JP3727187B2 - Manufacturing method of nitride semiconductor laser device - Google Patents
Manufacturing method of nitride semiconductor laser device Download PDFInfo
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Description
【０００１】
【産業上の利用分野】
本発明は、例えばＬＥＤ（発光ダイオード）、ＬＤ（レーザダイオード）等の窒化物半導体（ＩｎＸＡｌＹＧａ１−Ｘ−ＹＮ、０≦Ｘ、０≦Ｙ、Ｘ＋Ｙ≦１）よりなる素子の製造方法に関する。
【０００２】
【従来の技術】
近年、窒化物半導体からなる青色、青緑色の発光ダイオード、レーザダイオードが実用化されたり、実用可能になっている。このような窒化物半導体素子は、現在のところ窒化物半導体と完全に格子整合する基板が未だ開発されていないため、格子定数が異なるサファイアの上に窒化物半導体を強制的に成長させて形成されている。そのためサファイア基板上に成長された窒化物半導体の結晶には、格子整合した基板上に成長された赤色レーザ素子と比べると、非常に多くの結晶欠陥が発生する。
【０００３】
本発明者等は、結晶欠陥を大幅に低減できる窒化物半導体の結晶成長方法として、窒化物半導体と異なる異種基板上に窒化ガリウム基板を形成し、その窒化ガリウム基板上に素子構造を形成することにより、波長約４００ｎｍ、光出力２ｎＷで連続発振約１万時間を達成できる窒化物半導体レーザー素子などを開示している（例えば「ＩｎＧａＮ系多重量子井戸構造半導体レーザの現状」、第５８回応用物理学会学術講演会、講演番号４ａＺＣ−２，１９９７年１０月、”Ｐｒｅｓｅｎｔ Ｓｔａｔｕｓ ｏｆ ＩｎＧａＮ／ＡｌＧａＮ ｂａｓｅｄ Ｌａｓｅｒ Ｄｉｏｄｅｓ”、Ｔｈｅ Ｓｅｃｏｎｄ Ｉｎｔｅｒｎａｔｉｏｎａｌ Ｃｏｎｆｅｒｅｎｃｅ ｏｎ Ｎｉｔｒｉｄｅ Ｓｅｍｉｃｏｎｄｕｃｔｏｒｓ（ＩＣＮＳ’９７）、講演番号Ｓ−１、１９９７年１０月などに記載されている。）。
【０００４】
上記の結晶成長方法は、サファイア基板上に従来の結晶欠陥が非常に多い窒化ガリウム層を薄く成長させ、その上にＳｉＯ２よりなる保護膜を部分的に形成し、その保護膜の上からハライド気相成長法（ＨＶＰＥ）、有機金属気相成長法（ＭＯＶＰＥ）等の気相成長法により、窒化ガリウムの横方向への成長を利用し、再度窒化ガリウム層を成長させることにより、結晶欠陥の少ない窒化ガリウム基板（膜厚１０μｍ）を形成する技術である。この方法は窒化物半導体を保護膜上で横方向に成長させることから、一般にラテラルオーバーグロウス（ｌａｔｅｒａｌ ｏｖｅｒ ｇｒｏｗｔｈ：ＬＯＧ）と呼ばれている。
【０００５】
上記技術において、結晶欠陥が少なくなった窒化ガリウム基板を用いることにより素子の性能の向上が見られたものの、上記窒化物半導体素子の基板とされるサファイアは、非常に硬く劈開性がないために、ウエハーをチップ化するのに高度な技術を必要とする。更に、サファイアには劈開性がないために、レーザ素子の形成において基板の劈開性を用いて窒化物半導体の劈開面を共振面としにくく、共振面の形成に時間と手間がかかる。
【０００６】
【発明が解決しようとする課題】
そこで、サファイア基板を除去して、窒化ガリウム基板のみを用いることで窒化ガリウムの劈開性を利用した共振面の形成を試みた。この方法は窒化ガリウムに電磁波を照射して、変質させた層を形成することで、サファイア基板を容易に分離し、窒化ガリウム基板のみが得られるというものである。今までは、この方法によって得た窒化ガリウム基板上の窒化物半導体素子を劈開する際、窒化ガリウムのＭ面を劈開面としていた。Ｍ面とは窒化物半導体を六角柱状の六方晶系で近似した場合に、その劈開面に相当する四角形の面であり、
【０００７】
【外７】
（以下、Ｍ面と記載する。）面などの６種類の面方位で示すことができる。窒化物半導体のＭ面で劈開すると、非常に歩留良く、また鏡面に近い共振面を含む劈開面を得ることができる。
【０００９】
【課題を解決するための手段】
本願発明は窒化物半導体基板の上にレーザ素子の構造が積層されてなる窒化物半導体レーザ素子の製造方法であって、第１の窒化物半導体をサファイア基板上にＧａＮよりなるバッファ層、アンドープＧａＮよりなる下地層、ストライプ状の第１の保護膜を順に形成した異種基板上に成長させ、該第１の窒化物半導体にストライプ状の段差を形成し、該段差の上面に第２の保護膜を形成する工程と、第２の窒化物半導体を前記第１の窒化物半導体の前記第２の保護膜で覆われていない部位から横方向のみに成長させ、続いて縦方向と横方向に成長させるラテラルオーバーグロウスにより形成する工程と、前記第１の窒化物半導体及び第２の窒化物半導体から前記異種基板を除去して窒化物半導体基板を形成する工程と、前記窒化物半導体基板上にレーザ素子の構造を積層する工程と、前記窒化物半導体のＭ面と平行になるようにリッジを形成する工程と、前記基板をリッジに対して垂直に劈開して（外１）乃至（外６）面内のいずれかの面方位で割ることにより半導体レーザ素子の光共振面を形成する工程と、を備えたことを特徴とする。また、前記保護膜は、ＳｉＯ２であることが望ましい。
【００１０】
【００１１】
【００１２】
【００１３】
【００１４】
【００１５】
【００１６】
前記（外８）乃至（外１３）面は同一Ａ面を示すものである。前記窒化物半導体レーザ素子の製造方法によって、劈開面を鏡面に近い共振面とすることができる。
【００１７】
【発明の実施の形態】
更に図を用いて説明する。
図１は窒化物半導体の結晶構造を模式的に示すユニットセル図である。
窒化物半導体は正確には菱面体構造であるが、このように六方晶系で近似できる。
ＧａＮにおいては劈開面としてＭ面とＡ面とがある。この劈開面を使って窒化物半導体が積層されたウエハーをチップ化すれば、鏡面に近い共振面を得ることができる。
【００１８】
図２及び図３は、窒化ガリウム基板上に積層した窒化物半導体レーザの共振方向に垂直な面で切断したときの図である。図２はｐ電極とｎ電極が同一面上に、図３は別の面上に形成されている。この切断面を窒化物半導体のＡ面の劈開性を用いて形成する。その方法は、ｐ側層表面をエッチングしてリッジを形成する際に窒化物半導体のＭ面と平行（Ａ面と垂直）になるようにリッジを形成し、このリッジに対して垂直に劈開をする。それがすなわちＡ面の劈開性を用いて共振面を形成したことになる。
【００１９】
【実施例】
以下に本発明の実施例を示すが本発明はこれに限定されない。
［実施例１］
図２はレーザ光の共振方向に垂直な方向で素子を切断した際の図を示している。以下、この図を元に実施例１について説明する。
【００２０】
まずＧａＮ基板１を得る。
異種基板として、サファイア基板をＭＯＶＰＥ反応容器内にセットし、ＧａＮよりなるバッファ層を２００オングストローム、アンドープＧａＮよりなる下地層を４μｍ（下地層とは次の窒化物半導体基板を選択成長させるための層）、ＣＶＤ装置によりＳｉＯ２よりなる第１の保護膜をストライプ状（ストライプ幅１０μｍ、ストライプ間隔（窓部）２μｍ）に１μｍ、ＭＯＶＰＥ法でアンドープＧａＮよりなる窒化物半導体基板を１０μｍ、ＨＶＰＥ法でアンドープＧａＮよりなるＧａＮ基板を２００μｍ、それぞれの膜厚で積層する。
【００２１】
次に図２に示すように積層したＧａＮにエッチングによりストライプ状の段差を設ける。この段差の上面すべてにＳｉＯ２等の第２の保護膜３１を形成して、続いてＧａＮを積層する際のＧａＮの上面への縦方向の成長を抑え、ＧａＮは第２の保護膜３１で覆われていない部位からの横方向の成長を始める。ＧａＮの縦方向の成長を抑え、横方向のみに成長させ、続いて縦と横方向に成長させることで、結晶欠陥の極めて少ない、結晶性の良好なＧａＮ基板１を得ることができる。
【００２２】
続いてウエハーに、サファイア基板側からＧａＮ成長方向と同方向に電磁波としてＫｒＦエキシマレーザを照射し、約１００℃で加熱処理を施すと、下地ＧａＮとサファイア基板との界面近傍で分離でき、第１の保護膜を除去するまで研磨することでＧａＮ基板１のみを得る。
【００２３】
次にＧａＮ基板上に窒化物半導体をｎ側バッファ層、クラック防止層、ｎ側クラッド層、ｎ側光ガイド層、活性層、ｐ側キャップ層、ｐ側光ガイド層、ｐ側クラッド層、ｐ側コンタクト層の順で積層した。
以上のようにしてＧａＮ基板上に積層した窒化物半導体に、ｐ側コンタクト層とｐ側クラッド層をエッチングして、ＧａＮのＭ面と平行（Ａ面と垂直）になるようにリッジを形成し、リッジをマスク後、リッジと平行にエッチングしてｎ側バッファ層の表面を露出させる。また、形成したリッジ表面にｐ電極を、露出させたｎ側バッファ層上にｎ電極を形成し、最後にｐ電極とｎ電極との間に絶縁膜を介し、ｐ電極上にｐパッド電極、ｎ電極上にｎパッド電極を形成して、ウエハーを完成させる。
【００２４】
このウエハーをチップ化する際、まずＡ面で劈開（リッジと垂直に劈開）することで、共振面を作製する。共振面の両方あるいはどちらか一方にＳｉＯ2とＴｉＯ2よりなる誘電体多層膜を形成し、最後にリッジと平行な方向で、バーを切断してレーザチップとした。このレーザ素子は室温でレーザ発振を示し、閾値電流密度１．５ｋＡ／ｃｍ2において室温連続発振を示し、２０ｍＷの出力において１０００時間以上の寿命を示し、Ｍ面で共振面を形成したときと同等の結果が得られた。
【００２５】
［参考例１］図３は本発明の参考例に係るレーザ素子の構造を示す模式的な断面図であり、図２と同じくレーザ光の共振方向に垂直な方向で素子を切断した際の図を示している。以下この図を元に参考例１について説明する。まず異種基板として、サファイア基板をＭＯＶＰＥ反応容器内にセットし、ＧａＮよりなるバッファ層を２００オングストローム、アンドープＧａＮよりなる下地層を４μｍ、ＣＶＤ装置によりＳｉＯ2よりなる第１の保護膜をストライプ状（ストライプ幅１０μｍ、ストライプ間隔（窓部）２μｍ）に１μｍ、ＭＯＶＰＥ法でＳｉドープＧａＮよりなる窒化物半導体基板を１０μｍ、ＨＶＰＥ法でＳｉドープＧａＮよりなるＧａＮ基板を２００μｍ、それぞれの膜厚で積層し、続いてウエハーを、サファイア基板側から第１の保護膜までを研磨していき、ＧａＮ基板１のみを得る。
【００２６】
第１の保護膜を除去した後のＧａＮ基板１の表面を第１の主面と第２の主面とし、第１の主面上に、ｎ側光ガイド層と活性層の間にｎ側キャップ層を成長させる以外は実施例１と同様にして、ｎ側バッファ層、クラック防止層、ｎ側クラッド層、ｎ側光ガイド層、ｎ側キャップ層、活性層、ｐ側キャップ層、ｐ側光ガイド層、ｐ側クラッド層、ｐ側コンタクト層の順で積層する。
【００２７】
ＧａＮのＭ面と平行（Ａ面と垂直）になるようにリッジを形成後、リッジ最表面に絶縁膜、ｐ電極およびｐパッド電極を形成した。ｐ側電極形成後、第２の主面上にｎ電極およびボンディング用電極を形成する。
このウエハーをチップ化する際、実施例１と同様にして、まずＡ面で劈開（リッジと垂直に劈開）することで、共振面を作製する。共振面の両方あるいはどちらか一方にＳｉＯ２とＴｉＯ２よりなる誘電体多層膜を形成し、最後にｐ電極に平行な方向で、バーを切断してレーザチップとした。
【００２８】
このレーザ素子も実施例１と同様に室温で連続発振を示し、閾値電流密度１．５ｋＡ／ｃｍ２において室温連続発振を示し、２０ｍＷの出力において１０００時間以上の寿命を示し、Ｍ面で共振面を形成したときと同等の結果が得られた。
【００２９】
【発明の効果】
以上示したように本発明はサファイア基板から分離した窒化ガリウム基板上の窒化物半導体素子を劈開する際、新たに窒化ガリウムのＡ面を劈開面として劈開することで、鏡面に近い共振面を持つ窒化物半導体レーザが実現可能となった。なお、本発明では窒化ガリウム基板について説明したが、サファイア基板やスピネル基板上に積層し、窒化物半導体を積層した後、そのサファイア基板やスピネル基板を薄く研磨した場合についても適用可能である。
【図面の簡単な説明】
【図１】 窒化物半導体の結晶構造を模式的に示すユニットセル図である。
【図２】 本発明の一実施例に係るレーザ素子の構造を示す概略断面図である。
【図３】 本発明の一参考例に係るレーザ素子の構造を示す概略断面図である。[0001]
[Industrial application fields]
The present invention is, for example, LED (light emitting diode), LD (laser diode) nitride such as semiconductor (In X Al Y Ga 1- X-Y N, 0 ≦ X, 0 ≦ Y, X + Y ≦ 1) than consisting of elements It relates to a manufacturing method.
[0002]
[Prior art]
In recent years, blue and blue-green light emitting diodes and laser diodes made of nitride semiconductors have been put into practical use or become practical. Such a nitride semiconductor device is formed by forcibly growing a nitride semiconductor on sapphire having a different lattice constant because a substrate that is completely lattice-matched with the nitride semiconductor has not yet been developed. ing. For this reason, the crystal of the nitride semiconductor grown on the sapphire substrate has a larger number of crystal defects than the red laser device grown on the lattice-matched substrate.
[0003]
As a method for growing a nitride semiconductor crystal capable of greatly reducing crystal defects, the present inventors form a gallium nitride substrate on a different substrate different from the nitride semiconductor and form an element structure on the gallium nitride substrate. Discloses a nitride semiconductor laser device capable of achieving continuous oscillation of about 10,000 hours at a wavelength of about 400 nm and an optical output of 2 nW (for example, “Current Status of InGaN-based Multiple Quantum Well Structure Semiconductor Laser”, 58th Applied Physics) Academic academic conference, lecture number 4aZC-2, October 1997, "Present Status of InGaN / AlGaN based Laser Diodes", The Second International Conference on Nitride Semiconductor-1's ICC, 1N In October 997, etc.).
[0004]
In the above crystal growth method, a conventional gallium nitride layer having a large number of crystal defects is thinly grown on a sapphire substrate, and a protective film made of SiO 2 is partially formed on the gallium nitride layer, and a halide is formed on the protective film. By growing the gallium nitride layer again by using the lateral growth of gallium nitride by vapor phase growth methods such as vapor phase growth method (HVPE) and metal organic vapor phase growth method (MOVPE), This is a technique for forming a small gallium nitride substrate (film thickness: 10 μm). This method is generally called lateral over growth (LOG) because a nitride semiconductor is grown laterally on the protective film.
[0005]
In the above technique, although the performance of the device has been improved by using a gallium nitride substrate with fewer crystal defects, the sapphire used as the substrate of the nitride semiconductor device is very hard and has no cleaving property. Advanced technology is required to make a wafer into chips. Furthermore, since sapphire does not have a cleavage property, it is difficult to make the cleavage surface of the nitride semiconductor a resonance surface by using the cleavage property of the substrate in forming the laser element, and it takes time and labor to form the resonance surface.
[0006]
[Problems to be solved by the invention]
Therefore, the sapphire substrate was removed and only the gallium nitride substrate was used, so that an attempt was made to form a resonance surface using the cleavage of gallium nitride. In this method, gallium nitride is irradiated with electromagnetic waves to form a modified layer, whereby the sapphire substrate can be easily separated and only the gallium nitride substrate can be obtained. Until now, when the nitride semiconductor device on the gallium nitride substrate obtained by this method is cleaved, the M-plane of gallium nitride has been used as a cleavage plane. The M plane is a quadrangular plane corresponding to the cleavage plane when a nitride semiconductor is approximated by a hexagonal columnar hexagonal system,
[0007]
[Outside 7]
(Hereinafter referred to as the M plane) It can be indicated by six types of plane orientations such as a plane. When cleavage is performed on the M-plane of the nitride semiconductor, it is possible to obtain a cleavage plane that has a very good yield and includes a resonance plane close to a mirror plane.
[0009]
[Means for Solving the Problems]
The present invention relates to a method of manufacturing a nitride semiconductor laser device in which a structure of a laser device is laminated on a nitride semiconductor substrate , wherein the first nitride semiconductor is formed on a sapphire substrate with a buffer layer made of GaN, undoped GaN. And a stripe-shaped step is formed on the first nitride semiconductor, and a second protection film is formed on the upper surface of the step. And forming a second nitride semiconductor in a lateral direction only from a portion of the first nitride semiconductor not covered with the second protective film, and subsequently growing in a vertical direction and a horizontal direction. forming a lateral over Grouse to the steps of forming a nitride semiconductor substrate by removing the foreign substrate from the first nitride semiconductor and the second nitride semiconductor, the nitride semiconductor substrate Laminating the structure of the laser element on the substrate, forming a ridge parallel to the M-plane of the nitride semiconductor, and cleaving the substrate perpendicularly to the ridge (outside 1) to (outside 6) forming an optical resonant surface of the semiconductor laser element by dividing by any plane orientation in the plane. Further, the protective film is preferably a SiO 2.
[0010]
[0011]
[0012]
[0013]
[0014]
[0015]
[0016]
The (outer 8) to (outer 13) surfaces indicate the same A surface . By the method for manufacturing the nitride semiconductor laser element, the cleavage plane can be made a resonance plane close to a mirror surface.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Furthermore, it demonstrates using a figure.
FIG. 1 is a unit cell diagram schematically showing a crystal structure of a nitride semiconductor.
Although a nitride semiconductor has a rhombohedral structure precisely, it can be approximated in a hexagonal system in this way.
In GaN, there are an M plane and an A plane as cleavage planes. By using this cleaved surface to chip a wafer on which nitride semiconductors are stacked, a resonant surface close to a mirror surface can be obtained.
[0018]
2 and 3 are views of the nitride semiconductor laser laminated on the gallium nitride substrate, taken along a plane perpendicular to the resonance direction. In FIG. 2, the p electrode and the n electrode are formed on the same surface, and FIG. 3 is formed on another surface. This cut surface is formed by using the cleavage property of the A surface of the nitride semiconductor. In the method, when the ridge is formed by etching the p-side layer surface, the ridge is formed so as to be parallel to the M-plane of the nitride semiconductor (perpendicular to the A-plane), and cleaved perpendicularly to the ridge. To do. That is, the resonance surface is formed by using the cleavage of the A surface.
[0019]
【Example】
Although the Example of this invention is shown below, this invention is not limited to this.
[Example 1]
FIG. 2 shows a diagram when the element is cut in a direction perpendicular to the resonance direction of the laser beam. Hereinafter, Example 1 is demonstrated based on this figure.
[0020]
First, a
As a heterogeneous substrate, a sapphire substrate is set in a MOVPE reaction vessel, a buffer layer made of GaN is 200 Å, an underlayer made of undoped GaN is 4 μm (the underlayer is a layer for selectively growing the next nitride semiconductor substrate) ), A first protective film made of SiO 2 in a stripe shape (stripe width 10 μm, stripe interval (window portion) 2 μm) by a CVD apparatus, a nitride semiconductor substrate made of undoped GaN by MOVPE method, 10 μm, and HVPE method A GaN substrate made of undoped GaN is stacked with a thickness of 200 μm.
[0021]
Next, as shown in FIG. 2, striped steps are provided by etching the stacked GaN. A second protective film 31 of SiO 2 or the like is formed on the entire upper surface of the step, and the vertical growth on the upper surface of GaN when subsequently stacking GaN is suppressed. Begin lateral growth from uncovered sites. By suppressing the growth in the vertical direction of GaN, growing only in the horizontal direction, and subsequently growing in the vertical and horizontal directions, the
[0022]
Subsequently, when the wafer is irradiated with a KrF excimer laser as an electromagnetic wave in the same direction as the GaN growth direction from the sapphire substrate side and subjected to heat treatment at about 100 ° C., the wafer can be separated in the vicinity of the interface between the underlying GaN and the sapphire substrate. By polishing until the protective film is removed, only the
[0023]
Next, a nitride semiconductor is formed on the GaN substrate with an n-side buffer layer, a crack prevention layer, an n-side cladding layer, an n-side light guide layer, an active layer, a p-side cap layer, a p-side light guide layer, a p-side cladding layer, p The side contact layers were stacked in this order.
In the nitride semiconductor laminated on the GaN substrate as described above, the p-side contact layer and the p-side cladding layer are etched to form a ridge so as to be parallel to the GaN M-plane (perpendicular to the A-plane). After the ridge is masked, etching is performed in parallel with the ridge to expose the surface of the n-side buffer layer. Further, a p-electrode is formed on the formed ridge surface, an n-electrode is formed on the exposed n-side buffer layer, and finally a p-pad electrode is formed on the p-electrode via an insulating film between the p-electrode and the n-electrode. An n pad electrode is formed on the n electrode to complete the wafer.
[0024]
When the wafer is made into chips, first, a resonance surface is produced by cleaving the surface A (cleaving perpendicularly to the ridge). A dielectric multilayer film made of SiO 2 and TiO 2 was formed on both or one of the resonance surfaces, and finally a bar was cut in a direction parallel to the ridge to form a laser chip. This laser element oscillates at room temperature, exhibits continuous oscillation at room temperature at a threshold current density of 1.5 kA / cm 2 , exhibits a lifetime of 1000 hours or more at an output of 20 mW, and is equivalent to when a resonant surface is formed on the M plane. Results were obtained.
[0025]
[Reference Example 1] FIG. 3 is a schematic cross-sectional view showing the structure of a laser device according to a reference example of the present invention, and is a view when the device is cut in a direction perpendicular to the resonance direction of laser light as in FIG. Is shown. Reference Example 1 will be described below with reference to this figure. First, as a heterogeneous substrate, a sapphire substrate is set in a MOVPE reaction vessel, a buffer layer made of GaN is 200 Å, an underlayer made of undoped GaN is 4 μm, and a first protective film made of SiO 2 is striped by a CVD apparatus ( 1 μm in stripe width 10 μm, stripe interval (window portion 2 μm), nitride semiconductor substrate made of Si-doped GaN by MOVPE method, 10 μm, and GaN substrate made of Si-doped GaN by HVPE method, each having a thickness of 200 μm. Subsequently, the wafer is polished from the sapphire substrate side to the first protective film to obtain only the
[0026]
The surface of the
[0027]
After forming a ridge so as to be parallel to the GaN M-plane (perpendicular to the A-plane), an insulating film, a p-electrode, and a p-pad electrode were formed on the ridge outermost surface. After forming the p-side electrode, an n-electrode and a bonding electrode are formed on the second main surface.
When this wafer is made into chips, as in Example 1, first, the resonance plane is produced by cleaving on the A plane (cleaving perpendicularly to the ridge). A dielectric multilayer film made of SiO 2 and TiO 2 was formed on both or one of the resonance surfaces, and finally a bar was cut in a direction parallel to the p-electrode to form a laser chip.
[0028]
This laser element also shows continuous oscillation at room temperature as in Example 1, shows continuous oscillation at room temperature at a threshold current density of 1.5 kA / cm 2 , shows a lifetime of 1000 hours or more at an output of 20 mW, and has a resonant surface at the M plane. A result equivalent to that obtained when forming was obtained.
[0029]
【The invention's effect】
As described above, according to the present invention, when a nitride semiconductor element on a gallium nitride substrate separated from a sapphire substrate is cleaved, a new resonance plane near the mirror surface is obtained by cleaving the gallium nitride A-plane as a cleavage plane. Nitride semiconductor lasers have become feasible. Note that although the gallium nitride substrate has been described in the present invention, the present invention can also be applied to a case where the sapphire substrate or the spinel substrate is thinly polished after being stacked on the sapphire substrate or the spinel substrate and the nitride semiconductor is stacked.
[Brief description of the drawings]
FIG. 1 is a unit cell diagram schematically showing a crystal structure of a nitride semiconductor.
FIG. 2 is a schematic cross-sectional view showing the structure of a laser device according to an embodiment of the present invention.
FIG. 3 is a schematic cross-sectional view showing the structure of a laser device according to a reference example of the present invention.
Claims (2)
第１の窒化物半導体をサファイア基板上にＧａＮよりなるバッファ層、アンドープＧａＮよりなる下地層、ストライプ状の第１の保護膜を順に形成した異種基板上に成長させ、該第１の窒化物半導体にストライプ状の段差を形成し、該段差の上面に第２の保護膜を形成する工程と、
第２の窒化物半導体を前記第１の窒化物半導体の前記第２の保護膜で覆われていない部位から横方向のみに成長させ、続いて縦方向と横方向に成長させるラテラルオーバーグロウスにより形成する工程と、
前記第１の窒化物半導体及び第２の窒化物半導体から前記異種基板を除去して窒化物半導体基板を形成する工程と、
前記窒化物半導体基板上にレーザ素子の構造を積層する工程と、
前記窒化物半導体のＭ面と平行になるようにリッジを形成する工程と、
前記基板をリッジに対して垂直に劈開して
【外１】
A first nitride semiconductor is grown on a heterogeneous substrate in which a buffer layer made of GaN, an underlayer made of undoped GaN, and a striped first protective film are sequentially formed on a sapphire substrate, and the first nitride semiconductor is grown. Forming a stripe-shaped step on the upper surface and forming a second protective film on the upper surface of the step;
A second nitride semiconductor is formed by lateral overgrowth in which the first nitride semiconductor is grown only in the lateral direction from a portion not covered with the second protective film, and then grown in the longitudinal and lateral directions. And a process of
Forming a nitride semiconductor substrate by removing the foreign substrate from the first nitride semiconductor and the second nitride semiconductor,
Laminating a structure of a laser element on the nitride semiconductor substrate;
Forming a ridge so as to be parallel to the M-plane of the nitride semiconductor;
Cleave the substrate perpendicular to the ridge [Outside 1]
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| US6562644B2 (en) * | 2000-08-08 | 2003-05-13 | Matsushita Electric Industrial Co., Ltd. | Semiconductor substrate, method of manufacturing the semiconductor substrate, semiconductor device and pattern forming method |
| JP4683731B2 (en) * | 2001-01-15 | 2011-05-18 | シャープ株式会社 | Nitride semiconductor laser device and optical device including the same |
| WO2002065556A1 (en) * | 2001-02-15 | 2002-08-22 | Sharp Kabushiki Kaisha | Nitride semiconductor light emitting element and production therefor |
| MY141883A (en) | 2001-06-06 | 2010-07-16 | Ammono Sp Zoo | Process and apparatus for obtaining bulk mono-crystalline gallium-containing nitride |
| PL225235B1 (en) | 2001-10-26 | 2017-03-31 | Ammono Spółka Z Ograniczoną Odpowiedzialnością | Substrate for epitaxy |
| AU2002354463A1 (en) | 2002-05-17 | 2003-12-02 | Ammono Sp.Zo.O. | Bulk single crystal production facility employing supercritical ammonia |
| KR100494557B1 (en) * | 2002-09-05 | 2005-06-13 | 한국전자통신연구원 | Efficient LED having highly refractive cover layer |
| JP4540347B2 (en) * | 2004-01-05 | 2010-09-08 | シャープ株式会社 | Nitride semiconductor laser device and manufacturing method thereof |
| JP2005322786A (en) * | 2004-05-10 | 2005-11-17 | Sharp Corp | Nitride semiconductor element and its manufacturing method |
| WO2007008394A1 (en) * | 2005-07-11 | 2007-01-18 | Cree, Inc. | Laser diode orientation on mis-cut substrates |
| JP2006339675A (en) * | 2006-09-07 | 2006-12-14 | Sharp Corp | Nitride semiconductor laser element and semiconductor optical device |
| JP4146881B2 (en) * | 2007-03-20 | 2008-09-10 | シャープ株式会社 | Nitride semiconductor light-emitting device, epi-wafer and method of manufacturing the same |
| JP2008235790A (en) | 2007-03-23 | 2008-10-02 | Mitsubishi Electric Corp | Manufacturing method of semiconductor light element |
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