KR19990049361A - GAN single crystal manufacturing method - Google Patents
GAN single crystal manufacturing method Download PDFInfo
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- KR19990049361A KR19990049361A KR1019970068298A KR19970068298A KR19990049361A KR 19990049361 A KR19990049361 A KR 19990049361A KR 1019970068298 A KR1019970068298 A KR 1019970068298A KR 19970068298 A KR19970068298 A KR 19970068298A KR 19990049361 A KR19990049361 A KR 19990049361A
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- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
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- C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
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- C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
- C30B25/02—Epitaxial-layer growth
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Abstract
본 발명에 따른 GaN 단결정 제조 방법은, 사파이어 기판 상에 GaN을 소정의 제1 온도에서 성장시켜 제1 버퍼층을 형성하는 단계와, 제1 버퍼층 위에 GaN을 상기 제1 온도보다 높은 제2 온도에서 성장시켜 제2 버퍼층을 형성하는 단계와, 제2 버퍼층 위에 AlxGa1-xN(0＜x≤1)을 상기 제1 온도보다 높은 제3 온도에서 성장시키되, AlxGa1-xN 성장층의 두께 및 x값을 조절하여 GaN과 유사한 격자 상수를 갖는 제3 버퍼층을 형성하는 단계, 및 제3 버퍼층 위에 GaN 단결정을 성장시키는 단계를 포함한다.In the GaN single crystal manufacturing method according to the present invention, GaN is grown on a sapphire substrate at a predetermined first temperature to form a first buffer layer, and GaN is grown on the first buffer layer at a second temperature higher than the first temperature. Forming a second buffer layer, and growing Al x Ga 1-x N (0 <x≤1) on the second buffer layer at a third temperature higher than the first temperature, wherein Al x Ga 1-x N is grown. Adjusting the thickness and x value of the layer to form a third buffer layer having a lattice constant similar to GaN, and growing a GaN single crystal on the third buffer layer.
Description
본 발명은 GaN 단결정(Single Crystalline of Gallium-Nitride) 제조 방법에 관한 것이다.The present invention relates to a method for producing GaN single crystal (Single Crystalline of Gallium-Nitride).
GaN을 재료로서 사용하여 제작되는 GaN계 반도체 소자는 에너지 밴드갭이 3.39eV로서, 직접 전자 천이(Direct Electron Transition) 특성이 있는 광대역 밴드 갭(wide bandgap)을 나타내므로, 단파장 영역의 발광 소자로서 유용한 물질이다. 그리고, 이러한 GaN계 반도체 소자는 GaN 단결정 기판을 사용하는 호모에피탁씨에 의해 제조되는 것이 가장 바람직하다.A GaN semiconductor device fabricated using GaN as a material has an energy bandgap of 3.39 eV and exhibits a wide bandgap with direct electron transition characteristics, and thus is useful as a light emitting device in a short wavelength region. It is a substance. The GaN semiconductor device is most preferably manufactured by Homo Epitaxy using a GaN single crystal substrate.
그런데, GaN 단결정 성분 중의 하나인 질소는 고온에서 증기압이 높기 때문에, 액상 결정 성장을 위해서는 1500℃ 이상의 고온과 약 15000기압 이상의 질소 압력이 필요하므로, 대량 생산이 어려울 뿐만 아니라, 현재 사용 가능한 결정 크기도 80㎟의 박판형이므로 이를 소자 제작에 사용하기 곤란하다. 따라서, 대부분의 GaN 단결정은, MOCVD(Metal Organic Chemical Vapor Deposition), MBE(Molecular Beam Deposition), HVPE(Hydride or Hallide Vapor Phase Epitaxy), SVPE(Sublimation Vapor Phase Epitaxy) 등의 기상 성장법에 의해 제조되며, 이때 기판으로서는 사파이어(Al2O3) 단결정 또는 SiC 단결정을 사용하였다.However, since nitrogen, which is one of the GaN single crystal components, has a high vapor pressure at high temperatures, it is difficult to mass-produce as well as difficult to mass-produce, since liquid crystal growth requires a high temperature of 1500 ° C or higher and a nitrogen pressure of about 15000 atm or higher. Since it is a thin plate type of 80 mm 2, it is difficult to use it for device fabrication. Therefore, most GaN single crystals are produced by vapor phase growth methods such as metal organic chemical vapor deposition (MOCVD), molecular beam deposition (MBE), hydrochloride or hallide vapor phase epitaxy (HVPE), and sublimation vapor phase epitaxy (SVPE). In this case, a sapphire (Al 2 O 3 ) single crystal or a SiC single crystal was used as the substrate.
사파이어나 SiC는 모두 고온에서 안정하며, GaN과 같은 육방정계의 구조를 갖는다. 특히, SiC는 GaN과의 격자 상수의 차 및 열팽창 계수의 차가 사파이어보다 작고, 열전도도 및 전기 전도도가 우수하다는 장점이 있다. 그러나, 가격이 사파이어보다 약 40배 비싸며, SiC 기판 내의 마이크로파이프(micropipe)가 GaN 박막으로 전파되어 GaN 소자의 특성을 저하시키는 단점이 있으므로 현재는 SiC 기판보다 사파이어 기판을 더 많이 사용한다.Sapphire and SiC are both stable at high temperatures and have a hexagonal structure such as GaN. In particular, SiC has an advantage that the difference between the lattice constant and the coefficient of thermal expansion with GaN is smaller than that of sapphire, and is excellent in thermal conductivity and electrical conductivity. However, since the price is about 40 times higher than that of sapphire, and micropipes in the SiC substrate are propagated to the GaN thin film, the characteristics of the GaN device are deteriorated.
그러나, 사파이어는 GaN과의 격자 상수 차(약 16%) 및 열팽창 계수 차(약 35%) 때문에 계면에서 스트레인(strain)이 유발되고, 이 스트레인이 결정 내 격자 결함을 발생시켜 고품질의 GaN 박막의 성장을 어렵게 할 뿐만 아니라, GaN 박막을 사용하여 제작한 소자의 수명을 단축시킨다.However, sapphire causes strain at the interface due to the lattice constant difference (about 16%) and the coefficient of thermal expansion (about 35%) with GaN, and this strain causes lattice defects in the crystal, resulting in high quality GaN thin film. Not only makes it difficult to grow, but also shortens the life of devices fabricated using GaN thin films.
따라서, 종래에는 사파이어 기판 상에 버퍼층을 형성하여 계면에서의 스트레인을 감소시킨 후, 그 버퍼층 위에 GaN 단결정을 성장시켰다. 이 과정을 도 1a 내지 도 1c에 도시된 단면도를 참조하면서 설명하면 다음과 같다.Therefore, conventionally, after forming a buffer layer on a sapphire substrate to reduce strain at the interface, GaN single crystals were grown on the buffer layer. This process is described below with reference to the cross-sectional views shown in FIGS. 1A to 1C.
먼저, 도 1a에 도시된 바와 같이, 두께가 약 300㎛인 사파이어 기판(10)을 마련한다. 그리고, 도 1b에 도시된 바와 같이, 상기 사파이어 기판(10) 위에 두께가 약 500Å인 버퍼층(11)을 성장시킨다. 이때, 버퍼층(11)은 GaN 또는 AlGaN을 저온, 예컨대 500℃에서 성장시켜 형성한다. 그리고, 도 1c에 도시된 바와 같이, MOCVD, MBE, HVPE, SVPE 등과 같은 기상 성장법에 의해 GaN 단결정(13)을 상기 GaN 또는 AlGaN 버퍼층(11) 위에 성장시킨다.First, as shown in FIG. 1A, a sapphire substrate 10 having a thickness of about 300 μm is prepared. As shown in FIG. 1B, a buffer layer 11 having a thickness of about 500 μs is grown on the sapphire substrate 10. In this case, the buffer layer 11 is formed by growing GaN or AlGaN at low temperature, for example, 500 ° C. As shown in FIG. 1C, the GaN single crystal 13 is grown on the GaN or AlGaN buffer layer 11 by vapor phase growth such as MOCVD, MBE, HVPE, SVPE, or the like.
그런데, GaN 또는 AlGaN 버퍼층(11) 위에서 성장된 GaN 단결정(13)에는 스트레스가 감소되었지만, 여전히 스트레스가 존재하며 이로 인한 결함이 발생된다. 특히, 두께가 약 15㎛ 이상의 GaN 후막 성장시에는 결정 내에 크랙(crack)이 발생하게 되며, 결정 내의 격자 결함, 특히 전위 밀도의 경우 107/㎠ 이하의 것을 얻을 수 없어 고품질의 소자를 제작할 수 없다는 문제가 있다.By the way, although the stress is reduced in the GaN single crystal 13 grown on the GaN or AlGaN buffer layer 11, there is still stress and defects are generated. In particular, when the GaN thick film is grown to a thickness of about 15 μm or more, cracks are generated in the crystal, and lattice defects in the crystal, in particular, in the case of dislocation density, are not obtained below 10 7 / cm 2, and thus a high-quality device can be manufactured. There is no problem.
본 발명은 상기와 같은 문제점을 개선하기 위하여 창출된 것으로서, 스트레스에 의한 결함 발생이 제거된 양질의 GaN 단결정 제조 방법을 제공하는데 그 목적이 있다.The present invention has been made to improve the above problems, and an object thereof is to provide a high quality GaN single crystal manufacturing method in which defects caused by stress are eliminated.
도 1a 내지 도 1c는 종래의 GaN 단결정 제조 방법에 따른 공정 단면도,1A to 1C are cross-sectional views of a process according to a conventional GaN single crystal manufacturing method;
그리고 도 2a 내지 도 2e는 본 발명에 따른 GaN 단결정 제조 방법에 따른 공정 단면도이다.2A to 2E are cross-sectional views illustrating a method of manufacturing GaN single crystal according to the present invention.
<도면의 주요 부분에 대한 부호의 설명><Explanation of symbols for main parts of the drawings>
20...사파이어 기판 21...GaN을 저온 성장시킨 제1 버퍼층20. First buffer layer in which sapphire substrate 21 ... GaN is grown at low temperature
22...GaN을 고온 성장시킨 제2 버퍼층22. Second buffer layer grown by GaN at high temperature
23...AlxGa1-xN을 고온 성장시킨 제3 버퍼층23 ... third buffer layer in which Al x Ga 1-x N is grown at high temperature
24...GaN 단결정24 ... GaN single crystal
상기 목적을 달성하기 위하여, 본 발명에 따른 GaN 단결정 제조 방법은, (가) 사파이어 기판 상에 GaN을 소정의 제1 온도에서 성장시켜 제1 버퍼층을 형성하는 단계; (나) 상기 제1 버퍼층 위에 GaN을 상기 제1 온도보다 높은 제2 온도에서 성장시켜 제2 버퍼층을 형성하는 단계; (다) 상기 제2 버퍼층 위에 AlxGa1-xN(0＜x≤1)을 상기 제1 온도보다 높은 제3 온도에서 성장시키되, 상기 AlxGa1-xN 성장층의 두께 및 상기 x값을 조절하여 GaN과 유사한 격자 상수를 갖는 제3 버퍼층을 형성하는 단계; 및 (라) 상기 제3 버퍼층 위에 GaN 단결정을 성장시키는 단계를 포함하는 것을 특징으로 한다.In order to achieve the above object, GaN single crystal manufacturing method according to the present invention, (A) forming a first buffer layer by growing GaN on a sapphire substrate at a predetermined first temperature; (B) growing a GaN on the first buffer layer at a second temperature higher than the first temperature to form a second buffer layer; (C) Al x Ga 1-x N (0 <x≤1) is grown on the second buffer layer at a third temperature higher than the first temperature, and the thickness of the Al x Ga 1-x N growth layer and the adjusting the x value to form a third buffer layer having a lattice constant similar to GaN; And (D) growing a GaN single crystal on the third buffer layer.
본 발명에 있어서, 상기 단계 (가)에서, 상기 제1 버퍼층은 MOCVD에 의해 상기 제1 온도 에서 트리메틸갈륨과 암모니아 가스를 반응시켜 형성되며, 이 때 상기 제1 온도는 것이 500-600℃인 것이 바람직하다.In the present invention, in the step (a), the first buffer layer is formed by reacting trimethylgallium and ammonia gas at the first temperature by MOCVD, wherein the first temperature is 500-600 ℃ desirable.
상기 단계 (나)에서, 상기 제2 버퍼층은 MOCVD에 의해 상기 제2 온도에서 트리메틸갈륨과 암모니아 가스를 반응시켜 형성되며, 이 때 상기 제2 온도는 1050℃인 것이 바람직하다.In the step (b), the second buffer layer is formed by reacting trimethylgallium and ammonia gas at the second temperature by MOCVD, wherein the second temperature is preferably 1050 ° C.
상기 단계 (다)에서, 상기 제3 버퍼층은 MOCVD에 의해 상기 제3 온도에서 트리메틸알루미늄과 암모니아 가스를 반응시켜 형성되며, 이 때 상기 제3 온도는 1050℃인 것이 바람직하다.In the step (c), the third buffer layer is formed by reacting trimethylaluminum and ammonia gas at the third temperature by MOCVD, wherein the third temperature is preferably 1050 ° C.
또한, 본 발명에 있어서, 상기 제1, 제2 및 제3 버퍼층의 두께는 각각 100-2000Å인 것이 바람직하며, 이 때, 상기 AlxGa1-xN(0＜x≤1)의 x는 0-0.2인 값을 갖는 것이 바람직하다.In the present invention, it is preferable that the thicknesses of the first, second and third buffer layers are each 100-2000 kPa, wherein x in the Al x Ga 1-x N (0 <x ≤ 1 ) is It is preferred to have a value of 0-0.2.
상기 단계 (라)에서, 상기 GaN 단결정은 HVPE법 혹은 SVPE법에 의해 성장되는 것이 바람직하다.In the step (d), the GaN single crystal is preferably grown by HVPE or SVPE.
이하, 첨부된 도면을 참조하면서 본 발명에 따른 GaN 단결정 제조 방법을 상세히 설명한다.Hereinafter, a GaN single crystal manufacturing method according to the present invention with reference to the accompanying drawings will be described in detail.
도 2a 내지 도 2e는 본 발명에 따른 GaN 단결정 제조 방법에 따른 공정 단면도이다. 도시된 바와 같이, 본 발명에 따른 GaN 단결정 제조 방법에서는, 기판으로서 사파이어 기판(20)을 사용하며, 이 사파이어 기판(20) 상에 제1, 제2 및 제3 버퍼층(21, 22, 23)을 순차적으로 형성한 후, 그 위에 GaN 단결정(24)을 성장시킨다. 이 때, GaN 단결정이 성장되는 제3 버퍼층(23)의 두께 및 조성비를 조절하여 GaN과 유사한 격자 상수를 갖도록 한 후에 GaN 단결정을 성장시키는 점에 본 발명의 특징이 있다.2A to 2E are cross-sectional views illustrating a method of manufacturing GaN single crystal according to the present invention. As shown, in the GaN single crystal manufacturing method according to the present invention, a sapphire substrate 20 is used as a substrate, and the first, second and third buffer layers 21, 22, and 23 are formed on the sapphire substrate 20. After forming sequentially, the GaN single crystal 24 is grown thereon. At this time, the GaN single crystal is characterized by growing the GaN single crystal after controlling the thickness and composition ratio of the third buffer layer 23 in which the GaN single crystal is grown to have a lattice constant similar to that of GaN.
그러면, 각 단계별 공정을 위주로 본 발명에 따른 제조 방법을 설명하기로 한다.Then, the manufacturing method according to the present invention will be described based on each step process.
먼저, 도 2a에 도시된 바와 같이, 두께가 약 300㎛인 (0001)사파이어(Al2O3) 기판(20)을 준비한다.First, as shown in FIG. 2A, a (0001) sapphire (Al 2 O 3 ) substrate 20 having a thickness of about 300 μm is prepared.
다음에, 도 2b에 도시된 바와 같이, 사파이어 기판(20) 상에 GaN을 저온 성장시켜 제1 버퍼층(21)을 형성한다. 이를 위하여, MOCVD에 의한 반응 챔버 내에서, 온도를 500-600℃로 유지한 상태에서 트리메틸갈륨(Ga(CH3)3)(TMG)과 암모니아(NH3) 가스를 반응시켜 두께가 약 100-2000Å인 GaN 제1 버퍼층(21)이 형성되도록 한다.Next, as shown in FIG. 2B, GaN is grown at low temperature on the sapphire substrate 20 to form the first buffer layer 21. To this end, in a reaction chamber by MOCVD, trimethylgallium (Ga (CH 3 ) 3 ) (TMG) and ammonia (NH 3 ) gas are reacted with a thickness of about 100- while maintaining the temperature at 500-600 ° C. A GaN first buffer layer 21 of 2000 mu s is formed.
이와 같이 형성된 GaN 제1 버퍼층(21)은 스트레스를 감소시키기 위하여 삽입된 층이다. 즉, 사파이어 기판(20) 상에 저온에서 결정 성장된 GaN 제1 버퍼층(21)은 대부분 비정질(amorphous)상이지만, 일부분은 섬(island)과 같은 형태로 결정화된다. 이 때, 이 섬과 같은 부분이 핵으로 작용하여 2차원 성장이 이루어지고, 이 2차원 성장이 이루어질 때 주변의 비정질상과 실질적인 원자 결합이 이루어지지 않으므로 계면에서의 스트레스는 크게 감소한다. 그러나, 사파이어와 GaN 단결정 사이의 격자 상수 차와 열팽창 계수 차로 인하여 발생되는 스트레스는 여전히 존재한다.The GaN first buffer layer 21 formed as described above is a layer inserted to reduce stress. That is, the GaN first buffer layer 21 crystal-grown on the sapphire substrate 20 at low temperature is mostly amorphous, but part of the GaN first buffer layer 21 is crystallized in an island-like form. At this time, the island-like portion acts as a nucleus to achieve two-dimensional growth, and when the two-dimensional growth is performed, substantial atomic bonds with the surrounding amorphous phase do not occur, so the stress at the interface is greatly reduced. However, there is still a stress caused by the lattice constant difference and the coefficient of thermal expansion between the sapphire and GaN single crystal.
따라서, 도 2c에 도시된 바와 같이, GaN을 저온 성장시켜 형성한 제1 버퍼층(21) 위에 GaN을 고온 성장시킴으로써 제2 버퍼층(22)을 형성한다. 즉, MOCVD에 의한 반응 챔버 내에서, 온도를 1050℃로 유지한 상태에서 트리메틸갈륨(Ga(CH3)3)(TMG)과 암모니아(NH3)가스를 반응시켜 두께가 약 100-2000Å인 GaN 제2 버퍼층(22)을 제1 버퍼층(21) 위에 형성한다.Therefore, as shown in FIG. 2C, the second buffer layer 22 is formed by growing GaN at a high temperature on the first buffer layer 21 formed by growing GaN at low temperature. That is, GaN having a thickness of about 100-2000 Pa by reacting trimethylgallium (Ga (CH 3 ) 3 ) (TMG) with ammonia (NH 3 ) gas while maintaining the temperature at 1050 ° C. in a MOCVD reaction chamber. The second buffer layer 22 is formed on the first buffer layer 21.
그런데, 이와 같이 형성된 GaN 제2 버퍼층(22)에는 앞서 설명한 바와 같이, 사파이어와 GaN과의 격자 상수 차 및 열팽창 계수 차로 인한 스트레스가 존재한다. 이 GaN 제2 버퍼층(22)에 존재하는 스트레스는 박막면에 평행한 방향으로 팽창하려는 스트레스인데, 그 이유는 사파이어의 격자 상수보다 GaN 단결정의 격자 상수가 더 크기 때문이다. 따라서, 도 2d에 도시된 바와 같이, GaN 제2 버퍼층(22) 위에 GaN보다 적은 격자 상수를 갖는 AlxGa1-xN(0＜x≤1)을 고온 성장시켜 제3 버퍼층(23)을 형성한다. 즉, MOCVD에 의한 반응 챔버 내에서, 온도를 1050℃로 유지한 상태에서 트리메틸갈륨(Ga(CH3)3)(TMG), 트리메틸알루미늄(Al(CH3)3)(TMA) 및 암모니아(NH3)가스를 반응시켜 두께가 약 100-2000Å인 AlxGa1-xN 제3 버퍼층(23)을 제2 버퍼층(22) 위에 형성한다.However, as described above, the GaN second buffer layer 22 formed as described above has a stress due to a lattice constant difference and a thermal expansion coefficient difference between sapphire and GaN. The stress present in the GaN second buffer layer 22 is a stress that is intended to expand in a direction parallel to the thin film plane because the lattice constant of the GaN single crystal is larger than that of sapphire. Therefore, as shown in FIG. 2D, Al x Ga 1-x N (0 <x ≦ 1) having a lattice constant less than GaN is grown on the GaN second buffer layer 22 at high temperature to thereby form the third buffer layer 23. Form. That is, in the reaction chamber by MOCVD, trimethylgallium (Ga (CH 3 ) 3 ) (TMG), trimethylaluminum (Al (CH 3 ) 3 ) (TMA) and ammonia (NH) while maintaining the temperature at 1050 ℃. 3 ) An Al x Ga 1-x N third buffer layer 23 having a thickness of about 100-2000 μs is formed on the second buffer layer 22 by reacting the gas.
이와 같이 형성된 AlxGa1-xN 제3 버퍼층(23)에는 박막면에 평행한 방향으로 수축하려는 스트레스가 존재한다. 그 이유는 AlxGa1-xN의 격자 상수가 GaN의 격자 상수보다 더 적기 때문이다. 따라서, AlxGa1-xN 제3 버퍼층(23)의 두께와 x의 값을 적절히 조절하면 GaN 단결정의 격자 상수와 같은 값을 갖도록 할 수 있다.The Al x Ga 1-x N third buffer layer 23 formed as described above has a stress to shrink in a direction parallel to the thin film surface. This is because the lattice constant of Al x Ga 1-x N is less than that of GaN. Therefore, by appropriately adjusting the thickness of the Al x Ga 1-x N third buffer layer 23 and the value of x, it is possible to have the same value as the lattice constant of the GaN single crystal.
다음에, 도 2e에 도시된 바와 같이, GaN 단결정과 같은 격자 상수를 갖도록 형성된 AlxGa1-xN 제3 버퍼층(23) 위에 결정 성장 속도가 빠른 HVPE나 SVPE법을 사용하여 GaN 단결정(24)을 성장시킨다.Next, as shown in FIG. 2E, the GaN single crystal 24 is formed on the Al x Ga 1-x N third buffer layer 23 formed to have the same lattice constant as the GaN single crystal by using HVPE or SVPE. Grow).
이하, 본 발명에 따른 GaN 단결정 제조 방법을 실시예를 들어 상세히 설명하기로 하되, 본 발명이 하기 실시예로만 한정되는 것은 아니다.Hereinafter, the GaN single crystal manufacturing method according to the present invention will be described in detail by way of examples, but the present invention is not limited only to the following examples.
<실시예><Example>
(0001)사파이어(Al2O3) 기판 상에 MOCVD에 의해 500-600℃의 온도에서 트리메틸갈륨(Ga(CH3)3)(TMG)과 NH3가스를 반응시켜 약 100-2000Å 두께의 저온 GaN 제1 버퍼층을 성장시켰다. 그리고, MOCVD에 의해 1050℃의 온도에서 트리메틸갈륨(Ga(CH3)3)(TMG)과 암모니아 가스를 반응시켜 약 100-2000Å 두께의 고온 GaN 제2 버퍼층을 상기 저온 GaN 제1 버퍼층 위에 성장시켰다. 다음에, MOCVD에 의해 1050℃의 온도에서 트리메틸갈륨(Ga(CH3)3)(TMG), 트리메틸알루미늄(Al(CH3)3)(TMA) 및 암모니아 가스를 반응시켜 약 100-2000Å 두께의 고온 AlxGa1-xN 제3 버퍼층을 상기 고온 GaN 제2 버퍼층 위에 성장시켰다. 이 때, x의 값은 0 내지 0.2의 값을 갖도록 하여 상기 AlxGa1-xN 제3 버퍼층의 격자 상수를 GaN과 거의 일치시켰다. 그리고, 상기 AlxGa1-xN 제3 버퍼층 위에 GaN 단결정을 HVPE 법에 의해 약 50㎛/h의 성장 속도로 성장시켜 5-200㎛의 두께를 갖는 GaN 박막을 형성하였다.A low temperature of about 100-2000 μs thick by reacting trimethylgallium (Ga (CH 3 ) 3 ) (TMG) with NH 3 gas at a temperature of 500-600 ° C. by MOCVD on a (0001) sapphire (Al 2 O 3 ) substrate. The GaN first buffer layer was grown. Then, trimethylgallium (Ga (CH 3 ) 3 ) (TMG) was reacted with ammonia gas at a temperature of 1050 ° C. by MOCVD to grow a high temperature GaN second buffer layer having a thickness of about 100-2000 μs on the low temperature GaN first buffer layer. . Next, trimethylgallium (Ga (CH 3 ) 3 ) (TMG), trimethylaluminum (Al (CH 3 ) 3 ) (TMA) and ammonia gas were reacted by MOCVD at a temperature of 1050 占 폚 to a thickness of about 100-2000 kPa. A high temperature Al x Ga 1-x N third buffer layer was grown on the high temperature GaN second buffer layer. At this time, the value of x was in the range of 0 to 0.2 so that the lattice constant of the Al x Ga 1-x N third buffer layer was approximately equal to GaN. The GaN single crystal was grown on the Al x Ga 1-x N third buffer layer at a growth rate of about 50 μm / h by HVPE to form a GaN thin film having a thickness of 5-200 μm.
이와 같이 형성된 GaN 단결정의 결함 밀도를 조사한 결과, 종래의 제조 방법에 의해 제조된 GaN 단결정의 결함 밀도인 109-1010/㎠보다 적은 107/㎠ 이하의 값이 나타났다. 그리고, 두께가 100㎛ 이상인 GaN 박막으로부터 사파이어 기판을 제거하여 프리 스탠딩(free standing) GaN 단결정 기판을 얻을 수 있었다.As a result of examining the defect density of the GaN single crystal thus formed, a value of 10 7 / cm 2 or less was found to be less than 10 9 -10 10 / cm 2, which is the defect density of the GaN single crystal manufactured by a conventional manufacturing method. Then, the sapphire substrate was removed from the GaN thin film having a thickness of 100 µm or more to obtain a free standing GaN single crystal substrate.
본 발명에 따른 GaN 단결정 제조 방법에 의하면, 사파이어 기판과 성장된 GaN 박막 사이에 존재하는 격자 상수 차 및 열팽창 계수 차에 의하여 발생한 스트레스를 제거할 수 있어, 크랙이 없고 결함이 적은 고품질의 GaN 단결정 기판을 얻을 수 있다. 또한, 본 발명의 제조 방법에 의해 제조된 GaN 단결정 기판 상에 발광 소자를 제조할 때, GaN 기판과 GaN 박막 사이에 격자 상수 차나 열팽창 계수 차가 존재하지 않아 고품질의 박막을 얻을 수 있으며, 수율이 향상되어 GaN 발광 소자의 제조 원가를 경감할 수 있다.According to the GaN single crystal manufacturing method according to the present invention, it is possible to eliminate the stress caused by the lattice constant difference and thermal expansion coefficient difference existing between the sapphire substrate and the grown GaN thin film, high quality GaN single crystal substrate with no cracks and fewer defects Can be obtained. In addition, when manufacturing a light emitting device on a GaN single crystal substrate produced by the manufacturing method of the present invention, there is no lattice constant difference or thermal expansion coefficient difference between the GaN substrate and the GaN thin film to obtain a high quality thin film, the yield is improved The manufacturing cost of the GaN light emitting device can be reduced.
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| KR101065132B1 (en) * | 2009-07-30 | 2011-09-16 | 서울시립대학교 산학협력단 | Method For Manufacturing Gallium Nitride Substrate Using Metal Silicide |
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| JP3396356B2 (en) * | 1995-12-11 | 2003-04-14 | 三菱電機株式会社 | Semiconductor device and method of manufacturing the same |
| JP3409958B2 (en) * | 1995-12-15 | 2003-05-26 | 株式会社東芝 | Semiconductor light emitting device |
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| KR101065132B1 (en) * | 2009-07-30 | 2011-09-16 | 서울시립대학교 산학협력단 | Method For Manufacturing Gallium Nitride Substrate Using Metal Silicide |
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