JP2001185755A - Semiconductor light emitting element - Google Patents
Semiconductor light emitting elementInfo
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- JP2001185755A JP2001185755A JP36772699A JP36772699A JP2001185755A JP 2001185755 A JP2001185755 A JP 2001185755A JP 36772699 A JP36772699 A JP 36772699A JP 36772699 A JP36772699 A JP 36772699A JP 2001185755 A JP2001185755 A JP 2001185755A
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- Prior art keywords
- layer
- semiconductor
- light emitting
- light
- active layer
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、半導体層が積層さ
れて発光層を形成する発光層形成部の表面側に光を取り
出す構造の半導体発光素子に関する。さらに詳しくは、
側面方向に光を取り出しやすくし、全体として発光する
光の外部への取出し効率（外部微分量子効率）を向上さ
せ得る構造の半導体発光素子に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting device having a structure in which a semiconductor layer is stacked to form a light emitting layer and a light is emitted to a surface side of a light emitting layer forming portion. For more information,
The present invention relates to a semiconductor light emitting device having a structure capable of easily taking out light in a lateral direction and improving the efficiency of taking out emitted light as a whole (external differential quantum efficiency).
【０００２】[0002]
【従来の技術】従来の可視光半導体発光素子は、たとえ
ば図５に示されるような構造になっている。すなわち、
図５において、ｎ形ＧａＡｓからなる半導体基板２１上
に、たとえばｎ形のＩｎＧａＡｌＰ系の半導体材料から
なるｎ形クラッド層２２、クラッド層よりバンドギャッ
プエネルギーが小さくなる組成のＩｎＧａＡｌＰ系の半
導体材料からなる活性層２３、ｎ形クラッド層と同じ組
成でｐ形のＩｎＧａＡｌＰ系の半導体材料からなるｐ形
クラッド層２４がそれぞれエピタキシャル成長され、ダ
ブルヘテロ構造の発光層形成部２９が形成されている。
さらにその表面にＡｌＧａＡｓ系化合物半導体からなる
ｐ形のウインドウ層（電流拡散層）２５が設けられてい
る。そして、その表面の中央部にＧａＡｓからなるコン
タクト層２６を介して上部（ｐ側）電極２７および半導
体基板の裏面に下部（ｎ側）電極２８が形成されてい
る。2. Description of the Related Art A conventional visible light semiconductor light emitting device has a structure as shown in FIG. That is,
In FIG. 5, an n-type cladding layer 22 made of, for example, an n-type InGaAlP-based semiconductor material, and an InGaAlP-based semiconductor material having a composition whose band gap energy is smaller than that of the cladding layer are formed on a semiconductor substrate 21 made of n-type GaAs. A p-type cladding layer 24 made of a p-type InGaAlP-based semiconductor material having the same composition as the active layer 23 and the n-type cladding layer is epitaxially grown, thereby forming a light emitting layer forming portion 29 having a double hetero structure.
Further, a p-type window layer (current diffusion layer) 25 made of an AlGaAs-based compound semiconductor is provided on the surface. An upper (p-side) electrode 27 is formed at the center of the surface via a contact layer 26 made of GaAs, and a lower (n-side) electrode 28 is formed on the back surface of the semiconductor substrate.
【０００３】この構造の半導体発光素子で、たとえば活
性層２３のＰ点で発光した光は、四方に放射（半導体基
板側にも進むが、半導体基板２１のＧａＡｓは光を吸収
して表面側に取り出すことが困難であるため図示してな
い）され、電極以外の表面およびウインドウ層２５の側
面から外部に取り出される。しかし、半導体層の屈折率
は３.５程度であり、空気の屈折率は１、ランプ型にす
る場合など周囲を透明樹脂で被覆する場合でも、樹脂の
屈折率は１.５程度であり、界面での入射角が小さくな
いと図５に示されるように、全反射をしてＬＥＤチップ
の内部を全反射しながら吸収などにより減衰してしま
う。In a semiconductor light emitting device having this structure, for example, light emitted at the point P of the active layer 23 is radiated in all directions (goes to the semiconductor substrate side, but GaAs of the semiconductor substrate 21 absorbs light and emits light toward the surface side). It is not shown because it is difficult to take out), and is taken out from the surface other than the electrodes and the side surface of the window layer 25 to the outside. However, the refractive index of the semiconductor layer is about 3.5, the refractive index of air is 1, and the refractive index of the resin is about 1.5 even when the surroundings are covered with a transparent resin such as a lamp type. If the angle of incidence at the interface is not small, as shown in FIG. 5, the light is totally reflected and totally reflected inside the LED chip and attenuated by absorption or the like.
【０００４】[0004]
【発明が解決しようとする課題】前述のように、半導体
層とその外周の空気または透明樹脂などとの屈折率の差
により、発光層で発光した光がチップの上面または側面
で全反射する割合が高い。一方、クラッド層や活性層な
どは完全な透明体ではなく、発光層で発光した光を吸収
し、また、半導体基板やコンタクト層などに用いられる
ＧａＡｓは、発光層で発光する光を吸収する材料である
ため、全反射を繰り返すうちに吸収されて減衰する。そ
のため、外部に取り出すことができる光の割合が小さく
なり、外部微分量子効率が向上しないという問題があ
る。As described above, the rate at which light emitted from the light emitting layer is totally reflected on the upper surface or side surface of the chip is determined by the difference in the refractive index between the semiconductor layer and the air or transparent resin around the semiconductor layer. Is high. On the other hand, the cladding layer and the active layer are not completely transparent and absorb light emitted from the light emitting layer, and GaAs used for the semiconductor substrate and the contact layer is a material that absorbs light emitted from the light emitting layer. Therefore, it is absorbed and attenuated while repeating total reflection. Therefore, there is a problem that the ratio of light that can be extracted to the outside is reduced, and the external differential quantum efficiency is not improved.
【０００５】本発明は、このような問題を解決するため
になされたもので、発光層で発光した光をチップの外側
にできるだけ取り出せる構造とし、外部微分量子効率を
向上させるこができる半導体発光素子を提供することを
目的とする。The present invention has been made to solve such a problem, and has a structure in which light emitted from a light-emitting layer can be extracted to the outside of a chip as much as possible, thereby improving the external differential quantum efficiency. The purpose is to provide.
【０００６】[0006]
【課題を解決するための手段】本発明者らは、発光した
光を外に有効に取り出すことができない原因を鋭意検討
を重ねて調べた結果、発光層（活性層）で発光する光は
四方に均一に放射されるが、とくに電流が集中して流れ
電流密度が大きいチップの中心部で発光する光は、真上
に行く光が上部電極で遮られ、コンタクト層で吸収され
たり、反射しても再度半導体基板側に反射して吸収され
てしまい、斜め方向に進む光は、上面または側面に大き
な入射角で入射して全反射し、有効に取り出せないこと
に原因があることを見出した。そして、上面から側面に
かけての界面（チップの外壁）を傾斜面とすることによ
り、斜め方向に進んできた光に対して入射角を小さく
し、全反射させないで外に取り出すことができることを
見出した。Means for Solving the Problems The inventors of the present invention have conducted intensive studies on the reason why the emitted light cannot be effectively extracted outside, and as a result, the light emitted from the light emitting layer (active layer) has four sides. The light emitted at the center of the chip, where the current is concentrated and the current density is high, is blocked by the upper electrode, and the light that is emitted directly above is blocked by the upper electrode and absorbed or reflected by the contact layer. However, it was found that light reflected and absorbed again on the semiconductor substrate side, and light traveling in an oblique direction was incident on the upper surface or side surface at a large incident angle, was totally reflected, and could not be effectively extracted. . And, by making the interface from the top surface to the side surface (the outer wall of the chip) an inclined surface, it is possible to reduce the incident angle with respect to the light traveling in an oblique direction and to take out the light without total reflection. .
【０００７】本発明による半導体発光素子は、半導体基
板と、該半導体基板の上に設けられ、少なくともｎ形層
およびｐ形層により活性層を挟持する発光層形成部を有
する半導体積層部と、該半導体積層部の表面側に設けら
れる上部電極と、前記半導体基板の裏面側に設けられる
下部電極とからなり、前記半導体積層部の前記活性層よ
り上層部に前記上部電極側の幅が狭く、前記活性層側で
幅が広くなるように側面に傾斜面が形成されている。A semiconductor light emitting device according to the present invention comprises a semiconductor substrate, a semiconductor laminated portion provided on the semiconductor substrate and having a light emitting layer forming portion sandwiching an active layer by at least an n-type layer and a p-type layer; An upper electrode provided on the front surface side of the semiconductor laminated portion, and a lower electrode provided on the back surface side of the semiconductor substrate, wherein the width of the upper electrode side is narrower in an upper layer portion than the active layer of the semiconductor laminated portion, An inclined surface is formed on the side surface so as to increase the width on the active layer side.
【０００８】この構造にすることにより、半導体積層部
の上部電極が設けられた部分以外の上表面および側面が
傾斜面となるため、斜めに表面側に向かってきた光も全
反射することなく外側に出やすい。また、ウインドウ層
（半導体積層部の上層部）の側面側に向かった光も、側
面が内側に傾斜しているため、チップの外部との境界面
では、その入射角が小さくなり、全反射しないで外部に
でやすくなる。その結果、外部への光の取り出し効率が
向上し、外部微分量子効率を向上させることができる。With this structure, the upper surface and side surfaces of the semiconductor laminated portion other than the portion where the upper electrode is provided become inclined surfaces. It is easy to come out. Also, the light directed toward the side surface of the window layer (the upper layer portion of the semiconductor laminated portion) has a small incident angle at the boundary surface with the outside of the chip because the side surface is inclined inward, and is not totally reflected. It is easy to go outside. As a result, the efficiency of extracting light to the outside is improved, and the external differential quantum efficiency can be improved.
【０００９】前記傾斜面が、外側が凸面となる傾斜面で
あれば、より一層チップ内部での入射角が小さくなり、
外側へ光を取り出しやすくなる。If the inclined surface is an inclined surface having a convex outer surface, the angle of incidence inside the chip is further reduced,
It becomes easier to extract light to the outside.
【００１０】前記半導体積層部の表面側が、ＡｌＧａＡ
ｓ系化合物半導体層からなり、表面側ほどＡｌの混晶比
が小さくなるように組成が変化する層であれば、Ｇａを
エッチングしやすいエッチャントを用いることにより、
Ａｌの混晶比の小さい上層部はエッチングされやすく、
Ａｌの混晶比の大きい下層はエッチングされにくいた
め、容易に傾斜面を作りやすい。この場合、Ａｌの組成
比の変化を直線的に変化させることもできるが、上部を
凸とする放物線状に変化させれば、エッチングのみで外
側が凸面となる傾斜面とすることができる。[0010] The surface side of the semiconductor laminated portion is made of AlGaAs.
If the layer is made of an s-based compound semiconductor layer and changes in composition so that the Al mixed crystal ratio becomes smaller toward the surface side, by using an etchant that can easily etch Ga,
The upper layer having a small Al mixed crystal ratio is easily etched,
Since the lower layer having a large Al mixed crystal ratio is difficult to be etched, it is easy to easily form an inclined surface. In this case, the change in the Al composition ratio can be changed linearly. However, if the change is made in a parabolic shape having a convex upper portion, the inclined surface having a convex outer surface can be formed only by etching.
【００１１】[0011]
【発明の実施の形態】つぎに、本発明による半導体発光
素子について、図面を参照しながら説明をする。本発明
による半導体発光素子は、図１にその一実施形態の断面
説明図が示されるように、半導体基板１の上に、少なく
ともｎ形層３およびｐ形層５により活性層４を挟持する
発光層形成部１１を有する半導体積層部１２が設けられ
ている。また、半導体積層部１２の表面側に上部電極
（ｐ側電極）８が設けられ、半導体基板１の裏面側に下
部電極（ｎ側電極）９が設けられている。そして、半導
体積層部１２の活性層４より上層部に上部電極８側の幅
が狭く、活性層４側で幅が広くなるように側面に傾斜面
が形成されていることに特徴がある。Next, a semiconductor light emitting device according to the present invention will be described with reference to the drawings. A semiconductor light emitting device according to the present invention has a light emitting structure in which an active layer 4 is sandwiched between a semiconductor substrate 1 and at least an n-type layer 3 and a p-type layer 5 as shown in FIG. A semiconductor lamination portion 12 having a layer formation portion 11 is provided. An upper electrode (p-side electrode) 8 is provided on the front surface side of the semiconductor laminated portion 12, and a lower electrode (n-side electrode) 9 is provided on the back surface side of the semiconductor substrate 1. The semiconductor lamination portion 12 is characterized in that the upper surface of the upper layer 8 is narrower in the upper layer portion than the active layer 4, and the side surface is formed with an inclined surface such that the width is wider on the active layer 4 side.
【００１２】発光層形成部１１は、たとえばＩｎ
0.49（Ｇａ1-xＡｌx）0.51Ｐ（０.６≦ｘ≦０.８、たと
えばｘ＝０.６７）からなるｎ形クラッド層３が０.１〜
２μｍ程度、たとえば５８７ｎｍ程度の発光波長とする
Ｉｎ0.49（Ｇａ1-yＡｌy）0.51Ｐ（０.２≦ｙ≦０.３、
たとえばｙ＝０.２６）からなる活性層４が０.１〜２μ
ｍ程度、Ｉｎ0.49（Ｇａ1-xＡｌx）0.51Ｐ（０.６≦ｘ
≦０.８、たとえばｘ＝０.６７）からなるｐ形クラッド
層５が０.１〜２μｍ程度それぞれ成長されて形成され
ている。なお、発光層形成部を構成する半導体層は、Ｉ
ｎＧａＡｌＰ系化合物半導体に限らず、ＡｌＧａＡｓ系
化合物半導体など、他の発光色の半導体層を用いること
ができる。The light emitting layer forming portion 11 is formed of, for example, In.
The n-type cladding layer 3 made of 0.49 (Ga 1-x Al x ) 0.51 P (0.6 ≦ x ≦ 0.8, for example, x = 0.67) has a thickness of 0.1 to 0.1.
About 2 [mu] m, e.g. In 0.49 (Ga 1-y Al y) 0.51 P (0.2 ≦ y ≦ 0.3 for the emission wavelength of about 587 nm,
For example, the active layer 4 made of y = 0.26) is 0.1 to 2 μm.
m, In 0.49 (Ga 1-x Al x ) 0.51 P (0.6 ≦ x
.Ltoreq.0.8 (for example, x = 0.67). The p-type cladding layer 5 is formed by growing about 0.1 to 2 .mu.m. Note that the semiconductor layer forming the light emitting layer forming portion is I
Not only the nGaAlP-based compound semiconductor but also a semiconductor layer of another emission color such as an AlGaAs-based compound semiconductor can be used.
【００１３】この発光層形成部１１の表面に、ＡｌzＧ
ａ1-zＡｓ（０.５≦ｚ≦０.８）からなるウインドウ層
６が１〜１０μｍ程度設けられている。また、ウインド
ウ層６の表面には、上部電極８の下側のみにＧａＡｓな
どからなるコンタクト層７が設けられ、これらにより半
導体積層部１２が形成されている。The surface of the light emitting layer forming portion 11 has Al z G
A window layer 6 made of a 1-z As (0.5 ≦ z ≦ 0.8) is provided in a thickness of about 1 to 10 μm. Further, on the surface of the window layer 6, a contact layer 7 made of GaAs or the like is provided only on the lower side of the upper electrode 8, thereby forming a semiconductor laminated portion 12.
【００１４】本発明の半導体発光素子においては、この
半導体積層部１２の活性層４より上層、たとえばウイン
ドウ層６の側面が、半導体基板１の面に対して垂直方向
ではなく、上部電極８側で幅が狭く、活性層４側で幅が
広くなるように傾斜面に形成されている。図１に示され
る例では、たとえばピラミッド形状の４角錐の上部が上
部電極８部分で底面に平行に切り取られた形状になって
おり、たとえばウインドウ層６の厚さＡが６μｍ程度
で、上部電極８からチップ側面までの距離Ｂが約５０μ
ｍ程度（チップの一辺が２００μｍ程度で、上部電極８
の一辺が１００μｍ程度）であり、傾斜角θは、約７°
程度になる。しかし、ウインドウ層をもっと厚くすれば
傾斜角も大きくすることができ、６０°以下程度であれ
ば、外部への光の取り出し効率を向上することができ
た。In the semiconductor light emitting device of the present invention, the upper side of the active layer 4 of the semiconductor laminated portion 12, for example, the side surface of the window layer 6 is not perpendicular to the surface of the semiconductor substrate 1 but on the upper electrode 8 side. It is formed on the inclined surface so that the width is narrow and the width is wide on the active layer 4 side. In the example shown in FIG. 1, for example, the upper part of a pyramid-shaped quadrangular pyramid is cut in parallel with the bottom surface at the upper electrode 8. For example, when the thickness A of the window layer 6 is about 6 μm, The distance B from 8 to the side of the chip is about 50μ
m (one side of the chip is about 200 μm, and the upper electrode 8
Is about 100 μm), and the inclination angle θ is about 7 °.
About. However, if the thickness of the window layer is further increased, the inclination angle can be increased, and if it is about 60 ° or less, the efficiency of extracting light to the outside can be improved.
【００１５】このような傾斜面を形成するには、たとえ
ば半導体積層部１２を形成し、その上に上部電極８を形
成してコンタクト層７をパターニングした後に、ウェハ
の状態で、図２に示されるように、チップの境界部に開
口部１６ａを形成したホトレジスト膜１６を設け、その
開口部１６ａから露出するウインドウ層６を、たとえば
昭和電工（株）商品名ショウポリッシュによりエッチン
グすることにより、表面側がオーバーエッチングされて
図２に示されるように凹部１７が形成される。この凹部
１７の中心部でダイシングすることにより、チップの側
面に傾斜面が形成されたＬＥＤチップが得られる。この
傾斜面の形成法としては、このようなエッチングによら
なくても、機械的研磨などの方法によっても形成するこ
とができる。In order to form such an inclined surface, for example, a semiconductor laminated portion 12 is formed, an upper electrode 8 is formed thereon, and a contact layer 7 is patterned. A photoresist film 16 having an opening 16a formed at the boundary of the chip is provided, and the window layer 6 exposed from the opening 16a is etched by, for example, Show polish (trade name, Showa Denko KK) to obtain a surface. The side is over-etched to form a recess 17 as shown in FIG. By dicing at the center of the concave portion 17, an LED chip having an inclined surface formed on the side surface of the chip is obtained. The inclined surface may be formed by a method such as mechanical polishing without using such etching.
【００１６】また、エッチングにより形成するにして
も、とくに前述のエッチャントは、Ｇａをよくエッチン
グするため、ウインドウ層として、前述のＡｌzＧａ1-z
Ａｓを使用し、Ａｌの組成を表面側にいくにしたがって
減らすことにより、表面側ほどよくエッチングされ、傾
斜面を形成しやすい。このウインドウ層６のＡｌの組成
を順次減らすには、図３（ａ）に示されるように、ウイ
ンドウ層の下面から上面に直線状にまたは階段状（図示
せず）に減らすこともできるし、図３（ｂ）に示される
ように、放物線状に減らすこともできる。この組成を変
化させるには、後述するＭＯＣＶＤ法により行う場合、
導入ガスの流量を変化させることにより、容易に変化さ
せることができる。In addition, even if the etchant is formed by etching, the above-described etchant is used as a window layer so that the above-mentioned Al z Ga 1 -z
By using As and decreasing the composition of Al toward the surface side, the surface side is etched better and an inclined surface is easily formed. In order to sequentially reduce the Al composition of the window layer 6, as shown in FIG. 3A, it can be reduced linearly or stepwise (not shown) from the lower surface to the upper surface of the window layer. As shown in FIG. 3B, it can be reduced to a parabolic shape. In order to change this composition, when the MOCVD method described below is used,
It can be easily changed by changing the flow rate of the introduced gas.
【００１７】このような放物線状にＡｌの組成を減らす
ことにより、エッチングスピードが放物線状に変化し、
図４にウインドウ層６部の断面説明図が示されるよう
に、側面の傾斜面が外側に凸の形状となる。このような
外側に凸の形状になるように傾斜面を形成すると、活性
層４で発光して斜め上方に向かう光はチップの境界面で
は凹面をなす界面に入射するため、より一層入射角が小
さくなり、全反射することなく光が透過しやすくなる。
その結果、より一層光の取り出し効率が向上して好まし
い。By reducing the composition of Al in such a parabolic manner, the etching speed changes in a parabolic manner,
As shown in the cross-sectional explanatory view of the window layer 6 in FIG. 4, the inclined surface on the side surface has a shape convex outward. When the inclined surface is formed so as to have such a convex shape on the outside, light emitted from the active layer 4 and directed obliquely upward enters the concave interface at the boundary surface of the chip, so that the incident angle is further increased. It becomes smaller, and light is easily transmitted without total reflection.
As a result, the light extraction efficiency is further improved, which is preferable.
【００１８】上部（ｐ側）電極８は、たとえばＡｕ-Ｂ
ｅ／Ｎｉ／Ｔｉ／Ａｕなどを全面に設けた後にパターニ
ングすることにより形成されてもよいし、電極が設けら
れる部分以外にマスクを設けて、全面に電極材料を被膜
してからマスクを除去するリフトオフ法により形成され
てもよい。また、ＧａＡｓからなる半導体基板１の裏面
には、全面にＡｕ-Ｇｅ／Ｎｉ／Ａｕなどが０.２〜０.
４μｍ程度の厚さに設けられ、ｎ側電極９が形成されて
いる。The upper (p-side) electrode 8 is made of, for example, Au-B
It may be formed by patterning after providing e / Ni / Ti / Au or the like on the entire surface, or by providing a mask other than the portion where the electrode is provided, coating the electrode material on the entire surface, and then removing the mask. It may be formed by a lift-off method. Au-Ge / Ni / Au or the like is entirely on the back surface of the GaAs semiconductor substrate 1 in a thickness of 0.2 to 0.2 mm.
The n-side electrode 9 is formed with a thickness of about 4 μm.
【００１９】本発明の半導体発光素子によれば、ウイン
ドウ層の上面および側面が繋がった傾斜面になっている
ため、たとえば図１（ｂ）に一部の発光経路が示される
ように、活性層４の発光部Ｐで発光し、斜め方向に進ん
だ光は、上面や側面に大きな入射角で入射しないで、傾
斜面に直接小さな入射角で入射する。すなわち、半導体
層の屈折率は、３.３〜３.７程度で、その外部に透明な
エポキシ樹脂が設けらる場合、その屈折率は１.５〜１.
５５程度であり、臨界角は３０°程度になる。すなわ
ち、入射角が３０°程度以下であれば全反射することな
くウインドウ層の界面から光が外に取り出されるが、そ
れより大きな入射角で入射すると全反射をする。しか
し、本発明によれば、斜め方向に向かう光に対して、傾
斜面が対向するため、入射角が小さくなり、光が外に出
やすくなる。According to the semiconductor light emitting device of the present invention, since the upper surface and the side surface of the window layer are inclined surfaces, for example, as shown in FIG. The light emitted from the light emitting portion P of No. 4 and traveling in an oblique direction does not enter the upper surface or the side surface at a large incident angle, but directly enters the inclined surface at a small incident angle. That is, the refractive index of the semiconductor layer is about 3.3 to 3.7, and when a transparent epoxy resin is provided outside, the refractive index is 1.5 to 1.5.
The critical angle is about 30 °. That is, when the incident angle is about 30 ° or less, light is extracted from the interface of the window layer to the outside without total reflection. However, when the incident angle is larger than that, the light is totally reflected. However, according to the present invention, since the inclined surface is opposed to the light traveling in the oblique direction, the incident angle is reduced, and the light is easily emitted outside.
【００２０】さらに、本発明では、上部電極を挟んで両
外側に傾斜面が形成されているため、傾斜面が互いに近
づくか遠ざかる方向で対向し、平行に向き合わない構造
になる。そのため、たとえ全反射をしても対向する傾斜
面では光が出やすくなる。その結果、チップ内部で何回
も全反射を繰り返して中で減衰しないで、効率よく外に
取り出すことができる。Further, in the present invention, since the inclined surfaces are formed on both outer sides with the upper electrode interposed therebetween, the inclined surfaces face each other in a direction approaching or moving away from each other, and do not face each other in parallel. Therefore, even if total reflection is performed, light is likely to be emitted from the inclined surfaces facing each other. As a result, it is possible to take out the light efficiently without repeatedly attenuating the total reflection many times inside the chip.
【００２１】また、前述のように傾斜面が外側に凸にな
るように形成されることにより、より一層傾斜面に対す
る入射角が小さくなり、光の取り出し効率が向上する。
このような傾斜面を簡単に形成するのに、たとえばＡｌ
ＧａＡｓ系化合物半導体のＡｌ組成など、その組成を変
化させることにより、選択的にエッチングをすることが
でき、組成の変化に応じた形状の傾斜面を形成すること
ができる。また、前述のＡｌＧａＡｓ系化合物半導体の
Ａｌ比率を表面側で少なくすることにより、腐食しやす
いＡｌの露出が少なくなり、保護層の機能も果たし、よ
り一層効果が大きい。とくに放物線状にＡｌの比率が小
さくなることにより、Ａｌの比率が小さくなると発光す
る光を吸収しやすくなるが、その層が非常に薄いため、
吸収の影響も殆どなくなる。Further, by forming the inclined surface so as to be convex outward as described above, the incident angle on the inclined surface is further reduced, and the light extraction efficiency is improved.
To easily form such an inclined surface, for example, Al
By changing the composition such as the Al composition of the GaAs-based compound semiconductor, selective etching can be performed, and an inclined surface having a shape corresponding to the change in the composition can be formed. Further, by reducing the Al ratio of the AlGaAs-based compound semiconductor on the surface side, exposure of easily corrodible Al is reduced, and the function of the protective layer is also achieved, so that the effect is further enhanced. In particular, when the ratio of Al is reduced in a parabolic manner, it becomes easier to absorb light emitted when the ratio of Al is reduced, but since the layer is very thin,
The effect of absorption is almost eliminated.
【００２２】この半導体発光素子を製造するには、たと
えばｎ形ＧａＡｓ基板１をＭＯＣＶＤ（有機金属化学気
相成長）装置内に入れ、反応ガスのトリエチルガリウム
（ＴＥＧ）またはトリメチルガリウム（ＴＭＧ）、アル
シン（ＡｓＨ3）、トリメチルアルミニウム（ＴＭ
Ａ）、トリメチルインジウム（ＴＭＩｎ）、ｎ形ドーパ
ントとしてのＨ2Ｓｅ、ｐ形層形成の場合はｐ形ドーパ
ントとしてのジメチル亜鉛（ＤＭＺｎ）の必要なガスを
それぞれ導入し、図１（ａ）に示されるように、Ｉｎ
0.49（Ｇａ0.3Ａｌ0.7）0.51Ｐからなるｎ形クラッド層
３を０.１〜２μｍ程度、ノンドープのＩｎ0.49（Ｇａ
0.75Ａｌ0.25）0.51Ｐからなる活性層４を０.１〜２μ
ｍ程度、Ｉｎ0.49（Ｇａ0.3Ａｌ0.7）0.51Ｐからなるｐ
形クラッド層５を０.１〜２μｍ程度、たとえばＡｌ0.7
Ｇａ0.3Ａｓからなるｐ形ウインドウ層６を１〜１０μ
ｍ程度、ＧａＡｓからなるコンタクト層７を０.２〜１
μｍ程度それぞれ連続的に成長する。In order to manufacture this semiconductor light emitting device, for example, an n-type GaAs substrate 1 is placed in a MOCVD (metal organic chemical vapor deposition) apparatus, and a reaction gas of triethylgallium (TEG) or trimethylgallium (TMG) or arsine is used. (AsH 3 ), trimethylaluminum (TM
A), trimethylindium (TMIn), H 2 Se as an n-type dopant, and dimethylzinc (DMZn) as a p-type dopant in the case of forming a p-type layer are introduced, respectively. As shown, In
An n-type cladding layer 3 made of 0.49 (Ga 0.3 Al 0.7 ) 0.51 P is formed to a thickness of about 0.1 to 2 μm, and the undoped In 0.49 (Ga
The active layer 4 made of 0.75 Al 0.25 ) 0.51 P is 0.1 μm to 2 μm.
m, p of In 0.49 (Ga 0.3 Al 0.7 ) 0.51 P
The shape of the cladding layer 5 is about 0.1 to 2 μm, for example, Al 0.7
The p-type window layer 6 made of Ga 0.3 As
The contact layer 7 made of GaAs is about 0.2 to 1 m.
Each of them grows continuously by about μm.
【００２３】その後、Ａｕ-Ｂｅ／Ｎｉ／Ｔｉ／Ａｕな
どをリフトオフ法、マスク蒸着、または全面に成膜した
後にホトリソグラフィ法によるパターニングにより、上
部（ｐ側）電極８を形成し、さらに半導体基板１の裏面
にＡｕ-Ｇｅ／Ｎｉ／Ａｕなどを全面に設けて下部（ｎ
側）電極９を形成する。その後、半導体積層部１２の表
面に上部電極８部を覆ってレジスト膜を設け、チップ境
界面に開口部を設ける。この開口部の大きさは、たとえ
ば前述のウインドウ層６の厚さＡが６μｍ程度で、横の
長さが５０μｍ程度、ウインドウ層６のＡｌzＧａ1-zＡ
ｓのｚを下面から上面まで、たとえば０.７から０.５程
度に変化させる場合、幅が３０μｍ程度の開口部を設け
ると良好な傾斜面が得られる。その後、エッチングによ
る凹部の底面でチップ化することにより図１（ａ）に示
されるＬＥＤチップが得られる。After that, an upper (p-side) electrode 8 is formed by a lift-off method, mask evaporation, or film formation on the entire surface after Au-Be / Ni / Ti / Au or the like is formed by photolithography. 1 is provided on the entire back surface with Au-Ge / Ni / Au or the like, and the lower portion (n
Side) An electrode 9 is formed. Thereafter, a resist film is provided on the surface of the semiconductor laminated portion 12 so as to cover the upper electrode 8 and an opening is provided at the chip boundary surface. The size of this opening is, for example, that the above-mentioned window layer 6 has a thickness A of about 6 μm, a horizontal length of about 50 μm, and Al z Ga 1 -z A of the window layer 6.
In the case where z of s is changed from the lower surface to the upper surface, for example, from about 0.7 to 0.5, a good inclined surface can be obtained by providing an opening having a width of about 30 μm. Then, the LED chip shown in FIG. 1A is obtained by forming a chip on the bottom surface of the concave portion by etching.
【００２４】[0024]
【発明の効果】本発明の半導体発光素子によれば、発光
部から斜め方向に進む光に対して、チップの壁面（半導
体積層部上層のたとえばウインドウ層の壁面）が傾斜面
により対向しているため、斜め方向に進んできた光をそ
のまま外に取り出すことができ、結果的に非常に外部微
分量子効率が向上する。しかも、斜め方向に進んできた
光を殆どそのまま透過させるため、チップから外に出た
光も四方に進みやすく、横方向の輝度が向上し、広い面
積を照射する用途に適し、たとえば液晶表示装置のバッ
クライトのように面全体を照射する光源に適する。その
結果、明るい液晶表示装置用のバックライトが得られ
る。According to the semiconductor light emitting device of the present invention, the wall surface of the chip (the wall surface of the upper layer of the semiconductor laminated portion, for example, the window layer) is opposed to the light traveling obliquely from the light emitting portion by the inclined surface. Therefore, the light traveling in the oblique direction can be extracted to the outside as it is, and as a result, the external differential quantum efficiency is greatly improved. In addition, since the light that has proceeded in the oblique direction is transmitted as it is, light that has exited the chip can easily travel in all directions, improving the brightness in the horizontal direction and suitable for applications that irradiate a wide area. For example, a liquid crystal display device It is suitable for a light source that illuminates the entire surface like a backlight. As a result, a bright backlight for a liquid crystal display device is obtained.
【図１】本発明の一実施形態であるＬＥＤチップの断面
説明図である。FIG. 1 is an explanatory cross-sectional view of an LED chip according to an embodiment of the present invention.
【図２】図１のＬＥＤチップの傾斜面を形成する工程の
断面説明図である。FIG. 2 is an explanatory sectional view of a step of forming an inclined surface of the LED chip of FIG. 1;
【図３】図１のＬＥＤチップの傾斜面を作るのに適した
ウインドウ層の組成の変化の例を示す図である。FIG. 3 is a diagram showing an example of a change in composition of a window layer suitable for forming an inclined surface of the LED chip of FIG. 1;
【図４】本発明による半導体発光素子における傾斜面の
他の構造例を示す図である。FIG. 4 is a diagram showing another example of the structure of the inclined surface in the semiconductor light emitting device according to the present invention.
【図５】従来のＬＥＤチップの構造例を示す断面説明図
である。FIG. 5 is an explanatory cross-sectional view showing a structural example of a conventional LED chip.
【符号の説明】 １ 半導体基板 ３ ｎ形クラッド層 ４ 活性層 ５ ｐ形クラッド層 ６ ウインドウ層 ８ 上部電極 ９ 下部電極 １１ 発光層形成部 １２ 半導体積層部DESCRIPTION OF SYMBOLS 1 semiconductor substrate 3 n-type cladding layer 4 active layer 5 p-type cladding layer 6 window layer 8 upper electrode 9 lower electrode 11 light emitting layer forming part 12 semiconductor laminating part
Claims (3)
られ、少なくともｎ形層およびｐ形層により活性層を挟
持する発光層形成部を有する半導体積層部と、該半導体
積層部の表面側に設けられる上部電極と、前記半導体基
板の裏面側に設けられる下部電極とからなり、前記半導
体積層部の前記活性層より上層部に前記上部電極側の幅
が狭く、前記活性層側で幅が広くなるように側面に傾斜
面が形成されてなる半導体発光素子。1. A semiconductor laminated portion provided on a semiconductor substrate, having a light emitting layer forming portion sandwiching an active layer by at least an n-type layer and a p-type layer, and a front surface side of the semiconductor laminated portion. And a lower electrode provided on the back side of the semiconductor substrate, wherein the width of the upper electrode side is narrower above the active layer of the semiconductor laminated portion, and the width is smaller on the active layer side. A semiconductor light emitting device in which an inclined surface is formed on a side surface so as to be wide.
である請求項１記載の半導体発光素子。2. The semiconductor light emitting device according to claim 1, wherein said inclined surface is an inclined surface having a convex outer surface.
Ａｓ系化合物半導体層からなり、表面側ほどＡｌの混晶
比が小さくなるように組成が変化する層である請求項１
または２記載の半導体発光素子。3. The method according to claim 1, wherein the surface side of the semiconductor laminated portion is formed of AlGa.
2. A layer comprising an As-based compound semiconductor layer, the composition of which changes so that the mixed crystal ratio of Al decreases toward the surface.
Or the semiconductor light emitting device according to 2.
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|---|---|---|---|
| JP36772699A JP4773597B2 (en) | 1999-12-24 | 1999-12-24 | Semiconductor light emitting device |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP36772699A JP4773597B2 (en) | 1999-12-24 | 1999-12-24 | Semiconductor light emitting device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2001185755A true JP2001185755A (en) | 2001-07-06 |
| JP4773597B2 JP4773597B2 (en) | 2011-09-14 |
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ID=18490045
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|---|---|---|---|
| JP36772699A Expired - Fee Related JP4773597B2 (en) | 1999-12-24 | 1999-12-24 | Semiconductor light emitting device |
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|---|---|---|---|---|
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| CN100463242C (en) * | 2007-03-08 | 2009-02-18 | 鹤山丽得电子实业有限公司 | Manufacturing method for enlarging lighting area of LED |
| JP2009177212A (en) * | 2009-05-11 | 2009-08-06 | Sanyo Electric Co Ltd | Light emitting element and method for manufacturing the same |
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| JP2004214531A (en) * | 2003-01-08 | 2004-07-29 | Toyoda Gosei Co Ltd | Light emitting diode and led light |
| JP2005252086A (en) * | 2004-03-05 | 2005-09-15 | Sony Corp | Manufacturing method for semiconductor light emitting device, semiconductor light emitting device, integrated semiconductor light emitting device, manufacturing process thereof, graphic display device, manufacturing process thereof, illuminating device and manufacturing process thereof |
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| US9209223B2 (en) | 2005-06-22 | 2015-12-08 | Seoul Viosys Co., Ltd. | Light emitting device and method of manufacturing the same |
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