JP2006066903A - Positive electrode for semiconductor light-emitting element - Google Patents

Positive electrode for semiconductor light-emitting element Download PDF

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JP2006066903A
JP2006066903A JP2005219266A JP2005219266A JP2006066903A JP 2006066903 A JP2006066903 A JP 2006066903A JP 2005219266 A JP2005219266 A JP 2005219266A JP 2005219266 A JP2005219266 A JP 2005219266A JP 2006066903 A JP2006066903 A JP 2006066903A
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layer
positive electrode
semiconductor light
emitting element
electrode
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JP2006066903A5 (en
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Hisayuki Miki
久幸 三木
Noritaka Muraki
典孝 村木
Munetaka Watanabe
宗隆 渡邉
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Resonac Holdings Corp
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Showa Denko KK
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive electrode for a face-up type semiconductor light-emitting element with a low driving voltage and high light luminous intensity. <P>SOLUTION: This positive electrode for the semiconductor light-emitting element is composed of a translucent electrode formed on a semiconductor layer and a bonding pad electrode formed on the translucent electrode. The bonding pad electrode has a reflective layer at least on a surface where the bonding pad electrode touches the translucent electrode. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は半導体発光素子用正極に関し、特に窒化ガリウム系化合物半導体発光素子に適した、低い駆動電圧で強い発光を得ることができる半導体発光素子用透光性正極に関する。   The present invention relates to a positive electrode for a semiconductor light emitting device, and more particularly to a translucent positive electrode for a semiconductor light emitting device, which is suitable for a gallium nitride compound semiconductor light emitting device and can obtain strong light emission at a low driving voltage.

近年、短波長光発光素子用の半導体材料としてＧａＮ系化合物半導体材料が注目を集めている。ＧａＮ系化合物半導体は、サファイア単結晶を始めとして、種々の酸化物やＩＩＩ−Ｖ族化合物を基板として、その上に有機金属気相化学反応法（ＭＯＣＶＤ法）や分子線エピタキシー法（ＭＢＥ法）等によって形成される。   In recent years, GaN-based compound semiconductor materials have attracted attention as semiconductor materials for short wavelength light emitting devices. GaN-based compound semiconductors include sapphire single crystals, various oxides and III-V compounds as substrates, and metalorganic vapor phase chemical reaction method (MOCVD method) or molecular beam epitaxy method (MBE method). And so on.

ＧａＮ系化合物半導体材料の特性として、横方向への電流拡散が小さいことがある。原因は、エピタキシャル結晶中に多く存在する基板から表面へ貫通する転位の存在であることが考えられるが、詳しいことは判っていない。さらに、ｐ型のＧａＮ系化合物半導体においてはｎ型のＧａＮ系化合物半導体の抵抗率に比べて抵抗率が高くその表面に金属を積層しただけではｐ型層内の横の電流の広がりはほとんど無く、ｐｎ接合を持ったＬＥＤ構造とした場合正極の直下しか発光しない。   A characteristic of the GaN-based compound semiconductor material is that current diffusion in the lateral direction is small. The cause is thought to be the presence of dislocations penetrating from the substrate present in the epitaxial crystal to the surface, but the details are not known. Furthermore, the p-type GaN-based compound semiconductor has a higher resistivity than the n-type GaN-based compound semiconductor, and there is almost no spread of lateral current in the p-type layer by simply laminating metal on the surface. In the case of an LED structure having a pn junction, light is emitted only directly below the positive electrode.

このため、正極の直下で発生した発光を、正極を通して外部に取り出す、透光性の正極が用いられることが多い。特に市場で用いられている技術として、正極としてｐ型層上にＮｉとＡｕを各々数１０ｎｍ程度積層させた後、酸素雰囲気下で加熱して合金化処理を行い、ｐ型層の低抵抗化の促進および透光性とオーミック性を有した正極の形成を同時に行なうことが提案されている（特許文献１参照）。   For this reason, a translucent positive electrode is often used that emits light emitted directly under the positive electrode through the positive electrode. In particular, as a technology used in the market, Ni and Au are stacked on the p-type layer as a positive electrode about several tens of nanometers each, and then heated in an oxygen atmosphere for alloying treatment to reduce the resistance of the p-type layer. It has been proposed to simultaneously promote the formation of a positive electrode having translucency and ohmic properties (see Patent Document 1).

透光性の電極のための材料としては、導電性の金属酸化物や極薄く形成した金属などがある。これらの材料および構造は直接ボンディングすることが困難であるため、ある程度の厚みを持ったボンディング用のパッド電極を、透光性の電極に電気的に接続させるように配置することが一般的である。しかしながら、このパッド電極はある程度の厚みを持った金属材料であるため、透光性がなく、パッド電極直下で発生した発光は外部に取り出せないという欠点があった。   Examples of the material for the light-transmitting electrode include a conductive metal oxide and an extremely thin metal. Since these materials and structures are difficult to bond directly, it is common to arrange a bonding pad electrode having a certain thickness so as to be electrically connected to a light-transmitting electrode. . However, since this pad electrode is a metal material having a certain thickness, there is a disadvantage that the pad electrode is not translucent and light emitted directly under the pad electrode cannot be extracted outside.

また、パッド電極の密着性を向上させるため、透光性電極の一部に切り欠きを作り、この部分及び隣接する透光性電極上にまたがるパッド電極を形成する事により、直接ＧａＮ半導体層に接する部分でボンディング強度を得ると共に透光性電極上に接する部分で電流拡散を行う構造が公開されている。（特許文献２参照）   In addition, in order to improve the adhesion of the pad electrode, a notch is formed in a part of the translucent electrode, and a pad electrode extending over this part and the adjacent translucent electrode is formed, so that the GaN semiconductor layer is directly formed. A structure has been disclosed in which bonding strength is obtained at the contacting portion and current diffusion is performed at the contacting portion on the translucent electrode. (See Patent Document 2)

また、パッド電極の直下で発生した発光が外部に取り出せないことから、電流を効率的に利用するために、これまではパッド電極直下には電流を注入せず、パッド電極直下では光を発生させないという方向の技術が考案されてきた。   In addition, since the light emitted immediately below the pad electrode cannot be extracted to the outside, in order to efficiently use the current, no current has been injected immediately below the pad electrode and no light has been generated immediately below the pad electrode. Technology in the direction has been devised.

例えば、パッド電極の下に絶縁領域を作製し、パッド下に電流を注入しないことにより効率的に発光を得ることができるとする技術が公開されている（特許文献３、４参照）。また、パッド電極の最下面をｐ型層に対して接触比抵抗の高い金属で形成することにより、この領域に電流を注入しないようにする技術も公開されている（特許文献５参照）。   For example, a technique is disclosed in which an insulating region is formed under a pad electrode and light can be efficiently obtained by not injecting current under the pad (see Patent Documents 3 and 4). In addition, a technique for preventing current from being injected into this region by forming the lowermost surface of the pad electrode with a metal having a high contact specific resistance with respect to the p-type layer has been disclosed (see Patent Document 5).

しかし我々の検討によれば、これらの手法を用いると正極がｐ型層に対してオーミック接触する面積が減少するため、駆動電圧が上昇するという欠点がある。   However, according to our study, when these methods are used, the area in which the positive electrode is in ohmic contact with the p-type layer is reduced, so that the drive voltage is increased.

特許第２８０３７４２号公報Japanese Patent No. 2803742 特開平７−９４７８２号公報Japanese Patent Laid-Open No. 7-94782 特開平８−２５０７６８号公報JP-A-8-250768 特開平８−２５０７６９号公報JP-A-8-250769 特開平１０−２４２５１６号公報JP-A-10-242516

本発明の目的は、上述の問題点を解決する為に、低い駆動電圧で強い発光を得ることのできるフェイスアップ型チップ用の透光性正極を提供することである。本発明において透光性とは、発光波長領域における光に対して透光性であることを意味する。窒化ガリウム系化合物半導体発光素子の場合、通常、発光波長領域は３００〜６００ｎｍの範囲内にある。   An object of the present invention is to provide a translucent positive electrode for a face-up chip capable of obtaining strong light emission with a low driving voltage in order to solve the above-mentioned problems. In the present invention, translucency means translucency with respect to light in the emission wavelength region. In the case of a gallium nitride-based compound semiconductor light emitting device, the emission wavelength region is usually in the range of 300 to 600 nm.

本発明は、以下の発明を提供する。
（１）半導体層上に形成された透光性電極および該透光性電極上に形成されたボンディングパッド電極からなり、該ボンディングパッド電極が少なくとも透光性電極と接する面に反射層を有することを特徴とする半導体発光素子用の正極。 The present invention provides the following inventions.
(1) It consists of a translucent electrode formed on a semiconductor layer and a bonding pad electrode formed on the translucent electrode, and the bonding pad electrode has a reflective layer at least on a surface in contact with the translucent electrode. A positive electrode for a semiconductor light emitting device.

（２）反射層と透光性電極との密着強度が、剥離強度で４９０ｍＮ（５０ｇｆ）以上である上記１項に記載の半導体発光素子用の正極。 (2) The positive electrode for a semiconductor light-emitting element according to the above item 1, wherein the adhesion strength between the reflective layer and the translucent electrode is 490 mN (50 gf) or more in terms of peel strength.

（３）透光性電極の、素子が発光する発光波長における光の透過率が６０％以上である上記１または２項に記載の半導体発光素子用の正極。 (3) The positive electrode for a semiconductor light-emitting element according to the above item 1 or 2, wherein the translucent electrode has a light transmittance of 60% or more at an emission wavelength at which the element emits light.

（４）反射層がＡｌ、Ａｇ、Ｐｔ族金属およびこれらの金属の少くとも一種を含む合金からなる群より選ばれた金属からなる上記１〜３項のいずれか一項に記載の半導体発光素子用の正極。 (4) The semiconductor light-emitting device according to any one of the above items 1 to 3, wherein the reflective layer is made of a metal selected from the group consisting of Al, Ag, Pt group metals and alloys containing at least one of these metals. Positive electrode.

（５）半導体発光素子が窒化ガリウム系化合物半導体発光素子である上記１〜４項のいずれか一項に記載の半導体発光素子用の正極。 (5) The positive electrode for a semiconductor light-emitting device according to any one of 1 to 4 above, wherein the semiconductor light-emitting device is a gallium nitride-based compound semiconductor light-emitting device.

（６）反射層がＡｌ、Ａｇ、Ｐｔ、およびこれらの金属の少なくとも一種を含む合金からなる群より選ばれた金属である上記１〜５項のいずれか一項に記載の半導体発光素子用の正極。 (6) The semiconductor light-emitting element according to any one of 1 to 5 above, wherein the reflective layer is a metal selected from the group consisting of Al, Ag, Pt, and an alloy containing at least one of these metals. Positive electrode.

（７）反射層の厚さが２０〜３０００ｎｍである上記１〜６項のいずれか一項に記載の半導体発光素子用の正極。 (7) The positive electrode for a semiconductor light-emitting element according to any one of the above items 1 to 6, wherein the reflective layer has a thickness of 20 to 3000 nm.

（８）ボンディングパッド電極が層状構造であり、反射層に加えて、Ｔｉ、ＣｒもしくはＡｌからなるバリア層、および／またはＡｕもしくはＡｌからなる最上層を有する上記１〜７項のいずれか一項に記載の半導体発光素子用の正極。 (8) The bonding pad electrode according to any one of the above items 1 to 7, wherein the bonding pad electrode has a layered structure and has a barrier layer made of Ti, Cr or Al and / or an uppermost layer made of Au or Al in addition to the reflective layer. The positive electrode for semiconductor light emitting elements as described in any one of.

（９）透光性電極のボンディングパッド電極側が金属からなる層である上記１〜８項のいずれか一項に記載の半導体発光素子用の正極。 (9) The positive electrode for a semiconductor light-emitting element according to any one of (1) to (8), wherein the bonding pad electrode side of the translucent electrode is a layer made of metal.

（１０）透光性電極のボンディングパッド電極側が透明材料からなる層である上記１〜８項のいずれか一項に記載の半導体発光素子用の正極。 (10) The positive electrode for a semiconductor light-emitting element according to any one of (1) to (8), wherein the bonding pad electrode side of the translucent electrode is a layer made of a transparent material.

（１１）透光性電極が、金属以外の透明材料のみからなる上記１０項に記載の半導体発光素子用の正極。 (11) The positive electrode for a semiconductor light-emitting element according to the above item 10, wherein the translucent electrode is made of only a transparent material other than metal.

（１２）透光性電極の最表面層に光を取り出すための加工が施されている上記１〜１１項のいずれか一項に記載の半導体発光素子用の正極。 (12) The positive electrode for a semiconductor light-emitting element according to any one of (1) to (11), wherein a process for extracting light is performed on the outermost surface layer of the translucent electrode.

（１３）透光性電極の最表面層が透明材料である上記１２項に記載の半導体発光素子用の正極。 (13) The positive electrode for a semiconductor light-emitting element according to the above item 12, wherein the outermost surface layer of the translucent electrode is a transparent material.

（１４）透光性電極がｐ型半導体層に接するコンタクト層および該コンタクト層上の電流拡散層を有する上記１〜１３項のいずれか一項に記載の半導体発光素子用の正極。 (14) The positive electrode for a semiconductor light-emitting element according to any one of (1) to (13), wherein the translucent electrode has a contact layer in contact with the p-type semiconductor layer and a current diffusion layer on the contact layer.

（１５）コンタクト層が白金族金属またはその合金である上記１４項に記載の半導体発光素子用の正極。 (15) The positive electrode for a semiconductor light-emitting element according to the above item 14, wherein the contact layer is a platinum group metal or an alloy thereof.

（１６）コンタクト層が白金である上記１５項に記載の半導体発光素子用の正極。
（１７）コンタクト層の厚さが０．１〜７．５ｎｍである上記１４〜１６項のいずれか一項に記載の半導体発光素子用の正極。 (16) The positive electrode for a semiconductor light emitting device as described in 15 above, wherein the contact layer is platinum.
(17) The positive electrode for a semiconductor light-emitting element according to any one of the above 14 to 16, wherein the contact layer has a thickness of 0.1 to 7.5 nm.

（１８）コンタクト層の厚さが０．５〜２．５ｎｍである上記１７項に記載の半導体発光素子用の正極。 (18) The positive electrode for a semiconductor light-emitting element according to the above item 17, wherein the contact layer has a thickness of 0.5 to 2.5 nm.

（１９）電流拡散層が金、銀および銅からなる群から選ばれた金属または少なくともそれらの一種を含む合金である上記１４〜１８項のいずれか一項に記載の半導体発光素子用の正極。 (19) The positive electrode for a semiconductor light-emitting element according to any one of the above items 14 to 18, wherein the current diffusion layer is a metal selected from the group consisting of gold, silver and copper or an alloy containing at least one of them.

（２０）電流拡散層が金または金合金である上記１９項に記載の半導体発光素子用の正極。
（２１）電流拡散層の厚さが１〜２０ｎｍである上記１４〜２０項のいずれか一項に記載の半導体発光素子用の正極。 (20) The positive electrode for a semiconductor light-emitting element according to the above item 19, wherein the current diffusion layer is gold or a gold alloy.
(21) The positive electrode for a semiconductor light-emitting element according to any one of the above 14 to 20, wherein the current diffusion layer has a thickness of 1 to 20 nm.

（２２）電流拡散層の厚さが３〜６ｎｍである上記２１項に記載の半導体発光素子用の正極。 (22) The positive electrode for a semiconductor light-emitting element according to the above item 21, wherein the current diffusion layer has a thickness of 3 to 6 nm.

（２３）電流拡散層が導電性の透明材料である上記１４〜１８項のいずれか一項に記載の半導体発光素子用の正極。 (23) The positive electrode for a semiconductor light-emitting element according to any one of the above items 14 to 18, wherein the current diffusion layer is a conductive transparent material.

（２４）透明材料がＩＴＯ、酸化亜鉛、酸化アルミニウム亜鉛、フッ素ドープ酸化錫、酸化チタン、硫化亜鉛、酸化ビスマスおよび酸化マグネシウムからなる群から選ばれた少なくとも１種類である上記１０、１１、１３および２３のいずれか一項に記載の半導体発光素子用の正極。 (24) The above 10, 11, 13, wherein the transparent material is at least one selected from the group consisting of ITO, zinc oxide, aluminum zinc oxide, fluorine-doped tin oxide, titanium oxide, zinc sulfide, bismuth oxide and magnesium oxide; 24. The positive electrode for a semiconductor light-emitting element according to any one of 23.

（２５）透明材料がＩＴＯ、酸化亜鉛、酸化アルミニウム亜鉛およびフッ素ドープ酸化錫
からなる群から選ばれた少なくとも１種類である上記２４項に記載の半導体発光素子用の正極。 (25) The positive electrode for a semiconductor light-emitting element according to the above item 24, wherein the transparent material is at least one selected from the group consisting of ITO, zinc oxide, aluminum zinc oxide and fluorine-doped tin oxide.

（２６）透明材料の厚さが１０〜５０００ｎｍである上記１０、１１、１３および２３〜２５項のいずれか一項に記載の半導体発光素子用の正極。 (26) The positive electrode for a semiconductor light-emitting element according to any one of the above 10, 11, 13, and 23 to 25, wherein the transparent material has a thickness of 10 to 5000 nm.

（２７）透明材料の厚さが１００〜１０００ｎｍである上記２６項に記載の半導体発光素子用の正極。
（２８）上記１〜２７項のいずれか一項に記載の正極を用いた半導体発光素子。 (27) The positive electrode for a semiconductor light-emitting element according to the above item 26, wherein the transparent material has a thickness of 100 to 1000 nm.
(28) A semiconductor light-emitting device using the positive electrode according to any one of items 1 to 27.

（２９）基板上に窒化ガリウム系化合物半導体からなる、ｎ型半導体層、発光層およびｐ型半導体層をこの順序で有し、ｐ型半導体層およびｎ型半導体層に正極および負極がそれぞれ設けられた発光素子において、正極が上記１〜２７項のいずれか一項に記載の正極である窒化ガリウム系化合物半導体発光素子。
（３０）上記２８または２９項に記載の発光素子を用いてなるランプ。 (29) An n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer made of a gallium nitride compound semiconductor are provided in this order on a substrate, and a positive electrode and a negative electrode are provided on the p-type semiconductor layer and the n-type semiconductor layer, respectively. 28. A gallium nitride-based compound semiconductor light-emitting element, wherein the positive electrode is the positive electrode according to any one of 1 to 27 above.
(30) A lamp comprising the light emitting device as described in 28 or 29 above.

透光性電極に電流を流すためのボンディングパッド電極の少なくとも透光性電極と接する面に反射層を設けることにより、ボンディングパッド電極と透光性電極と接する面での光の吸収による光の減衰の程度を下げることができ、発光した光の取り出しの効率を上げ、発光強度を高めることができる。   Attenuation of light due to absorption of light at the surface in contact with the bonding pad electrode and the translucent electrode by providing a reflective layer on at least the surface in contact with the translucent electrode of the bonding pad electrode for passing a current through the translucent electrode The efficiency of extracting emitted light can be increased, and the emission intensity can be increased.

図１は、本発明の正極を有する発光素子の一例の断面を示した模式図である。１０が本発明の正極であり、透光性電極（１１）およびボンディングパッド電極（１３）から構成される。透光性電極（１１）は、例えばコンタクト層（１１１）および電流拡散層（１１２）から構成されている。ボンディングパッド電極（１３）は、例えば反射層（１３１）、バリア層（１３２）および最上層（１３３）の３層構造からなる。１は基板である。２はＧａＮ系化合物半導体層であり、ｎ型半導体層３、発光層４およびｐ型半導体層５から構成される。６はバッファ層であり、２０は負極である。   FIG. 1 is a schematic view showing a cross section of an example of a light emitting device having a positive electrode of the present invention. Reference numeral 10 denotes a positive electrode according to the present invention, which includes a translucent electrode (11) and a bonding pad electrode (13). The translucent electrode (11) is composed of, for example, a contact layer (111) and a current diffusion layer (112). The bonding pad electrode (13) has, for example, a three-layer structure of a reflective layer (131), a barrier layer (132), and an uppermost layer (133). Reference numeral 1 denotes a substrate. Reference numeral 2 denotes a GaN-based compound semiconductor layer, which includes an n-type semiconductor layer 3, a light emitting layer 4, and a p-type semiconductor layer 5. 6 is a buffer layer, and 20 is a negative electrode.

透光性正極を備えたフェイスアップ型チップでは、発光層（４）で発光した光の内、ボンディングパッド電極が存在しない透光性電極部に向かった光およびチップの側面に向かった光のみが外部に取り出される。   In the face-up type chip provided with the translucent positive electrode, only the light emitted from the light emitting layer (4) toward the translucent electrode portion where the bonding pad electrode does not exist and the light directed toward the side surface of the chip. Take out to the outside.

本発明の正極を用いると、ボンディングパッド電極（１３）に向かった光は、ボンディングパッド電極最下面（透光性電極と接する面）の反射層（１３１）で反射され、一部は散乱されて横方向あるいは斜め方向に進み、一部はボンディングパッド電極の直下に進む。散乱されて横方向や斜め方向に進んだ光は、チップの側面から外部に取り出される。一方、ボンディングパッド電極の直下の方向に進んだ光は、チップの下面でさらに散乱や反射されて、側面や透光性電極（上にボンディングパッド電極が存在しない部分）を通じて外部へ取り出される。   When the positive electrode of the present invention is used, the light directed to the bonding pad electrode (13) is reflected by the reflective layer (131) on the lowermost surface of the bonding pad electrode (the surface in contact with the translucent electrode), and a part thereof is scattered. Proceeding in the horizontal or diagonal direction, a part proceeds directly under the bonding pad electrode. The light that has been scattered and traveled in the lateral direction or the oblique direction is taken out from the side surface of the chip. On the other hand, the light traveling in the direction immediately below the bonding pad electrode is further scattered and reflected by the lower surface of the chip, and is extracted to the outside through the side surface and the translucent electrode (portion where the bonding pad electrode does not exist).

このように、ボンディングパッド電極最下面に反射層を設けることで、ボンディングパッド電極直下で発生した発光を外部へ取り出すことができ、高い発光強度を保つことができる。ボンディングパッド電極最下面で光の吸収がある場合、パッド電極直下で発生した発光はそのほとんどがパッド電極の最下面で吸収されてしまい、外部に取り出すことができない。   As described above, by providing the reflective layer on the lowermost surface of the bonding pad electrode, light emitted immediately below the bonding pad electrode can be extracted to the outside, and high light emission intensity can be maintained. In the case where light is absorbed at the lowermost surface of the bonding pad electrode, most of the light emitted directly under the pad electrode is absorbed at the lowermost surface of the pad electrode and cannot be extracted outside.

反射層は、透光性電極に直接密着していることが、本発明の効果を顕現するための要件である。このため、ボンディングパッドが充分な強度を得るためには、反射層が透光性電極に対して強固に接着されていることが必要である。最低限、一般的な方法でボンディングパッドに金線を接続する工程で剥離してはならず、そのためには、剥離強度で４９０ｍＮ（５０ｇｆ）程度の強度を持つことが望ましい。さらに望ましくは、７８４ｍＮ（８０ｇｆ）以上であり、９８０ｍＮ（１００ｇｆ）以上であれば尚更望ましい。   It is a requirement for the reflective layer to be in direct contact with the translucent electrode to manifest the effects of the present invention. For this reason, in order for the bonding pad to obtain sufficient strength, it is necessary that the reflective layer is firmly bonded to the translucent electrode. At the very least, it should not be peeled off in the step of connecting the gold wire to the bonding pad by a general method. For that purpose, it is desirable to have a peel strength of about 490 mN (50 gf). More desirably, it is 784 mN (80 gf) or more, and more desirably 980 mN (100 gf) or more.

反射層と透光性電極の密着強度を増強させるためには、透光性電極の表面の前処理を工夫する、反射層の形成後に熱処理を施す、などの方法がある。   In order to enhance the adhesion strength between the reflective layer and the translucent electrode, there are methods such as devising a pretreatment of the surface of the translucent electrode, or performing a heat treatment after the formation of the reflective layer.

反射層の反射率は、反射層を構成する材料によって大きく変わるが、６０％以上であることが望ましい。更には、８０％以上であることが望ましく、９０％以上であればなお良い。   The reflectance of the reflective layer varies greatly depending on the material constituting the reflective layer, but is preferably 60% or more. Further, it is preferably 80% or more, and more preferably 90% or more.

反射率は、分光光度計と呼ばれる装置などで比較的容易に測定することが可能である。しかし、ボンディングパッド電極そのものは面積が小さいために反射率を測定することは難しい。そこで、透明な例えばガラス製の、面積の大きい「ダミー基板」をボンディングパッド電極形成時にチャンバに入れて、同時にダミー基板上に同じボンディングパッド電極を作成して測定するなどの方法を用いて測定することができる。   The reflectance can be measured relatively easily with an apparatus called a spectrophotometer. However, since the bonding pad electrode itself has a small area, it is difficult to measure the reflectance. Therefore, a transparent “dummy substrate” made of glass, for example, having a large area is placed in the chamber when forming the bonding pad electrode, and at the same time, the same bonding pad electrode is created on the dummy substrate and measured. be able to.

ボンディングパッド電極の反射層は、反射率の高い金属で構成することが好ましく、Ｐｔ、Ｒｈ、Ｒｕ、Ｉｒ等の白金族金属、Ａｌ、Ａｇ、およびこれらの金属の少なくも一種を含む合金で構成することがより好ましい。なかでも、Ａｌ、Ａｇ、Ｐｔおよびこれらの金属の少なくも一種を含む合金は、電極用の材料として一般的であり、入手のし易さ、取り扱いの容易さなどの点から、優れている。   The reflective layer of the bonding pad electrode is preferably composed of a highly reflective metal, and is composed of a platinum group metal such as Pt, Rh, Ru, Ir, Al, Ag, and an alloy containing at least one of these metals. More preferably. Among these, Al, Ag, Pt, and alloys containing at least one of these metals are common as electrode materials, and are excellent in terms of easy availability and handling.

ボンディングパッド電極は、透光性電極に切り欠き部、あるいは窓部を形成せずに、透光性電極上に直接形成する。透光性電極上に形成されていることにより、オーミック接触する面積を下げることがなく、またボンディングパッド電極の直下であっても電極の接触抵抗が上がることがないので、駆動電圧の上昇を防ぐことができる。また、透光性電極を透過した光がボンディングパッド電極最下面の反射層で反射されるので光の無駄な吸収を抑えることが可能である。   The bonding pad electrode is formed directly on the translucent electrode without forming a notch or window in the translucent electrode. Since it is formed on the translucent electrode, the ohmic contact area is not reduced, and the contact resistance of the electrode does not increase even immediately under the bonding pad electrode, thereby preventing an increase in driving voltage. be able to. Further, since the light transmitted through the translucent electrode is reflected by the reflective layer on the lowermost surface of the bonding pad electrode, it is possible to suppress unnecessary absorption of light.

ボンディングパッド電極は、透光性電極の上であれば、どこへでも形成することができる。例えば負極から最も遠い位置に形成してもよいし、チップの中心などに形成してもよい。しかし、あまりにも負極に近接した位置に形成すると、ボンディングした際にワイヤ間、ボール間のショートを生じてしまうため好ましくない。   The bonding pad electrode can be formed anywhere as long as it is on the translucent electrode. For example, it may be formed at a position farthest from the negative electrode, or may be formed at the center of the chip. However, if it is formed too close to the negative electrode, it is not preferable because a short circuit between wires and balls occurs during bonding.

また、ボンディングパッド電極面積としては、できるだけ大きいほうがボンディング作業はしやすいものの、発光の取り出しの妨げになる。例えば、チップ面の面積の半分を超えるような面積を覆っては、発光の取り出しの妨げとなり、出力が著しく低下する。逆に小さすぎるとボンディング作業がしにくくなり、製品の収率を低下させる。具体的には、ボンディングボールの直径よりもわずかに大きい程度が好ましく、直径１００μｍの円形程度であることが一般的である。   The bonding pad electrode area is as large as possible, but the bonding operation is easy, but it prevents the light emission from being taken out. For example, covering an area that exceeds half the area of the chip surface hinders the extraction of light emission, and the output is significantly reduced. On the other hand, if it is too small, the bonding work becomes difficult and the yield of the product is lowered. Specifically, it is preferably slightly larger than the diameter of the bonding ball, and generally has a circular shape with a diameter of 100 μm.

ボンディングパッド電極の反射層は、高い反射率を有する金属で形成した場合、厚さが２０〜３０００ｎｍであることが望ましい。反射層が薄すぎると充分な反射の効果が得らない。厚すぎると特に利点は生じず、工程時間の長時間化と材料の無駄を生じるのみである。更に望ましくは、５０〜１０００ｎｍであり、最も望ましいのは１００〜５００ｎｍである。   When the reflective layer of the bonding pad electrode is formed of a metal having a high reflectance, the thickness is desirably 20 to 3000 nm. If the reflective layer is too thin, a sufficient reflection effect cannot be obtained. If it is too thick, there is no particular advantage, and only a long process time and material waste are caused. More desirably, the thickness is 50 to 1000 nm, and most desirably 100 to 500 nm.

ボンディングパッド電極は上述した反射率の高い金属のみで構成することもできる。即ち、ボンディングパッド電極は反射層のみから構成されていてもよい。しかし、ボンディングパッド電極として各種の材料を用いた各種の構造のものが知られており、これら公知のものの半導体層側（透光性電極側）に上述の反射層を新たに設けてもよいし、また、これら公知のものの半導体層側の最下層を上述の反射層に置き換えてもよい。   The bonding pad electrode can be made of only the metal having the high reflectance described above. That is, the bonding pad electrode may be composed only of the reflective layer. However, various structures using various materials are known as bonding pad electrodes, and the above-described reflective layer may be newly provided on the semiconductor layer side (translucent electrode side) of these known materials. Moreover, the lowermost layer on the semiconductor layer side of these known ones may be replaced with the above-described reflective layer.

このような積層構造の場合、反射層より上の積層構造部については、特に制限されることなく、どのような構造でも用いることが出来る。例えば、ボンディングパッド電極の反射層の上に形成される層には、ボンディングパッド電極全体の強度を強化する役割がある。このため、比較的強固な金属材料を使用するか、充分に膜厚を厚くする必要がある。材料として望ましいのは、Ｔｉ、ＣｒまたはＡｌである。中でも、Ｔｉは材料の強度の点で望ましい。このような機能を付与した場合、この層をバリア層と呼ぶ。   In the case of such a laminated structure, the laminated structure portion above the reflective layer is not particularly limited, and any structure can be used. For example, the layer formed on the reflective layer of the bonding pad electrode has a role of enhancing the strength of the entire bonding pad electrode. For this reason, it is necessary to use a relatively strong metal material or to sufficiently increase the film thickness. Desirable materials are Ti, Cr or Al. Among these, Ti is desirable in terms of material strength. When such a function is given, this layer is called a barrier layer.

バリア層は反射層が兼ねても良い。良好な反射率を持ち、機械的にも強固な金属材料を厚く形成した場合には、敢えてバリア層を形成する必要はない。例えば、Ａｌを反射層として使用した場合には、バリア層を形成する必要はない。   The barrier layer may also serve as a reflective layer. When a thick metal material having good reflectivity and mechanically strong is formed, it is not necessary to form a barrier layer. For example, when Al is used as the reflective layer, it is not necessary to form a barrier layer.

バリア層の厚さは２０〜３０００ｎｍであることが望ましい。バリア層が薄すぎると充分な強度強化の効果が得られず、厚すぎても特に利点は生ぜず、コスト増大を招くのみである。更に望ましくは、５０〜１０００ｎｍであり、最も望ましいのは１００〜５００ｎｍである。   The thickness of the barrier layer is preferably 20 to 3000 nm. If the barrier layer is too thin, a sufficient strength strengthening effect cannot be obtained, and if it is too thick, no particular advantage is produced and only an increase in cost is caused. More desirably, the thickness is 50 to 1000 nm, and most desirably 100 to 500 nm.

ボンディングパッド電極の最上層（反射層と反対側）はボンディングボールとの密着性の良い材料とすることが望ましい。ボンディングボールには金を使用することが多く、金ボールとの密着性の良い金属としてはＡｕとＡｌが知られている。中でも、特に望ましいのは金である。この最上層の厚さは５０〜１０００ｎｍが望ましく、更に望ましくは１００〜５００ｎｍである。薄すぎるとボンディングボールとの密着性が悪くなり、厚すぎても特に利点は生ぜず、コスト増大を招くのみである。   The uppermost layer of the bonding pad electrode (on the side opposite to the reflective layer) is preferably made of a material having good adhesion to the bonding ball. Gold is often used for the bonding balls, and Au and Al are known as metals having good adhesion to the gold balls. Of these, gold is particularly desirable. The thickness of the uppermost layer is desirably 50 to 1000 nm, and more desirably 100 to 500 nm. If it is too thin, the adhesion to the bonding ball will be poor, and if it is too thick, no particular advantage will be produced, and only the cost will increase.

半導体層（ｐ型層）上に形成される透光性電極に要求される好ましい性能としては、ｐ型層との接触抵抗が小さいこと、発光層からの光を電極面側より取り出すフェイスアップマウント型の発光素子にあっては優れた光透過性、およびｐ型層全面に亙って均一に電流を分散させるために優れた導電性が挙げられる。   Preferred performances required for the translucent electrode formed on the semiconductor layer (p-type layer) include a low contact resistance with the p-type layer and a face-up mount that extracts light from the light-emitting layer from the electrode surface side. In the case of the type light emitting device, excellent light transmittance and excellent conductivity for uniformly distributing the current over the entire surface of the p-type layer can be mentioned.

透光性電極として各種の材料を用いた各種の構造のものが知られており、本発明においてもこれら公知の透光性電極を何ら制限なく使用できる。しかし、上述の要求性能を満足するためには、ｐ型層と接するコンタクト層および該コンタクト層上にあって電流拡散を補助する電流拡散層の少なくとも２層構造の透光性電極が好ましい。もちろん、上述の要求性能を満足しさえすれば、コンタクト層と電流拡散層の機能を兼ね備えた一層としても良く、一層構造とした場合には工程の煩雑さがないという利点がある。   Various structures using various materials are known as the translucent electrode, and these known translucent electrodes can be used without any limitation in the present invention. However, in order to satisfy the above-mentioned required performance, a translucent electrode having at least two layers of a contact layer in contact with the p-type layer and a current diffusion layer on the contact layer for assisting current diffusion is preferable. Of course, as long as the above-mentioned required performance is satisfied, a single layer having the functions of the contact layer and the current diffusion layer may be provided, and in the case of a single layer structure, there is an advantage that the process is not complicated.

コンタクト層に要求される性能としては、ｐ型層との接触抵抗が小さいことが好ましく、この観点から、コンタクト層の材料は白金（Ｐｔ）、ルテニウム（Ｒｕ）、オスミウム（Ｏｓ）、ロジウム（Ｒｈ）、イリジウム（Ｉｒ）、パラジウム（Ｐｄ）等の白金族金属またはその合金が好ましい。これらの中でもＰｔまたはその合金は、仕事関数が高く、高温熱処理を施していない比較的高抵抗なｐ型ＧａＮ系化合物半導体層に対して非加熱で良好なオーミック接触を得ることが可能なので、特に好ましい。   As the performance required for the contact layer, it is preferable that the contact resistance with the p-type layer is small. From this viewpoint, the material of the contact layer is platinum (Pt), ruthenium (Ru), osmium (Os), rhodium (Rh). ), Platinum group metals such as iridium (Ir) and palladium (Pd) or alloys thereof are preferred. Among these, Pt or an alloy thereof has a high work function and can obtain a good ohmic contact without heating to a relatively high resistance p-type GaN compound semiconductor layer not subjected to high-temperature heat treatment. preferable.

コンタクト層を白金族金属またはその合金で構成した場合、光透過性の観点から、その厚さを非常に薄くすることが必要である。コンタクト層の厚さは、０．１〜７．５ｎｍの範囲が好ましい。０．１ｎｍ未満では安定した薄層が得られ難い。７．５ｎｍを超えると透光性が低下し、５ｎｍ以下がさらに好ましい。また、その後の電流拡散層の積層による透光性の低下と成膜の安定性を考慮すると、０．５〜２．５ｎｍの範囲が特に好ましい。   When the contact layer is composed of a platinum group metal or an alloy thereof, it is necessary to make the thickness very thin from the viewpoint of light transmittance. The thickness of the contact layer is preferably in the range of 0.1 to 7.5 nm. If it is less than 0.1 nm, it is difficult to obtain a stable thin layer. When it exceeds 7.5 nm, the translucency is lowered, and more preferably 5 nm or less. In consideration of a decrease in translucency due to subsequent lamination of the current diffusion layer and stability of film formation, the range of 0.5 to 2.5 nm is particularly preferable.

しかし、コンタクト層の厚さを薄くすることでコンタクト層の面方向の電気抵抗が高くなり、かつ比較的高抵抗なｐ型層とあいまって電流注入部であるボンディングパッド電極の周辺部しか電流が拡がらず、結果として不均一な発光パターンとなり、発光出力が低下する。   However, by reducing the thickness of the contact layer, the electrical resistance in the surface direction of the contact layer increases, and the current flows only in the periphery of the bonding pad electrode, which is the current injection portion, together with the p-type layer having a relatively high resistance. It does not spread, resulting in a non-uniform light emission pattern, and the light emission output decreases.

そこで、コンタクト層の電流拡散性を補う手段として高光透過率で高導電性の電流拡散層をコンタクト層上に配置することにより、白金族金属の低接触抵抗性や光透過率を大きく損なうことなく電流を均一に広げることが可能となり、結果として発光出力の高い発光素子を得ることが出来る。   Therefore, by arranging a high light transmittance and high conductivity current diffusion layer on the contact layer as a means to supplement the current diffusivity of the contact layer, the low contact resistance and light transmittance of the platinum group metal are not greatly impaired. It is possible to spread the current uniformly, and as a result, a light emitting element having a high light emission output can be obtained.

電流拡散層の材料は、導電率の高い金属、例えば金、銀および銅からなる群から選ばれた金属または少なくともそれらの一種を含む合金が好ましい。中でも金は、薄膜とした時の光透過率が高いことから最も好ましい。   The material of the current spreading layer is preferably a metal having a high conductivity, for example, a metal selected from the group consisting of gold, silver and copper, or an alloy containing at least one of them. Of these, gold is most preferable because of its high light transmittance when it is made into a thin film.

一方、電流拡散層の材料は、導電率の高い硫化亜鉛および金属酸化物、例えばＩＴＯ、ＺｎＯ、酸化アルミニウム亜鉛、フッ素ドープ酸化錫、酸化チタン、酸化ビスマスおよび酸化マグネシウムなどの透明材料で形成することができる。このような透明材料は光透過率も高いので好ましい。中でもＩＴＯ、ＺｎＯ、酸化アルミニウム亜鉛およびフッ素ドープ酸化錫は、導電性が高いことが知られており、最も好ましい。   On the other hand, the material of the current spreading layer should be made of a transparent material such as zinc sulfide and metal oxide having high conductivity, such as ITO, ZnO, aluminum zinc oxide, fluorine-doped tin oxide, titanium oxide, bismuth oxide and magnesium oxide. Can do. Such a transparent material is preferable because of its high light transmittance. Among them, ITO, ZnO, aluminum zinc oxide, and fluorine-doped tin oxide are known to have high conductivity and are most preferable.

金属で電流拡散層を形成する場合、その厚さは、１〜２０ｎｍが好ましい。１ｎｍ未満では電流拡散効果が十分発揮されない。２０ｎｍを超えると、電流拡散層の光透過性の低下が著しく発光出力の低下が危惧される。１０ｎｍ以下がさらに好ましい。さらに厚さを３〜６ｎｍの範囲とすることで電流拡散層の光透過性と電流拡散の効果のバランスが最も良くなり、上記のコンタクト層と合わせることで正極上の全面で均一に発光し、かつ高出力な発光が得られる。   When the current spreading layer is formed of metal, the thickness is preferably 1 to 20 nm. If it is less than 1 nm, the current diffusion effect is not sufficiently exhibited. If it exceeds 20 nm, the light transmittance of the current diffusion layer is significantly reduced, and there is a fear that the light emission output is reduced. More preferably, it is 10 nm or less. Furthermore, by making the thickness in the range of 3 to 6 nm, the balance between the light transmittance of the current diffusion layer and the effect of current diffusion is the best, and by combining with the above contact layer, light is emitted uniformly over the entire surface of the positive electrode, In addition, high output light emission can be obtained.

透明材料で電流拡散層を形成する場合、その厚さは、１０〜５０００ｎｍが好ましい。１０ｎｍ未満では電流拡散効果が十分発揮されない。５０００ｎｍを超えると、電流拡散層の光透過性が低下し、発光出力の低下が危惧される。５０〜２０００ｎｍがさらに好ましい。さらに厚さを１００〜１０００ｎｍの範囲とすることで電流拡散層の光透過性と電流拡散の効果のバランスが最も良くなり、上記のコンタクト層と合わせることで正極上の全面で均一に発光し、かつ高出力な発光が得られる。   When the current diffusion layer is formed of a transparent material, the thickness is preferably 10 to 5000 nm. If it is less than 10 nm, the current diffusion effect is not sufficiently exhibited. If it exceeds 5000 nm, the light transmittance of the current diffusion layer is lowered, and there is a concern that the light emission output is lowered. 50 to 2000 nm is more preferable. Furthermore, by making the thickness in the range of 100 to 1000 nm, the balance between the light transmittance of the current diffusion layer and the effect of current diffusion is the best, and by combining with the above contact layer, light is emitted uniformly over the entire surface of the positive electrode, In addition, high output light emission can be obtained.

透光性電極上にボンディングパッド電極を形成する場合、透光性電極の最上層は金属で覆われていてもよいし、金属酸化物で覆われていてもよい。   When the bonding pad electrode is formed on the translucent electrode, the uppermost layer of the translucent electrode may be covered with a metal or a metal oxide.

透光性電極の最上層は、電流拡散層であっても構わないし、電流拡散層の上にボンディングパッド電極接合のための層を形成しても構わない。接合のための層を形成することで透光性が悪くなるので、最上層は電流拡散層であることが望ましい。   The uppermost layer of the translucent electrode may be a current diffusion layer, or a layer for bonding pad electrode bonding may be formed on the current diffusion layer. Since the light-transmitting property is deteriorated by forming a layer for bonding, the uppermost layer is preferably a current diffusion layer.

透光性電極の最表面には光を取り出すために面に凹凸を付けても良い。凹凸の作製には、パターニングを用いる方法や湿式処理によって凹凸をつけるやり方を採用することができる。凹凸の形状は、ストライプ状や格子状、ドット状など、公知のものを何の制限なく使用できる。   In order to extract light, the surface of the translucent electrode may be uneven. For the production of the irregularities, a method using patterning or a method of providing irregularities by wet processing can be employed. As the uneven shape, a known shape such as a stripe shape, a lattice shape, or a dot shape can be used without any limitation.

また、このような凹凸の形状を持った表面に対してボンディングパッドを形成することにより、パッドの密着強度を上げることができる。   Further, the bonding strength of the pad can be increased by forming the bonding pad on the surface having such an uneven shape.

コンタクト層および電流拡散層ならびにボンディングパッド電極の成膜方法については、特に制限されることはなく公知の真空蒸着法やスパッタ法を用いることができる。   The method for forming the contact layer, the current diffusion layer, and the bonding pad electrode is not particularly limited, and a known vacuum deposition method or sputtering method can be used.

本発明の正極は、図１に示したような、基板上にバッファ層を介して窒化ガリウム系化合物半導体を積層し、ｎ型半導体層、発光層およびｐ型半導体層を形成した従来公知の窒化ガリウム系化合物半導体発光素子を含む半導体発光素子に何ら制限無く用いることができる。   As shown in FIG. 1, the positive electrode of the present invention is a conventionally known nitridation in which a gallium nitride compound semiconductor is stacked on a substrate via a buffer layer to form an n-type semiconductor layer, a light emitting layer, and a p-type semiconductor layer. It can be used for semiconductor light emitting devices including gallium compound semiconductor light emitting devices without any limitation.

基板には、サファイア単結晶（Ａｌ2Ｏ3；Ａ面、Ｃ面、Ｍ面、Ｒ面）、スピネル単結晶（ＭｇＡｌ2Ｏ4）、ＺｎＯ単結晶、ＬｉＡｌＯ2単結晶、ＬｉＧａＯ2単結晶、ＭｇＯ単結晶などの酸化物単結晶、Ｓｉ単結晶、ＳｉＣ単結晶、ＧａＡｓ単結晶、ＡｌＮ単結晶、ＧａＮ単結晶およびＺｒＢ2などのホウ化物単結晶などの基板材料を何ら制限なく用いることができる。なお、基板の面方位は特に限定されない。また、ジャスト基板でも良いしオフ角を付与した基板であっても良い。 For the substrate, sapphire single crystal (Al 2 O 3 ; A plane, C plane, M plane, R plane), spinel single crystal (MgAl 2 O 4 ), ZnO single crystal, LiAlO 2 single crystal, LiGaO 2 single crystal, Substrate materials such as oxide single crystals such as MgO single crystals, Si single crystals, SiC single crystals, GaAs single crystals, AlN single crystals, GaN single crystals, and boride single crystals such as ZrB 2 can be used without any limitation. . The plane orientation of the substrate is not particularly limited. Moreover, a just board | substrate may be sufficient and the board | substrate which provided the off angle may be sufficient.

ｎ型半導体層、発光層およびｐ型半導体層は、各種周知の構造のものを含め何ら制限なく用いることができる。特にｐ型半導体層のキャリア濃度は一般的な濃度のものを用いてもよいが、比較的キャリア濃度の低い、例えば１×１０17ｃｍ-3程度のｐ型半導体層にも本発明の透光性電極は適用できる。 The n-type semiconductor layer, the light emitting layer, and the p-type semiconductor layer can be used without any limitation including those of various known structures. In particular, the carrier concentration of the p-type semiconductor layer may be a general concentration, but the light-transmitting property of the present invention is also applied to a p-type semiconductor layer having a relatively low carrier concentration, for example, about 1 × 10 17 cm −3. A sex electrode is applicable.

本発明におけるｎ型半導体層、発光層およびｐ型半導体層を構成する窒化ガリウム系化合物半導体として、一般式ＡｌxＩｎyＧａ1-x-yＮ（０≦ｘ＜１，０≦ｙ＜１，０≦ｘ＋ｙ＜１）で表わされる各種組成の半導体を何ら制限なく用いることができる。 As the gallium nitride compound semiconductor constituting the n-type semiconductor layer, the light emitting layer, and the p-type semiconductor layer in the present invention, the general formula Al x In y Ga 1-xy N (0 ≦ x <1, 0 ≦ y <1,0) Semiconductors having various compositions represented by ≦ x + y <1) can be used without any limitation.

これらの窒化ガリウム系化合物半導体の成長方法は特に限定されず、ＭＯＣＶＤ（有機金属化学気相成長法）、ＨＶＰＥ（ハイドライド気相成長法）、ＭＢＥ（分子線エピタキシー法）、などＩＩＩ族窒化物半導体を成長させることが知られている全ての方法を適用できる。好ましい成長方法としては、膜厚制御性、量産性の観点からＭＯＣＶＤ法である。ＭＯＣＶＤ法では、キャリアガスとして水素（Ｈ2）または窒素（Ｎ2）、ＩＩＩ族原料であるＧａ源としてトリメチルガリウム（ＴＭＧ）またはトリエチルガリウム（ＴＥＧ）、Ａｌ源としてトリメチルアルミニウム（ＴＭＡ）またはトリエチルアルミニウム（ＴＥＡ）、Ｉｎ源としてトリメチルインジウム（ＴＭＩ）またはトリエチルインジウム（ＴＥＩ）、Ｖ族原料であるＮ源としてアンモニア（ＮＨ3）、ヒドラジン（Ｎ2Ｈ4）などが用いられる。また、ドーパントとしては、ｎ型にはＳｉ原料としてモノシラン（ＳｉＨ4）またはジシラン（Ｓｉ2Ｈ6）を、Ｇｅ原料としてゲルマン（ＧｅＨ4）または有機ゲルマニウム化合物を用い、ｐ型にはＭｇ原料としては例えばビスシクロペンタジエニルマグネシウム（Ｃｐ2Ｍｇ）またはビスエチルシクロペンタジエニルマグネシウム（（ＥｔＣｐ）2Ｍｇ）を用いる。 The growth method of these gallium nitride-based compound semiconductors is not particularly limited. Group III nitride semiconductors such as MOCVD (metal organic chemical vapor deposition), HVPE (hydride vapor deposition), MBE (molecular beam epitaxy), etc. All methods known to grow can be applied. A preferred growth method is the MOCVD method from the viewpoint of film thickness controllability and mass productivity. In the MOCVD method, hydrogen (H 2 ) or nitrogen (N 2 ) is used as a carrier gas, trimethyl gallium (TMG) or triethyl gallium (TEG) is used as a Ga source as a group III source, and trimethyl aluminum (TMA) or triethyl aluminum is used as an Al source. (TEA), trimethylindium (TMI) or triethylindium (TEI) as an In source, ammonia (NH 3 ), hydrazine (N 2 H 4 ), or the like as an N source that is a group V source. In addition, as a dopant, monosilane (SiH 4 ) or disilane (Si 2 H 6 ) is used as an Si raw material for n-type, germane (GeH 4 ) or an organic germanium compound is used as a Ge raw material, and Mg raw material is used for a p-type. For example, biscyclopentadienyl magnesium (Cp 2 Mg) or bisethylcyclopentadienyl magnesium ((EtCp) 2 Mg) is used.

基板上にｎ型半導体層、発光層およびｐ型半導体層が順次積層された窒化ガリウム系化合物半導体のｎ型半導体層に接して負極を形成するために、発光層およびｐ型半導体層の一部を除去して、ｎ型半導体層を露出させる。その後残したｐ型半導体層上に本発明の正極を形成し、露出させたｎ型半導体層上に負極を形成する。負極としては、周知の負極を含め、各種組成および構造の負極を何ら制限無く用いることができる。   In order to form a negative electrode in contact with an n-type semiconductor layer of a gallium nitride compound semiconductor in which an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer are sequentially stacked on a substrate, a part of the light-emitting layer and the p-type semiconductor layer To remove the n-type semiconductor layer. Thereafter, the positive electrode of the present invention is formed on the remaining p-type semiconductor layer, and the negative electrode is formed on the exposed n-type semiconductor layer. As the negative electrode, negative electrodes having various compositions and structures, including known negative electrodes, can be used without any limitation.

サファイアやＳｉＣなどの発光する波長に対して透明な基板を用いた素子の場合、基板の裏面には反射膜を形成しても良い。反射膜を形成すると、基板下面での光の損失を減らすことができ、発光を外部に取り出す効率が更に向上するので望ましい。   In the case of an element using a substrate that is transparent with respect to the light emission wavelength, such as sapphire or SiC, a reflective film may be formed on the back surface of the substrate. Forming a reflective film is desirable because it can reduce the loss of light on the lower surface of the substrate and further improve the efficiency of extracting emitted light to the outside.

また、半導体層、透明電極層、あるいは基板の裏面などに、凹凸をつける加工を施すことができ、この加工によっても発光を外部に取り出す効率を向上させることができる。加工は基板に対して垂直な面を形成する他、斜めの面を形成することが考えられる。多重反射を防ぐ目的では、斜めの面を形成することが望ましい。   In addition, the semiconductor layer, the transparent electrode layer, the back surface of the substrate, or the like can be processed to be uneven, and the efficiency of extracting emitted light to the outside can also be improved by this processing. In addition to forming a surface perpendicular to the substrate, the processing can be performed by forming an oblique surface. In order to prevent multiple reflection, it is desirable to form an oblique surface.

加工は、上記の半導体層、透明電極層、あるいは基板の裏面を削ることで施す方法のほか、透明な材料でできた構造物を付着させる方法をとることもできる。   The processing can be performed by scraping the semiconductor layer, the transparent electrode layer, or the back surface of the substrate, or by attaching a structure made of a transparent material.

本発明の半導体発光素子用の正極を用いると、高い発光強度の窒化ガリウム系化合物半導体発光素子を得ることができる。つまり、この技術によって高輝度のＬＥＤランプを作製することができるため、この技術によって作製したチップを組み込んだ携帯電話、ディスプレイ、パネル類などの電子機器や、その電子機器を組み込んだ自動車、コンピュータ、ゲーム機、などの機械装置類は、低電力での駆動が可能となり、高い特性を実現することが可能である。特に、携帯電話、ゲーム機、玩具、自動車部品などの、バッテリ駆動させる機器類において、省電力の効果を発揮する。   When the positive electrode for a semiconductor light-emitting device of the present invention is used, a gallium nitride compound semiconductor light-emitting device having high emission intensity can be obtained. In other words, since this technology can produce a high-intensity LED lamp, electronic devices such as mobile phones, displays, and panels incorporating a chip produced by this technology, automobiles, computers incorporating such electronic devices, Machine devices such as game machines can be driven with low power and can achieve high characteristics. In particular, the battery-powered devices such as mobile phones, game machines, toys, and automobile parts exhibit power saving effects.

次に、本発明を実施例によりさらに詳細に説明するが、本発明はこれらの実施例にのみ限定されるものではない。   EXAMPLES Next, although an Example demonstrates this invention still in detail, this invention is not limited only to these Examples.

（実施例１）
図２は本実施例で作製した窒化ガリウム系化合物半導体発光素子の断面を示した模式図であり、図３はその平面を示した模式図である。サファイアからなる基板（１）上に、ＡｌＮからなるバッファ層（６）を介して、厚さ８μｍのアンドープＧａＮからなる下地層（３ａ）、厚さ２μｍのＳｉドープｎ型ＧａＮコンタクト層（３ｂ）、厚さ２５０ｎｍのｎ型Ｉｎ0.1Ｇａ0.9Ｎクラッド層（３ｃ）、厚さ１６ｎｍのＳｉドープＧａＮ障壁層および厚さ２．５ｎｍのＩｎ0.2Ｇａ0.8Ｎ井戸層を５回積層し、最後に障壁層を設けた多重量子井戸構造の発光層（４）、厚さ０．０１μｍのＭｇドープｐ型Ａｌ0.07Ｇａ0.93Ｎクラッド層（５ａ）、厚さ０．１５μｍのＭｇドープｐ型ＧａＮコンタクト層（５ｂ）を順に積層した窒化ガリウム系化合物半導体のｐ型ＧａＮコンタクト層上に、厚さ１．５ｎｍのＰｔコンタクト層（１１１）と厚さ５ｎｍのＡｕ電流拡散層（１１２）からなる透光性電極（１１）および５０ｎｍのＰｔ層（１３ａ）、２０ｎｍのＴｉ層（１３ｂ）、１０ｎｍのＡｌ層（１３ｃ）、１００ｎｍのＴｉ層（１３ｄ）、２００ｎｍのＡｕ層（１３ｅ）からなる５層構造のボンディングパッド電極（１３）よりなる本発明の正極（１０）を形成した。ボンディングパッド電極を形成する５層のうち、５０ｎｍのＰｔ層（１３ａ）が高反射率の反射層にあたる。次にｎ型ＧａＮコンタクト層上にＴｉ／Ａｕの二層構造の負極（２０）を形成し、光取り出し面を半導体側とした発光素子である。正極および負極の形状は図３に示したとおりである。 Example 1
FIG. 2 is a schematic view showing a cross section of the gallium nitride compound semiconductor light emitting device manufactured in this example, and FIG. 3 is a schematic view showing the plane thereof. An underlayer (3a) made of undoped GaN with a thickness of 8 μm and a Si-doped n-type GaN contact layer (3b) with a thickness of 2 μm on a substrate (1) made of sapphire via a buffer layer (6) made of AlN. Then, an n-type In 0.1 Ga 0.9 N cladding layer (3c) having a thickness of 250 nm, an Si-doped GaN barrier layer having a thickness of 16 nm, and an In 0.2 Ga 0.8 N well layer having a thickness of 2.5 nm are stacked five times, and finally the barrier A light emitting layer (4) having a multiple quantum well structure provided with a layer, a 0.01 μm-thick Mg-doped p-type Al 0.07 Ga 0.93 N cladding layer (5a), and a 0.15-μm-thick Mg-doped p-type GaN contact layer ( On the p-type GaN contact layer of a gallium nitride compound semiconductor in which 5b) are sequentially stacked, a Pt contact layer (111) having a thickness of 1.5 nm and an Au current diffusion layer (112) having a thickness of 5 nm are formed. 5 consisting of translucent electrode (11) and 50 nm Pt layer (13a), 20 nm Ti layer (13b), 10 nm Al layer (13c), 100 nm Ti layer (13d), 200 nm Au layer (13e) A positive electrode (10) of the present invention comprising a layered bonding pad electrode (13) was formed. Of the five layers forming the bonding pad electrode, the 50 nm Pt layer (13a) corresponds to the reflective layer having a high reflectance. Next, a light-emitting element in which a Ti / Au double-layer negative electrode (20) is formed on an n-type GaN contact layer and the light extraction surface is the semiconductor side. The shapes of the positive electrode and the negative electrode are as shown in FIG.

この構造において、ｎ型ＧａＮコンタクト層のキャリア濃度は１×１０19ｃｍ-3であり、ＧａＮ障壁層のＳｉドープ量は１×１０18ｃｍ-3であり、ｐ型ＧａＮコンタクト層のキャリア濃度は５×１０18ｃｍ-3であり、ｐ型ＡｌＧａＮクラッド層のＭｇドープ量は５×１０19ｃｍ-3であった。 In this structure, the carrier concentration of the n-type GaN contact layer is 1 × 10 19 cm −3 , the Si doping amount of the GaN barrier layer is 1 × 10 18 cm −3 , and the carrier concentration of the p-type GaN contact layer is 5 is a × 10 18 cm -3, Mg doping amount of p-type AlGaN cladding layer was 5 × 10 19 cm -3.

窒化ガリウム系化合物半導体層の積層は、ＭＯＣＶＤ法により、当該技術分野においてよく知られた通常の条件で行なった。また、正極および負極は次の手順で形成した。   Lamination of the gallium nitride compound semiconductor layers was performed by MOCVD under normal conditions well known in the art. Moreover, the positive electrode and the negative electrode were formed in the following procedure.

初めに反応性イオンエッチング法によって負極を形成する部分のｎ型ＧａＮコンタクト層を下記手順により露出させた。   First, the n-type GaN contact layer for forming the negative electrode by the reactive ion etching method was exposed by the following procedure.

まず、エッチングマスクをｐ型半導体層上に形成した。形成手順は以下の通りである。レジストを全面に一様に塗布した後、公知のリソグラフィー技術を用いて、正極領域より一回り大きい領域からレジストを除去した。真空蒸着装置内にセットして、圧力４×１０-4Ｐａ以下でＮｉおよびＴｉをエレクトロンビーム法により膜厚がそれぞれ約５０ｎｍおよび３００ｎｍとなるように積層した。その後リフトオフ技術により、正極領域以外の金属膜をレジストとともに除去した。 First, an etching mask was formed on the p-type semiconductor layer. The formation procedure is as follows. After uniformly applying the resist over the entire surface, the resist was removed from a region that was slightly larger than the positive electrode region using a known lithography technique. It was set in a vacuum deposition apparatus, and Ni and Ti were laminated by an electron beam method at a pressure of 4 × 10 −4 Pa or less so that the film thicknesses were about 50 nm and 300 nm, respectively. Thereafter, the metal film other than the positive electrode region was removed together with the resist by a lift-off technique.

次いで、反応性イオンエッチング装置のエッチング室内の電極上に半導体積層基板を載置し、エッチング室を１０-4Ｐａに減圧した後、エッチングガスとしてＣｌ2を供給してｎ型ＧａＮコンタクト層が露出するまでエッチングした。エッチング後、反応性イオンエッチング装置より取り出し、上記エッチングマスクを硝酸およびフッ酸により除去した。 Next, the semiconductor laminated substrate is placed on the electrode in the etching chamber of the reactive ion etching apparatus, the pressure in the etching chamber is reduced to 10 −4 Pa, and then Cl 2 is supplied as an etching gas to expose the n-type GaN contact layer. Etched until After the etching, it was taken out from the reactive ion etching apparatus, and the etching mask was removed with nitric acid and hydrofluoric acid.

次に、公知のフォトリソグラフィー技術及びリフトオフ技術を用いて、ｐ型ＧａＮコンタクト層上の正極を形成する領域にのみ、Ｐｔからなるコンタクト層、Ａｕからなる電流拡散層を形成した。コンタクト層、電流拡散層の形成では、まず、窒化ガリウム系化合物半導体層を積層した基板を真空蒸着装置内に入れ、ｐ型ＧａＮコンタクト層上に初めにＰｔを１．５ｎｍ、次にＡｕを５ｎｍ積層した。引き続き真空室から取り出した後、通常リフトオフと呼ばれる周知の手順に則って処理し、さらに同様な手法で電流拡散層上の一部にＰｔからなる反射層（１３ａ）、Ｔｉからなるバリア層（１３ｂ）、Ａｌからなるバリア層（１３ｃ）、Ｔｉからなるバリア層（１３ｄ）、Ａｕからなる最上層（１３ｅ）を順に積層し、ボンディングパッド電極（１３）を形成した。このようにしてｐ型ＧａＮコンタクト層上に、本発明の正極を形成した。   Next, using a known photolithography technique and lift-off technique, a contact layer made of Pt and a current diffusion layer made of Au were formed only in the region where the positive electrode was formed on the p-type GaN contact layer. In the formation of the contact layer and the current diffusion layer, first, a substrate on which a gallium nitride compound semiconductor layer is stacked is placed in a vacuum deposition apparatus, and Pt is first deposited on the p-type GaN contact layer at 1.5 nm, and then Au is deposited at 5 nm. Laminated. Subsequently, after taking out from the vacuum chamber, it is processed in accordance with a well-known procedure generally called lift-off, and a reflection layer (13a) made of Pt and a barrier layer made of Ti (13b) are formed on a part of the current diffusion layer by a similar method. ), A barrier layer (13c) made of Al, a barrier layer (13d) made of Ti, and an uppermost layer (13e) made of Au were laminated in this order to form a bonding pad electrode (13). Thus, the positive electrode of the present invention was formed on the p-type GaN contact layer.

次に、露出したｎ型ＧａＮコンタクト層上に負極を以下の手順により形成した。レジストを全面に一様に塗布した後、公知リソグラフィー技術を用いて、露出したｎ型ＧａＮコンタクト層上の負極形成部分からレジストを除去して、通常用いられる真空蒸着法で半導体側から順にＴｉが１００ｎｍ、Ａｕが２００ｎｍよりなる負極を形成した。その後レジストを公知の方法で除去した。   Next, a negative electrode was formed on the exposed n-type GaN contact layer by the following procedure. After uniformly applying the resist to the entire surface, the resist is removed from the negative electrode forming portion on the exposed n-type GaN contact layer using a known lithography technique, and Ti is sequentially applied from the semiconductor side by a commonly used vacuum deposition method. A negative electrode having a thickness of 100 nm and Au of 200 nm was formed. Thereafter, the resist was removed by a known method.

このようにして正極および負極を形成したウエーハを、基板裏面を研削・研磨することにより８０μｍまで基板の板厚を薄くして、レーザスクライバを用いて半導体積層側から罫書き線を入れたあと、押し割って、３５０μｍ角のチップに切断した。続いてこれらのチップをプローブ針による通電で電流印加値２０ｍＡにおける順方向電圧の測定をしたところ２．９Ｖであった。   After the wafer having the positive electrode and the negative electrode formed in this manner is ground and polished on the back surface of the substrate, the substrate thickness is reduced to 80 μm, and a ruled line is entered from the semiconductor lamination side using a laser scriber. It was cut and cut into 350 μm square chips. Subsequently, when these chips were energized with a probe needle and the forward voltage was measured at a current application value of 20 mA, it was 2.9 V.

その後、ＴＯ−１８缶パッケージに実装してテスターによって発光出力を計測したところ印加電流２０ｍＡにおける発光出力は４．５ｍＷを示した。またその発光面の発光分布は正極下の全面で発光しているのが確認できた。   After that, when mounted on a TO-18 can package and measured for light output by a tester, the light output at an applied current of 20 mA showed 4.5 mW. Moreover, it was confirmed that the light emission distribution on the light emitting surface emitted light on the entire surface under the positive electrode.

また、本実施例で作製した反射層の反射率は４７０ｎｍの波長領域で９２％であった。この値は、ボンディングパッド電極形成時に同じチャンバに入れたガラス製のダミー基板を用いて、分光光度計で測定した。   Further, the reflectance of the reflective layer produced in this example was 92% in the wavelength region of 470 nm. This value was measured with a spectrophotometer using a glass dummy substrate placed in the same chamber when the bonding pad electrode was formed.

また、シェアテスタと呼ばれる一般的な装置によりボンディングパッド電極の剥離強度を測定したところ、平均して９８０ｍＮ（１００ｇｆ）以上であり、ボンディングパッド電極と透明電極との間で剥離したものはなかった。   Moreover, when the peeling strength of the bonding pad electrode was measured by a general apparatus called a shear tester, it was 980 mN (100 gf) or more on average, and there was no peeling between the bonding pad electrode and the transparent electrode.

（比較例１）
ボンディングパッド電極を形成すべき部分に透光性電極を設けなかったこと、およびボンディングパッド電極に反射層（１３ａ）を設けなかったこと以外は、実施例１と同様に発光素子を作製した。従って、本比較例では、ボンディングパッド電極の最下層（半導体側）がＴｉからなる層（１３ｂ）であり、その層が直接ｐ型コンタクト層（５ｂ）に接している。 (Comparative Example 1)
A light-emitting element was fabricated in the same manner as in Example 1 except that the translucent electrode was not provided on the portion where the bonding pad electrode was to be formed and the reflective layer (13a) was not provided on the bonding pad electrode. Therefore, in this comparative example, the lowermost layer (semiconductor side) of the bonding pad electrode is a layer (13b) made of Ti, and the layer is in direct contact with the p-type contact layer (5b).

なお、ボンディングパッド電極と透光性電極との電気的接触のために、ボンディングパッド電極の周辺部が透光性電極と接触する構造とし、接触する面積はボンディングパッド電極の面積の５％程度とした。電流はこの接触部を通してボンディングパッド電極から透光性電極へ流れる。   In order to make electrical contact between the bonding pad electrode and the translucent electrode, the periphery of the bonding pad electrode is in contact with the translucent electrode, and the contact area is about 5% of the area of the bonding pad electrode. did. A current flows from the bonding pad electrode to the translucent electrode through this contact portion.

得られた発光素子を実施例１と同様に評価したところ、順方向電圧は３．１Ｖであり、発光出力は４．２ｍＷであった。またその発光面の発光分布は、ボンディングパッド電極直下では発光していないのが確認できた。ＴｉはＰｔに比較し、ｐ型コンタクト層（５ｂ）との接触抵抗が高く、反射率が低いことを示している。   When the obtained light emitting device was evaluated in the same manner as in Example 1, the forward voltage was 3.1 V and the light emission output was 4.2 mW. In addition, it was confirmed that the light emission distribution on the light emitting surface did not emit light immediately below the bonding pad electrode. Ti has higher contact resistance with the p-type contact layer (5b) and lower reflectance than Pt.

（実施例２）
透光性電極（１１）のＰｔコンタクト層（１１１）の厚さを１ｎｍとし、電流拡散層（１１２）をスパッタリング法で形成した厚さ１００ｎｍのＩＴＯとしたこと、およびボンディングパッド電極（１３）の反射層（１３ａ）をＡｌを用いて形成したこと以外は実施例１と同様に発光素子を作製した。 (Example 2)
The thickness of the Pt contact layer (111) of the translucent electrode (11) is 1 nm, the current diffusion layer (112) is ITO having a thickness of 100 nm formed by sputtering, and the bonding pad electrode (13) A light emitting device was produced in the same manner as in Example 1 except that the reflective layer (13a) was formed using Al.

得られた発光素子を実施例１と同様に評価したところ、順方向電圧は２．９Ｖであり、発光出力は５．０ｍＷであった。   When the obtained light emitting device was evaluated in the same manner as in Example 1, the forward voltage was 2.9 V and the light emission output was 5.0 mW.

また、シェアテスタと呼ばれる一般的な装置によりボンディングパッド電極の剥離強度を測定したところ、平均して９８０ｍＮ（１００ｇｆ）以上であった。剥離がボンディングパッド電極と透明電極との間で起きたサンプルが数個あった。   Further, when the peel strength of the bonding pad electrode was measured by a general apparatus called a shear tester, it was 980 mN (100 gf) or more on average. There were several samples in which peeling occurred between the bonding pad electrode and the transparent electrode.

（比較例２）
ボンディングパッド電極（１３）の反射層（１３ａ）を設けなかったこと以外は実施例２と同様に発光素子を作製した。得られた発光素子を実施例１と同様に評価したところ、順方向電圧は２．９Ｖで、実施例２と同様に低かったが、発光出力は４．７ｍＷに低下した。 (Comparative Example 2)
A light emitting device was fabricated in the same manner as in Example 2 except that the reflective layer (13a) of the bonding pad electrode (13) was not provided. When the obtained light emitting device was evaluated in the same manner as in Example 1, the forward voltage was 2.9 V, which was as low as in Example 2, but the light emission output decreased to 4.7 mW.

（実施例３）
実施例３では、実施例１と同様な方法で、以下のような積層構造を持つエピタキシャル基板を作製して用いた。つまり、サファイアからなる基板（１）上に、ＡｌＮからなるバッファ層（６）を介して、厚さ６μｍのアンドープＧａＮからなる下地層（３ａ）、厚さ４μｍのＧｅドープｎ型ＧａＮコンタクト層（３ｂ）、厚さ１８０ｎｍのＳｉをドープしたｎ型Ｉｎ0.1Ｇａ0.9Ｎクラッド層（３ｃ）、厚さ１６ｎｍのＳｉドープＧａＮ障壁層および厚さ２．５ｎｍのＩｎ0.2Ｇａ0.8Ｎ井戸層を５回積層し、最後に障壁層を設けた多重量子井戸構造の発光層（４）、厚さ０．０１μｍのＭｇドープｐ型Ａｌ0.07Ｇａ0.93Ｎクラッド層（５ａ）、厚さ０．１７５μｍのＭｇドープｐ型Ａｌ0.02Ｇａ0.98Ｎコンタクト層（５ｂ）を順に積層し、最後にＧｅをドープしたｎ型ＧａＮトンネル層（図示せず）を２０ｎｍ形成した。ｎ型ＧａＮトンネル層窒化ガリウム系化合物半導体の上に、厚さ２５０ｎｍのＩＴＯ電流拡散層（１１２）のみからなる透光性電極（１１）および５０ｎｍのＡｌ層（１３ａ）、２０ｎｍのＴｉ層（１３ｂ）、１０ｎｍのＡｌ層（１３ｃ）、１００ｎｍのＴｉ層（１３ｄ）、２００ｎｍのＡｕ層（１３ｅ）からなる５層構造のボンディングパッド電極（１３）よりなる本発明の正極（１０）を形成した。ボンディングパッド電極を形成する５層のうち、５０ｎｍのＡｌ層（１３ａ）が高反射率の反射層にあたる。次にｎ型ＧａＮコンタクト層上にＴｉ／Ａｕの二層構造の負極（２０）を形成し、光取り出し面を半導体側とした発光素子である。正極および負極の形状は図３に示したとおりである。 (Example 3)
In Example 3, an epitaxial substrate having the following laminated structure was prepared and used in the same manner as in Example 1. That is, an underlayer (3a) made of undoped GaN having a thickness of 6 μm and a Ge-doped n-type GaN contact layer having a thickness of 4 μm are formed on a substrate (1) made of sapphire via a buffer layer (6) made of AlN. 3b), an n-type In 0.1 Ga 0.9 N cladding layer (3c) doped with Si with a thickness of 180 nm, a Si-doped GaN barrier layer with a thickness of 16 nm and an In 0.2 Ga 0.8 N well layer with a thickness of 2.5 nm five times Multi-quantum well structure light-emitting layer (4) laminated and finally provided with a barrier layer, Mg-doped p-type Al 0.07 Ga 0.93 N clad layer (5a) with a thickness of 0.01 μm, Mg-doped with a thickness of 0.175 μm A p-type Al 0.02 Ga 0.98 N contact layer (5b) was sequentially stacked, and finally an n-type GaN tunnel layer (not shown) doped with Ge was formed to a thickness of 20 nm. On the n-type GaN tunnel layer gallium nitride compound semiconductor, a translucent electrode (11) consisting only of an ITO current diffusion layer (112) having a thickness of 250 nm, an Al layer (13a) of 50 nm, a Ti layer (13b) of 20 nm ) A positive electrode (10) of the present invention comprising a five-layer bonding pad electrode (13) comprising a 10 nm Al layer (13c), a 100 nm Ti layer (13d), and a 200 nm Au layer (13e) was formed. Of the five layers forming the bonding pad electrode, the Al layer (13a) of 50 nm corresponds to the reflective layer having a high reflectance. Next, a light-emitting element in which a Ti / Au double-layer negative electrode (20) is formed on an n-type GaN contact layer and the light extraction surface is the semiconductor side. The shapes of the positive electrode and the negative electrode are as shown in FIG.

この構造において、ｎ型ＧａＮコンタクト層のキャリア濃度は８×１０18ｃｍ-3であり、ｎ型ＩｎＧａＮクラッド層のＳｉドープ量は７×１０18ｃｍ-3であり、ＧａＮ障壁層のＳｉドープ量は１×１０17ｃｍ-3であり、ｐ型ＡｌＧａＮコンタクト層のキャリア濃度は５×１０17ｃｍ-3であり、ｐ型ＡｌＧａＮクラッド層のＭｇドープ量は２×１０20ｃｍ-3であった。また、ｎ型ＧａＮトンネル層のＧｅのドープ量は２×１０19ｃｍ-3とした。 In this structure, the carrier concentration of the n-type GaN contact layer is 8 × 10 18 cm −3 , the Si doping amount of the n-type InGaN cladding layer is 7 × 10 18 cm −3 , and the Si doping amount of the GaN barrier layer Was 1 × 10 17 cm −3 , the carrier concentration of the p-type AlGaN contact layer was 5 × 10 17 cm −3 , and the Mg doping amount of the p-type AlGaN cladding layer was 2 × 10 20 cm −3 . . The doping amount of Ge in the n-type GaN tunnel layer was 2 × 10 19 cm −3 .

得られた発光素子を実施例１と同様に評価したところ、順方向電圧は３．２Ｖであり、発光出力は８．５ｍＷであった。   When the obtained light emitting device was evaluated in the same manner as in Example 1, the forward voltage was 3.2 V and the light emission output was 8.5 mW.

また、シェアテスタと呼ばれる一般的な装置によりボンディングパッドの剥離強度を測定したところ、平均して１００ｇｆ以上であった。剥離がボンディングパッドと透明電極との間で起きたサンプルが数個あった。   Moreover, when the peeling strength of the bonding pad was measured by a general apparatus called a shear tester, the average was 100 gf or more. There were several samples where peeling occurred between the bonding pad and the transparent electrode.

本発明の正極を用いて提供される半導体発光素子は、駆動電圧が低く、かつ、発光強度が高いのでランプ等の材料として極めて有用である。   The semiconductor light emitting device provided by using the positive electrode of the present invention is extremely useful as a material for a lamp or the like because of low driving voltage and high emission intensity.

本発明の正極を有する半導体発光素子の一例の断面を示した模式図である。It is the schematic diagram which showed the cross section of an example of the semiconductor light-emitting device which has a positive electrode of this invention. 実施例で作製した本発明の正極を有する窒化ガリウム系化合物半導体発光素子の断面を示した模式図である。It is the schematic diagram which showed the cross section of the gallium nitride type compound semiconductor light-emitting device which has the positive electrode of this invention produced in the Example. 実施例で作製した本発明の正極を有する窒化ガリウム系化合物半導体発光素子の平面を示した模式図である。It is the schematic diagram which showed the plane of the gallium nitride type compound semiconductor light-emitting device which has the positive electrode of this invention produced in the Example.

符号の説明Explanation of symbols

１ 基板
２ ＧａＮ系化合物半導体層
３ ｎ型半導体層
４ 発光層
５ ｐ型半導体層
６ バッファ層
１０ 正極
１１ 透光性電極
１３ ボンディングパッド電極
２０ 負極 DESCRIPTION OF SYMBOLS 1 Substrate 2 GaN-based compound semiconductor layer 3 n-type semiconductor layer 4 light emitting layer 5 p-type semiconductor layer 6 buffer layer 10 positive electrode 11 translucent electrode 13 bonding pad electrode 20 negative electrode

Claims (30)

半導体層上に形成された透光性電極および該透光性電極上に形成されたボンディングパッド電極からなり、該ボンディングパッド電極が少なくとも透光性電極と接する面に反射層を有することを特徴とする半導体発光素子用の正極。   A translucent electrode formed on a semiconductor layer and a bonding pad electrode formed on the translucent electrode, wherein the bonding pad electrode has a reflective layer at least on a surface in contact with the translucent electrode. A positive electrode for a semiconductor light emitting device. 反射層と透光性電極との密着強度が、剥離強度で４９０ｍＮ（５０ｇｆ）以上である請求項１に記載の半導体発光素子用の正極。   The positive electrode for a semiconductor light-emitting element according to claim 1, wherein the adhesion strength between the reflective layer and the translucent electrode is 490 mN (50 gf) or more in terms of peel strength. 透光性電極の、素子が発光する発光波長における光の透過率が６０％以上である請求項１または２に記載の半導体発光素子用の正極。   The positive electrode for a semiconductor light-emitting element according to claim 1, wherein the translucent electrode has a light transmittance of 60% or more at an emission wavelength at which the element emits light. 反射層がＡｌ、Ａｇ、Ｐｔ族金属およびこれらの金属の少くとも一種を含む合金からなる群より選ばれた金属からなる請求項１〜３のいずれか一項に記載の半導体発光素子用の正極。   The positive electrode for a semiconductor light-emitting element according to any one of claims 1 to 3, wherein the reflective layer is made of a metal selected from the group consisting of Al, Ag, Pt group metals and alloys containing at least one of these metals. . 半導体発光素子が窒化ガリウム系化合物半導体発光素子である請求項１〜４のいずれか一項に記載の半導体発光素子用の正極。   The positive electrode for a semiconductor light-emitting element according to claim 1, wherein the semiconductor light-emitting element is a gallium nitride-based compound semiconductor light-emitting element. 反射層がＡｌ、Ａｇ、Ｐｔ、およびこれらの金属の少なくとも一種を含む合金からなる群より選ばれた金属である請求項１〜５のいずれか一項に記載の半導体発光素子用の正極。   The positive electrode for a semiconductor light-emitting element according to claim 1, wherein the reflective layer is a metal selected from the group consisting of Al, Ag, Pt, and an alloy containing at least one of these metals. 反射層の厚さが２０〜３０００ｎｍである請求項１〜６のいずれか一項に記載の半導体発光素子用の正極。   The thickness of a reflective layer is 20-3000 nm, The positive electrode for semiconductor light-emitting devices as described in any one of Claims 1-6. ボンディングパッド電極が層状構造であり、反射層に加えて、Ｔｉ、ＣｒもしくはＡｌからなるバリア層、および／またはＡｕもしくはＡｌからなる最上層を有する請求項１〜６のいずれか一項に記載の半導体発光素子用の正極。   The bonding pad electrode has a layered structure, and has a barrier layer made of Ti, Cr, or Al and / or an uppermost layer made of Au or Al in addition to the reflective layer. Positive electrode for semiconductor light emitting device. 透光性電極のボンディングパッド電極側が金属からなる層である請求項１〜８のいずれか一項に記載の半導体発光素子用の正極。   The positive electrode for a semiconductor light emitting element according to claim 1, wherein the translucent electrode is a metal layer on the bonding pad electrode side. 透光性電極のボンディングパッド電極側が透明材料からなる層である請求項１〜８のいずれか一項に記載の半導体発光素子用の正極。   The positive electrode for a semiconductor light-emitting element according to claim 1, wherein the translucent electrode is a layer made of a transparent material on the bonding pad electrode side. 透光性電極が、金属以外の透明材料のみからなる請求項１０に記載の半導体発光素子用の正極。   The positive electrode for a semiconductor light-emitting element according to claim 10, wherein the translucent electrode is made of only a transparent material other than metal. 透光性電極の最表面層に光を取り出すための加工が施されている請求項１〜１１のいずれか一項に記載の半導体発光素子用の正極。   The positive electrode for a semiconductor light-emitting element according to claim 1, wherein a process for extracting light is performed on the outermost surface layer of the translucent electrode. 透光性電極の最表面層が透明材料である請求項１２に記載の半導体発光素子用の正極。   The positive electrode for a semiconductor light-emitting element according to claim 12, wherein the outermost surface layer of the translucent electrode is a transparent material. 透光性電極がｐ型半導体層に接するコンタクト層および該コンタクト層上の電流拡散層を有する請求項１〜１３のいずれか一項に記載の半導体発光素子用の正極。   The positive electrode for a semiconductor light-emitting element according to claim 1, wherein the translucent electrode has a contact layer in contact with the p-type semiconductor layer and a current diffusion layer on the contact layer. コンタクト層が白金族金属またはその合金である請求項１４に記載の半導体発光素子用の正極。   The positive electrode for a semiconductor light-emitting element according to claim 14, wherein the contact layer is a platinum group metal or an alloy thereof. コンタクト層が白金である請求項１５に記載の半導体発光素子用の正極。   The positive electrode for a semiconductor light-emitting element according to claim 15, wherein the contact layer is platinum. コンタクト層の厚さが０．１〜７．５ｎｍである請求項１４〜１６のいずれか一項に記載の半導体発光素子用の正極。   The thickness of a contact layer is 0.1-7.5 nm, The positive electrode for semiconductor light-emitting devices as described in any one of Claims 14-16. コンタクト層の厚さが０．５〜２．５ｎｍである請求項１７に記載の半導体発光素子用の正極。   The positive electrode for a semiconductor light-emitting element according to claim 17, wherein the contact layer has a thickness of 0.5 to 2.5 nm. 電流拡散層が金、銀および銅からなる群から選ばれた金属または少なくともそれらの一種を含む合金である請求項１４〜１８のいずれか一項に記載の半導体発光素子用の正極。   The positive electrode for a semiconductor light emitting element according to any one of claims 14 to 18, wherein the current spreading layer is a metal selected from the group consisting of gold, silver and copper, or an alloy containing at least one of them. 電流拡散層が金または金合金である請求項１９に記載の半導体発光素子用の正極。   The positive electrode for a semiconductor light-emitting element according to claim 19, wherein the current diffusion layer is gold or a gold alloy. 電流拡散層の厚さが１〜２０ｎｍである請求項１４〜２０のいずれか一項に記載の半導体発光素子用の正極。   The positive electrode for a semiconductor light-emitting element according to any one of claims 14 to 20, wherein the current diffusion layer has a thickness of 1 to 20 nm. 電流拡散層の厚さが３〜６ｎｍである請求項２１に記載の半導体発光素子用の正極。   The positive electrode for a semiconductor light-emitting element according to claim 21, wherein the current diffusion layer has a thickness of 3 to 6 nm. 電流拡散層が導電性の透明材料である請求項１４〜１８のいずれか一項に記載の半導体発光素子用の正極。   The positive electrode for a semiconductor light-emitting element according to claim 14, wherein the current diffusion layer is a conductive transparent material. 透明材料がＩＴＯ、酸化亜鉛、酸化アルミニウム亜鉛、フッ素ドープ酸化錫、酸化チタン、硫化亜鉛、酸化ビスマスおよび酸化マグネシウムからなる群から選ばれた少なくとも１種類である請求項１０、１１、１３および２３のいずれか一項に記載の半導体発光素子用の正極。   The transparent material is at least one selected from the group consisting of ITO, zinc oxide, zinc aluminum oxide, fluorine-doped tin oxide, titanium oxide, zinc sulfide, bismuth oxide and magnesium oxide. The positive electrode for semiconductor light-emitting devices as described in any one. 透明材料がＩＴＯ、酸化亜鉛、酸化アルミニウム亜鉛およびフッ素ドープ酸化錫からなる群から選ばれた少なくとも１種類である請求項２４に記載の半導体発光素子用の正極。   The positive electrode for a semiconductor light-emitting element according to claim 24, wherein the transparent material is at least one selected from the group consisting of ITO, zinc oxide, aluminum zinc oxide, and fluorine-doped tin oxide. 透明材料の厚さが１０〜５０００ｎｍである請求項１０、１１、１３および２３〜２５のいずれか一項に記載の半導体発光素子用の正極。   The positive electrode for a semiconductor light-emitting element according to any one of claims 10, 11, 13, and 23 to 25, wherein the transparent material has a thickness of 10 to 5000 nm. 透明材料の厚さが１００〜１０００ｎｍである請求項２６に記載の半導体発光素子用の正極。   27. The positive electrode for a semiconductor light-emitting element according to claim 26, wherein the transparent material has a thickness of 100 to 1000 nm. 請求項１〜２７のいずれか一項に記載の正極を用いた半導体発光素子。   The semiconductor light-emitting device using the positive electrode as described in any one of Claims 1-27. 基板上に窒化ガリウム系化合物半導体からなる、ｎ型半導体層、発光層およびｐ型半導体層をこの順序で有し、ｐ型半導体層およびｎ型半導体層に正極および負極がそれぞれ設けられた発光素子において、正極が請求項１〜２７のいずれか一項に記載の正極である窒化ガリウム系化合物半導体発光素子。   A light-emitting element comprising an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer made of a gallium nitride compound semiconductor on a substrate in this order, and a positive electrode and a negative electrode provided on the p-type semiconductor layer and the n-type semiconductor layer, respectively A gallium nitride-based compound semiconductor light-emitting element, wherein the positive electrode is the positive electrode according to any one of claims 1 to 27. 請求項２８または２９に記載の発光素子を用いてなるランプ。   A lamp comprising the light emitting device according to claim 28 or 29.
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US8994054B2 (en) 2009-02-20 2015-03-31 Kabushiki Kaisha Toshiba Nitride LED with a schottky electrode penetrating a transparent electrode
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