臺灣博碩士論文加值系統

在本篇論文中，針對了高功率、高頻的多通道三閘極氮化鎵氮化 鋁鎵之高電子遷移率電晶體在設計上的優化。眾所皆知，近年來鰭 式場效電晶體的應用在元件微縮下的表現都能有效的降低短通道效 應。但是這種結構在氮化鎵氮化鋁鎵的電晶體中存在著二維電子氣 形成的問題，由於這種高載子遷移率的二維電子氣是透過材料本身 的極化效應形成的，而在鰭式場效電晶體結構中，側壁方向是沒有 極化場存在的，所以減少了傳輸通道中二維電子氣的總量。因此， 雖然鰭式場效電晶體的結構能有效的降低短通道效應，卻也犧牲了 部分的載子傳輸。所以有人提出利用多層的氮化鎵氮化鋁鎵異質結 構形成的多通道結構，來補償因寬度縮減而減少的載子傳輸量。
在第三章中、透過模擬，來探討在氮化鋁鎵中摻雜濃度的影響。 由於二維電子氣是透過極化場以及表面狀態來形成的，所以為了增 加二維電子氣的總量，額外的載子來源如摻雜是必須的。同時多層 異質結構中，氮化鎵傳輸層的厚度也會影響極化場分佈，進而影響 二維電子氣的形成以及其在每一層通道中的分佈。再者、經由模擬 不同鰭寬來去探討其對多通道元件的影響，並且找出常態關閉元件 的條件，以及對電性影響。綜合以上的設計議題探討，找出優化的 設計方向。
在本篇論文的結果中，透過三維模擬我們討論了優化設計的多 通道鰭式場效電晶體的表現以及熱效應的影響。在鰭寬等於40奈米 時、元件能達到常態關閉，且在最大電導值的表現上對比單通道的 鰭式場效電晶體提升了3.2倍。同時常態關閉的四通道元件與傳統 平面結構元件相比也維持了高的導通電流且很好的抑制了短通道效 應。

In this dissertation, the design of multi-channels tri-gate AlGaN/GaN high-electron-mobility transistors (HEMTs) is optimized for high-power and high-frequency applications. The application of FinFET structure has reduced the short channel effect as device shrinks. But the sidewall depletion of two dimensional electron gas reduces the current density is another issue to be overcome. Using multiple AlGaN/GaN heterostructures has been proposed to compensate the current loss from the channel width.
The 2DEG of the GaN HEMT is induced by the polarization charge difference at AlGaN/GaN interface. The source of 2DEG are generally believed to be coming from the surface state. To generate more 2DEG for multi-channel structures, the modulation doping to pro- vide additional carrier source is needed. In addition, the thickness of GaN channel layer between the top and bottom AlGaN layers affects the carrier distribution and performance of the device as well. Thus, different doping density and thickness of GaN configuration were simulated to find the optimized design. Furthermore, different fin width of device with different number of channel are simulated to investigate the changes of transconductance curve.
With a full 3D FEM modeling on carrier transport and heating issues, the optimized design for multi-channel FinFETs was discussed. With a proper design, the optimized normally-on four channel transistor shows 3.2 times higher maximum transconductance (gm,max), as compared to single channel tri-gate device. The on-current is compatible to planar structure while keeping the device to be operated at enhance mode with the suppression of short channel effects.

口試委員會審定書... i
誌謝... ii
中文摘要... iv
英文摘要... vi
目錄... viii
圖目錄... x
表目錄... xvi
1 Introduction... 1
1.1 Motivation... 1
1.2 The property of GaN and AlGaN/GaN based HEMTs... 3
1.3 Defect and Self-heating effect... 7
1.4 The Short Channel Effect... 12
1.5 Tri-gate technology... 15
2 Methodology for the three dimensional simulation... 19
2.1 Electrical Modeling... 19
2.1.1 3D Poisson and drift-diffusion solver... 19
2.1.2 Carrier Transport in AlGaN/GaN HEMT... 21
2.2 Thermal model in AlGaN/GaN HEMTs... 23
2.3 Summary of Simulation Work Flow... 25
3 Investigation of the design issue for optimizing AlGaN/GaN based multi-channel FinFETs... 27
3.1 Simulation model of AlGaN/GaN based multi-channel
FinFETs... 27
3.2 Design issue and optimization... 30
3.2.1 Modulation doping... 30
3.2.2 Thickness of channel layer... 32
3.3 Sidewall gate electrode effect... 35
4 Result of the optimized multi-channel AlGaN/GaN based FinFETs... 41
4.1 Simulation structures... 41
4.2 I-V curve characteristic... 44
4.3 Thermal effect... 48
4.4 Unit current gain frequency fT and unit power-gain cut-off frequency fmax... 50
5 Conclusion... 58
Reference... 60

[1] https : //semiconductor.kaust.edu.sa/Pages/Page − 2017 − 02 − 2610 − 44 − 57 − AM.aspx.
[2] F. Fornetti, Characterisation and Performance Optimisation of GaN HEMTs and Amplifiers for Radar Applications. PhD thesis, University of Bristol, 2010.
[3] N. Goyal and T. A. Fjeldly, “Effects of strain relaxation on bare surface barrier height and two-dimensional electron gas in AlxGa1-xN/GaN heterostructures,” Journal of Applied Physics, vol. 113, no. 1, p. 014505, 2013.
[4] H. Hasegawa, T. Inagaki, S. Ootomo, and T. Hashizume, “Mech- anisms of current collapse and gate leakage currents in Al- GaN/GaN heterostructure field effect transistors,” Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena, vol. 21, no. 4, pp. 1844–1855, 2003.
[5] G. Zhu, H. Wang, Y. Wang, X. Feng, and A. Song, “Performance enhancement of AlGaN/AlN/GaN high electron mobility transistors by thermally evaporated SiO passivation,” Applied Physics Letters, vol. 109, no. 11, p. 113503, 2016.
[6] D. K. shi Shibata, R. Kajitani, M. Ogawa, K. Tanaka, S. Tamura, T. Hatsuda, M. Ishida, and T. Ueda, “1.7 kV/1.0 mΩcm2 normally-off vertical GaN transistor on GaN substrate with re- grown p-GaN/AlGaN/GaN semipolar gate structure,” 2016 IEEE International Electron Devices Meeting (IEDM), pp. 10.1.1– 10.1.4, 2016.
[7] M. Dammann, M. Baeumler, P. Bru ̈ckner, W. Bronner, S. Maroldt, H. Konstanzer, M. Wespel, R. Quay, M. Mikulla, A. Graff, et al., “Degradation of 0.25 μm GaN HEMTs under high temperature stress test,” Microelectronics Reliability, vol. 55, no. 9-10, pp. 1667–1671, 2015.
[8] S. Arulkumaran, T. Egawa, H. Ishikawa, and T. Jimbo, “High- temperature effects of AlGaN/GaN high-electron-mobility transistors on sapphire and semi-insulating SiC substrates,” Applied physics letters, vol. 80, no. 12, pp. 2186–2188, 2002.
[9] E. Ture, GaN-Based Tri-Gate High Electron Mobility Transistors. BoD–Books on Demand, 2018.
[10] T. Hashizume, K. Nishiguchi, S. Kaneki, J. Kuzmik, and Z. Yatabe, “State of the art on gate insulation and surface passivation for GaN-based power HEMTs,” Materials science in semi- conductor processing, vol. 78, pp. 85–95, 2018.
[11] S. Takashima, Z. Li, and T. P. Chow, “Sidewall dominated characteristics on fin-gate AlGaN/GaN MOS-channel-HEMTs,” IEEE Transactions on Electron Devices, vol. 60, no. 10, pp. 3025–3031, 2013.
[12] P.-C. Chou, T.-E. Hsieh, S. Cheng, J. A. del Alamo, and E. Y. Chang, “Comprehensive dynamic on-resistance assessments in GaN-on-Si MIS-HEMTs for power switching applications,” Semi- conductor Science and Technology, vol. 33, no. 5, p. 055012, 2018.
[13] S. M. C. . sales, “Gallium Nitride ( GaN ) Microwave Transistor Technology For Radar Applications,” 2008.
[14] R. Balmer, D. Soley, D. Wallis, A. Pidduck, L. Koker, and M. Uren, “Gallium nitride growth on silicon for microwave heterojunction field effect transistors,” 09 2019.
[15] Z. Liu, “High Frequency Small-Signal Modelling of GaN High
Electron Mobility Transistors for RF applications,” Master’s thesis, University of Victoria, 2016.
[16] T. Palacios, A. Chakraborty, S. Heikman, S. Keller, S. DenBaars, and U. Mishra, “AlGaN/GaN high electron mobility transistors with InGaN back-barriers,” IEEE Electron Device Letters, vol. 27, no. 1, pp. 13–15, 2005.
[17] D. S. Lee, X. Gao, S. Guo, and T. Palacios, “InAlN/GaN HEMTs with AlGaN back barriers,” IEEE Electron Device Letters, vol. 32, no. 5, pp. 617–619, 2011.
[18] L.-C. Chang, J.-H. Lin, C.-J. Dai, M. Yang, Y.-H. Jiang, Y.-R. Wu, and C.-H. Wu, “Systematic investigation of the threshold voltage modulation of AlGaN/GaN Schottky-gate Fin-HEMTs,” Journal of Applied Physics, vol. 125, no. 9, p. 094502, 2019.
[19] C.-Y. Chen and Y.-R. Wu, “Studying the short channel effect in the scaling of the AlGaN/GaN nanowire transistors,” Journal of Applied Physics, vol. 113, no. 21, p. 214501, 2013.
[20] R. Chu, Y. Zhou, J. Liu, D. Wang, K. J. Chen, and K. M. Lau, “AlGaN-GaN double-channel HEMTs,” IEEE Transactions on electron devices, vol. 52, no. 4, pp. 438–446, 2005.
[21] A. Botchkarev, H. Tang, A. Salvador, O ̈. Aktas, W. Kim, H. Morko ̧c, et al., “AlGaN/GaN double heterostructure channel modulation doped field effect transistors (MODFETs),” Electronics Letters, vol. 33, no. 9, pp. 814–815, 1997.
[22] R. Gaska, M. Shur, T. Fjeldly, and A. Bykhovski, “Two-channel AlGaN/GaN heterostructure field effect transistor for high power applications,” Journal of applied physics, vol. 85, no. 5, pp. 3009– 3011, 1999.
[23] N. H. Sheng, C. P. Lee, R. T. Chen, D. L. Miller, and S. J. Lee, “Multiple-channel GaAs/AlGaAs high electron mobility transistors,” IEEE Electron Device Letters, vol. 6, pp. 307–310, June 1985.
[24] K. J. Chen, O. Hberlen, A. Lidow, C. l. Tsai, T. Ueda, Y. Ue- moto, and Y. Wu, “GaN-on-Si Power Technology: Devices and Applications,” IEEE Transactions on Electron Devices, vol. 64, pp. 779–795, March 2017.
[25] E. A. Jones, F. F. Wang, and D. Costinett, “Review of Com- mercial GaN Power Devices and GaN-Based Converter Design Challenges,” IEEE Journal of Emerging and Selected Topics in Power Electronics, vol. 4, pp. 707–719, Sep. 2016.
[26] S. L. Selvaraj, A. Watanabe, A. Wakejima, and T. Egawa, “1.4- kV Breakdown Voltage for AlGaN/GaN High-Electron-Mobility Transistors on Silicon Substrate,” IEEE Electron Device Letters, vol. 33, pp. 1375–1377, Oct 2012.
[27] U. K. Mishra, L. Shen, T. E. Kazior, and Y. Wu, “GaN-Based RF Power Devices and Amplifiers,” Proceedings of the IEEE, vol. 96, pp. 287–305, Feb 2008.
[28] J. M. Tirado, J. L. Sanchez-Rojas, and J. I. Izpura, “Trapping effects in the transient response of AlGaN/GaN HEMT devices,” IEEE Transactions on Electron Devices, vol. 54, no. 3, pp. 410– 417, 2007.
[29] G. Meneghesso, G. Verzellesi, R. Pierobon, F. Rampazzo, A. Chini, U. K. Mishra, C. Canali, and E. Zanoni, “Surface- related drain current dispersion effects in AlGaN-GaN HEMTs,” IEEE Transactions on Electron Devices, vol. 51, no. 10, pp. 1554– 1561, 2004.
[30] R. Vetury, N. Q. Zhang, S. Keller, and U. K. Mishra, “The impact of surface states on the DC and RF characteristics of AlGaN/GaN HFETs,” IEEE Transactions on Electron Devices, vol. 48, no. 3, pp. 560–566, 2001.
[31] M. Sun, Y. Zhang, X. Gao, and T. Palacios, “High-performance GaN vertical fin power transistors on bulk GaN substrates,” IEEE Electron Device Letters, vol. 38, no. 4, pp. 509–512, 2017.
[32] R. Joshi, “Temperature-dependent electron mobility in GaN: Effects of space charge and interface roughness scattering,” Applied physics letters, vol. 64, no. 2, pp. 223–225, 1994.
[33] O. Aktas, Z. Fan, A. Botchkarev, S. Mohammad, M. Roth, T. Jenkins, L. Kehias, and H. Morkoc, “Microwave performance of AlGaN/GaN inverted MODFET’s,” IEEE Electron Device Let- ters, vol. 18, no. 6, pp. 293–295, 1997.
[34] M. Asif Khan, J. Kuznia, D. Olson, W. Schaff, J. Burm, and M. Shur, “Microwave performance of a 0.25 μm gate AlGaN/GaN heterostructure field effect transistor,” Applied Physics Letters, vol. 65, no. 9, pp. 1121–1123, 1994.
[35] W. Lu, J. Yang, M. A. Khan, and I. Adesida, “AlGaN/GaN HEMTs on SiC with over 100 GHz fT and low microwave noise,” IEEE Transactions on Electron Devices, vol. 48, no. 3, pp. 581– 585, 2001.
[36] U. K. Mishra, Y.-F. Wu, B. P. Keller, S. Keller, and S. P. Den- baars, “GaN microwave electronics,” IEEE transactions on mi- crowave theory and techniques, vol. 46, no. 6, pp. 756–761, 1998.
[37] B. Doyle, B. Boyanov, S. Datta, M. Doczy, S. Hareland, B. Jin, J. Kavalieros, T. Linton, R. Rios, and R. Chau, “Tri-gate fully- depleted CMOS transistors: Fabrication, design and layout,” in 2003 Symposium on VLSI Technology. Digest of Technical Papers (IEEE Cat. No. 03CH37407), pp. 133–134, IEEE, 2003.
[38] J.-P. Colinge et al., FinFETs and other multi-gate transistors, vol. 73. Springer, 2008.
[39] B. Doyle, S. Datta, M. Doczy, S. Hareland, B. Jin, J. Kavalieros, T. Linton, A. Murthy, R. Rios, and R. Chau, “High performance fully-depleted tri-gate CMOS transistors,” IEEE Electron Device Letters, vol. 24, no. 4, pp. 263–265, 2003.
[40] C.-K. Li, M. Rosmeulen, E. Simoen, and Y.-R. Wu, “Study on the optimization for current spreading effect of lateral GaN/InGaN LEDs,” IEEE Transactions on Electron Devices, vol. 61, no. 2, pp. 511–517, 2013.
[41] C.-K. Wu, C.-K. Li, and Y.-R. Wu, “Percolation transport study in nitride based LED by considering the random alloy fluctuation,” Journal of Computational Electronics, vol. 14, no. 2, pp. 416–424, 2015.
[42] T. T. Mnatsakanov, M. E. Levinshtein, L. I. Pomortseva, S. N. Yurkov, G. S. Simin, and M. A. Khan, “Carrier mobility model for GaN,” Solid-State Electronics, vol. 47, no. 1, pp. 111–115, 2003.
[43] J. P. Ibbetson, P. Fini, K. Ness, S. DenBaars, J. Speck, and U. Mishra, “Polarization effects, surface states, and the source of electrons in AlGaN/GaN heterostructure field effect transistors,” Applied Physics Letters, vol. 77, no. 2, pp. 250–252, 2000.
[44] B. Jogai, “Influence of surface states on the two-dimensional electron gas in AlGaN/GaN heterojunction field-effect transistors,” Journal of applied physics, vol. 93, no. 3, pp. 1631–1635, 2003.
[45] J. Ma, C. Erine, P. Xiang, K. Cheng, and E. Matioli, “Multi- channel tri-gate normally-on/off AlGaN/GaN MOSHEMTs on Si substrate with high breakdown voltage and low ON-resistance,” Applied Physics Letters, vol. 113, no. 24, p. 242102, 2018.
[46] W. Walukiewicz, H. Ruda, J. Lagowski, and H. Gatos, “Electron mobility in modulation-doped heterostructures,” Physical Review B, vol. 30, no. 8, p. 4571, 1984.
[47] C. Wang, X. Wang, X. Zheng, Q. He, J. Wu, Y. Tian, W. Mao, X. Ma, and Y. Hao, “GaN-based FinFET with double-channel AlGaN/GaN heterostructure,” Electronics Letters, vol. 54, no. 5, pp. 313–315, 2018.
[48] W. Saito, Y. Takada, M. Kuraguchi, K. Tsuda, and I. Omura, “Recessed-gate structure approach toward normally off high- Voltage AlGaN/GaN HEMT for power electronics applications,” IEEE Transactions on Electron Devices, vol. 53, pp. 356–362, Feb 2006.
[49] G. Greco, F. Iucolano, and F. Roccaforte, “Review of technology for normally-off HEMTs with p-GaN gate,” Materials Science in Semiconductor Processing, vol. 78, pp. 96–106, 2018.