因為具有較高的載子遷移率以及與矽好的製程相容性，鍺被視為有潛力能夠取代矽的電晶體通道材料。隨著電晶體尺寸微縮，鍺作為電晶體通道材料，能夠增加驅動電流進而改善元件的操作速度。雖然鍺在載子遷移率上優於矽，但還有許多問題需要去討論與解決，鍺的n型場效電晶體，在源極和汲極有相當高的接觸電阻，這可歸因於在鍺中低的n型摻雜活化程度與嚴重的費米能階釘紮，嚴重的摻雜物擴散以及較低的固態溶解度，導致在鍺中有較低的n型摻雜活化程度。本論文中使用雷射退火來進行摻雜活化，短時間且高溫的雷射退火，能夠抑制摻雜物的擴散，以及達到最大的摻雜固態溶解度。
磷摻雜的鍺晶圓分別經快速升溫熱退火、Nd:YAG綠光雷射與CO2雷射退火來進行活化，與快速升溫熱退火相比，兩種雷射退火均有抑制摻雜物擴散的效果。隨著能量增加，綠光雷射退火會導致摻雜物的擴散變強，而由於鍺對CO2雷射有較低的吸收率，因此摻雜活化主要是經由自由載子吸收機制來達成，能量增加只使得摻雜物有些微的擴散，因此可以達到極淺的接面深度。佈植缺陷若未完全修復會導致鍺PN接面極大的漏電，CO2雷射退火在修復PN接面中深層的能態缺陷能力上，會比綠光雷射退火還優異許多，使用CO2雷射退火形成的鍺PN接面漏電流可降低到3×〖10〗^(-4) A/cm2，並且在1V時開關電流比可達到5×〖10〗^4 。另外，我們使用微分霍爾量測來量測表面載子濃度，可發現到磷佈植鍺晶圓經綠光雷射退火後，表面載子濃度有大幅度下降的趨勢，隨著能量的增加，載子濃度下降的幅度越大，從原子力顯微鏡也觀察到表面也變越粗糙，這是因鍺經綠光雷射退火過程中有融化的情形發生，導致相鄰表層有重新結晶的現象，形成表面缺陷，致使電阻率上升。鍺在CO2雷射退火後，則並未觀察到同樣的現象，經磷佈植的鍺晶圓，使用CO2雷射退火後，其距晶圓表面20奈米深度的載子濃度可以達到約1×〖10〗^20 cm-3，接觸電阻率也大幅度降低到3.7×〖10〗^(-7) ohm-cm2，鍺使用CO2雷射退火能夠達到極淺的接面，並且能夠抑制接面漏電以及降低接觸電阻率。

Germanium is considered as a promising transistor channel material to replace silicon due to its higher carrier mobility and good process compatibility with silicon. With shrinking the transistor size, germanium as a transistor channel material can increase drive current and improve the operating speed of the device. Although germanium is superior to silicon in carrier mobility, there are still many problems that need to be solved. Germanium n-MOSFET has relatively high contact resistance at the source and drain, which can be attributed to the low n-type dopant activation in germanium and the strong Fermi level pinning. Severe dopant diffusion and low dopant solubility lead to low n-type dopant activation in germanium. In this study, laser annealing was used to activate phosphorus-doped germanium. Fast and high temperature laser annealing can inhibit the diffusion of dopant and achieve the maximum dopant solubility.
Phosphorus-doped germanium wafers were activated by rapid thermal annealing (RTA), Nd:YAG green laser annealing and CO2 laser annealing, respectively. Compared to RTA, laser annealing had the inhibiting effect of the dopant diffusion. However, as the energy increased, green laser annealing would result in a strong diffusion of dopant. Since germanium had a low absorption rate for CO2 laser, the dopant activation was mainly achieved through the free carrier absorption mechanism. The increase in laser energy only caused slight diffusion of dopant, so extremely shallow junction could be achieved. If the implant damage was not completely repaired, it would cause large leakage current of the germanium PN junction. CO2 laser annealing could repair deep level defects in the PN junction and was much better than green laser annealing. The leakage current of the germanium PN junction caused by CO2 laser annealing could be reduced to 3×〖10〗^(-4)A/cm2, and on/off current ratio could reach 5×〖10〗^4at 1V. We also used differential Hall measurement to evaluate the surface carrier concentration of germanium, and it was found that the surface carrier concentration tended to drop significantly after green laser annealing. As the energy increased, the carrier concentration decreased more and the surface became rougher as observed from the atomic force microscope. This was attributed to the melting of germanium during the green laser annealing process, and it caused the adjacent surface layer to recrystallize and form surface defects and hence increase resistivity. However, the results were not observed for CO2 laser annealing on germanium. For phosphorus-doped germanium activated by CO2 laser annealing, the carrier concentration of 20nm depth from the wafer surface could reach about 1×〖10〗^20cm-3, and the contact resistivity was also reduced to 3.7×〖10〗^(-7) ohm-cm2. Phosphorus-doped germanium activated by CO2 laser annealing could achieve a very shallow junction and suppress junction leakage and reduce contact resistivity .

摘要 i
Abstract iii
致謝 v
目錄 vi
表目錄 ix
圖目錄 x
第一章 序論 1
1.1 前言 1
1.2 鍺需要克服的問題 2
1.3 接觸電阻 3
1.3.1 接觸電阻率與載子傳輸機制 4
1.4 鍺中摻雜活化程度 5
1.4.1 固態溶解度 5
1.4.2 摻雜物在鍺中的擴散速率 6
1.5 增加摻雜溶解度的退火方式 7
1.5.1 雷射退火 7
1.5.2 多次佈植和多次退火 8
1.6 蕭特基能障 8
1.6.1 費米能階釘紮 8
1.6.2 緩解費米能階釘紮的方法 9
1.7研究動機 10
第二章 元件製程與量測 25
2.1 實驗製程與原理 25
2.1.1 離子佈植 26
2.1.2 雷射退火 26
2.1.3 晶圓清洗 27
2.1.4 圖形定義 27
2.1.5 乾式電漿蝕刻 28
2.1.6 沉積金屬電極 28
2.1.7 舉離製程(lift off) 28
2.2 電性量測 28
2.2.1 微分霍爾量測 28
2.2.2 圓形傳輸線模型 31
2.2.3 PN接面 32
2.3 物性分析 32
2.3.1 二次離子質譜儀 32
2.3.2 能量色散X射線光譜 33
2.3.3 穿透式電子顯微鏡 33
2.3.4 原子力顯微鏡 33
第三章 雷射退火對摻雜活化與接觸電阻率的影響 42
3.1 研究方法 42
3.2 製程與條件 42
3.3 實驗結果與討論 43
3.3.1 摻雜物擴散程度 43
3.3.2 佈植損傷與PN接面漏電 44
3.3.3 不同退火條件下活化後載子濃度 45
3.3.4 接觸電阻率 46
第四章 結論與展望 63
4.1 結論 63
4.2 未來展望 64
第五章 參考文獻 65

[1] J. Bardeen, W.H. Brattain, "The transistor, a semi-conductor triode", Physical Review, vol. 74, no. 2, 1948, p. 230.
[2]W. Shockley, "The Theory of p‐n Junctions in Semiconductors and p‐n Junction Transistors", Bell System Technical Journal, vol. 28, no. 3, 1949, pp. 435-489.
[3] G.E. Moore, Cramming more components onto integrated circuits, McGraw-Hill New York, NY, USA:, 1965.
[4] Y. Kamata, "High-k/Ge MOSFETs for future nanoelectronics", Materials Today, vol. 11, no. 1-2, 2008, pp. 30-38.
[5] M. Grundmann, Physics of Semiconductors, Springer, 2010.
[6] C.O. Chui, K. Gopalakrishnan, P.B. Griffin, J.D. Plummer, K.C. Saraswat, "Activation and diffusion studies of ion-implanted p and n dopants in germanium", Applied Physics Letters, vol.83, no. 16, 2003, pp. 3275-3277.
[7] H. Shang, M.M. Frank, E.P. Gusev, J.O. Chu, S.W. Bedell, K.W. Guarini, M. Ieong, "Germanium channel MOSFETs: Opportunities and challenges", IBM Journal of Research and Development, vol. 50, no. 4-5, 2006, pp. 377-386.
[8] K. Prabhakaran, F. Maeda, Y. Watanabe, T. Ogino, "Distinctly different thermal decomposition pathways of ultrathin oxide layer on Ge and Si surfaces", Applied Physics Letters, vol. 76, no. 16, 2000, pp. 2244-2246.
[9] A. Dimoulas, P. Tsipas, A. Sotiropoulos, E. Evangelou, "Fermi-level pinning and charge neutrality level in germanium", Applied Physics Letters, vol.89, no. 25, 2006, p. 252110.
[10] H.H. Radamson, X. He, Q. Zhang, J. Liu, H. Cui, J. Xiang, Z. Kong, W. Xiong, J. Li, J. Gao, "Miniaturization of CMOS", Micromachines, vol.10, no. 5, 2019, p. 293.
[11] H. Wu, O. Gluschenkov, G. Tsutsui, C. Niu, K. Brew, C. Durfee, C. Prindle, V. Kamineni, S. Mochizuki, C. Lavoie, "Parasitic resistance reduction strategies for advanced CMOS FinFETs beyond 7nm", 2018 IEEE International Electron Devices Meeting (IEDM), IEEE, 2018, pp. 35.4. 1-35.4. 4.
[12] A. Razavieh, P. Zeitzoff, E.J. Nowak, "Challenges and limitations of CMOS scaling for FinFET and beyond architectures", IEEE Transactions on Nanotechnology, vol. 18, 2019, pp. 999-1004.
[13] D.K. Schroder, Semiconductor material and device characterization, John Wiley & Sons, 2015.
[14] D.A. Neamen, Semiconductor physics and devices: basic principles, New York, NY: McGraw-Hill, 2012.
[15] R. Hall, "Variation of the distribution coefficient and solid solubility with temperature", Journal of Physics and Chemistry of Solids, vol. 3, no. 1-2, 1957, pp. 63-73.
[16] A. Satta, E. Simoen, T. Janssens, T. Clarysse, B. De Jaeger, A. Benedetti, I. Hoflijk, B. Brijs, M. Meuris, W. Vandervorst, "Shallow junction ion implantation in Ge and associated defect control", Journal of The Electrochemical Society, vol. 153, no. 3, 2006, p. G229.
[17] C. Claeys, E. Simoen, Germanium-based technologies: from materials to devices, Elsevier, 2011.
[18] A. Chroneos, H. Bracht, "Diffusion of n-type dopants in germanium", Applied Physics Reviews, vol. 1, no. 1, 2014, p. 011301.
[19] L. Rebohle, S. Prucnal, W. Skorupa, "A review of thermal processing in the subsecond range: semiconductors and beyond", Semiconductor Science and Technology, vol. 3, no. 1, (10), 2016, p. 103001.
[20] G. Thareja, S. Chopra, B. Adams, Y. Kim, S. Moffatt, K. Saraswat, Y. Nishi, "High n-Type Antimony Dopant Activation in Germanium Using Laser Annealing for n+/p Junction Diode", IEEE Electron Device Letters, vol. 32, no. 7, 2011, pp. 838-840.
[21] A. Nemecek, G. Zach, R. Swoboda, K. Oberhauser, H. Zimmermann, "Integrated BiCMOS pin photodetectors with high bandwidth and high responsivity", IEEE Journal of Selected Topics in Quantum Electronics, vol. 12, no. 6, 2006, pp. 1469-1475.
[22] T.-T. Wu, C.-H. Shen, J.-M. Shieh, W.-H. Huang, H.-H. Wang, F.-K. Hsueh, H.-C. Chen, C.-C. Yang, T.-Y. Hsieh, B.-Y. Chen, "Low-cost and TSV-free monolithic 3D-IC with heterogeneous integration of logic, memory and sensor analogy circuitry for Internet of Things", 2015 IEEE International Electron Devices Meeting (IEDM), IEEE, 2015, pp. 25.4. 1-25.4. 4.
[23] A. Bajard, O. Aubreton, G. Eren, P. Sallamand, F. Truchetet, "3D digitization of metallic specular surfaces using scanning from heating approach", Three-Dimensional Imaging, Interaction, and Measurement, International Society for Optics and Photonics, 2011, p. 786413.
[24] J. Kim, S.W. Bedell, D.K. Sadana, "Improved germanium n+/p junction diodes formed by coimplantation of antimony and phosphorus", Applied Physics Letters, vol. 98, no. 8, 2011, p. H12.
[25] J. Kim, S.W. Bedell, D.K. Sadana, "Multiple implantation and multiple annealing of phosphorus doped germanium to achieve n-type activation near the theoretical limit", Applied Physics Letters, vol. 101, no. 11, 2012, p. 112107.
[26] R. Islam, G. Shine, K.C. Saraswat, "Schottky barrier height reduction for holes by Fermi level depinning using metal/nickel oxide/silicon contacts", Applied Physics Letters, vol. 105, no. 18, 2014, p. 182103.
[27] J.-R. Wu, Y.-H. Wu, C.-Y. Hou, M.-L. Wu, C.-C. Lin, L.-L. Chen, "Impact of fluorine treatment on Fermi level depinning for metal/germanium Schottky junctions", Applied Physics Letters, vol. 99, no. 25, 2011, p. 253504.
[28] G.-S. Kim, S.-H. Kim, J.-K. Kim, C. Shin, J.-H. Park, K.C. Saraswat, B.J. Cho, H.-Y. Yu, "Surface passivation of germanium using SF 6 plasma to reduce source/drain contact resistance in germanium n-FET", IEEE Electron Device Letters, vol. 36, no. 8, 2015, pp. 745-747.
[29] J.-Y.J. Lin, A.M. Roy, Y. Sun, K.C. Saraswat, "Metal-insulator-semiconductor contacts on Ge: Physics and applications", 2012 International Silicon-Germanium Technology and Device Meeting (ISTDM), IEEE, 2012, pp. 1-2.
[30] H. Yu, M. Schaekers, T. Schram, S. Demuynck, N. Horiguchi, K. Barla, N. Collaert, A.V.-Y. Thean, K. De Meyer, "Thermal stability concern of metal-insulator-semiconductor contact: A case study of Ti/TiO2/n-Si contact", IEEE Transactions on Electron Devices, vol. 63, no. 7, 2016, p. 2671-2676.
[31] Z. Li, X. An, M. Li, Q. Yun, M. Lin, M. Li, X. Zhang, R. Huang, "Low electron Schottky barrier height of NiGe/Ge achieved by ion implantation after germanidation technique", IEEE Electron Device Letters, vol. 33, no. 12, 2012, pp. 1687-1689.
[32] C.-P. Chou, H.-H. Chang, Y.-H. Wu, "Enabling low contact resistivity on n-Ge by implantation after Ti germanide", IEEE Electron Device Letters, vol. 39, no. 1, 2017, pp. 91-94.
[33] O. Svelto, D.C. Hanna, Principles of Lasers, Springer, 2010.
[34] J. Mayer, O. Marsh, G. Shifrin, R. Baron, "Ion implantation of silicon: II. electrical evaluation using hall-effect measurements", Canadian Journal of Physics, vol. 45, no. 12, 1967, pp. 4073-4089.
[35] R. Baron, G. Shifrin, O. Marsh, J.W. Mayer, "Electrical behavior of group III and V implanted dopants in silicon", Journal of Applied Physics, vol. 40, no. 9, 1969, pp. 3702-3719.
[36] N. Johansson, J.W. Mayer, O. Marsh, "Technique used in Hall effect analysis of ion implanted Si and Ge", Solid-State Electronics, vol. 13, no. 3, 1970, pp. 317-335.
[37] J.-Y.J. Lin, Low resistance contacts to n-type germanium, Stanford University, 2013.
[38] T. Liu, R. Huang, F. Li, Z. Huang, J. Zhang, J. Liu, L. Zhang, S. Zhang, A. Dingsun, H. Yang, "Study on the measurement accuracy of circular transmission line model for low-resistance Ohmic contacts on III-V wide band-gap semiconductors", Current Applied Physics, vol. 18, no. 7, 2018, pp. 853-858.
[39] T.C. Liu, H. Ikegaya, T. Nishimura, A. Toriumi, "Ge n+/p junctions with high ON-to-OFF current ratio by surface passivation", IEEE Electron Device Letters, vol. 37, no. 7, 2016, pp. 847-850.
[40] M. Miyao, K. Ohyu, T. Tokuyama, "Annealing of phosphorus‐ion‐implanted silicon using a CO2 laser", Applied Physics Letters, vol. 35, no. 3, 1979, pp. 227-229.
[41] M. Shayesteh, D. O’Connell, F. Gity, P. Murphy-Armando, R. Yu, K. Huet, I. Toqué-Tresonne, F. Cristiano, S. Boninelli, H.H. Henrichsen, "Optimized laser thermal annealing on germanium for high dopant activation and low leakage current", IEEE Transactions on Electron Devices, vol.61, no. 12, 2014, pp. 4047-4055.
[42] P. Tsouroutas, D. Tsoukalas, A. Florakis, I. Zergioti, A. Serafetinides, N. Cherkashin, B. Marty, A. Claverie, "Laser annealing for n+/p junction formation in germanium", Materials Science in Semiconductor Processing, vol. 9, no. 4-5, 2006, pp. 644-649.
[43] L.-j. Huang, B.-j. Li, N.-f. Ren, "Enhancing optical and electrical properties of Al-doped ZnO coated polyethylene terephthalate substrates by laser annealing using overlap rate controlling strategy", Ceramics International, vol. 42, no. 6, 2016, pp. 7246-7252.
[44] S.-C. Teng, Z.-Y. Liang, C.-P. Chou, Y.-H. Tsai, P.-W. Chiu, Y.-H. Wu, "Nearly Epitaxial Low-Resistive Co Germanide Formed by Atomic Layer Deposited Cobalt and Laser Thermal Annealing", IEEE Electron Device Letters, vol. 41, no. 2, 2019, pp. 272-275.
[45] T. Nishimura, X. Luo, S. Matsumoto, T. Yajima, A. Toriumi, "Almost pinning-free bismuth/Ge and/Si interfaces", AIP Advances, vol. 9, no. 9, 2019, p. 095013.