JP3934730B2 - Semiconductor light emitting device - Google Patents

Semiconductor light emitting device Download PDF

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JP3934730B2
JP3934730B2 JP7781797A JP7781797A JP3934730B2 JP 3934730 B2 JP3934730 B2 JP 3934730B2 JP 7781797 A JP7781797 A JP 7781797A JP 7781797 A JP7781797 A JP 7781797A JP 3934730 B2 JP3934730 B2 JP 3934730B2
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light emitting
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type layer
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electrode
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JPH10275935A (en
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範和 伊藤
俊次 中田
幸男 尺田
雅之 園部
毅 筒井
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Rohm Co Ltd
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Rohm Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/15—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission
    • H01L27/153—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission in a repetitive configuration, e.g. LED bars
    • H01L27/156—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission in a repetitive configuration, e.g. LED bars two-dimensional arrays

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Description

【０００１】
【発明の属する技術分野】
本発明は、発光面積を大きくして輝度を大きくする半導体発光素子に関する。さらに詳しくは、たとえば青色系の発光素子などに用いられるチッ化ガリウム系化合物半導体のように、半導体層の抵抗が大きい半導体が用いられる場合に輝度を向上させ得る半導体発光素子に関する。
【０００２】
【従来の技術】
従来、青色系の光を発光する半導体発光素子のチップ（以下、ＬＥＤチップという）は、たとえば図４に示されるような構造になっている。すなわち、ウェハ状のサファイア基板２１上にたとえばｎ形のＧａＮがエピタキシャル成長されたｎ形層（クラッド層）２３と、バンドギャップエネルギーがクラッド層のそれよりも小さくなる材料、たとえばＩｎＧａＮ系（ＩｎとＧａの比率が種々変わり得ることを意味する、以下同じ）化合物半導体からなる活性層２４と、ｐ形のＧａＮからなるｐ形層（クラッド層）２５とが積層され、その表面のｐ形層２５に電気的に接続してｐ側電極２８が、積層された半導体層の一部がエッチングされて露出するｎ形層２３と電気的に接続してｎ側電極２９が設けられることにより、ＬＥＤチップ２０が形成されている。なお、ｐ側電極２８からの電流をＬＥＤチップの全体に広げるために、ｐ形層２５の表面に光を通す薄い金属膜からなる電流拡散層が設けられることがある。
【０００３】
このＬＥＤチップは、ｐ側電極とｎ側電極との間に順方向の電圧が印加されることにより、その活性層にキャリアの閉込めが生じ発光する。この発光量は電流を多くしてキャリアの閉込め量を多くすることにより大きな輝度で発光する。
【０００４】
【発明が解決しようとする課題】
前述のような青色系の半導体発光素子に用いられるチッ化ガリウムのような半導体材料は、ドーパントのドーピングが充分に行われず、その直列抵抗が大きくなりやすい。とくにｐ形のドーパントはドーパントとして充分に作用せず、熱損失が発生しやすい。そのため、電圧を高くしてもある値を超えると輝度が充分に上らず、発熱による半導体層の劣化などの信頼性上の問題が発生する。
【０００５】
一方、ＬＥＤチップの面積を大きくして広い範囲で発光させようとすると、前述のように、とくにｐ形層のドーパント作用が充分ではないため、電流が充分にＬＥＤチップの全体に広がらない。しかし、表面側から光を取り出すため、光を遮断する電極を全面に設けることができず、電流拡散層を設けるだけでは、電流分布が不均一になって発光分布も不均一になり、充分に輝度の向上を図れない。また、ＬＥＤチップを複数個マウントし、並列に接続して動作させようとすると、マウントが複雑になり、組立工数が増加すると共に、前述のようなサファイア基板が用いられる場合にはそのチップへの切断分離が大変であるのに切断分離したチップを複数個並べてマウントするのはムダで、コストアップになるという問題がある。
【０００６】
本発明はこのような状況に鑑みてなされたもので、ドーパントの作用が充分でなく直列抵抗の大きい半導体層が用いられる半導体発光素子においてもチップ面積を大きくして輝度を上げることができる半導体発光素子を提供することを目的とする。
【０００７】
【課題を解決するための手段】
本発明による半導体発光素子は、四角形状の基板と、該基板上に第１導電形層および第２導電形層が積層され発光層を形成する発光層形成部と、該発光層形成部の上層側に設けられる第１導電形層および前記発光層形成部の下層側に設けられる第２導電形層にそれぞれ電気的に接続して設けられる電極とからなる発光素子チップを有し、前記発光素子チップのほぼ中心部を通る十字状溝により前記第１導電形層が４分割されると共に、前記第２導電形層が連続して形成され、前記発光素子のほぼ中心部で前記発光層形成部の一部がエッチングにより除去されて露出する前記第２導電形層上に第２の電極が形成され、前記４分割された第１導電形層のそれぞれと電気的に接続して、かつ、前記中心部から一番遠い角部に第１の電極が形成され、全体として１つの発光色で均一に発光し得る構造である。
【０００８】
このようにすることにより、チップ面積が大きくなって電流の拡散が充分に行われにくい場合でも、電極が複数個設けられるため発光層形成部の全体に電流が流れ、チップ面積の全体で均一に発光して、複数個のチップが並列接続されたのと同様に輝度が向上する。しかも１チップであるため、組立ても非常に簡単に行われる。
【０００９】
本発明の半導体発光素子の他の形態は、四角形状の基板と、該基板上に第１導電形層および第２導電形層が積層され発光層を形成する発光層形成部と、該発光層形成部の上層側に設けられる第１導電形層および前記発光層形成部の下層側に設けられる第２導電形層にそれぞれ電気的に接続して設けられる電極とからなる発光素子チップを有し、前記発光素子チップのほぼ中心部を通る十字状溝により前記第１導電形層が４分割されると共に、前記第２導電形層が連続して形成され、前記発光素子チップの周縁部の全周に前記発光層形成部の一部がエッチングにより除去されて露出する前記第２導電形層上に第２の電極が形成され、前記４分割された第１導電形層のそれぞれと電気的に接続して、かつ、前記中心部に一番近い角部に第１の電極が形成され、全体として１つの発光色で均一に発光し得る構造である。
また、前記４分割された第１導電形層に電気的に接続して設けられる第１の電極が、それぞれ独立して電源に接続し得るように形成されていることが好ましい。そうすることにより、各電極ごとに独立して電圧を供給することができ、発光層形成部が対応する電極ごとに分割されていなくても、抵抗が小さいところに電流が集中するということがなく、全体で均一に発光し輝度が向上しやすい。
【００１０】
ここに複数個の電極が独立して設けられるとは、チップの状態で配線などにより接続されていないことを意味し、ワイヤボンディングなどにより並列に接続されることは構わない。
【００１１】
前記発光層形成部がチッ化ガリウム系化合物半導体からなり、前記第１導電形層がｐ形層であれば、ｐ側電極が複数個設けられることにより、とくにドーパントが作用しにくいチッ化ガリウム系化合物半導体のｐ形層の全体に電流を流しやすくなり、高輝度の発光に寄与する。
【００１２】
ここにチッ化ガリウム系化合物半導体とは、III 族元素のＧａとＶ族元素のＮとの化合物またはIII 族元素のＧａの一部がＡｌ、Ｉｎなどの他のIII 族元素と置換したものおよび／またはＶ族元素のＮの一部がＰ、Ａｓなどの他のＶ族元素と置換した化合物からなる半導体をいう。
【００１３】
【発明の実施の形態】
つぎに、図面を参照しながら本発明の半導体発光素子について説明をする。図１には、青色系の発光に適したチッ化ガリウム系化合物半導体層をサファイア基板上に積層された本発明の半導体発光素子の一実施形態の１チップの状態の斜視説明図が示されている。
【００１４】
本発明の半導体発光素子は、図１に示されるように、たとえばサファイア（Ａｌ2 Ｏ3 単結晶）などからなる基板１上に第１導電形層（ｐ形層）５および第２導電形層（ｎ形層）３が積層され発光層を形成する発光層形成部１０と、該発光層形成部１０の第１導電形層（ｐ形層）５および第２導電形層（ｎ形層）３にそれぞれ電気的に接続して設けられる電極（ｐ側電極８およびｎ側電極９）とからＬＥＤチップが形成されている。そして、前記電極の少なくともｐ形層５に接続されるｐ側電極８（第１の電極）は、ｐ形層５の異なる場所に接続されるように複数個設けられると共に、前記発光層形成部１０が、前記複数個設けられるｐ側電極８に対応するブロックに分割されてている。この複数個の電極８は、絶縁膜などを介した配線により接続されていてもよい。
【００１５】
ここに第１導電形層や第２導電形層に電気的に接続されるとは、直接第１導電形層や第２導電形層に電極が設けられる場合のみではなく、図１に示されるように薄い金属層からなる電流拡散層７を介して電極が設けられたり、その導電形と同じ導電形の他の半導体層（たとえばｐ形層５上に設けられるｐ形ウインドウ層（図示せず）や、ｎ形層３側に設けられるバッファ層（図示せず）や導電性基板からなる基板など）が発光層形成部の上下に設けられてその半導体層などを介して設けられる場合も含む意味である。
【００１６】
図１に示される例では、１チップの一辺の長さがたとえば７２０μｍ程度と通常の青色系のＬＥＤチップの２倍程度（面積で４倍程度）に大きく形成されると共に、発光層形成部１０がｎ形層３に至るまでのエッチングにより、４つのブロック１１、１２、１３、１４に分割されている。この４つのブロック１１〜１４は基板１およびｎ形層３により連結されており、全体で１チップになっている。そして、それぞれのブロックのｐ形層５上に薄い金属膜からなる電流拡散層７を介してｐ側電極８が設けられると共に、ＬＥＤチップの中心部で４つのブロックに跨がるように発光層形成部１０がエッチングされてｎ形層３を露出させ、その露出するｎ形層３にｎ側電極９が形成されている。すなわち、ｎ側電極９は４つのブロックに共通して１個設けられており、ｐ側電極８は４つのブロック１１〜１４のそれぞれに設けられている。なお、電流拡散層７は設けられなくてもよいし、各ブロックのｐ側電極８は絶縁膜を介した配線により連結されていてもよい。
【００１７】
発光層形成部１０は、たとえばＧａＮからなる低温バッファ層、クラッド層となるｎ形のＧａＮおよび／またはＡｌＧａＮ系（ＡｌとＧａの比率が種々変わり得ることを意味する、以下同じ）化合物半導体の積層構造からなるｎ形層３、バンドギャップエネルギーがクラッド層のそれよりも小さくなる材料、たとえばＩｎＧａＮ系化合物半導体からなる活性層４、およびｐ形のＡｌＧａＮ系化合物半導体層および／またはＧａＮ層からなるｐ形層（クラッド層）５が、サファイア（Ａｌ2 Ｏ3 単結晶）などからなる基板１上にそれぞれ順次積層されることにより構成されている。
【００１８】
この半導体発光素子を製造するには、たとえば有機金属化学気相成長法（ＭＯＣＶＤ法）により、反応ガスおよび必要なドーパントガスを導入してｎ形層３を１〜５μｍ程度、活性層４を０.０５〜０.３μｍ程度、およびｐ形層５を０.２〜１μｍ程度、それぞれエピタキシャル成長する。ついで、ＮｉおよびＡｕを蒸着してシンターすることにより、メタル層などからなる電流拡散層７を２〜１００ｎｍ程度形成する。
【００１９】
その後、電流拡散層７の表面にレジスト膜などを設けてパターニングをし、電流拡散層７および積層された半導体層３〜５（発光層形成部１０）の一部をエッチングして図１に示されるように、ＬＥＤチップの中心部およびチップの周縁部と、たとえば４つのブロックに分割するための十字の溝が形成されるようにｎ形層３を露出させる。このエッチングは、塩素ガスなどによる反応性イオンエッチングにより行うことができる。この周縁部をエッチングするのは、各チップへのブレークを容易にするためのもので、中心部のエッチングはｎ側電極９を設けるためのものである。この中心部の露出したｎ形層３の表面に、ｎ側電極９の形成のための金属のＴｉおよびＡｌをそれぞれ０.１μｍ程度と０.３μｍ程度づつ真空蒸着などにより成膜してシンターし、さらにｐ側電極８のために図示しないＳｉＮなどの保護膜の一部を除去してＴｉとＡｕをそれぞれ真空蒸着して積層することにより、上部電極８および下部電極９を形成する。
【００２０】
本発明によれば、半導体層でドーパントが作用をしにくく抵抗が大きい場合でも、その半導体層側に接続される電極が１チップ内で複数個設けられると共に、発光層形成部１０もその電極８に対応して分割されているため、チップ全体に電流を広げやすい。すなわち、たとえばチッ化ガリウム系化合物半導体が用いられる青色系の半導体発光素子では、とくにｐ形層でドーパントの作用が弱く、充分にキャリア濃度を上げることができないこと、ｐ形層は発光面側に設けられるため、光の吸収を抑えるためからも厚く形成できないことなどのため電流の拡散が充分に行われないが、本発明の複数個の電極が設けられることにより、ＬＥＤチップの全体に効率的に電流を拡散させることができる。しかも、発光層形成部１０も分割されているため、小さいチップが集合したのと同様で、全体に電流が広がりやすい。一方、ｎ形層では、比較的ドーパントが入りやすいことと、厚くしやすいことのため、余り半導体層の抵抗が問題にならず、図１に示されるように、ｎ形層に接続されるｎ側電極９は１チップ内で１個にすることにより、電極面積を節約することができ、別々のＬＥＤチップを寄せ集めるより表面積を効率的に利用することができる。その結果、チップの全体で均一に発光し、チップ面積を大きくすることにより、輝度を高くすることができる。
【００２１】
なお、ｐ側電極８は全て、または複数個を連結して電源側に接続することもできるし、それぞれ別々に独立させて別個の電源に接続させることもできる。別個の電源に接続すれば、発光層のブロックのどれかに抵抗の小さいのがあっても、そこに電流が集中することがなく、一層発光が均一化されて輝度が向上する。
【００２２】
図１に示される例では、ｐ側電極８が設けられるブロックごとに発光層形成部１０が分割されると共に、ＬＥＤチップの中心部にｎ側電極９が設けられている。この構成にすることにより、ｎ側電極９を小さい面積で形成しながらＬＥＤチップ内全面に均一に電流を流すのに都合がよいが、図２に示されるように、ＬＥＤチップの周縁部にｎ側電極９が設けられてもよい。前述のように、ＬＥＤチップの周縁部には、チップへのブレークを容易にするためのエッチングがなされてｎ形層３が露出しているため、その幅を少し広くするだけでｎ側電極９を形成することができ、表面積を殆ど減すことなくｎ側電極９が形成される。なお、この場合、各ブロックごとにｎ側電極９およびｐ側電極８が離れた位置で対応するように設けられる方が電流が広がりやすいため、図２に示されるようにｐ側電極８はＬＥＤチップの中心部で、分割された各ブロックごとに設けられることが好ましい。この場合も前述と同様に、チップ面積が大きくなっても部分的に電流が集中することがなく、均一で高輝度の発光をさせることができる。なお、図１と同じ部分には同じ符号を付してその説明を省略する。
【００２３】
図１〜２に示される例では、ｐ側電極が複数個設けられ、そのｐ側電極に応じて発光層形成部１０が分割されていたが、図３に示されるように、発光層形成部１０は分割されないで、積層された半導体層の表面または電流拡散層などを介して点在的に複数個の電極が設けられてもよい。この構造にすれば電極から離れて電流が流れにくくなる部分に別の電極が設けられることになり、広いチップ内で均等に電流を流すことができる。さらに、ｐ側電極の各々を並列に接続しないで、別々に電圧を印加させることにより、半導体層の一部に抵抗の低いところがあってもその部分に電流が集中することなくチップ内に全体に亘って電流を流すことができる。なお、図３において図１〜２と同じ部分には同じ符号を付してその説明を省略する。
【００２４】
なお、前述の各例は、半導体層をチッ化ガリウム系化合物半導体が発光層形成部として用いられる例であったが、チッ化ガリウム系化合物半導体は半導体層の抵抗が大きいため効果が大きい。しかし、他の半導体層が用いられる半導体発光素子にも適用できる。さらに、発光層形成部としてｎ形層とｐ形層とにより活性層が挟持されるダブルヘテロ接合構造であったが、ｎ形層とｐ形層とが直接接合するｐｎ接合構造のものでもよい。
【００２５】
【発明の効果】
本発明によれば、電極が複数個設けられることにより、電流を充分に拡散させることができるため、チップ面積を大きくすることができ、高輝度の発光素子を得ることができる。
【図面の簡単な説明】
【図１】本発明の半導体発光素子の一実施形態の斜視説明図である。
【図２】図１の半導体発光素子の変形例を示す斜視説明図である。
【図３】本発明の半導体発光素子の他の実施形態の斜視説明図である。
【図４】従来の半導体発光素子の一例の斜視説明図である。
【符号の説明】
１ 基板
３ ｎ形層
５ ｐ形層
８ ｐ側電極
９ ｎ側電極
１０ 発光層形成部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor light emitting device that increases the luminance by increasing the light emitting area. More specifically, the present invention relates to a semiconductor light emitting device capable of improving luminance when a semiconductor having a large resistance of a semiconductor layer is used, such as a gallium nitride compound semiconductor used for a blue light emitting device.
[0002]
[Prior art]
Conventionally, a chip of a semiconductor light emitting element that emits blue light (hereinafter referred to as an LED chip) has a structure as shown in FIG. That is, an n-type layer (cladding layer) 23 in which, for example, n-type GaN is epitaxially grown on a wafer-like sapphire substrate 21, and a material whose band gap energy is smaller than that of the cladding layer, such as InGaN-based (In and Ga The active layer 24 made of a compound semiconductor and a p-type layer (cladding layer) 25 made of p-type GaN are laminated, and the p-type layer 25 on the surface thereof is laminated. The p-side electrode 28 is electrically connected to the n-type layer 23 that is exposed by etching a part of the laminated semiconductor layer, and the n-side electrode 29 is provided to thereby provide the LED chip 20. Is formed. In order to spread the current from the p-side electrode 28 over the entire LED chip, a current diffusion layer made of a thin metal film that transmits light may be provided on the surface of the p-type layer 25 in some cases.
[0003]
In this LED chip, when a forward voltage is applied between the p-side electrode and the n-side electrode, carriers are confined in the active layer to emit light. The amount of emitted light is emitted with high luminance by increasing the current and increasing the amount of confinement of carriers.
[0004]
[Problems to be solved by the invention]
A semiconductor material such as gallium nitride used for the blue semiconductor light emitting element as described above is not sufficiently doped with dopant, and its series resistance tends to increase. In particular, a p-type dopant does not sufficiently function as a dopant, and heat loss is likely to occur. Therefore, even if the voltage is increased, if the value exceeds a certain value, the luminance is not sufficiently increased, and a problem in reliability such as deterioration of the semiconductor layer due to heat generation occurs.
[0005]
On the other hand, if the area of the LED chip is increased to emit light over a wide range, as described above, since the dopant action of the p-type layer is not sufficient, the current does not sufficiently spread over the entire LED chip. However, since light is extracted from the surface side, an electrode for blocking light cannot be provided on the entire surface, and merely providing a current diffusion layer results in non-uniform current distribution and non-uniform light emission distribution. The brightness cannot be improved. Also, mounting a plurality of LED chips and connecting them in parallel increases the mounting complexity, increases the number of assembly steps, and when a sapphire substrate as described above is used, Although it is difficult to cut and separate, mounting a plurality of chips separated and separated is wasteful and there is a problem that costs increase.
[0006]
The present invention has been made in view of such a situation, and semiconductor light-emitting that can increase the brightness by increasing the chip area even in a semiconductor light-emitting device in which a semiconductor layer having a large series resistance is used because the action of the dopant is not sufficient. An object is to provide an element.
[0007]
[Means for Solving the Problems]
A semiconductor light emitting device according to the present invention includes a rectangular substrate, a light emitting layer forming portion in which a first conductive type layer and a second conductive type layer are laminated on the substrate to form a light emitting layer, and an upper layer of the light emitting layer forming portion. A light emitting element chip comprising a first conductive type layer provided on the side and an electrode electrically connected to a second conductive type layer provided on a lower layer side of the light emitting layer forming portion, and the light emitting element The first conductivity type layer is divided into four by a cruciform groove passing through substantially the center of the chip, and the second conductivity type layer is continuously formed, and the light emitting layer forming portion is formed substantially at the center of the light emitting element. A second electrode is formed on the second conductivity type layer exposed by being partially removed by etching, and electrically connected to each of the four first conductivity type layers ; and the first electrode is formed from the center to the farthest corners, Ru structure der capable of uniformly emitting a single luminescent color as the body.
[0008]
By doing so, even when the chip area is large and current diffusion is difficult to be performed sufficiently, since a plurality of electrodes are provided, current flows through the entire light emitting layer forming portion, and the entire chip area is uniform. It emits light, and the luminance is improved in the same way as a plurality of chips are connected in parallel. Moreover, since it is a single chip, it is very easy to assemble.
[0009]
Another embodiment of the semiconductor light emitting device of the present invention includes a rectangular substrate, a light emitting layer forming portion in which a first conductive type layer and a second conductive type layer are stacked on the substrate to form a light emitting layer, and the light emitting layer A light emitting element chip comprising a first conductivity type layer provided on the upper layer side of the formation part and an electrode provided in electrical connection with the second conductivity type layer provided on the lower layer side of the light emitting layer formation part; The first conductivity type layer is divided into four by a cross-shaped groove passing through substantially the center of the light emitting element chip, and the second conductivity type layer is continuously formed, and the entire periphery of the light emitting element chip is formed. A second electrode is formed on the second conductive type layer, which is exposed by removing a part of the light emitting layer forming portion by etching, and electrically connected to each of the four divided first conductive type layers. Connected and the first electrode at the corner closest to the center Is formed, Ru structure der capable of uniformly emitting a single luminescent color as a whole.
In addition, it is preferable that the first electrodes provided to be electrically connected to the four divided first conductivity type layers are formed so as to be independently connected to a power source. By doing so, it is possible to supply a voltage independently for each electrode, and even if the light emitting layer forming portion is not divided for each corresponding electrode, current does not concentrate at a place where the resistance is small. , It emits light uniformly throughout and tends to improve brightness.
[0010]
Here, a plurality of electrodes provided independently means that they are not connected by wiring or the like in a chip state, and may be connected in parallel by wire bonding or the like.
[0011]
If the light emitting layer forming portion is made of a gallium nitride compound semiconductor and the first conductivity type layer is a p-type layer, a plurality of p-side electrodes are provided. It becomes easy to pass an electric current through the whole p-type layer of a compound semiconductor, and contributes to high-intensity light emission .
[0012]
Here, the gallium nitride compound semiconductor is a compound in which a group III element Ga and a group V element N or a part of the group III element Ga is substituted with another group III element such as Al or In, and A semiconductor composed of a compound in which a part of N of the group V element is substituted with another group V element such as P or As.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Next, the semiconductor light emitting device of the present invention will be described with reference to the drawings. FIG. 1 is a perspective explanatory view of a one-chip state of an embodiment of a semiconductor light emitting device of the present invention in which a gallium nitride compound semiconductor layer suitable for blue light emission is stacked on a sapphire substrate. Yes.
[0014]
As shown in FIG. 1, the semiconductor light emitting device of the present invention includes a first conductivity type layer (p-type layer) 5 and a second conductivity type layer on a substrate 1 made of sapphire (Al 2 O 3 single crystal), for example. The (n-type layer) 3 is laminated to form a light-emitting layer, the light-emitting layer forming part 10, the first conductivity type layer (p-type layer) 5 and the second conductivity-type layer (n-type layer) of the light-emitting layer forming part 10 LED chip is formed from electrodes (p-side electrode 8 and n-side electrode 9) that are electrically connected to 3 respectively. A plurality of p-side electrodes 8 (first electrodes) connected to at least the p-type layer 5 of the electrode are provided so as to be connected to different locations of the p-type layer 5, and the light emitting layer forming portion 10 is divided into blocks corresponding to the plurality of p-side electrodes 8 provided. The plurality of electrodes 8 may be connected by wiring via an insulating film or the like.
[0015]
Here, being electrically connected to the first conductivity type layer or the second conductivity type layer is not limited to the case where electrodes are directly provided on the first conductivity type layer or the second conductivity type layer, but is shown in FIG. Thus, an electrode is provided through the current diffusion layer 7 made of a thin metal layer, or another semiconductor layer having the same conductivity type (for example, a p-type window layer (not shown) provided on the p-type layer 5). Or a buffer layer (not shown) provided on the n-type layer 3 side or a substrate made of a conductive substrate) is provided above and below the light emitting layer forming portion and provided via the semiconductor layer. Meaning.
[0016]
In the example shown in FIG. 1, the length of one side of one chip is, for example, about 720 μm, which is about twice as large as that of a normal blue LED chip (about four times in area), and the light emitting layer forming portion 10 Is divided into four blocks 11, 12, 13, and 14 by etching up to the n-type layer 3. The four blocks 11 to 14 are connected by the substrate 1 and the n-type layer 3 to form one chip as a whole. A p-side electrode 8 is provided on the p-type layer 5 of each block via a current diffusion layer 7 made of a thin metal film, and the light emitting layer extends over four blocks at the center of the LED chip. The formation portion 10 is etched to expose the n-type layer 3, and the n-side electrode 9 is formed on the exposed n-type layer 3. That is, one n-side electrode 9 is provided in common to the four blocks, and the p-side electrode 8 is provided in each of the four blocks 11 to 14. Note that the current diffusion layer 7 may not be provided, and the p-side electrode 8 of each block may be connected by a wiring through an insulating film.
[0017]
The light emitting layer forming unit 10 is a stacked layer of a compound semiconductor, for example, a low-temperature buffer layer made of GaN, n-type GaN and / or AlGaN-based (which means that the ratio of Al and Ga can be changed variously). An n-type layer 3 having a structure, a material having a band gap energy smaller than that of the cladding layer, for example, an active layer 4 made of an InGaN-based compound semiconductor, and a p-type made of a p-type AlGaN-based compound semiconductor layer and / or a GaN layer. A shape layer (cladding layer) 5 is formed by sequentially laminating on a substrate 1 made of sapphire (Al 2 O 3 single crystal) or the like.
[0018]
In order to manufacture this semiconductor light emitting device, the reaction gas and the necessary dopant gas are introduced by, for example, metal organic chemical vapor deposition (MOCVD method), the n-type layer 3 is about 1 to 5 μm, and the active layer 4 is 0 Epitaxial growth of about 0.05 to 0.3 μm and the p-type layer 5 of about 0.2 to 1 μm are performed. Next, Ni and Au are deposited and sintered to form the current diffusion layer 7 made of a metal layer or the like with a thickness of about 2 to 100 nm.
[0019]
Thereafter, a resist film or the like is provided on the surface of the current diffusion layer 7 for patterning, and the current diffusion layer 7 and a part of the laminated semiconductor layers 3 to 5 (light emitting layer forming portion 10) are etched and shown in FIG. As shown, the n-type layer 3 is exposed so that the center part of the LED chip and the peripheral edge part of the chip and, for example, a cross groove for dividing into four blocks are formed. This etching can be performed by reactive ion etching using chlorine gas or the like. The peripheral portion is etched for facilitating breaks to the respective chips, and the central portion is etched for providing the n-side electrode 9. On the surface of the n-type layer 3 exposed at the center, metal Ti and Al for forming the n-side electrode 9 are formed by vacuum deposition or the like by about 0.1 μm and 0.3 μm, respectively, and sintered. Further, the upper electrode 8 and the lower electrode 9 are formed by removing a part of a protective film such as SiN (not shown) for the p-side electrode 8 and laminating Ti and Au by vacuum deposition.
[0020]
According to the present invention, even when the dopant hardly acts on the semiconductor layer and the resistance is large, a plurality of electrodes connected to the semiconductor layer side are provided in one chip, and the light emitting layer forming portion 10 is also the electrode 8. It is easy to spread the current over the entire chip. That is, for example, in a blue semiconductor light emitting device using a gallium nitride compound semiconductor, the action of the dopant is particularly weak in the p-type layer, and the carrier concentration cannot be sufficiently increased. However, the current cannot be sufficiently diffused because it cannot be formed thick in order to suppress the absorption of light. However, by providing a plurality of electrodes of the present invention, the entire LED chip is efficient. Current can be diffused. In addition, since the light emitting layer forming part 10 is also divided, the current is likely to spread over the whole as in the case where small chips are assembled. On the other hand, in the n-type layer, since the dopant is relatively easy to enter and is easy to increase in thickness, the resistance of the semiconductor layer is not a problem, and n connected to the n-type layer as shown in FIG. By using one side electrode 9 in one chip, the electrode area can be saved, and the surface area can be used more efficiently than gathering separate LED chips. As a result, the entire chip can emit light uniformly, and the luminance can be increased by increasing the chip area.
[0021]
Note that all or a plurality of p-side electrodes 8 can be connected to the power supply side, or can be connected independently to separate power supplies. If connected to a separate power source, even if any of the blocks of the light emitting layer has a low resistance, the current does not concentrate there, and the light emission is made more uniform and the luminance is improved.
[0022]
In the example shown in FIG. 1, the light emitting layer forming portion 10 is divided for each block where the p-side electrode 8 is provided, and the n-side electrode 9 is provided at the center of the LED chip. With this configuration, it is convenient to allow a current to flow uniformly over the entire surface of the LED chip while forming the n-side electrode 9 with a small area. However, as shown in FIG. A side electrode 9 may be provided. As described above, since the n-type layer 3 is exposed at the peripheral portion of the LED chip so as to facilitate break to the chip, the n-side electrode 9 can be obtained by slightly widening the width. The n-side electrode 9 can be formed without substantially reducing the surface area. In this case, since it is easier for the current to spread when the n-side electrode 9 and the p-side electrode 8 are provided so as to correspond to each block at a position apart from each other, the p-side electrode 8 is an LED as shown in FIG. It is preferable to be provided for each divided block at the center of the chip. In this case as well, as described above, even when the chip area is increased, current is not partially concentrated, and uniform and high-luminance light emission can be achieved. In addition, the same code | symbol is attached | subjected to the same part as FIG. 1, and the description is abbreviate | omitted.
[0023]
In the example shown in FIGS. 1 and 2, a plurality of p-side electrodes are provided, and the light emitting layer forming portion 10 is divided according to the p side electrodes. However, as shown in FIG. 10 is not divided, and a plurality of electrodes may be provided interspersed via the surface of the laminated semiconductor layer or the current diffusion layer. With this structure, another electrode is provided in a portion where it is difficult for the current to flow away from the electrode, and the current can flow evenly in a wide chip. Furthermore, by applying a voltage separately without connecting each of the p-side electrodes in parallel, even if a part of the semiconductor layer has a low resistance, current does not concentrate on that part, and the entire part is within the chip. A current can be passed over. In FIG. 3, the same parts as those in FIGS.
[0024]
In each of the above examples, a gallium nitride compound semiconductor is used as the light emitting layer forming portion of the semiconductor layer. However, the gallium nitride compound semiconductor has a large effect because the resistance of the semiconductor layer is large. However, the present invention can also be applied to a semiconductor light emitting device using other semiconductor layers. Further, although the active layer is sandwiched between the n-type layer and the p-type layer as the light emitting layer forming portion, a pn junction structure in which the n-type layer and the p-type layer are directly joined may be used. .
[0025]
【The invention's effect】
According to the present invention, by providing a plurality of electrodes, current can be sufficiently diffused, so that the chip area can be increased and a light-emitting element with high luminance can be obtained.
[Brief description of the drawings]
FIG. 1 is an explanatory perspective view of one embodiment of a semiconductor light emitting device of the present invention.
FIG. 2 is an explanatory perspective view showing a modification of the semiconductor light emitting device of FIG. 1;
FIG. 3 is a perspective explanatory view of another embodiment of the semiconductor light emitting device of the present invention.
FIG. 4 is a perspective explanatory view of an example of a conventional semiconductor light emitting element.
[Explanation of symbols]
1 substrate 3 n-type layer 5 p-type layer 8 p-side electrode 9 n-side electrode 10 light emitting layer forming part

Claims (4)

四角形状の基板と、該基板上に第１導電形層および第２導電形層が積層され発光層を形成する発光層形成部と、該発光層形成部の上層側に設けられる第１導電形層および前記発光層形成部の下層側に設けられる第２導電形層にそれぞれ電気的に接続して設けられる電極とからなる発光素子チップを有し、前記発光素子チップのほぼ中心部を通る十字状溝により前記第１導電形層が４分割されると共に、前記第２導電形層が連続して形成され、前記発光素子のほぼ中心部で前記発光層形成部の一部がエッチングにより除去されて露出する前記第２導電形層上に第２の電極が形成され、前記４分割された第１導電形層のそれぞれと電気的に接続して、かつ、前記中心部から一番遠い角部に第１の電極が形成され、全体として１つの発光色で均一に発光し得る構造である半導体発光素子。 A rectangular substrate, a light emitting layer forming part in which a first conductive type layer and a second conductive type layer are laminated on the substrate to form a light emitting layer, and a first conductive type provided on the upper layer side of the light emitting layer forming part And a cross that passes through substantially the center of the light emitting element chip. The light emitting element chip includes a layer and an electrode that is electrically connected to a second conductivity type layer provided on a lower layer side of the light emitting layer forming portion. The first conductivity type layer is divided into four by the groove, and the second conductivity type layer is continuously formed. A part of the light emitting layer forming portion is removed by etching at substantially the center of the light emitting element. The second electrode is formed on the second conductivity type layer exposed in this manner, and is electrically connected to each of the four divided first conductivity type layers and is the farthest corner from the central portion. a first electrode is formed, as a whole uniformly in one emission color in Structure der Ru semiconductor light emitting element capable of light. 四角形状の基板と、該基板上に第１導電形層および第２導電形層が積層され発光層を形成する発光層形成部と、該発光層形成部の上層側に設けられる第１導電形層および前記発光層形成部の下層側に設けられる第２導電形層にそれぞれ電気的に接続して設けられる電極とからなる発光素子チップを有し、前記発光素子チップのほぼ中心部を通る十字状溝により前記第１導電形層が４分割されると共に、前記第２導電形層が連続して形成され、前記発光素子チップの周縁部の全周に前記発光層形成部の一部がエッチングにより除去されて露出する前記第２導電形層上に第２の電極が形成され、前記４分割された第１導電形層のそれぞれと電気的に接続して、かつ、前記中心部に一番近い角部に第１の電極が形成され、全体として１つの発光色で均一に発光し得る構造である半導体発光素子。 A rectangular substrate, a light emitting layer forming part in which a first conductive type layer and a second conductive type layer are laminated on the substrate to form a light emitting layer, and a first conductive type provided on the upper layer side of the light emitting layer forming part And a cross that passes through substantially the center of the light emitting element chip. The light emitting element chip includes a layer and an electrode that is electrically connected to a second conductivity type layer provided on a lower layer side of the light emitting layer forming portion. The first conductivity type layer is divided into four by a groove, and the second conductivity type layer is continuously formed. A part of the light emitting layer forming portion is etched all around the periphery of the light emitting element chip. A second electrode is formed on the second conductivity type layer that is removed and exposed by the step, is electrically connected to each of the four first conductivity type layers , and is most at the center. is a first electrode formed near the corners, one emission color as a whole The semiconductor light emitting device Ru structure der capable of emitting one. 前記発光層形成部がチッ化ガリウム系化合物半導体からなり、前記第１導電形層がｐ形層である請求項１または２記載の半導体発光素子。  3. The semiconductor light emitting element according to claim 1, wherein the light emitting layer forming portion is made of a gallium nitride compound semiconductor, and the first conductivity type layer is a p-type layer. 前記４分割された第１導電形層に電気的に接続して設けられる第１の電極が、それぞれ独立して電源に接続し得るように形成されてなる請求項１、２または３記載の半導体発光素子。 4. The first electrode according to claim 1 , 2, or 3, wherein the first electrode provided to be electrically connected to the four divided first conductivity type layers is formed so as to be independently connected to a power source . Semiconductor light emitting device.
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