Source: http://www.google.com/patents/US7829435?dq=6978253
Timestamp: 2016-06-29 20:07:27
Document Index: 282791924

Matched Legal Cases: ['art, 28', 'Application No. 06730906', 'Application No. 2006800107591', 'Application No. 10156010', 'Application No. 2007', 'Application No. 10']

Patent US7829435 - Method for growth of GaN single crystal, method for preparation of GaN ... - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inPatentsA GaN-based thin film (thick film) is grown using a metal buffer layer grown on a substrate. (a) A metal buffer layer (210) made of, for example, Cr or Cu is vapor-deposited on a sapphire substrate (120). (b) A substrate obtained by vapor-depositing the metal buffer layer (210) on the sapphire substrate...http://www.google.com/patents/US7829435?utm_source=gb-gplus-sharePatent US7829435 - Method for growth of GaN single crystal, method for preparation of GaN substrate, process for producing GaN-based element, and GaN-based elementAdvanced Patent SearchPublication numberUS7829435 B2Publication typeGrantApplication numberUS 12/545,575Publication dateNov 9, 2010Filing dateAug 21, 2009Priority dateApr 4, 2005Fee statusPaidAlso published asCN101180420A, CN101180420B, CN102634849A, CN102634849B, DE602006017195D1, EP1876270A1, EP1876270A4, EP1876270B1, EP2192624A1, EP2192625A1, EP2192625B1, EP2194167A1, EP2194167B1, EP2197049A1, EP2197049B1, EP2197050A1, EP2204477A1, EP2219236A1, EP2219236B1, US8124504, US20080261378, US20100009516, US20100120234, WO2006126330A1Publication number12545575, 545575, US 7829435 B2, US 7829435B2, US-B2-7829435, US7829435 B2, US7829435B2InventorsTakafumi Yao, Meoung-Whan ChoOriginal AssigneeTohoku Techno Arch Co., Ltd., Furukawa Co., Ltd., Mitsubishi Chemical Corporation, Dowa Holdings Co., Ltd., Epivalley Co., Ltd., Wavesquare Inc.Export CitationBiBTeX, EndNote, RefManPatent Citations (18), Non-Patent Citations (12), Referenced by (2), Classifications (32), Legal Events (3) External Links: USPTO, USPTO Assignment, EspacenetMethod for growth of GaN single crystal, method for preparation of GaN substrate, process for producing GaN-based element, and GaN-based element
US 7829435 B2Abstract
1. A GaN-based element fabrication method comprising:
a growing step of sequentially growing a metal buffer layer, a metal nitride layer and a single-crystal GaN layer on an underlying substrate;
an element structure fabrication step of fabricating a GaN-based element structure on the GaN single-crystal layer; and
a chip separation step of separating a stacking structure including the underlying substrate, the metal buffer layer, the metal nitride layer, the single-crystal GaN layer, and the GaN-based element structure, into a plurality of chips
wherein the metal buffer layer and the metal nitride layer respectively include a Cu layer and a Cu nitride layer, alternatively the metal buffer layer and the metal nitride layer respectively include a chromium layer and a chromium nitride layer; and
the chip separation step includes:
a bonding step of bonding a conductive support substrate to the GaN-based element structure through a conductive junction;
a primary scribing step of scribing the stacking structure supported by the conductive support substrate, such that the stacking structure is divided into a plurality of stacking bodies;
an etching step of etching the metal buffer layer and the metal nitride layer by selective chemical etching to remove the underlying substrate from each of the stacking bodies;
a secondary scribing step of scribing the conductive support substrate at spaces between the stacking bodies, such that the stacking bodies are separated into the plurality of chips.
a chemical solution is supplied to the metal buffer layer and the metal nitride layer through the spaces between the stacking bodies formed in the primary scribing step.
This application is a divisional of application Ser. No. 11/910,609, filed Jun. 16, 2008 the entire disclosure of which is hereby incorporated by reference.
At present, however, the important subjects of the GaN-based light emitting elements are a high efficiency, a high output, and a short wavelength in the ultraviolet region. GaN-based thin films and thick films can be grown by methods such as MOCVD (Metal Organic Chemical Vapor Deposition), MBE (Molecular Beam Epitaxy), and HVPE (Hydride Vapor Epitaxy), in accordance with the purposes of the growth, and optical elements or electronic elements are implemented by using these methods. In particular, the HVPE growth method is mainly used in the fabrication of a GaN freestanding substrate obtained by growing a thick GaN film on a sapphire substrate at a high growth rate of 100 μm/hr or more, and separating the substrate and thick GaN film by the laser lift-off method. In the fabrication of GaN-based optical or electronic elements, sapphire or SiC is presently mainly used as a substrate for crystal growth. However, a large lattice mismatching and a large thermal expansion coefficient difference cause a high defect density, that is, a dislocation density of about 1010/cm2, thereby posing many problems such as element characteristic deterioration and the difficulty in element processing caused by the chemical resistance characteristic. Low-defect thin films can be grown by using various buffer layers to decrease the dislocation density, and by using the selective growth or lateral growth technique such as LEO (Lateral Epitaxial Overgrowth) or the PENDEO epitaxy method (non-patent reference 1). However, these growth techniques increase the unit cost of production because a number of steps are necessary to fabricate a substrate before the growth, and also have problems in reproducibility and yield.
As described in the prior art, a high-quality GaN freestanding substrate fabrication technique is desirable to truly put GaN-based elements into practical use. This requires both a technique that forms a high-quality GaN layer on a substrate made of, for example, sapphire, and a technique that separates the GaN layer from the substrate. The present inventors have shown that, although MBE growth method is used, a GaN film having high crystallinity is obtained by epitaxially growing CrN on a sapphire substrate, and subsequently growing GaN layer.
It is an object of the present invention to obtain an industrially practical technique on the basis of the findings on MBE growth method obtained by the present inventors, thereby providing a GaN freestanding substrate fabrication technique.
Since a GaN freestanding substrate is fabricated by selective chemical etching of a metal buffer layer or/and a metal nitride layer, it is possible to greatly improve the fabrication process after lift-off, thereby increasing the throughput and largely reducing the fabrication process cost.
That is, as shown in FIG. 5-2, when GaN is grown on an ideal (111) plane of CrN formed on a c-plane sapphire substrate, the lattice mismatching is 6.6% between the CrN (111) plane and c-plane sapphire, and 8.9% between the GaN (0001) plane and CrN (111) plane, that is, the lattice mismatching can be reduced step by step compared to the case that GaN is directly grown on c-plane sapphire (the lattice mismatching is 16.1%). This suppresses the formation of crystal defects compared to the case that GaN is directly grown. In addition, CrN has a thermal expansion coefficient of 6.00�10−6 [/K], and this value is also an intermediate value between GaN and sapphire. A difference in thermal expansion at GaN(/a buffer layer)/the substrate interface(s) generates cracks in a thick GaN film on a sapphire substrate when the temperature decreases. However, the use of CrN as the buffer layer can presumably reduce the cracks because the thermal expansion coefficient difference can be reduced stepwise. On the other hand, as shown in FIG. 5-1, the relationship between the thermal expansion coefficients of AlN and TiN is AlN (0001)<GaN (0001)<CrN (111)<Al2O3 (0001)<TiN (111), so AlN and TiN cannot reduce the thermal expansion coefficient difference stepwise.
1) First, as shown in FIG. 13 a, a light emitting element or electronic element structure is fabricated by using MOCVD method or MBE method on a GaN template substrate including a GaN single-crystal layer 220 formed by HVPE method or MOCVD method. It is also possible to form a template substrate by forming a single-crystal layer of InxGa1-xN, AlxGa1-xN, or AlxInyGa1-x-yN, instead of the GaN single-crystal layer 220. A light emitting element structure or electronic element structure is fabricated on this template substrate by using MOCVD method or MBE method. FIG. 13 a shows the case that a light emitting element is formed, so the fabrication of this light emitting element will be explained below with reference to FIG. 13.
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS6358770 *Jan 12, 2001Mar 19, 2002Matsushita Electric Industrial Co., Ltd.Method for growing nitride semiconductor crystals, nitride semiconductor device, and method for fabricating the sameUS6455340Dec 21, 2001Sep 24, 2002Xerox CorporationMethod of fabricating GaN semiconductor structures using laser-assisted epitaxial liftoffUS6824610 *Mar 26, 2002Nov 30, 2004Nec CorporationProcess for producing gallium nitride crystal substrate, and gallium nitride crystal substrateUS20010005023Jan 12, 2001Jun 28, 2001Kunio ItohMethod for growing nitride semiconductor crystals, nitride semiconductor device, and method for fabricating the sameUS20020020341Aug 3, 2001Feb 21, 2002The Regents Of The University Of CaliforniaMethod of controlling stress in gallium nitride films deposited on substratesUS20020175340Mar 26, 2002Nov 28, 2002Masatomo ShibataProcess for producing gallium nitride crystal substrate, and gallium nitride crystal substrateCN1617298ANov 17, 2004May 18, 2005金芃Quasi aluminium nitride and quasi gallium nitride base growing substrate and method for growing on alumimium nitride ceramic sheetEP1245702A2Mar 26, 2002Oct 2, 2002Hitachi Cable, Ltd.Process for producing a gallium nitride crystal substrateJP2000049092A Title not availableJP2002284600A Title not availableJP2003095799A Title not availableJP2004039810A Title not availableJP2004059325A Title not availableJP2004247753A Title not availableJP2004269313A Title not availableJP2004363213A Title not availableKR20020076167A Title not availableKR20040067283A Title not available* Cited by examinerNon-Patent CitationsReference1CrN Buffer Layer Study for GaN Growth Using Molecular Beam Epitaxy (22nd North America Conference on Molecular Beam epitaxy: Oct. 2004).2Growth and Characterization of HVPE GaN on c-sapphire with CrN Buffer Layer (31st International Symposium on Compound Semiconductors: Sep. 2004).3Low-Temperature CrN Buffer Layers for GaN Growth Using Molecular Beam Epitaxy (31st International Symposium on Compound Semiconductors: announced in Sep. 12 to 16, 2004).4Pendeo-epitaxy versus Lateral Epitaxial Overgrowth of GaN: A comparative study via finite element Analysis, Zheleva, W.M. Ashmawi, K.A. Jones, phys. Stat. sol. (a) 176, 545 (1999).5RI Kyokugen, et al., "MBE-ho ni yoru Teion CrxN Buffer-so o Mochiita GaN no Seicho", Dai 51 Kai Oyo Butsurigaku Kankei Rengo Koenkai Koen Yokoshu, Mar. 28, 2004, No. 1, p. 364, middle part, 28p-YK-5.6T. Yodo, et al., Influence of substrate nitridation before growth on initial growth process of GaN heteroepitaxial layers grown on Si (001) and Si (111) substrates by ECR-MBE, Journal of Crystal Growth, 2001, vols. 227 to 228, pp. 431 to436, 2. Experimental procedure.7The above reference was cited in a Aug. 24, 2009 Supplementary European Search Report of the counterpart European Patent Application No. 06730906.2.8The above reference was cited in a Jun. 12, 2010 Chinese Office Action, a copy of which is enclosed with Partial English Translation, that issued in Chinese Patent Application No. 2006800107591.9The above reference was cited in a Search Report issued on Apr. 28, 2010, concerning the corresponding European Patent Application No. 10156010.0, which is enclosed.10The above references were cited in a Jun. 1, 2009 Korean Office Action that issued in Korean Patent Application No. 2007-7025453, which is enclosed without English Translation.11The above references were cited in a May 13, 2010 Korean Notice of Allowance, which is enclosed without an English Translation, that issued in Korean Application No. 10 2007-7025453.12This reference was cited in a Mar. 30, 2010 U.S. Office Action, that issued in Parent U.S. Appl. No. 11/910,609.Referenced byCiting PatentFiling datePublication dateApplicantTitleUS7906409 *Mar 15, 2011Canon Kabushiki KaishaDevice manufacturing methodUS20090239356 *Mar 17, 2009Sep 24, 2009Takafumi YaoDevice manufacturing method* Cited by examinerClassifications U.S. Classification438/458, 438/455, 257/E21.602, 438/478, 257/E21.13, 257/E21.108, 257/E21.121International ClassificationH01L33/32, H01L33/12, H01L21/30Cooperative ClassificationH01L33/12, H01L21/0254, H01L21/02614, C30B25/183, H01L21/02458, H01L21/02488, H01L29/2003, H01L21/0237, C30B25/02, H01L33/007, H01L21/02502, H01L21/02491, C30B29/406European ClassificationC30B25/02, C30B29/40B2, H01L21/02K4B1B1, H01L21/02K4B5L2, H01L21/02K4C1B1, H01L21/02K4B1J, H01L21/02K4A1, H01L21/02K4B1L, C30B25/18BLegal EventsDateCodeEventDescriptionMay 19, 2010ASAssignmentOwner name: FURUKAWA CO., LTD.,JAPANFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:TOHOKU TECHNO ARCH CO., LTD.;REEL/FRAME:024406/0302Effective date: 20090901Owner name: MITSUBISHI CHEMICAL CORPORATION,JAPANFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:TOHOKU TECHNO ARCH CO., LTD.;REEL/FRAME:024406/0302Effective date: 20090901Owner name: DOWA HOLDINGS CO., LTD.,JAPANFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:TOHOKU TECHNO ARCH CO., LTD.;REEL/FRAME:024406/0302Effective date: 20090901Owner name: EPIVALLEY CO., LTD.,KOREA, DEMOCRATIC PEOPLE S REPFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:TOHOKU TECHNO ARCH CO., LTD.;REEL/FRAME:024406/0302Effective date: 20090901Owner name: WAVESQUARE INC.,KOREA, DEMOCRATIC PEOPLE S REPUBLIFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:TOHOKU TECHNO ARCH CO., LTD.;REEL/FRAME:024406/0302Effective date: 20090901Owner name: EPIVALLEY CO., LTD., KOREA, DEMOCRATIC PEOPLE S REFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:TOHOKU TECHNO ARCH CO., LTD.;REEL/FRAME:024406/0302Effective date: 20090901Owner name: FURUKAWA CO., LTD., JAPANFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:TOHOKU TECHNO ARCH CO., LTD.;REEL/FRAME:024406/0302Effective date: 20090901Owner name: WAVESQUARE INC., KOREA, DEMOCRATIC PEOPLE S REPUBLFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:TOHOKU TECHNO ARCH CO., LTD.;REEL/FRAME:024406/0302Effective date: 20090901Owner name: MITSUBISHI CHEMICAL CORPORATION, JAPANFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:TOHOKU TECHNO ARCH CO., LTD.;REEL/FRAME:024406/0302Effective date: 20090901Owner name: DOWA HOLDINGS CO., LTD., JAPANFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:TOHOKU TECHNO ARCH CO., LTD.;REEL/FRAME:024406/0302Effective date: 20090901Sep 29, 2010ASAssignmentOwner name: FURUKAWA CO., LTD., JAPANFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:TOHOKU TECHNO ARCH CO., LTD.;REEL/FRAME:025091/0620Effective date: 20090901Owner name: MITSUBISHI CHEMICAL CORPORATION, JAPANFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:TOHOKU TECHNO ARCH CO., LTD.;REEL/FRAME:025091/0620Effective date: 20090901Owner name: EPIVALLEY CO., LTD., KOREA, REPUBLIC OFFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:TOHOKU TECHNO ARCH CO., LTD.;REEL/FRAME:025091/0620Effective date: 20090901Owner name: WAVESQUARE INC., KOREA, REPUBLIC OFFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:TOHOKU TECHNO ARCH CO., LTD.;REEL/FRAME:025091/0620Effective date: 20090901Owner name: DOWA HOLDINGS CO., LTD., JAPANFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:TOHOKU TECHNO ARCH CO., LTD.;REEL/FRAME:025091/0620Effective date: 20090901May 7, 2014FPAYFee paymentYear of fee payment: 4RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services