とリード電極とを対向させるフリップチップ実装をすることも可能である。
次に、フェニルメチル系シリコーン樹脂組成物100wt%(屈折率1.53)に対して、拡散剤として平均粒子径1.0μm、吸油量70ml/100g、である軽質炭酸カルシウム(屈折率1.62)を3wt%含有させ、自転公転ミキサーにて5分間攪拌を行う。次に攪拌処理により生じた熱を冷ますため、30分間放置し樹脂を定温に戻し安定化させる。
このような軽質炭酸カルシウムは、粒子径のバラツキが少なく、前記組成物中においてほぼ均一に分散することができる。また、本実施例で用いられた軽質炭酸カルシウムは、柱状の形状を有し、且つあられ石型(アラゴナイト型)結晶を有している。このような拡散剤は、高い樹脂吸収性能と光拡散性能とを有しており、信頼性および光学特性に優れた発光装置を形成することができる。
軽質炭酸カルシウムは、消石炭を高温にて炭酸ガスと反応させ焼成し、化学的に製造される。このため、純度の低い非晶質石灰石を原料とすることが可能でありコストを低くすることができる。また、設計の自由度が大きく、形状及び粒度をコントロールして、各粒子が均質な拡散剤を得ることができる。
こうして得られた硬化性組成物を前記パッケージ凹部内に、前記凹部の両端部上面と同一平面ラインまで充填させる。最後に、70℃×3時間、及び150℃×1時間熱処理を施す。これにより、前記凹部の両端部上面から中央部にかけてほぼ左右対称の放物線状に凹みを有する発光面が得られる。
また、前記硬化性組成物の硬化物からなる封止部材は、前記拡散剤の含有量の多い第一の層と、前記第一の層より前記拡散剤の含有量の少ないもしくは含有していない第二の層との2層に分離しており、前記LEDチップの表面は前記第一の層にて被覆されている。これにより、LEDチップから発光される光を効率良く外部へ取り出すことができると共に均一な発光が得られる。前記第一の層は、前記凹部の底面から前記LEDチップの表面にかけて連続して形成されていることが好ましく、これにより、発光面の形状を滑らかな凹部とすることができる。
このようにして得られた半導体装置は、光度500mcd、光出力4mWであり、更に良好な指向特性が得られる。また、高温保管試験(100℃)、高温高湿保管試験(80℃、85%RH)、低温保管試験(−40℃)において、出力の低下はほとんどみられず、高い信頼性を有するといえる。
比較例1.
比較のために、拡散剤を用いない以外は実施例1と同様にして半導体装置を形成する。このようにして得られた比較例1の半導体装置は、タック性を有する封止部材表面と前記凹部の両端部上面とがほぼ同一平面ラインである。このため、封止部材の表面に異物が付着し、外観上および光学特性上に悪影響が生じる。また、前記封止部材表面の信頼性を損なわないように実装することは非常に困難である。また、この比較例の半導体装置の光度及び光出力を測定すると、実施例1の半導体装置と比較して光度および光出力はともに5%低下する。
比較例2.
比較のために、拡散剤を有しない硬化性組成物を前記パッケージ凹部内に、実施例1よりも少なく充填する以外は、実施例1と同様にして半導体装置を形成する。このようにして得られた比較例2の半導体装置は、各半導体装置間において封止部材の膜厚にバラツキが生じる。このため、各半導体装置間において光度および光出力がさまざまとなる。
実施例2.
封止部材に蛍光物質を含有させる以外は、実施例1と同様にして半導体装置を形成する。
蛍光物質は、Y、Gd、Ceの希土類元素を化学量論比で酸に溶解した溶解液を蓚酸で共沈させ、これを焼成して得られる共沈酸化物と、酸化アルミニウムとを混合して混合原料を得る。さらにフラックスとしてフッ化バリウムを混合した後坩堝に詰め、空気中1400℃の温度で3時間焼成することにより焼成品が得られる。焼成品を水中でボールミルして、洗浄、分離、乾燥、最後に篩を通して中心粒径が22Aμmである(Y0.995Gd0.0052.750Al12:Ce0.250蛍光物質を形成する。
上記シリコーン樹脂組成物(屈折率1.53)に、上記蛍光物質(屈折率1.84)5.5wt%、及び拡散剤として平均粒子径2.0μm、吸油量70ml/100gである軽質炭酸カルシウム(屈折率1.62)を3wt%含有させ、自転公転ミキサーにて5分間攪拌を行う。次に攪拌処理により生じた熱を冷ますため、30分間放置し樹脂を定温に戻し安定化させる。こうして得られた硬化性組成物を前記パッケージ凹部内に、前記凹部の両端部上面と同一平面ラインまで充填させる。最後に、70℃×2時間、及び150℃×1時間熱処理を施す。これにより、前記凹部の両端部上面から中央部にかけてほぼ左右対称の放物線状に凹みを有する発光面が得られる。
また、本実施例の封止部材は、前記蛍光物質を有する色変換層と、前記拡散剤の含有量の多い第一の層と、前記第一の層より前記拡散剤の含有量の少ないもしくは含有していない第二の層との、3層に分離しており、前記LEDチップの表面は前記色変換層と第一の層の2層にて被覆されている。これにより、LEDチップから発光される光の一部が色変換層にて効率よく波長変換され、前記第一の層にて前記LEDチップから発光される光と変換後の光とを良好に混合分散することができる。このように、混色分散を発光面から離れた箇所にて行うことにより、光の均一性が向上される。また、色変換層とLEDチップとの屈折率差(0.26)は、前記色変換層と第一の層との屈折率差(0.22)と近似のため、光を効率良く外部へ取り出すことができる。前記色変換層および第一の層は、前記凹部の底面から前記LEDチップの表面にかけて連続して形成されていることが好ましく、これにより、発光面の形状を滑らかな凹部とすることができる。また各層は、それぞれ均一な膜厚を有することが好ましい。
このようにして得られた色変換型半導体装置は、光度500mcd、光出力4mWであり、更に良好な指向特性が得られる。また、高温保管試験(100℃)、高温高湿保管試験(80℃、85%RH)、低温保管試験(−40℃)において、出力の低下はほとんどみられず、高い信頼性を有するといえる。またCIE色度座標における色度の3σは0.0099であり、色バラツキが非常に少ない半導体装置が得られる。
実施例3
蛍光物質として、発光素子の波長を吸収し黄緑色に発光するY(Al0.8Ga0.212:Ceと、前記発光素子の波長を吸収し赤色に発光する(Sr0.679Ca0.291Eu0.03Siとを使用する以外は、実施例2と同様にして発光ダイオードを形成すると、さらに演色性に優れた発光ダイオードが得られる。
実施例4.
蛍光物質として、組成式が(Y0.995Gd0.0052.750Al12:Ce0.250蛍光物質を用いる以外は、実施例2と同様にして発光ダイオードを形成すると、さらに演色性に優れた発光ダイオードが得られる。
実施例5
蛍光物質として、中心粒径が約4μmであるY2.965Al5.1512:Ce0.035と中心粒径が約8μmである(Y0.98Gd0.022.965Al5.1512:Ce0.15とを1:1に混合した混合蛍光体を用いる以外は、実施例2と同様にして発光ダイオードを形成するとさらに均一性および演色性に優れ輝度の高い発光ダイオードが得られる。このように、同じ励起光により励起され同系色でありながら微妙に異なる波長の光を発光する2種類の蛍光物質を用いることにより、発光色の調整幅を広げることができる。また、前記2種類の蛍光物質は、それぞれ異なる中心粒径値を有しているので、これらの相互作用により好ましく分散することができ、発光色の均一性を高めることができる。また、本実施例で用いた蛍光物質の如く、Gdの置換量の少ないYAG系蛍光体は、温度特性に優れているため、長時間の使用においても高輝度に発光することが可能である。
実施例6
主波長が464nmであるLEDチップを用い、蛍光物質として中心粒径が約8μmである(Y0.95Gd0.052.850Al5.1512:Ce0.15を用いる以外は、実施例2と同様にして発光ダイオードを形成すると、さらに均一性および演色性に優れ輝度の高い発光ダイオードが得られる。
実施例7
主波長が466nmであるLEDチップを用い、蛍光物質として中心粒径が約8μmである(Y0.90Gd0.12.850Al5.1512:Ce0.15を用いる以外は、実施例2と同様にして発光ダイオードを形成すると、さらに均一性および演色性に優れ輝度の高い発光ダイオードが得られる。
実施例8
拡散剤として平均粒子径が5μm、吸油量32ml/100gである重質炭酸カルシウム(屈折率1.57)を用いる。実施例1と同様の膜厚の封止部材を得るためには、重質炭酸カルシウムの含有量は、フェニルメチル系シリコーン樹脂組成物100wt%(屈折率1.53)に対して3wt%必要となり、実施例1と比較すると若干光取り出し効率が低下する。
このような重質炭酸カルシウムは、採掘した石灰石をそのまま粉砕・分級したものを用いる。このため、純度の高い結晶質石灰石を原料として用いることが好ましい。
実施例9.
拡散剤として、炭酸カルシウムとリン酸系化合物の反応物である多孔質炭酸カルシウムを用いる。実施例1と同様の膜厚を有する封止部材を形成するには、フェニルメチル系シリコーン樹脂組成物100wt%(屈折率1.53)に対して対して3wt%となり、少ない含有量で所望とする発光ダイオードが得られる。
本実施例における多孔質炭酸カルシウムは、原料の炭酸カルシウムにリン酸系化合物を反応させ、多孔質化したものである。
原料として用いられる炭酸カルシウムは、特に限定されず、重質炭酸カルシウム、軽質炭酸カルシウム等、種々のものを用いることができる。また、粒子の大きさ、形状、分散状態、結晶形、炭酸カルシウム中の不純物の程度等も特に限定されない。
また、使用するリン酸系化合物は、用いる炭酸カルシウムとの反応性が良好であることが好ましく、可溶性リン酸系化合物が好ましい。可溶性リン酸系化合物としては、例えばHPO、KPO、KHPO、NaHPO・12HO、(NH)PO・3HO等が挙げられる。使用するリン酸系化合物は、1種類に限定されず、2種以上を併用してもよい。
実施例10.
樹脂組成物としてジメチルシロキサン系シリコーン樹脂組成物を使用する以外は、実施例1と同様にして発光ダイオードを形成すると、実施例1と同様の効果が得られるが、実施例1と比較して封止部材の硬化前と硬化後における体積減少率は低くなる。
実施例11
LEDチップの各電極上にAuバンプを形成し、超音波接合にてパッケージ凹部底面から露出された各リード電極とそれぞれ電気的導通を取る、フリップチップ実装を行う以外は、実施例1と同様にして発光ダイオードを形成すると、実施例3と同様の硬化が得られる他、発光面側に光を遮断するワイヤーが存在しないため、さらに均一な発光が得られる。また、LEDチップとリード電極との接合にエポキシ樹脂等の耐光性および耐熱性に弱い部材を使用せず、金属のみにて接合するため、大電流を投下した際においても高い信頼性を維持することができるる。
産業状の利用の可能性
以上のように、本発明の半導体装置は、熱安定性の高い親水性主鎖と疎水性主鎖からなるポリマー樹脂を用い、これと共に光拡散作用と共に前記ポリマー樹脂の体積を熱硬化過程において減少させることが可能な拡散剤を用いて封止部材を形成することにより、高い信頼性を有し且つ良好な光学特性を有する半導体装置を量産性良く得ることができる。また、大電流を投下しても劣化することなく信頼性を維持することも可能であり、信頼性が高く且つ照明と同等の明るさを発光することが可能な半導体装置を提供でき、産業上の利用価値は極めて高い。
【図面の簡単な説明】
図1は本発明の発光装置を示す模式的平面図及び模式的断面図である。
図2は本発明の他の発光装置を示す模式的平面図及び模式的断面図である。
図3は本発明の他の発光装置を示す模式的平面図及び模式的断面図である。
Technical field
The present invention relates to a semiconductor device used as a light source for lighting inside a switch, a full-color display, a liquid crystal backlight, and the like, and more particularly to a highly reliable light emitting device.
Background art
Today, high-brightness, high-output semiconductor elements and small and highly sensitive light-emitting devices have been developed and used in various fields. Such light emitting devices are used for light sources of optical printer heads, liquid crystal backlight sources, light sources of various meters, and various reading sensors, for example, by utilizing features such as small size, low power consumption, and light weight.
Such a light emitting device has, for example, a recess having a recess capable of accommodating a semiconductor element, and a package in which positive and negative lead electrodes are inserted and integrally molded from the bottom of the recess so that one main surface is exposed, An LED chip is die-bonded as a semiconductor element on a lead electrode exposed from the bottom surface of the concave portion, and each electrode of the LED chip is electrically connected to a lead electrode provided on a package by a gold wire or the like. The LED chip and the gold wire are covered with a resin as a sealing member in the recess. Thus, the components inside the package are protected from the external environment such as moisture and external force, and a highly reliable light emitting device can be obtained.
At present, rapid progress of technology has realized high output and short wavelength of LED chips. Such an LED chip can emit high-output light by dropping a large current, but involves high-temperature heat generation during light emission. This causes discoloration and deterioration of the sealing resin disposed near the LED chip. In particular, when a light-transmissive organic member having a carbon-carbon double bond that is vulnerable to heat is used as a sealing member disposed in the vicinity of the LED chip, the bond is broken and yellowing is caused, and optical characteristics are impaired. Also, due to the difference in the coefficient of thermal expansion of each member, wire breakage and cracks occur in each member, and the reliability tends to rapidly decrease as the elapsed time of use increases.
Therefore, when using a light emitting element that emits light in the near-ultraviolet region and generates high heat, a silicone resin having excellent light resistance and heat resistance to light in the near-ultraviolet region and having plasticity against thermal stress is preferably used. ing. Since the main skeleton of the silicone resin does not have a carbon-carbon double bond that causes photodegradation, electron transition absorption is unlikely to occur, and hardly deteriorates even when light is irradiated for a long time. Further, since the semiconductor device has excellent flexibility, damage to the semiconductor device due to thermal stress can be prevented.
On the other hand, when the cured product mainly composed of a silicone resin is excellent in flexibility, the surface of the falling object has low mechanical strength and tackiness. The silicone resin has high stability to heat, and the shape of the cured product mainly composed of silicone does not shrink during the curing process and is determined at the time of filling before curing. Therefore, when the sealing member made of silicone resin is provided in the package having the concave portion as described above, it is necessary to finely adjust the filling amount of the silicone resin so that the surface does not contact the outside. Specifically, by injecting and thermally curing a composition mainly composed of silicone resin up to a position one step lower than the upper surface of the outer edge of the package, the surface having tackiness is suppressed from contacting the outside. I have. Thereby, a highly reliable light emitting device can be obtained.
However, at the present time when a light emitting device having a smaller size and a thinner shape is desired, it is very difficult to finely adjust and fill the silicone resin composition into the package having the concave portion as described above. Efficiency is poor and good yield cannot be obtained.
Disclosure of the invention
The present invention has been made to solve the above-described problem, and has as its object to obtain a miniaturized semiconductor device having high reliability and good optical characteristics with a high yield.
As a result of various experiments, the present inventors have found that a diffusing agent whose oil absorption can be adjusted is used for a cured material of a thermosetting composition mainly composed of a resin having excellent thermal stability and a volume that does not change before and after curing. It has been found that when added and cured, the volume of the thermosetting composition can be reduced in the thermosetting process, and the present invention has been accomplished.
A semiconductor device of the present invention is a semiconductor device comprising: a semiconductor element; a package having a recess in which the semiconductor element is housed; and a sealing member filled in the recess.
The sealing member is a light-transmitting polymer resin having a hydrophilic main chain and a hydrophobic side chain, and a diffusing agent capable of absorbing at least the polymer resin, and a curable composition containing an essential component. It is a cured product.
The semiconductor device thus configured has excellent reliability and optical characteristics, and can be obtained with high yield.
Further, in the semiconductor device of the present invention, the hardness of the sealing member is preferably 5 shore (A) to 80 shore (D), whereby a large current can be dropped and a high-output semiconductor device can be obtained. Can be
Further, in the semiconductor device of the present invention, the upper surface of the sealing member preferably has a parabolic recess from the end to the center, whereby the upper surface having tackiness is connected to the outside during mounting or the like. Contact can be further suppressed. Further, when the sealing member is translucent, a light emitting device capable of uniformly emitting light on one surface is obtained.
Further, in the semiconductor device of the present invention, it is preferable that the diffusing agent has a needle-like or columnar shape, whereby the polymer resin absorption of the diffusing agent is increased, and a desired amount of the diffusing agent is small. Can be realized.
Further, in the semiconductor device of the present invention, the diffusing agent is preferably a hailstone type crystal, whereby a semiconductor device capable of diffusing light well and emitting light uniformly is obtained.
Further, in the semiconductor device of the present invention, the diffusing agent preferably has an average particle diameter of 0.1 μm to 5.0 μm, whereby color unevenness is suppressed, and light is emitted at a uniform and high luminous intensity. Is obtained.
Further, in the semiconductor device of the present invention, the refractive index of the diffusing agent is preferably lower than the refractive index of the light emitting element and higher than the refractive index of the translucent polymer resin, whereby light is emitted from the semiconductor element. Light can be favorably extracted to the outside without sealing inside, and a high luminous intensity can be obtained.
Further, in the semiconductor device of the present invention, the sealing member includes a first layer having a higher content of the diffusing agent and a second layer having a lower content of the diffusing agent than the first layer from the semiconductor element side. And a surface of the light emitting element is preferably substantially covered with the first layer. Thus, the efficiency of extracting light emitted from the semiconductor element can be increased.
In the semiconductor device of the present invention, the sealing member may contain a fluorescent substance capable of absorbing at least a part of light emitted from the semiconductor element and emitting light having a different wavelength. Accordingly, a color conversion type semiconductor device capable of emitting light uniformly with little color variation between light emitting devices can be obtained.
Further, in the semiconductor device of the present invention, it is preferable that the refractive index of the fluorescent substance is lower than the refractive index of the light emitting element and higher than the refractive index of the diffusing agent, thereby extracting light emitted from the semiconductor element. Efficiency can be improved.
Further, in the semiconductor device of the present invention, the difference in the refractive index between the fluorescent substance and the light emitting element is preferably substantially equal to the difference in the refractive index between the fluorescent substance and the diffusing agent. A light emitting device is obtained.
Further, in the semiconductor device of the present invention, a sealing member formed by curing a curable composition containing a translucent polymer resin, a diffusing agent, and a fluorescent substance as essential components, the semiconductor element and the first layer It is preferable to have a color conversion layer containing the fluorescent substance between them. That is, on the surface of the semiconductor element, a color conversion layer containing a fluorescent substance, a first layer having a large content of a diffusing agent, and a second layer having a small content of a diffusing agent than the first layer. It is preferable that the light is emitted from the semiconductor element and the light that is partially absorbed and converted by the color conversion layer is reflected by the first layer. Scattered and well mixed. Next, the directivity of the mixed color light is improved by passing through the second layer. This effect is prominent when a fluorescent substance having a large particle diameter, particularly a fluorescent substance having a center particle diameter of 15 μm to 50 μm is used, and a light emitting device capable of emitting light with high luminance and uniformity can be obtained.
In addition, a method of forming a semiconductor device according to the present invention is directed to forming a light emitting device including a semiconductor element, a package having a recess capable of accommodating the semiconductor element, and a sealing member filled in the recess. The method,
A first method of preparing a curable composition liquid containing a light-transmitting polymer resin having a hydrophilic main chain and a hydrophobic side chain and a diffusing agent capable of absorbing the light-transmitting polymer resin as essential components Process and
A second step of injecting the curable composition liquid into the concave portion of the package up to a line substantially flush with the package upper surface,
A third step of performing a heat treatment to cure the curable composition liquid;
It is characterized by having. Thus, a semiconductor device having excellent reliability and optical characteristics can be obtained with good mass productivity.
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic plan view and a schematic cross-sectional view of an SMD light emitting diode according to an embodiment of the present invention. The resin package 1 has a concave portion, and the surfaces of the tip portions of the pair of lead electrodes 2 and 3 are exposed from the bottom surface of the concave portion. The light emitting element 4 is mounted on the bottom surface of the concave portion, and each electrode of the light emitting element 4 and the tip of each of the lead electrodes are electrically connected by a gold wire 6. The light-emitting element 4 includes a nitride semiconductor (Al) on a sapphire substrate via a buffer layer of gallium nitride. X Ga Y In Z N, 0 ≦ X ≦ 1, 0 ≦ Y ≦ 1, 0 ≦ Z ≦ 1, X + Y + Z = 1). The light emitting element 4 installed in this manner is a light transmitting polymer resin having a hydrophilic main chain and a hydrophobic side chain, and a diffusing agent capable of adjusting at least the degree of absorbing the polymer resin is stirred. It is covered with the cured product 8 of the obtained curable composition. Hereinafter, each configuration in the embodiment of the present invention will be described in detail.
(Semiconductor element 4)
In the present invention, the semiconductor element 4 is not particularly limited, but in this embodiment, a light-emitting element that emits light to the outside is formed using a light-emitting element. In this embodiment, when a fluorescent substance is used together, a light-emitting element having a light-emitting layer which emits light capable of efficiently exciting the fluorescent substance is preferable. As such a light emitting element, various semiconductors such as ZnSe and GaN can be cited, but a nitride semiconductor (In) capable of emitting a short wavelength capable of efficiently exciting a fluorescent substance can be used. X Al Y Ga 1-XY N, 0 ≦ X, 0 ≦ Y, X + Y ≦ 1) are preferred. Further, the nitride semiconductor may contain boron or phosphorus as desired. Examples of the structure of the semiconductor layer include a homostructure having a MIS junction, a PIN junction, and a pn junction, a heterostructure, and a double heterostructure. For such a semiconductor layer, various emission wavelengths can be selected depending on the material and the degree of mixed crystal thereof. Further, a single quantum well structure or a multiple quantum well structure in which the semiconductor active layer is formed as a thin film in which a quantum effect occurs can be used.
When a nitride semiconductor is used, a material such as sapphire, spinel, SiC, Si, ZnO, or GaN is preferably used for the semiconductor substrate. In order to form a nitride semiconductor with good crystallinity with high productivity, it is preferable to use a sapphire substrate. A nitride semiconductor can be formed on the sapphire substrate using MOCVD or the like. For example, a buffer layer of GaN, AlN, GaAIN, or the like is formed on a sapphire substrate, and a nitride semiconductor having a pn junction is formed thereon to obtain a semiconductor element. After the semiconductor layer is stacked on the substrate, the substrate can be removed to obtain a semiconductor element having no substrate.
Examples of a semiconductor device having a pn junction using a nitride semiconductor include a first contact layer formed of n-type gallium nitride, a first cladding layer formed of n-type aluminum / gallium nitride on a buffer layer, A double hetero structure in which an active layer formed of indium gallium, a second cladding layer formed of p-type aluminum gallium nitride, and a second contact layer formed of p-type gallium nitride are sequentially stacked. A nitride semiconductor shows n-type conductivity without doping impurities. When a desired n-type nitride semiconductor is formed, for example, to improve luminous efficiency, it is preferable to appropriately introduce Si, Ge, Se, Te, C, or the like as an n-type dopant. On the other hand, in the case of forming a p-type nitride semiconductor, the p-type dopant such as Zn, Mg, Be, Ca, Sr, or Ba is doped. Since it is difficult to convert a nitride semiconductor into a p-type simply by doping with a p-type dopant, it is preferable to reduce the resistance by introducing a p-type dopant into the furnace by heating in a furnace, irradiating plasma, or the like. After the electrodes are formed, a semiconductor element made of a nitride semiconductor can be formed by cutting the semiconductor wafer into chips. Also, by patterning, only the bonding portion of each electrode is exposed to cover the entire device. 2 By forming an insulating protective film made of such as above, a miniaturized semiconductor device can be formed with high reliability.
In the light-emitting device of the present invention, when emitting white light, the emission wavelength of the semiconductor element is preferably 400 nm or more and 530 nm or less in consideration of the complementary color relationship with the emission wavelength from the fluorescent substance and the deterioration of the light-transmitting resin. , 420 nm or more and 490 nm or less. In order to further improve the excitation efficiency of the semiconductor element and the emission efficiency of the fluorescent substance, the emission wavelength of the semiconductor element is preferably 450 nm or more and 475 nm or less.
Further, the resin used for the sealing member of the present invention is relatively hard to be deteriorated by ultraviolet rays, and a semiconductor element having a main emission wavelength in an ultraviolet region shorter than 400 nm or a short wavelength region of visible light can be used. In addition, by combining such a light-emitting element that emits light in the near-ultraviolet region and a fluorescent substance that can absorb part of the wavelength and emit light of another wavelength, color with less color unevenness can be obtained. A conversion type light emitting device can be obtained. Since the color of the color conversion type light emitting device uses only the light emitted from the fluorescent substance, color adjustment can be performed relatively easily. In particular, when a semiconductor device that emits light in the ultraviolet region is used, compared to the case where a semiconductor device that emits visible light is used, variations in the wavelength and the like between the semiconductor devices are absorbed, and only the emission color of the fluorescent substance is used. Since the chromaticity can be determined by this, mass productivity can be improved.
(Sealing member 8)
In this embodiment mode, a sealing member having a light-emitting surface is provided in a concave portion of a package in which the semiconductor element is provided. The sealing member is formed of a cured product of a curable composition having a light-transmitting polymer resin having a hydrophilic main chain and a hydrophobic side chain, and a diffusing agent capable of absorbing the polymer resin. The upper surface of the sealing member is located below the outer upper surface of the package.
Such a sealing member is, for example, a liquid curable composition having the polymer resin and an oil-absorbing diffusing agent, for example, the same as the upper surface of both ends of the concave portion in a concave package in which a light emitting element is disposed. After filling up to a flat line or more lines, when cured by heat treatment, the cured product has a reduced volume compared to before curing, and the upper surface height of the obtained cured product is higher than the upper surface of both ends of the recess. It will be below. As described above, the volume of the composition can be reduced during the curing reaction by allowing the oil-absorbing diffusing agent to coexist with the composition mainly composed of a resin that does not inherently cure and shrink by heat treatment. Thus, even when a composition having a tacky cured surface is used, the surface can be located inside the outer contour of the package without finely adjusting the filling amount of the composition. Thereby, a highly reliable light emitting device can be obtained both inside and outside.
As described above, the sealing member of the present invention can be filled with the curable composition liquid containing the translucent polymer resin and the diffusing agent as essential components in a line substantially flush with the outer top surface of the concave package, and only thermally cured. It can be easily obtained, and it is not necessary to finely adjust the filling amount by visual inspection. Further, the filling amount of the sealing member is determined by the volume of the package, and the volume shrinkage from before curing to after curing of the sealing member is determined by the degree and content of the surface treatment of the diffusing agent. The volume of the stop member can be constant. Thereby, mass productivity and yield are improved. As described above, the diffusing agent used in the present invention can easily form a sealing member using a highly reliable resin to a desired thickness. In particular, in the present invention, a highly reliable semiconductor device can be formed with high mass productivity by using a thermosetting composition containing a polymer resin having high thermal stability as an essential component.
Further, the upper surface of the sealing member, which becomes the light emitting surface of the semiconductor device, is preferably smooth and has a parabolically concave shape from both ends to the center, thereby providing high reliability and excellent optical characteristics. Semiconductor device is obtained. Further, it is preferable that the dent is substantially symmetrical in the major axis and the minor axis, whereby a light emitting device having good directivity characteristics can be obtained. Such a light-emitting surface uses a composition comprising a polymer resin having a highly heat-stable hydrophilic main chain and a hydrophobic main chain and a diffusing agent having an adjustable oil absorption as essential components, and the polymer is cured in a curing process. It can be easily obtained by reducing the volume of the resin.
On the other hand, without using the diffusing agent, a small amount of a composition containing a polymer resin consisting of a hydrophilic main chain and a hydrophobic main chain having high thermal stability as an essential component is injected into the package concave portion to form a sealing member. Then, it is difficult to make the injection amount of the polymer resin constant in each semiconductor device, and the thickness of the sealing member varies among the semiconductor devices. Further, when the sealing member is formed by curing a resin composition having a high viscosity, the upper surface of the sealing member tends to be uneven, which causes color unevenness and variation in directional characteristics. Further, when a fluorescent substance or the like is contained in the polymer resin, color variation occurs between the respective light emitting devices.
As described above, in the present invention, the curable composition containing the polymer resin and the diffusing agent as essential components is injected so as to always seal the entire volume of the package. Can be injected. Accordingly, a semiconductor device with little color variation and excellent yield even when a fluorescent substance or a pigment is contained can be obtained.
Here, a specific method for forming the sealing member in the semiconductor device of the present embodiment will be described.
1. First step
As the translucent polymer resin, a silicone resin having a viscosity of 7000 mPa · S and a refractive index of 1.53 is used, and a silicone resin composition mainly composed of the silicone resin has an average particle diameter of 1.0 μtm and oil absorption. Stir light calcium carbonate in an amount of 70 ml / 100 g.
(Transparent polymer resin)
The cured product of the curable composition mainly comprising a light-transmitting polymer resin having a hydrophilic main chain and a hydrophobic side chain, which is used in the present invention, has excellent light resistance and flexibility due to the properties of the hydrophilic main chain. , And thermal stability. Examples of such a resin include a siloxane-based silicone resin having a siloxane bond as a skeleton and an organic group directly bonded to the silicon element. As the organic group used for the siloxane-based silicone resin, a methyl group and a phenyl group are preferably used from the viewpoint of heat resistance, and a dimethylsiloxane-based silicone resin, a phenylsiloxane-based silicone resin, and a phenylmethylsiloxane-based silicone resin are preferably used. In particular, when a nitride-based semiconductor device is used, it is preferable to use a phenylmethylsiloxane-based silicone resin because light can be extracted well.
The viscosity of the translucent polymer resin is preferably from 2,000 mPa · s to 20,000 mPa · s, more preferably from 3,000 mPa · s to 10,000 mPa · s, from the viewpoint of workability.
When the light-transmitting polymer resin contains the diffusing agent and is agitated, heat is generated and the resin tends to be heated and tends to be in an unstable state. It is preferable to leave it for a certain period of time. By using a resin having high thermal stability and a viscosity in the above-mentioned range, it is possible to maintain the dispersed state of the diffusing agent in the resin in a preferable state even if the resin is left for a certain period of time after stirring. Thereby, reliability and yield are improved.
The hardness after curing is preferably from 5 shore (A) to 80 shore (D), and more preferably from 5 shore (A) to 40 shore (D). This can prevent wire breakage and cracks in each member due to internal stress. By using a resin having excellent thermal stability and excellent flexibility, a semiconductor device capable of emitting a large current and emitting light with high luminance can be obtained.
In addition, in consideration of use with the semiconductor element (refractive index 2), the refractive index of the polymer resin is preferably 1.4 to 1.65. In the present invention, a translucent polymer resin having a hydrophilic main chain and a hydrophobic main chain such as a silicone resin is used, but the polymer resin used is not particularly limited, and an epoxy resin, an acrylic resin, a urethane resin, and a diallyl phthalate resin are used. , Fluorine resin, etc. can also be used.
(Diffusing agent)
In the present invention, an oil-absorbable diffusing agent is used as a diffusing agent capable of absorbing at least the polymer resin in the curable composition mainly composed of the polymer resin. Specific examples of the diffusing agent used in the present invention include light calcium carbonate, heavy calcium carbonate, talc, white carbon, magnesium carbonate, hydrous aluminum / magnesium silicate, and barium sulfate.
The diffusing agent used in the present invention may have various structures such as a cubic shape such as a hexagonal shape, a spindle shape, a crushed shape, a rod shape such as a needle shape or a column shape, and the like. Particularly, it is preferable to use a diffusing agent having a rod shape such as a needle shape or a column shape. When such a diffusing agent is dispersed in a polymer resin and filled in a package recess, the surface of the diffusing agent having a large area faces the light emitting element. Settles in a state where it has been done. When a diffusing agent having smaller particles is used, the diffusing agent forms an agglomerate at one end due to the attraction between the particles and one at the other end apart from each other. Such agglomerates can favorably shrink the sealing member in the thickness direction, and can provide a constant distance between each particle and between the respective agglomerates. Light can be diffused.
The particle size of the diffusing agent is preferably such that the average particle size is in the range of 0.1 μm to 5.0 μm, more preferably 1.0 μm to 2.5 μm. The diffusing agent having such an average particle diameter value can efficiently absorb the polymer resin by a heat effect at the time of curing.
Here, in this specification, the average particle diameter is measured by a sub-sieve sizer method based on an air permeation method as a basic principle. Further, when the diffusing agent is a rod-like crystal such as a crushed, needle-like, or columnar-like crystal, the long side length measured by transmission electron microscopy is preferably from 1.0 μm to 3.0 μm.
Further, the diffusing agent preferably has a refractive index lower than the refractive index of the semiconductor element and higher than the polymer resin, whereby the light extraction efficiency is preferably improved. In particular, as the diffusing agent composed of calcium carbonate, it is preferable to use a hail type (aragonite type) crystal diffusing agent, whereby light can be satisfactorily refracted by the diffusing agent.
The volume reduction rate of the light-transmitting polymer resin can be adjusted by adjusting the content of the diffusing agent and by the degree of surface treatment applied to the diffusing agent. The surface treatment of such a diffusing agent is performed by using Al 2 O 3 , Fe 2 O 3 , Si or the like. The diffusing agent tends to have a smaller oil absorption as the degree of surface treatment increases. Further, the light-transmitting polymer resin in the present invention is preferably used with almost no surface treatment, whereby the volume of the light-transmitting polymer resin can be significantly reduced with a small content. That is, it is considered that the amount of absorption of the light-transmitting polymer resin and the amount of oil absorption of the light-diffusing agent are interrelated, and as the content of the light-diffusing agent increases, the sealing member mainly containing the light-transmitting polymer resin becomes larger. The volume reduction rate before and after curing becomes large. As described above, the diffusing agent can be adjusted and used in accordance with the desired volume reduction of the resin, and the present invention can be applied to a semiconductor device using a package of any volume size.
The oil absorption of the diffusing agent is preferably from 30 ml / 100 g to 150 ml / 100 g, and more preferably from 50 ml / 100 g to 150 ml / 100 g, without surface treatment. This makes it possible to set a wide range of oil absorption by performing surface treatment later. In the present specification, the oil absorption is a value measured by an oil absorption test method of Japanese Industrial Standards (JIS K5101).
Further, the content of the diffusing agent in the sealing member is preferably 0.5% to 5%, thereby improving the luminous intensity, reliability, and workability of the light emitting device without lowering the light extraction efficiency of the light emitting element. The volume of the curable composition can be reduced after the heat treatment.
2. Second and third steps
After the obtained curable composition liquid is left for a certain period of time to return the heat of the resin to a constant temperature, it is poured into a package concave portion in which the light emitting means is arranged up to a line substantially flush with the upper surface of the end of the concave portion (the first line). Second step) and heat curing (third step). In this heat curing process, the volume of the curable composition after filling is reduced by some action of light calcium carbonate. The surface of the sealing member, which is a cured product obtained in this manner, has a shape having a parabolic concave portion from the upper surface of the end to the center. The recess is substantially symmetrical about the major axis and the minor axis.
This effect is probably due to the fact that the ratio of oil absorption of light calcium carbonate is accelerated in the heat curing process, and a part of the silicone resin is absorbed by light calcium carbonate. Further, it is considered that the volume of the light calcium carbonate does not increase even after absorbing the resin, and is substantially constant. Alternatively, it is considered that the volume decrease rate of the silicone resin is higher than the volume increase rate of light calcium carbonate due to absorption of the silicone resin. As a result, the volume of the sealing member after curing is smaller than that at the time of filling, and as a result, the surface of the sealing member that has been cured and shrunk is parabolic from the upper surface of both ends of the package concave portion to the central portion and has a long axis as viewed from the light emitting surface. And a concave portion substantially symmetrical with respect to the short axis. Thereby, a semiconductor device having a good light emitting surface and excellent directional characteristics can be obtained. Further, since the surface is formed below the upper surface of both ends of the package concave portion, the surface can be prevented from contacting the outside during inspection or mounting, and a highly reliable semiconductor device can be obtained.
(Fluorescent substance 8)
In the semiconductor device of the present embodiment, the fluorescent material 8 may be contained in the sealing member. Here, the fluorescent substance used in the present invention will be described in detail. In the present invention, various fluorescent substances such as an inorganic tendency substance and an organic fluorescent substance can be contained in each constituent member. An example of such a fluorescent substance is a fluorescent substance containing a rare earth element which is an inorganic fluorescent substance. As the rare earth element-containing fluorescent material, specifically, at least one element selected from the group consisting of Y, Lu, Sc, La, Gd, and Sm and at least one element selected from the group consisting of Al, Ga, and In (Garnet) type phosphor having two elements.
The fluorescent substance used in the semiconductor device of this embodiment was activated by cerium, which can excite light emitted from a semiconductor semiconductor element having a light emitting layer of a nitride semiconductor and emit light of different wavelengths. It is based on a yttrium / aluminum oxide fluorescent substance. As a specific yttrium / aluminum oxide fluorescent substance, YAlO 3 : Ce, Y 3 Al 5 O 12 : Ce (YAG: Ce) or Y 4 Al 2 O 9 : Ce, and mixtures thereof. The yttrium / aluminum oxide fluorescent material may contain at least one of Ba, Sr, Mg, Ca, Zn, and Pr. Further, by containing Si, the reaction of crystal growth can be suppressed and the particles of the fluorescent substance can be made uniform.
In the present specification, the yttrium-aluminum oxide-based fluorescent material activated by Ce shall be interpreted in a broad sense, and a part or the whole of yttrium is selected from the group consisting of Lu, Sc, La, Gd and Sm. It is replaced with at least one element, or a part or the whole of aluminum is used in a broad sense including a phosphor having a fluorescent action, which is replaced by any one or both of Ba, Tl, Ga and In.
More specifically, the general formula (Y z Gd 1-z ) 3 Al 5 O 12 : Ce (where 0 <z ≦ 1), a photoluminescent phosphor represented by the general formula (Re) 1-a Sm a ) 3 Re ' 5 O 12 : Ce (where 0 ≦ a <1, 0 ≦ b ≦ 1, Re is at least one selected from Y, Gd, La, Sc, and Re ′ is at least one selected from Al, Ga, In.) Is a photoluminescent phosphor represented by the formula:
In addition, the photoluminescence phosphor can increase the excitation light emission efficiency in a long wavelength region of 460 nm or more by containing Gd (gadolinium) in the crystal. As the Gd content increases, the emission peak wavelength shifts to a longer wavelength, and the overall emission wavelength shifts to the longer wavelength side. That is, when a reddish luminescent color is required, it can be achieved by increasing the replacement amount of Gd. On the other hand, as Gd increases, the emission luminance of photoluminescence due to blue light tends to decrease. Further, Tb, Cu, Ag, Au, Fe, Cr, Nd, Dy, Co, Ni, Ti, Eu, Pr and the like can be contained in addition to Ce as desired.
In addition, when part of Al in the yttrium-aluminum-garnet-based phosphor having a garnet structure is replaced with Ga, the emission wavelength can be shifted to a shorter wavelength side. On the other hand, when part of Y in the composition is replaced with Gd, the emission wavelength can be shifted to the longer wavelength side. When a part of Y is substituted with Gd, it is preferable that the substitution with Gd is less than 10% and the content (substitution) of Ce is 0.03 to 1.0. If the substitution with Gd is less than 20%, the green component is large and the red component is small, but by increasing the content of Ce, the red component can be supplemented and a desired color tone can be obtained without lowering the luminance. With such a composition, the temperature characteristics of the fluorescent substance itself are improved, and the reliability of the light emitting diode can be improved. In addition, when a photoluminescent phosphor adjusted to have many red components is used, an intermediate color such as pink can be emitted, and a semiconductor device having excellent color rendering properties can be formed.
Such a photoluminescent phosphor uses an oxide or a compound which easily becomes an oxide at a high temperature as a raw material of Y, Gd, Al, and Ce, and mixes them sufficiently in a stoichiometric ratio to obtain a raw material. Get. Alternatively, a mixed material obtained by mixing a coprecipitated oxide obtained by calcining a solution obtained by dissolving a rare earth element of Y, Gd, and Ce in an acid at a stoichiometric ratio with oxalic acid and aluminum oxide and aluminum oxide Get. A suitable amount of a fluoride such as barium fluoride or ammonium fluoride is mixed into a crucible as a flux, and calcined in air at a temperature of 1350 to 1450 ° C. for 2 to 5 hours to obtain a calcined product. Can be obtained by ball milling in water, washing, separating, drying and finally sieving.
In the semiconductor device of the present invention, such a photoluminescent phosphor may be a mixture of two or more types of yttrium aluminum garnet phosphor activated with cerium and other phosphors.
On the other hand, when the emission spectrum emitted from the semiconductor element is in the ultraviolet region or visible light (for example, 420 nm or less) with extremely low luminosity, at least a part of the emission spectrum is absorbed and emission having two or more emission peaks is obtained. It is preferable to use a fluorescent substance which emits a spectrum and at least a part of the emission spectrum is a fluorescent light which is complementary to each other. Since the fluorescent substance has two or more emission spectrum peaks including a complementary color region, the color shift of the fluorescent substance itself is extremely small, and the variation of the semiconductor element is absorbed to suppress the color shift of the semiconductor device. it can. In the emission spectrum having two or more peaks, it is preferable that the half-width of the emission peak on the short wavelength side is narrower than the half-width of the emission peak on the longer wavelength side. A semiconductor device which can be easily taken out and has excellent color rendering properties can be obtained. When another fluorescent substance having an emission peak between the two or more emission peaks is used together with the fluorescent substance, a semiconductor device capable of emitting white light and emitting a desired intermediate color with high luminance can be obtained. . Furthermore, if the intensity ratio of two or more emission spectra, at least a part of which is a complementary color, is adjusted depending on the composition, the human eyes can be sensitively sensitive to a slight shift in the white area, but this allows fine adjustment. Becomes possible.
Specific fluorescent substances include, for example, an element represented by M including at least one selected from Mg, Ca, Ba, Sr, and Zn and at least one selected from Mn, Fe, Cr, and Sn. An alkaline earth metal halide apatite phosphor activated with Eu and an element represented by M ′ can be used, and a semiconductor device capable of emitting white light with high luminance with good mass productivity can be obtained. In particular, the alkaline earth metal halogenapatite phosphor activated with Eu containing at least Mn and / or Cl is excellent in light resistance and environmental resistance. Further, the emission spectrum emitted from the nitride semiconductor can be efficiently absorbed. Furthermore, the white region can emit light and the region can be adjusted by the composition. In addition, it can emit yellow or red light with high luminance by absorbing a long wavelength ultraviolet region. Therefore, a semiconductor device having excellent color rendering properties can be obtained. Needless to say, an alkaline earth metal chloroapatite phosphor is included as an example of the alkaline earth metal halogen apatite phosphor.
In the alkaline earth metal halogen apatite phosphor, the general formula is (M 1-xy Eu x M ' y ) 10 (PO 4 ) 6 Q 2 (Where M is at least one selected from Mg, Ca, Ba, Sr and Zn, M 'is at least one selected from Mn, Fe, Cr and Sn, and Q is a halogen element At least one selected from the group consisting of F, Cl, Br, and I. 0.0001 ≦ x ≦ 0.5, and 0.0001 ≦ y ≦ 0.5. A semiconductor device capable of emitting light is obtained.
Further, in addition to the alkaline earth metal halogen apatite phosphor, BaMg 2 Al 16 O 27 : Eu, (Sr, Ca, Ba) 5 (PO 4 ) 3 Cl: Eu, SrAl 2 O 4 : Eu, ZnS: Cu, Zn 2 GeO 4 : Mn, BaMg 2 Al 16 O 27 : Eu, Mn, Zn 2 GeO 4 : Mn, Y 2 O 2 S: Eu, La 2 O 2 S: Eu, Gd 2 O 2 When at least one phosphor selected from S: Eu is contained, more detailed color tone can be adjusted, and white light with high color rendering properties can be obtained with a relatively simple configuration.
The phosphor can be obtained by the following method. Predetermined amounts of phosphate oxides of constituent elements or various compounds that can be converted into oxides by thermal decomposition and ammonium chloride are weighed and mixed in a ball mill or the like, and then put into a crucible. 2 , H 2 In a reducing atmosphere of 800 to 1200 ° C. for 3 to 7 hours. The obtained fired product is wet-milled, sieved, dehydrated, and dried to obtain an alkaline earth metal halogen apatite phosphor.
The x value indicates the composition ratio of the first activator Eu element, and is preferably 0.0001 ≦ x ≦ 0.5. When x is less than 0.0001, the emission luminance is reduced and x is 0.5. Even if it exceeds, the emission luminance tends to decrease due to concentration quenching. More preferably, 0.005 ≦ x ≦ 0.4, and still more preferably, 0.01 ≦ x ≦ 0.2.
The y value indicates a composition ratio of at least one element of Mn, Fe, Cr, and Sn, and is preferably 0.0001 ≦ y ≦ 0.5, more preferably 0.005 ≦ y. ≦ 0.4, more preferably 0.01 ≦ y ≦ 0.3. When y exceeds 0.5, the light emission luminance tends to decrease due to concentration quenching.
This phosphor emits visible light from blue to white (for example, white in a conventional color of JIS Z8110, or a system color name diagram) by exciting visible light of a relatively short wavelength from ultraviolet (for example, a main wavelength of 440 nm or less). White, which is a basic color), and a red emission color.
In particular, since it can efficiently emit light with high luminance even by ultraviolet light having a relatively long wavelength of about 365 nm and sufficiently contains a red component, it is possible to obtain good color rendering properties with an average color rendering index Ra of 80 or more. .
Also, it can be seen that the color tone of the phosphor can be variously changed from blue to white to red by adjusting the composition ratio to adjust the color tone. That is, when M is Sr, Eu having a peak near 450 nm 2+ The emission color of the phosphor emits blue light, but when the value of y is increased by Mn of M ′, the emission color of the phosphor exhibits a blue-white-red emission color by the emission of Mn. When M is Ca, a similar change occurs in the amounts of Eu and Mn, but when M is Ba, the change in the emission color is small. Further, the phosphor used in the present invention is efficiently excited by long-wavelength ultraviolet light to relatively short-wavelength visible light (for example, from 230 nm to 300 nm to 400 nm to 425 nm), and the emission color is a basic color name in JIS Z8110. Included in white areas. In addition, since this phosphor is efficiently excited in the entire region of ultraviolet rays, it can be expected that the phosphor can be effectively used for short wavelength ultraviolet rays.
A semiconductor device using such a phosphor emits an emission spectrum having two peaks of about 460 nm and about 580 nm among the above-mentioned phosphors excited by the ultraviolet LED or the ultraviolet LD. It is possible to do. This emission spectrum has at least a spectrum component around 460 nm and a spectrum component around 580 nm, and emits fluorescent light complementary to each other. The alkaline earth metal halogenapatite phosphor activated by Eu containing at least Mn and / or Cl is SrAl as a phosphor emitting green light. 2 O 4 : The color rendering properties can be further enhanced by adding Eu.
Further, the above-described phosphor may contain Tb, Cu, Ag, Au, Cr, Nd, Dy, Co, Ni, Ti, Pr, etc., in addition to Eu, if desired.
The particle size of the fluorescent substance used in the present invention is preferably in the range of 1 μm to 100 μm, more preferably in the range of 10 μm to 50 μm, and still more preferably in the range of 15 μm to 30 μm. A fluorescent substance having a particle diameter of less than 15 μm relatively easily forms an aggregate, and is densely settled in the liquid resin, thereby reducing light transmission efficiency. In the present invention, by using such a fluorescent substance having no fluorescent substance, light hiding by the fluorescent substance is suppressed, and the output of the semiconductor device is improved. In addition, the fluorescent substance having the particle size range according to the present invention has high light absorption and conversion efficiency, and has a wide excitation wavelength. As described above, by including a large-diameter fluorescent substance having optically excellent characteristics, light around the main wavelength of the semiconductor element can be well converted and emitted, thereby improving the mass productivity of the semiconductor device. Is done.
Here, in the present invention, the particle size of the fluorescent substance is a value obtained by a volume-based particle size distribution curve. The volume-based particle size distribution curve can be obtained by measuring the particle size distribution by a laser diffraction / scattering method. Specifically, under an environment of a temperature of 25 ° C. and a humidity of 70%, hexametaline having a concentration of 0.05% Each substance is dispersed in an aqueous solution of sodium acid and measured by a laser diffraction particle size distribution analyzer (SALD-2000A) in a particle size range of 0.03 μm to 700 μm. In the present specification, the particle size when the integrated value is 50% in this volume-based particle size distribution curve is referred to as the center particle size, and the center particle size of the fluorescent substance used in the present invention is in the range of 15 μm to 50 μm. Is preferred. Further, it is preferable that the fluorescent substance having the central particle diameter value is contained frequently, and the frequency value is preferably 20% to 50%. By using a fluorescent substance having a small variation in particle diameter, color unevenness is suppressed and a semiconductor device having a favorable color tone can be obtained. Further, the fluorescent substance preferably has a shape similar to that of the diffusing agent used in the present invention. In the present specification, the similar shape refers to a circularity representing the degree of approximation of each particle size to a perfect circle (circularity = perimeter of a perfect circle equal to the projected area of the particle / perimeter of the projection of the particle). Is less than 20%. Thereby, the diffusion of the light by the diffusing agent and the light from the excited phosphor are mixed in an ideal state, and more uniform light emission can be obtained.
Example
Hereinafter, examples of the present invention will be described. Note that the present invention is not limited to only the following examples.
Embodiment 1 FIG.
As the semiconductor device of the present invention, a surface mount (SMD) type semiconductor device as shown in FIG. 1 is formed. The LED chip has a 475 nm In monochromatic emission peak of visible light as a light emitting layer. 0.2 Ga 0.8 A nitride semiconductor element having an N semiconductor is used. More specifically, in the LED chip, a TMG (trimethyl gallium) gas, a TMI (trimethyl indium) gas, a nitrogen gas and a dopant gas are flowed together with a carrier gas on a cleaned sapphire substrate, and a nitride semiconductor is formed by MOCVD. This can be formed. SiH as dopant gas 4 And Cp 2 By switching Mg, a layer to be an n-type nitride semiconductor or a p-type nitride semiconductor is formed.
As the device structure of the LED chip, an n-type GaN layer as an undoped nitride semiconductor, a GaN layer as an n-type contact layer formed by forming an Si-doped n-type electrode on a sapphire substrate, and n as an undoped nitride semiconductor A GaN layer serving as a barrier layer, a GaN layer serving as a well layer, an InGaN layer serving as a well layer, and a GaN layer serving as a barrier layer are set as one set, and five InGaN layers sandwiched between GaN layers are stacked. It has a multiple quantum well structure. On the light emitting layer, an AlGaN layer as a Mg-doped p-type cladding layer and a GaN layer as a Mg-doped p-type contact layer are sequentially laminated. (Note that a GaN layer is formed on the sapphire substrate at a low temperature to serve as a buffer layer. The p-type semiconductor is annealed at 400 ° C. or higher after film formation.)
The surface of each pn contact layer is exposed on the same side of the nitride semiconductor on the sapphire substrate by etching. Positive and negative pedestal electrodes were formed on the respective contact layers using a sputtering method. A metal thin film is formed as a light-transmitting electrode on the entire surface of the p-type nitride semiconductor, and then a pedestal electrode is formed on a part of the light-transmitting electrode. After a scribe line is drawn on the completed semiconductor wafer, the semiconductor wafer is divided by an external force to form an LED chip (light refractive index 2.1) having a main light emission wavelength of 460 nm.
Next, a molding PPC resin melted from a gate on the lower surface side of the package molded body is poured into a mold closed by inserting a pair of positive and negative lead electrodes, and cured to form a package. . The package has a recess capable of accommodating a semiconductor element, and the positive and negative lead electrodes are integrally formed so that one main surface is exposed from the bottom of the recess. In this package, the outer lead portions of the positive and negative lead electrodes are bent inward along both ends of the bonding surface of the package along the bonding surface, and are soldered at the portions bent inside. It is configured as follows.
The LED chip is die-bonded to the bottom of the concave portion of the package thus formed using epoxy resin. Here, the joining member used for die bonding is not particularly limited, and a resin or glass containing an Au-Sn alloy, a conductive material, or the like can be used. The conductive material to be contained is preferably Ag. If an Ag paste having a content of 80% to 90% is used, a semiconductor device having excellent heat dissipation properties and small stress after bonding can be obtained. Next, each of the electrodes of the die-bonded LED chip and each of the lead electrodes exposed from the bottom surface of the concave portion of the package are electrically connected to each other by Au wires. In this embodiment, electrical connection is made by wires, but flip-chip mounting in which each electrode and the lead electrode face each other is also possible.
Next, light calcium carbonate (refractive index 1.62) having an average particle diameter of 1.0 μm and an oil absorption of 70 ml / 100 g as a diffusing agent with respect to 100 wt% (refractive index 1.53) of the phenylmethyl silicone resin composition. ) Is contained in an amount of 3 wt%, and the mixture is stirred for 5 minutes by a rotation and revolution mixer. Next, in order to cool the heat generated by the stirring treatment, the resin is left for 30 minutes to return to a constant temperature and stabilized.
Such light calcium carbonate has a small variation in particle diameter and can be dispersed almost uniformly in the composition. The light calcium carbonate used in this example has a columnar shape and has a aragonite type (aragonite type) crystal. Such a diffusing agent has high resin absorption performance and light diffusion performance, and can form a light emitting device excellent in reliability and optical characteristics.
Light calcium carbonate is produced chemically by reacting calcined coal with carbon dioxide at a high temperature and calcining it. For this reason, amorphous limestone with low purity can be used as a raw material, and the cost can be reduced. Further, the degree of freedom in design is large, and the shape and particle size can be controlled to obtain a diffusing agent in which each particle is homogeneous.
The curable composition thus obtained is filled into the package recess up to the same plane line as the upper surfaces of both ends of the recess. Finally, heat treatment is performed at 70 ° C. for 3 hours and at 150 ° C. for 1 hour. As a result, a light emitting surface having a parabolic recess substantially bilaterally symmetrical from the upper surface to the center of both ends of the recess is obtained.
In addition, the sealing member made of a cured product of the curable composition has a first layer having a high content of the diffusing agent, and a low content or not containing the diffusing agent than the first layer. The LED chip is separated into a second layer and a second layer, and the surface of the LED chip is covered with the first layer. Thus, light emitted from the LED chip can be efficiently extracted to the outside, and uniform light emission can be obtained. It is preferable that the first layer is formed continuously from the bottom surface of the concave portion to the surface of the LED chip, so that the shape of the light emitting surface can be a smooth concave portion.
The semiconductor device thus obtained has a luminous intensity of 500 mcd and an optical output of 4 mW, and further excellent directional characteristics can be obtained. Further, in the high-temperature storage test (100 ° C.), the high-temperature and high-humidity storage test (80 ° C., 85% RH), and the low-temperature storage test (−40 ° C.), the output is hardly reduced, and it can be said that it has high reliability. .
Comparative Example 1
For comparison, a semiconductor device is formed in the same manner as in Example 1 except that no diffusing agent is used. In the semiconductor device of Comparative Example 1 thus obtained, the surface of the sealing member having tackiness and the upper surfaces of both ends of the concave portion are substantially the same plane line. For this reason, foreign matter adheres to the surface of the sealing member, which has an adverse effect on appearance and optical characteristics. Moreover, it is very difficult to mount the sealing member so as not to impair the reliability of the surface. When the luminous intensity and the optical output of the semiconductor device of this comparative example are measured, both the luminous intensity and the optical output are reduced by 5% as compared with the semiconductor device of the first embodiment.
Comparative Example 2.
For comparison, a semiconductor device is formed in the same manner as in Example 1 except that the curable composition having no diffusing agent is filled in the package recesses less than in Example 1. In the semiconductor device of Comparative Example 2 thus obtained, the thickness of the sealing member varies among the semiconductor devices. For this reason, the luminous intensity and the optical output vary among the semiconductor devices.
Embodiment 2. FIG.
A semiconductor device is formed in the same manner as in Example 1 except that the sealing member contains a fluorescent substance.
The fluorescent substance is obtained by co-precipitating a solution obtained by dissolving rare earth elements of Y, Gd, and Ce in an stoichiometric ratio with an acid, co-precipitating the resulting solution with oxalic acid, and mixing aluminum oxide with aluminum oxide. To obtain a mixed raw material. Further, after mixing barium fluoride as a flux, the mixture is packed in a crucible and fired in air at 1400 ° C. for 3 hours to obtain a fired product. The calcined product is ball-milled in water, washed, separated, dried, and finally passed through a sieve to have a center particle size of 22 A μm (Y 0.995 Gd 0.005 ) 2.750 Al 5 O 12 : Ce 0.250 Form fluorescent material.
5.5 wt% of the fluorescent substance (refractive index 1.84) in the silicone resin composition (refractive index 1.53), and light calcium carbonate having an average particle diameter of 2.0 μm and an oil absorption of 70 ml / 100 g as a diffusing agent (Refractive index 1.62) is contained in an amount of 3 wt%, and the mixture is stirred for 5 minutes by a rotation and revolution mixer. Next, in order to cool the heat generated by the stirring treatment, the resin is left for 30 minutes to return to a constant temperature and stabilized. The curable composition thus obtained is filled into the package recess up to the same plane line as the upper surfaces of both ends of the recess. Finally, heat treatment is performed at 70 ° C. × 2 hours and 150 ° C. × 1 hour. As a result, a light emitting surface having a parabolic recess substantially bilaterally symmetrical from the upper surface to the center of both ends of the recess is obtained.
Further, the sealing member of the present embodiment has a color conversion layer having the fluorescent substance, a first layer having a high content of the diffusing agent, and a content of the diffusing agent smaller than that of the first layer. The LED chip is separated into three layers, that is, a second layer that is not contained, and the surface of the LED chip is covered with two layers of the color conversion layer and the first layer. Thereby, a part of the light emitted from the LED chip is efficiently wavelength-converted in the color conversion layer, and the light emitted from the LED chip and the converted light are mixed well in the first layer. Can be dispersed. As described above, by performing the color mixture dispersion at a place away from the light emitting surface, the uniformity of light is improved. Further, since the refractive index difference (0.26) between the color conversion layer and the LED chip is similar to the refractive index difference (0.22) between the color conversion layer and the first layer, light is efficiently transmitted to the outside. Can be taken out. The color conversion layer and the first layer are preferably formed continuously from the bottom surface of the concave portion to the surface of the LED chip, whereby the shape of the light emitting surface can be a smooth concave portion. Each layer preferably has a uniform thickness.
The color conversion type semiconductor device obtained in this way has a luminous intensity of 500 mcd and an optical output of 4 mW, and further excellent directional characteristics can be obtained. Further, in the high-temperature storage test (100 ° C.), the high-temperature and high-humidity storage test (80 ° C., 85% RH), and the low-temperature storage test (−40 ° C.), the output is hardly reduced, and it can be said that it has high reliability. . The chromaticity 3σ in the CIE chromaticity coordinates is 0.0099, and a semiconductor device with very little color variation can be obtained.
Example 3
Y that emits yellow-green light by absorbing the wavelength of the light-emitting element as a fluorescent substance 3 (Al 0.8 Ga 0.2 ) 5 O 12 : Ce and absorbs the wavelength of the light emitting element to emit red light (Sr 0.679 Ca 0.291 Eu 0.03 ) 2 Si 5 N 8 When a light emitting diode is formed in the same manner as in Example 2 except that the light emitting diode is used, a light emitting diode having more excellent color rendering properties can be obtained.
Embodiment 4. FIG.
As a fluorescent substance, the composition formula is (Y 0.995 Gd 0.005 ) 2.750 Al 5 O 12 : Ce 0.250 When a light emitting diode is formed in the same manner as in Example 2 except that a fluorescent substance is used, a light emitting diode having more excellent color rendering properties can be obtained.
Example 5
As a fluorescent substance, Y having a center particle size of about 4 μm 2.965 Al 5.15 O 12 : Ce 0.035 And the central particle size is about 8 μm (Y 0.98 Gd 0.02 ) 2.965 Al 5.15 O 12 : Ce 0.15 When a light emitting diode is formed in the same manner as in Example 2 except that a mixed phosphor obtained by mixing 1: 1 is used, a light emitting diode having more excellent uniformity and color rendering and high luminance can be obtained. As described above, by using two types of fluorescent substances that emit light of slightly different wavelengths while being of the same color and excited by the same excitation light, the range of adjustment of the emitted color can be widened. Further, since the two kinds of fluorescent substances have different center particle diameter values, the two kinds of fluorescent substances can be preferably dispersed by their interaction, and the uniformity of emission color can be improved. Further, a YAG-based phosphor having a small amount of Gd substitution, such as the phosphor used in this example, has excellent temperature characteristics, and thus can emit light with high luminance even when used for a long time.
Example 6
An LED chip having a main wavelength of 464 nm is used, and the central particle diameter of the fluorescent substance is about 8 μm (Y 0.95 Gd 0.05 ) 2.850 Al 5.15 O 12 : Ce 0.15 When a light emitting diode is formed in the same manner as in Example 2 except that the light emitting diode is used, a light emitting diode excellent in uniformity and color rendering properties and having high luminance can be obtained.
Example 7
An LED chip having a main wavelength of 466 nm is used, and the central particle size of the fluorescent substance is about 8 μm (Y 0.90 Gd 0.1 ) 2.850 Al 5.15 O 12 : Ce 0.15 When a light emitting diode is formed in the same manner as in Example 2 except that the light emitting diode is used, a light emitting diode excellent in uniformity and color rendering properties and having high luminance can be obtained.
Example 8
Heavy calcium carbonate (refractive index 1.57) having an average particle size of 5 μm and an oil absorption of 32 ml / 100 g is used as a diffusing agent. In order to obtain a sealing member having the same thickness as in Example 1, the content of heavy calcium carbonate is required to be 3% by weight based on 100% by weight (refractive index: 1.53) of the phenylmethyl-based silicone resin composition. The light extraction efficiency is slightly lower than that of the first embodiment.
Such heavy calcium carbonate is obtained by crushing and classifying mined limestone as it is. Therefore, it is preferable to use crystalline limestone having high purity as a raw material.
Embodiment 9 FIG.
Porous calcium carbonate, which is a reaction product of calcium carbonate and a phosphoric acid compound, is used as a diffusing agent. In order to form a sealing member having the same film thickness as in Example 1, the content is 3 wt% with respect to 100 wt% (refractive index 1.53) of the phenylmethyl-based silicone resin composition. Light emitting diode is obtained.
The porous calcium carbonate in the present embodiment is obtained by reacting a raw material calcium carbonate with a phosphoric acid compound to make it porous.
The calcium carbonate used as a raw material is not particularly limited, and various types such as heavy calcium carbonate and light calcium carbonate can be used. Further, the size, shape, dispersion state, crystal form, degree of impurities in calcium carbonate, and the like of the particles are not particularly limited.
The phosphoric acid compound used preferably has good reactivity with the calcium carbonate used, and a soluble phosphoric acid compound is preferable. As the soluble phosphate compound, for example, H 3 PO 4 , K 3 PO 4 , KH 2 PO 4 , Na 2 HPO 4 ・ 12H 2 O, (NH 4 ) PO 3 ・ 3H 2 O and the like. The phosphoric acid compound used is not limited to one type, and two or more types may be used in combination.
Embodiment 10 FIG.
When a light emitting diode is formed in the same manner as in Example 1 except that a dimethylsiloxane-based silicone resin composition is used as the resin composition, the same effect as in Example 1 is obtained. The volume reduction rate before and after curing of the stop member decreases.
Example 11
Same as Example 1 except that Au bumps are formed on the respective electrodes of the LED chip, and each of the lead electrodes exposed from the bottom surface of the package recess is electrically connected to each other by ultrasonic bonding, and flip chip mounting is performed. When the light emitting diode is formed by the method described above, the same curing as in the third embodiment can be obtained, and further, since there is no wire for blocking light on the light emitting surface side, more uniform light emission can be obtained. Also, since the LED chip and the lead electrode are joined only by metal without using a member having low light resistance and heat resistance such as epoxy resin, high reliability is maintained even when a large current is dropped. I can do it.
Possibility of industrial use
As described above, the semiconductor device of the present invention uses a polymer resin having a hydrophilic main chain and a hydrophobic main chain with high thermal stability, and reduces the volume of the polymer resin together with light diffusion during the thermosetting process. By forming the sealing member using a diffusing agent that can be made to be used, a semiconductor device having high reliability and good optical characteristics can be obtained with high mass productivity. In addition, reliability can be maintained without deterioration even when a large current is applied, and a semiconductor device which is highly reliable and can emit light at the same brightness as lighting can be provided. The utility value of is extremely high.
[Brief description of the drawings]
FIG. 1 is a schematic plan view and a schematic sectional view showing a light emitting device of the present invention.
FIG. 2 is a schematic plan view and a schematic sectional view showing another light emitting device of the present invention.
FIG. 3 is a schematic plan view and a schematic sectional view showing another light emitting device of the present invention.

Claims (13)

半導体素子と、該半導体素子が収納された凹部を有するパッケージと、前記凹部内に充填された封止部材と、を有する半導体装置であって、
前記封止部材は、親水性主鎖と疎水性側鎖とを有する透光性ポリマー樹脂と、少なくとも前記ポリマー樹脂を吸収することが可能な拡散剤と、を必須成分とする硬化性組成物の硬化物であることを特徴とする半導体装置。
A semiconductor device comprising: a semiconductor element; a package having a recess in which the semiconductor element is housed; and a sealing member filled in the recess.
The sealing member has a light-transmitting polymer resin having a hydrophilic main chain and a hydrophobic side chain, and a diffusing agent capable of absorbing at least the polymer resin, and a curable composition containing an essential component. A semiconductor device, which is a cured product.
前記封止部材の硬度は、5shore(A)〜80shore(D)であることを特徴とする請求項1記載の半導体装置。2. The semiconductor device according to claim 1, wherein the hardness of the sealing member is 5 shore (A) to 80 shore (D). 前記封止部材の上面は、端部から中央部にかけて放物線状の凹みを有することを特徴とする請求項1乃至2記載の半導体装置。3. The semiconductor device according to claim 1, wherein an upper surface of the sealing member has a parabolic depression from an end to a center. 前記拡散剤は、針状もしくは柱状形状であることを特徴とする請求項1乃至3記載の半導体装置。4. The semiconductor device according to claim 1, wherein the diffusing agent has a needle shape or a column shape. 前記拡散剤は、あられ石型結晶であることを特徴とする請求項1乃至4記載の半導体装置。5. The semiconductor device according to claim 1, wherein the diffusing agent is a aragonite crystal. 前記拡散剤は、平均粒子径値が0.1μm〜5.0μmであることを特徴とする請求項1乃至5記載の半導体装置。The semiconductor device according to claim 1, wherein the diffusing agent has an average particle size of 0.1 μm to 5.0 μm. 前記拡散剤の屈折率は、前記発光素子の屈折率より低く且つ前記透光性ポリマー樹脂の屈折率より高いことを特徴とする請求項1乃至6記載の半導体装置。7. The semiconductor device according to claim 1, wherein a refractive index of the diffusing agent is lower than a refractive index of the light emitting element and higher than a refractive index of the light transmitting polymer resin. 前記封止部材は、前記半導体素子側から前記拡散剤の含有量の多い第一の層と前記第一の層より前記拡散剤の含有量の少ない第二の層とを有し、前記発光素子の表面は前記第一の層にてほぼ被覆されていることを特徴とする請求項1乃至7記載の半導体装置。The sealing member has a first layer having a higher content of the diffusing agent and a second layer having a lower content of the diffusing agent than the first layer from the semiconductor element side, and the light-emitting element 8. The semiconductor device according to claim 1, wherein the surface of the semiconductor device is substantially covered with the first layer. 前記封止部材は、発光素子から発光される光の少なくとも一部を吸収し異なる波長を有する光を発光することが可能な蛍光物質を含有していることを特徴とする請求項1乃至8記載の半導体装置。9. The phosphor according to claim 1, wherein the sealing member contains a fluorescent substance capable of absorbing at least a part of light emitted from the light emitting element and emitting light having different wavelengths. Semiconductor device. 前記蛍光物質の屈折率は、前記発光素子の屈折率より低く且つ前記拡散剤の屈折率より高いことを特徴とする請求項9記載の半導体装置。10. The semiconductor device according to claim 9, wherein a refractive index of the fluorescent material is lower than a refractive index of the light emitting element and higher than a refractive index of the diffusing agent. 前記蛍光物質と前記発光素子との屈折率差は、前記蛍光物質と前記拡散剤との屈折率差とほぼ等しいことを特徴とする請求項9乃至10記載の半導体装置。11. The semiconductor device according to claim 9, wherein a difference in refractive index between the fluorescent substance and the light emitting element is substantially equal to a difference in refractive index between the fluorescent substance and the diffusing agent. 前記封止部材は、前記発光素子と前記第一の層との間に前記蛍光物質を含有する色変換層を有することを特徴とする9乃至11記載の半導体装置。12. The semiconductor device according to claim 9, wherein the sealing member has a color conversion layer containing the fluorescent substance between the light emitting element and the first layer. 半導体素子と、該半導体素子を収納することが可能な凹部を有するパッケージと、前記凹部内に充填された封止部材と、を有する半導体装置の形成方法であって、
親水性主鎖と疎水性側鎖とを有する透光性ポリマー樹脂と該透光性ポリマー樹脂を吸収することが可能な拡散剤とを必須成分とする硬化性組成物液を調整する第一の工程と、
前記硬化性組成物液を前記パッケージの凹部内にパッケージ上面とほぼ同一平面のラインまで注入する第二の工程と、
熱処理を施し前記硬化性組成物液を硬化させる第3の工程と、
を有することを特徴とする半導体装置の形成方法。
A method for forming a semiconductor device, comprising: a semiconductor element; a package having a recess capable of accommodating the semiconductor element; and a sealing member filled in the recess.
A first method of preparing a curable composition liquid containing a light-transmitting polymer resin having a hydrophilic main chain and a hydrophobic side chain and a diffusing agent capable of absorbing the light-transmitting polymer resin as essential components Process and
A second step of injecting the curable composition liquid into the concave portion of the package up to a line substantially flush with the package upper surface,
A third step of performing a heat treatment to cure the curable composition liquid;
A method for forming a semiconductor device, comprising:
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