由於金屬氧化物薄膜電晶體獨特的製程特質及材料特性，使它們在新興的薄膜電晶體應用上成為最具有競爭性的選擇，包含均勻性好可以應用在大尺寸的面板、低溫製程而應用於可撓式的結構以及低成本製作等特殊需求的產品上。為了尋求更好的薄膜電晶體(Thin-Film Transistor, TFT)效能，我們將使用CF4電漿處理搭配高介電常數(High-k)材料二氧化鉿(HfO2)閘極絕緣層(Gate Insulator)之非晶氧化銦鎵鋅薄膜電晶體(a-InGaZnO Thin-Film Transistor, a-IGZO TFT)，並針對電性及穩定性改善作探討。
首先，我們利用金屬遮罩(Shadow Mask)製作IGZO-TFT元件，分析各種CF4電漿處理元件之表現找出最佳參數。藉由SIMS及FT-IR的分析，觀察到氟離子確實摻雜進IGZO也擴散至半導體層及絕緣層之介面處，而處理瓦數的增加造成CF2及CF3原子團的增加，蝕刻效果增強影響其元件表現。在搭配高介電常數(High-k)材料二氧化鉿(HfO2)閘極絕緣層(Gate Insulator)之IGZO薄膜電晶體，我們觀察到在不論是電性或是劣化測試，以CF4電漿處理之元件都有較好之特性，尤其在遲滯以及正閘極偏壓劣化測試中都有大幅的改善。最後，我們希望薄化二氧化鉿(HfO2)閘極絕緣層厚度，找到最佳化元件參數。

Amorphous oxide semiconductor is considered to be the most competitive TFT material for last decade. It has several advantages such as great uniformity for large size display, low fabrication temperature and low production cost. In order to pursue greater metal oxide TFT performance and stability, there are many ways can improve such as fluorine-doped, nitrogen-doped and hydrogen-doped. Among all those doping material, the effects of fluorine incorporation in a-IGZO have not been studied complete. Therefore, we will focus on the electrical and stability of fluorinated amorphous InGaZnO-TFT by CF4 plasma treatment.
To begin with, we fabricated IGZO based TFT whose dielectric layer was SiO2 and use CF4 plasma to dope fluorine into IGZO. Through the SIMS depth profile, we discovered that fluorine atoms have diffused towards the a-IGZO/SiO2 interface. In addition, the FT-IR spectrum shows that the relatively content of CF2 and CF3 molecules depend on the plasma power. Next, high-k material HfO2 is selected as the gate insulator. Consequently, both high saturation carrier mobility and small S.S can simultaneously be obtained by the sample with CF4 plasma treatment. Moreover, this sample can operate in enhance mode and continuously positive gate bias with a small Vth shift. Overall, we want to try the best thickness of HfO2 layer with CF4 plasma treatment to achieve superior properties in the future.

[1] J. F. Wager, "Transparent Electronics, " Science, vol. 300, no. 5623, pp. 1245-1246, 2003.
[2] K. Nomura, A. Takagi, T. Kamiya, H. Ohta, M. Hirano and H. Hosono, "Amorphous Oxide Semiconductors for High-Performance Flexible Thin-Film Transistors, " Japanese Journal of Applied Physics, vol. 45, no. 5B, pp. 4303-4308, 2006.
[3] C. Feng, Handbook of Zinc Oxide and Related Materials: Volume Two, Devices and Nano-Engineering, Taylor & Francis Group, 2013.
[4] S.D.Brotherton, "Introduction to Thin Film Transistors Physics and Technology of TFTs, "Springer,pp. 99, 2012.
[5] T. Kim, Y. Nam, J. Hur, S. H. K. Park, and S. Jeon, "The Influence of Hydrogen on Defects of In-Ga-Zn-O Semiconductor Thin-Film Transistors With Atomic-Layer Deposition of Al2O3 , "IEEE Electron Device Letters, vol. 37, no. 9, pp. 1131-1134, 2016.
[6] C. D. Paine, "A study of low temperature crystallization of amorphous thin film indium-tin-oxide", Journal of Applied Physics, Vol. 85, pp. 8445, 1999.
[7] D. Kang, H. Lim, C. Kim, I. Song, J. Park, Y. Park, and J. G. Chung, "Amorphous gallium indium zinc oxide thin film transistors: Sensitive to oxygen molecules", Applied Physics Letters,vol. 90, p.192101,2007.
[8] P. T. Liu, C. H. Chang, C. S. Fuh, Y. T. Liao, and S. M. Sze, "Nitrogenated InGaZnO (a-IGZO:N) Thin Film Transistors, " Journal of Display Technology, vol. 12,no. 10,pp. 1070-1077, 2016.
[9] Z. Ye and M. Wong, "Characteristics of Thin-Film Transistors Fabricated on Fluorinated Zinc Oxide," IEEE Electron Device Letters, vol. 33, no. 4, pp. 549-551, 2012.
[10] L. X. Qian and P. T. Lai, "Fluorinated InGaZnO Thin-Film Transistor With HfLaO Gate Dielectric," IEEE Electron Device Letters, vol. 35, no. 3, pp. 363-365, 2014.
[11] C.L. Fan and M.C. Chen, "Performance Improvement of Excimer Laser Annealed Poly-Si TFTs Using Fluorine Ion Implantation”, Electrochemical and Solid-State Letters, vol. 5, no. 8,pp. G75-G77, 2002.
[12] Z. Ye and M. Wong, “Characteristics of Plasma-Fluorinated Zinc Oxide Thin-Film Transistors,” IEEE Electron Device Letters, vol. 33, no. 8, pp. 1147-1149, 2012.
[13] L. X. Qian and P. T. Lai, “Fluorinated InGaZnO Thin-Film Transistor With HfLaO Gate Dielectric,” IEEE Electron Device Letter., vol. 35, no. 3, pp. 363-365, 2014.
[14] B. Y. Tsui and H. W. Chang, "Formation of interfacial layer during reactive sputtering of hafnium oxide," Journal of Applied Physics, vol. 93, pp. 10119-10124, 2003.
[15] S. H. Lo, D. A. Buchanan, Y. Taur and W. Wang, "Quantum-mechanical modeling of electron tunneling current from the inversion layer of ultra-thin-oxide nMOSFET's," IEEE Electron Device Letters, vol. 18, no. 5, pp. 209-211, 1997.
[16] P. Zurcher, C. J. Tracy, R. E. Jones Jr, P. Alluri, P. Y. Chu, B. Jiang, M. Kim, B. M. Melnick, M. V. Raymond, D. Roberts, T. P. Remmel, T. L. Tsai, B. E. White, S. Zafar and S. J. Gillespie, "Barium Strontium Titanate Capacitors for Embedded Dram," Materials Research Society Symposium Proceedings, vol. 541, pp. 11-22, 1999.
[17] A. Grill, "Electrode structures for integration of ferroelectric or high dielectric constant films in semiconductor devices," Materials Research Society Symposium Proceedings, vol. 541, pp. 89-99, 1999.
[18] K. J. Hubbard and D. G. Schlom, "Thermodynamic stability of binary oxides in contact with silicon," Journal of Materials Research, vol. 11, no. 11, pp. 2757-2776, 1996.
[19] B. Cheng, M. C. Cao, R. Rao, A. Inani, P. V. Voorde, W. M. Greene, J. M. C. Stork, Z. Yu, M. Zeitzoff and J. C. S. Woo, "The impact of High-k gate dielectrics and metal gate electrodes on Sub-100 nm MOSFETs," IEEE Transactions on Electron Devices, vol. 46, no. 7, pp. 1537-1544, 1999.
[20] M. H. Cho, Y. S. Roh, C. N. Whang, K. Jeong, S. W. Nahm, D. H. Ko, J. H. Lee, N. I. Lee and K. Fujihara, "Thermal stability and structural characteristics of HfO2 films on Si (100) grown by atomic-layer deposition," Applied Physics Letters, vol. 81, no. 3, pp. 472-474, 2002.
[21] M. H. Cho, D. H. Ko, Y. G. Choi, K. Jeong, I. W. Lyo, D. Y. Noh, H. J. Kim and C. N. Whang, "Thickness dependence of Y2O3 films grown on an oxidized Si surface," Journal of Vacuum Science & Technology A, vol. 19, no. 1, pp. 200-206, 2001.
[22] B. H. Lee, Y. Jeon, K. Zawadzki, W. J. Qi and J. Lee, "Effects of interfacial layer growth on the electrical characteristics of thin titanium oxide films on silicon," Applied Physics Letters, vol. 74, no. 21, pp. 3143-3145, 1999.
[23] V. Mikhelashvili and G. Eisenstein, "Effects of annealing conditions on optical and electrical characteristics of titanium dioxide films deposited by electron beam evaporation," Journal of Applied Physics, vol. 89, no. 6, pp. 3256-3269, 2001.
[24] J. Robertson, "Band offsets of wide-band-gap oxides and implications for future electronic devices," Journal of Vacuum Science & Technology B, vol. 18, no. 3, pp. 1785-1791, 2000.
[25] G. D. Wilk, R. M. Wallace and J. M. Anthony, "High-K gate dielectrics: Current status and materials properties considerations," Journal of Applied Physics, vol. 89, no. 10, pp. 5243-5275, 2001.
[26] D. C. Hsu, Y. K. Chang, M. T. Wang, P. C. Juan, Y. L. Wang and J. Y. M. Lee, "The positive bias temperature instability of nn-channel metal-oxide-semiconductor field-effect transistors with ZrO2 gate dielectric," Applied Physics Letters, vol. 92, p. 202901, 2008.
[27] B. H. Lee, L. Kang, W. J. Qi, R. Nieh, Y. Jeon, K. Onishi and J. C. Lee, "Ultrathin hafnium oxide with low leakage and excellent reliability for alternative gate dielectric application," Technical Digest-International Electron Devices Meeting., vol. 1999, pp. 133-136, 1999.
[28] I. Barin, Thermochemical Data of Pure Substances, VCH, Weiheim, 1989.
[29] A. Convertino, A. Valentini, T. Ligonzo and R. Cingolani, "Organic–inorganic dielectric multilayer systems as high reflectivity distributed Bragg reflectors," Applied Physics Letters, vol. 71, p. 732, 1997.
[30] N. Miyata, M. Ichikawa, T. Nabatame, T. Horikawa and A. Toriumi, "Thermal stability of a thin HfO2/ultrathin SiO2/Si structure: Interfacial Si oxidation and silicidation," Japanese Jouranl of Applied Physics, vol. 42, pp. 138-140, 2003.
[31] K. J. Choi, W. C. Shin and S. G. Yoon, "Ultrathin HfO2 gate dielectric grown by plasma-enhanced chemical vapor deposition using Hf[OC(CH3)3]4 as a precursor in the absence of O2," Journal of Materials Research, vol. 18, no. 1, pp. 60-65, 2003.
[32] L. Pereira, A. Marques, H. Aguas, N. Nedev, S. Georgiev, E. Fortunato and R. Martins, "Performances of hafnium oxide produced by radio frequency sputtering for gate dielectric application," Materials Science and Engineering B, vol. 109, pp. 89-93, 2004.
[33] O. Renault, D. Samour, D. Rouchon, P. Holliger, A. M. Papon, D. Blin and S. Marthon, "Interface properties of ultra-thin HfO2 films grown by atomic layer deposition on SiO2/Si," Thin Solid Films, vol. 428, pp. 190-194, 2003.
[34] M. Orita, H. Ohta, M. Hirano, S. Narushima and H. Hosono, “Amorphous transparent conductive oxide InGaO3 (ZnO)m (m≤ 4): a Zn4s conductor, ” Philosophical Magazine Part B, vol. 81, no. 5, pp. 501-515, 2001.
[35] D. C. Paine, T. Whitson, D. Janiac, R. Beresford, C. Ow-Yang and B. Lewis, "A study of low temperature crystallization of amorphous thin film indium-tin-oxide," Journal of Applied Physics, vol. 85, no. 12, pp. 8445-8450, 1999.
[36] M. Yasukawa, H. Hosono, N. Ueda and H. Kawazoe, "Novel Transparent and Electroconductive Amorphous Semiconductor: amorphous AgSbO3 Film.," Journal of Applied Physics, vol. 34, no. 3A, pp. L281-L284, 1995.
[37] E. Arca, K. Fleischer and I. V. Shvets, "Magnesium, nitrogen codoped Cr2O3: A p-type transparent conducting oxide," Applied Physics Letters, vol. 99, no. 11, p. 111910, 2011.
[38] Y. Ogo, H. Hiramatsu, K. Nomura, H. Yanagi, T. Kamiya, M. Hirano and H. Hosono,"p-channel thin-film transistor using p-type oxide semiconductor, SnO," Applied Physics Letters, vol. 93, no. 3, p. 032113, 2008.
[39] H. Hiramatsu, K. Ueda, H. Ohta, M. Hirano, T. Kamiya and H. Hosono, "Degenerate p-type conductivity in wide-gap LaCuOS1−xSex (x=0–1) epitaxial film," Applied Physics Letters, vol. 82, no. 7, p. 1048, 2003.
[40] A. J. Bosman and C. Crevecoeur, "Mechanism of the Electrical Conduction in Li-Doped NiO," Physical Review, vol. 144, no. 2, pp. 763-770, 1966.
[41] M. L. Tu, Y. K. Su and C. Y. Ma, "Nitrogen-doped p-type ZnO films prepared from nitrogen gas radio-frequency magnetron sputtering," Journal of Applied Physics, vol. 100, no. 5, p. 053705, 2006.
[42] D. C. Look, G. M. Renlund, R. H. Burgener II and J. R. Sizelove, "As-doped p-type ZnO produced by an evaporation/sputtering process," Applied Physics Letters, vol. 85, no. 22, pp. 5269-5271, 2004.
[43] T. Kamiya, K. Nomura, and H. Hosono, "Origins of High Mobility and Low Operation Voltage of Amorphous Oxide TFTs: Electronic Structure, Electron Transport, Defects and Doping," Journal of Display Technology, vol. 5, no. 12, pp.468-483, 2009.
[44] H. Hosono, M. Yasukawa and H. Kawazoe, "Novel oxide amorphous semiconductors: Transparent conducting amorphous oxides," Journal of Non-Crystalline Solids, vol. 203, pp. 334-344, 1996.
[45] Y. Ohya, H. Saiki and Y. Takahashi, "Preparation of transparent, electrically conducting ZnO film from zinc acetate and alkoxide," Journal of Materials Science, vol. 29, no. 15, pp. 4099-4103, 1994.
[46] R. L. Huffman, "Zno-channel thin-film transistors: Channel mobility," Journal of Applied Physics, vol. 95, no. 10, pp. 5813-5819, 2004.
[47] H. Hosono, "Ionic amorphous oxide semiconductors: Material design, carrier transport, and device application," Journal of Non-Crystalline Solids, vol. 352, pp. 851-858, 2006.
[48] K. Takechi, M. Nakata, T. Eguchi, H. Yamaguchi and S. Kaneko, "Comparison of ultraviolet photo-field effects between hydrogenated amorphous silicon and amorphous InGaZnO4 thin-film transistors," Japanese Journal of Applied Physics, vol. 48, no. 1, p. 010203, 2009.
[49] 戴亞翔,TFT-LCD 面板的驅動與設計,五南圖書出版社股份有限公司, 2008.
[50] J. S. Park, J. K. Jeong, Y. G. Mo, H. D. Kim and C. J. Kim, "Control of threshold voltage in ZnO-based oxide thin film transistors," Applied Physics Letters, vol. 93, no. 3, p. 033513, 2008.
[51] P. Barquinha, L. Pereira, G. Gonalves, R. Martins and E. Fortunato, "The effect of deposition conditions and annealing on the performance of high-mobility GIZO TFTs," Electrochemical and Solid-State Letters, vol. 11, no. 9, pp. H248-H251, 2008.
[52] J. H. Jeong, H. W. Yang, J. S. Park, J. K. Jeong, Y. G. Mo, H. D. Kim, J. Song and C. S. Hwang, "Origin of subthreshold swing improvement in amorphous indium gallium zinc oxide transistors," Electrochemical and Solid-State Letters, vol. 11, no. 6, pp. H157-H159, 2008.
[53] K. Ide, Y. Kikuchi, K. Nomura, M. Kimura, T. Kamiya and H. Hosono, "Effects of excess oxygen on operation characteristics of amorphous In-Ga-Zn-O thin-film transistors," Applied Physics Letters, vol. 99, no. 9, p. 093507, 2011.
[54] S. Y. Huang, T. C. Chang, M. C. Chen, S. W. Tsao, S. C. Chen, C. T. Tsai and H. P. Lo, "Device characteristics of amorphous indium gallium zinc oxide thin film transistors with ammonia incorporation," Solid-State Electronics, vol. 61, no. 1, pp. 96-99, 2011.
[55] Y. K. Moon, S. Lee, W. S. Kim, B. W. Kang, C. O. Jeong, D. H. Lee and J. W. Park, "Improvement in the bias stability of amorphous indium gallium zinc oxide thin-film transistors using an O2 plasma-treated insulator," Applied Physics Letters, vol. 95, p. 013507, 2009.
[56] Luo, Y. R. Comprehensive Handbook of Chemical Bond Energies, CRC Press, Boca Raton, FL, 2007.
[57] K. Nomura, H. Ohta, A. Takagi, T. Kamiya, M. Hirano, and H. Hosono, "Room-temperature fabrication of transparent flexible thin-film transistors using amorphous oxide semiconductors" Nature, vol. 432, no. 25, pp. 488-492, Nov. 2004
[58] A. Takagi, K. Nomura, H. Ohta, H. Yanagi, T. Kamiya, M. Hirano, H. Hosono, "Carrier transport and electronic structure in amorphous oxide semiconductor, a-InGaZnO4,"Thin Solid Films, vol. 486, pp. 38-41, 2005.
[59] 莊東漢, 黃漢邦, 謝國煌, 蔡豐羽, 陳炳宏, 鄭晃忠, 平面顯示器概論,高立圖書有限公司, 2008.
[60] J. K. Um, S. Lee, S. Jin, M. Mativenga, S. Y. Oh, C. H. Lee, and J. Jang, "High-Performance Homojunction a-IGZO TFTs With Selectively Defined Low-Resistive a-IGZO Source/Drain Electrodes," IEEE Transactions on Electron Devices, vol. 62, no. 7,pp. 2212-2218, 2015.
[61] S. F. Durrant, R. P. Mota, and M. A. Bica de Moraes, "Relationships between the plasma environment and the composition and optical properties of plasma-polymerized thin films produced in rf discharges of acetylene-sulfur hexafluoride mixtures," Journal of Applied Physics, vol.71,no. 1,pp. 448-55, 1992.
[62] G. F. Bauerfeldt and G. Arbilla, "Kinetic analysis of the chemical processes in the decomposition of gaseous dielectrics by a non-equilibrium plasma - part 1: CF4 and CF4/O2," Journal of the Brazilian Chemical Society, vol.11, no.2,pp. 121-128, 2000.
[63] J. S. Seo, J. H. Jeon, Y. H. Hwang, H. Park, M. Ryu, S. H. Park and B. S. Bae, " Solution-processed flexible fluorine-doped indium zinc oxide thin-film transistors fabricated on plastic film at low temperature," Scientific Reports, vol. 3, no. 2085, pp. 1–9, 2013.
[64] L. X. Qian and P. T. Lai, "Fluorinated InGaZnO Thin-Film Transistor
With HfLaO Gate Dielectric," IEEE Electron Device Letters, vol. 35, no. 3, pp. 363-365, 2014.
[65] Y. S. Chun, S. Chang and S. Y. Lee, "Effects of gate insulators on the performance of a-IGZO TFT fabricated," Microelectronic Engineering, vol. 88, no. 7, pp. 1590-1593, 2011.
[66] S. Y. Lee, S. Chang and J. S. Lee, "Role of high-k gate insulators for oxide thin film transistors," Thin Solid Films, vol. 518, no. 11, pp. 3030-3032, 2010.
[67] X. D. Huang, J. Q. Song, and P. T. Lai, "Improved Stability of α-InGaZnO Thin-Film Transistor under Positive Gate Bias Stress by Using Fluorine Plasma Treatment," IEEE Electron Device Letters, vol. 38, no. 5, pp.576-579, 2017.
[68] J. K. Jeong, H. W. Yang, J. H. Jeong, Y. G. Mo and H. D. Kim, "Origin of threshold voltage instability in indium-gallium-zinc oxide thin film," Applied Physics Letters, vol. 93, p. 123508, 2008.
[69] J. S. Park, J. K. Jeong, H. J. Chung, Y. G. Mo and H. D. Kim, "Electronic transport properties of amorphous indium-gallium-zinc oxide semiconductor," Applied Physics Letters, vol. 92, p. 072104, 2008.
[70] H.K. Hsu, "Interdiffusion effect on the strained films La0.8Ba0.2MnO3/SrTio3 by off-axis sputtering," M.S. thesis, Phys. Dept., National Sun Yat-sen university, Kaohsiung City, 2006.
[71] R. Ortuño, C. García-Meca, F. J. Rodríguez-Fortuño, A. Håkansson, A. Griol, J. Hurtado, J. A. Ayucar, L. Bellieres, P. J. Rodríguez, F. López-Royo, J. Martí, and A. Martínez, "Midinfrared filters based on extraordinary optical transmission through subwavelength structured gold films," Journal of Applied Physics, pp. 124313, 2009.