臺灣博碩士論文加值系統

本論文主旨在進行具鍍鎳基板垂直結構氮化鎵蕭基二極體之研製。我們採用雷射剝離技術(Laser Lift Off, LLO)分離技術和電鍍鎳金屬以進行基板轉置的工作。

實驗結果歸納所得雷射剝離時的最佳加工條件是能量密度為850mJ/cm2 (對於1.70 A、5.20 V、溫度55oC，定電流鍍鎳90分鐘的條件下)。實驗中係以Ti/Al/Ti/Au製作n型GaN之歐姆接觸，經詳細分析退火條件對其接觸電阻值的影響，結果顯示Ti/Al/Ti/Au系統具有優良的熱穩定性和特徵接觸電阻值6.644×10-5 cm2。LLO製程後以AFM觀察undoped-GaN薄膜，其RMS值為4.598 nm。蕭基接觸研究方面，修正型Norde method萃取參數被用以評估不同的ICP及KOH表面處理條件下，對所製得的蕭基二極體電特性的影響，最後再以掃描式電子顯微鏡觀測其表面型態的改變。

In this thesis, the fabrication of GaN vertical Schottky Barrier diodes (SBDs) with Ni pseudo-substrate is studied. Laser Lift Off and Ni electroplating were employed for the removal of the GaN epilayers from the sapphire substrate and serving as a mechanical support for the huge strain in the epilayer as well as conducting substrate, respectively, for the realization of vertical-structure GaN SBDs.
The optimal laser energy to separate GaN epi layer and sapphire substrate is found to be of 850 mJ/cm2 with the nickel substrate was electroplated under the condition of 1.70A、5.20V at 55oC. Ti/Al/Ti/Au metal system was used as ohmic metal to the heavily doped n-type GaN. The influence of annealing condition on the Specific Contact Resistance (SCR) of the (Au/Ti/Al/Ti)/n-GaN contact system is also investigated. Experimental results reveal that the (Au/Ti/Al/Ti)/n-GaN contact system has a good thermal stability and a SCR value as low as 6.644×10-5 cm2. After laser lift off, surface quality of undoped GaN films was also observed by Atom Force Microscope (AFM) and Secondary Emission Microscopy (SEM) technology. Root-mean-square of surface roughness of 4.598 nm was obtained. Electronic characteristics of Schottky barrier diodes (SBDs) were also studied under different ICP and KOH surface treatment conditions.

中文摘要 Ⅰ
英文摘要 Ⅲ
目錄 Ⅴ
表目錄 Ⅷ
圖目錄 Ⅸ

第一章 緒論
1.1 氮化鎵的發展歷史--------------------------------1
1.1.1 氮化鎵的體單晶成長----------------------------1
1.1.2 氮化鎵的異質磊晶技術--------------------------2
1.2 氮化鎵的性質------------------------------------5
1.2.1 氮化鎵的電學特性------------------------------5
1.2.2 氮化鎵的材料特性------------------------------8
1.3 研究動機和本文結構------------------------------12

第二章 金屬與氮化鎵之歐姆接觸---------------------------15
2.1 引言--------------------------------------------15
2.2 金半接觸原理------------------------------------15
2.3 CTLM歐姆接觸電阻率測試原理和方法----------------17
2.4 垂直式氮化鎵蕭基二極體歐姆接觸製作--------------19
2.4.1 環型傳輸線模型實驗----------------------------20
2.4.2 Ti/Al/Ti/Au/n-GaN歐姆接觸---------------------22
2.4.3 熱穩定度分析----------------------------------25
2.4.4 CTLM量測結果整理------------------------------26

第三章 電鍍鎳基板及雷射剝離製程-------------------------30
3.1 電鍍鎳製程和沿革--------------------------------30
3.1.1 電鍍鎳技術和原理------------------------------30
3.1.2 電鍍液組成------------------------------------32
3.1.3 電鍍作業--------------------------------------33
3.2 雷射剝離原理------------------------------------36
3.2.1 準分子雷射系統簡介----------------------------37
3.2.2 氮化鎵的雷射加工機制--------------------------39
3.3 藍寶石基板剝離後結果----------------------------41

第四章 垂直式氮化鎵蕭基二極體之製作與量測分析-----------44
4.1 邊緣終結(Edge termination)技術------------------44
4.2 實驗步驟----------------------------------------46
4.3 結果和討論--------------------------------------50
4.3.1 參數萃取方法----------------------------------50
4.3.2 電性量測結果----------------------------------51
4.3.3 掃描式電子顯微鏡觀察分析----------------------57
4.3.4 雷射剝離後表面處理之必要性--------------------59

第五章 結論---------------------------------------------60

參考文獻-------------------------------------------------62

[1] S. Nakamura, M. Senoh, and T. Mukai, “High-power InGaN/GaN double-
heterostructure violet light emitting diodes,” Appl. Phys. Lett., vol.
62, no. 19, pp. 2390-2392, 1993.
[2] S. Nakamura, M. Senoh, S. Nagahata, N. Iwasa, T. Yamada, T. Matsushita,
H. Kiyoku, and Y. Sugimoto, “InGaN-Based Multi-Quantum-Well-Structure
Laser Diodes,” Jpn. J. Appl. Phys.,vol.35 part2, no. 1b, L74-L76, 1996.
[3] M. A. Khan, J. N. Kuznia, D. T. Olson, J. M. Van Hove, M. Blasingame, and
L. F. Reitz, “High-responsivity photoconductive ultraviolet sensors
based on insulating single-crystal GaN epilayers,” Appl. Phys. Lett.,
vol. 60, no. 23, pp. 2917-2919, 1992.
[4] J. I. Pankove, “Gallium Nitride (GaN) I,” Academic press, San Diego,
1998.
[5] R. B. Zeterstorm, “Synthesis and growth of single crystals of gallium
nitride,” J. Mater. Sci., vol. 5, no. 12, pp. 1102-1104, 1970.
[6] E. Ejder, “Growth and morphology of GaN,” J. Cryst. Growth, vol. 22,
pp. 44-46, 1974.
[7] Y. A. Vodakov, M. 1. Karklina, E. N. Mokhov, A. D. Roenkov, “Growth of
GaN epitaxial layers on sapphire and SiC substrates,” Inorg. Mater.,
vol.16, pp. 537-539, 1980.
[8] Claudio R. Misky, Michael K. Kelly, et al., “Freestanding GaN-substrates
and devices,” Phy. Stat. Sol. (c), vol. 0, no. 6, pp. 1627-1650, 2003.
[9] C. Haberstroh, R. Helbig, R. A. Stein, “Some new features of the
photoluminescence of SiC(6H), SiC(4H), and SiC(15R),” J. Appl. Phys.,
vol. 76, pp. 509-513, 1997.
[10] W. V. Muench, I. Pfaffeneder, “Breakdown field in vapor-grown
silicon carbide p-n junctions,” J. Appl. Phys., vol. 48, pp. 4831-4833,
1977.
[11] G. A. Slack, “Thermal Conductivity of Pure and Impure Silicon, Silicon
Carbide, and Diamond,” J. Appl. Phys., vol. 35, pp. 3460-3466, 1964.
[12] B. J. Baliga, “Modern Power Devices,” Wiley, New York 1987.
[13] Bykhovski A. D., Kaminski M. S., Shur V. V., Chen Q. C., Khan M. A,
“Pyroelectricity in gallium nitride thin films,” Appl. Phys. Lett., vol.
69, pp. 3254-3256, 1996.
[14] http://www.nitronex.com/education/chartApplications.html
[15] Lien, F. C. T. So, and M. A. Nicolet, “An improved forward I-V method
for non ideal Schottky diodes with high series resistance,” IEEE Trans.
Electron Devices, vol. ED-31, no. 10, pp. 1502-1503, 1984.
[16] Bohlin, “Generalized Norde plot including determination of the ideality
factor”, J. Appl. Phys. vol. 60, no. 3, pp. 1223-1224, 1986.
[17] M. Sze, “Physics of Semiconductor Devices,” 2ed. John Wiley & Sons, New
York, 1981.
[18] A. C. Schmitz, A. T. Ping, M. A. Khan, et al., “Metal Contacts to n-Type
GaN,” J. Electronic Materials, vol. 27, no. 4, pp. 255-260, 1998.
[19] L. Zhou, A. T. Ping, K. Boutros, et al., “Characterisation of rhenium
Schottky contacts on n-type AlGaN,” Electronics Letters, vol. 35, no. 9,
pp. 745-746, 1999.
[20] L. S. Yu, D. J. Qiao, Q. J. Xing, et al., “Ni and Ti Schottky barriers
on n-AlGaN grown on SiC substrates,” Appl. Phys. Lett., vol. 73, no. 2,
pp. 238-240, 1998.
[21] G. K. Reeves, “Specific contact resistance using a circular transmission
line model,” Solid-State Electron, vol. 23, no. 5 , pp. 487-490, 1980.
[22] K. Prabhakaran, T. G. Andersson, and K. Nozawa, “Nature of native oxide
on GaN surface and its reaction with Al,” Appl. Phys. Lett., vol. 69,
no. 21, pp. 3212-3214, 1996.
[23] B. P. Luther, et al., “Analysis of a thin AlN interfacial layer in Ti/Al
and Pd/Al ohmic contacts to n-type GaN,” Appl. Phys. Lett., vol. 71, no.
26, pp. 3859-3861, 1997.
[24] F. A. Lowenheim, “Electroplating,” McGraw-Hill, Inc., 1978.
[25] 熊楚強、王月，“電化學”，文京出版社，1997。
[26] J. Bohandy et al., “Metal deposition from a supported metal film using
an excimer laser,” Appl. Phys. Lett., vol.60, no. 4, pp. 1538-1539, 1986.
[27] M. Kelly et al., “Optical Process for Liftoff of Group III-Nitride
Films,” Phys. Stat Sol. (a), vol. 159, no. 1, pp. R3-R4, 1997.
[28] W.S. Wong et al., “Damage-free separation of GaN thin films from
sapphire substrates,” Appl. Phys. Lett., vol. 72, no. 5, pp. 599-601,
1998.
[29] Http://www.lambdaphysik.com
[30] D. C. Hays, K. P. Lee, B. P. Gila, F. Ren, C. R. Abernathy, and S. J.
Pearton, “Dry etching Selectivity of Gd2O3 to GaN and AlN,” J.
Electronic Materials, vol. 29, no. 3, pp. 285-290, 2000.
[31] O. Ambacher, M. S. Brandt, R. Dimitrov, et al., “Thermal stability and
desorption of Group III nitrides prepared by metal organic chemical vapor
deposition,” J. Vac. Sci. Technol. B, vol. 14, no. 6, pp. 3532-3542,
1996.
[32] J. Karpinski, J. Jun and S. Porowski, “Equilibrium pressure of N2 over
GaN and high pressure solution growth of GaN,” J. Cryst. Growth, vol.
66, no. 1, pp. 1-10, 1984.
[33] P. R. Tavernier and D. R. Clarker, “Mechanics of laser-assisted
debonding of films,” J. Appl. Phys., vol. 89, no. 3, pp. 1527-1536 ,2001.
[34] J. H. Bechtel, “Heating of solid targets with laser pulses,” J. Appl.
Phys, vol. 46, no. 4, pp. 1585-1593, 1975.
[35] 許智明“具新穎的邊緣終結設計高崩潰電壓SiC蕭基二極體之研製”國立成功大學92
學年度碩士論文。
[36] A. Motayed, M. Jah, A. K. Sharma, W. T. Anderson, C. W. Litton, and S. N.
Mohammad, “Two-step surface treatment technique: Realization of
nonalloyed low-resistance Ti/Al/Ti/Au ohmic contact to n-GaN, ”J. Vac.
Sci. Technol. B, vol. 22, pp. 663-667, 2004.
[37] J. Kriz, K. Gottfried, Th. Scholz, Ch. Kaufmann, T. GeBner, “Ohmic
contacts to n-type p- olycrystalline SiC for high-temperature
micromechanical applications”, Material Science and Engineering B46, pp.
180-185, 1997.
[38] A. Itoh, T. Kimoto and H. Matsunami, “Efficient Power Schottky
Rectifiers of 4H-SiC”,pr- oc. International Symposium on Power
Semiconductor Device & ICs, Yokohama, 1995.
[39] Shui Jinn Wang and Jiann Tyng Tzeng, “The double-metal schottky power
rectifier: an ad- justable schottky barrier height low-power-loss
diode”, submitted to 1997 International Conference on Solid State Device
sand Materials
[40] A. Castaldini, A. Cavallini, and L. Polenta, “Thickness-related features
observed in GaN epitaxial layers,” Appl. Phys. Lett., vol. 84, no. 24,
pp. 4851-4853, 2004.
[41] S. Ruvimov et al., “Effect of Si doping on the dislocation structure of
GaN grown on the A-face of sapphire,” Appl. Phys. Lett., vol. 69, no. 7,
pp. 990-992, 1996.
[42] Kenji Shiojimaa, Jerry M. Woodall, Christopher J. Eiting, Paul A.
Grudowski, and Russell D. Dupuis, “Effect of defect density on the
electrical characteristics of n-type GaN Schottky contacts,” J. Vac.
Sci. Technol. B, vol. 17, no. 5, pp.2030-2033, 1999.
[43] Uwe Karrer, Claudio R. Miskys, Oliver Ambacher and Martin Stutzmann,
“Free standing Pt/GaN Schottky diodes,” Walter Schottky Institute,
Research Annual report, 2000.
[44] T Palacios, F Calle, M Varela, C Ballesteros, E Monroy, F B Naranjo, M A
Sanchez-Garcia, E Calleja and E Munoz, “Wet etching of GaN grown by
molecular beam epitaxy on Si(111),” Semicond. Sci. and Technol., vol.
15, no. 10, pp. 996-998 (2000)