臺灣博碩士論文加值系統

因為非晶的氧化銦鎵鋅薄膜電晶體，具備較好的場效遷移率，較小的次臨界擺幅和較穩定的電性，目前已被廣泛研究，並且應用在下世代的主動式陣列顯示器，例如: 液晶顯示器和平板顯示器。

在這篇論文中，我們使用大氣壓電漿輔助化學氣相沉積系統之氫電漿來沉積我們氧化銦鎵鋅通道，這系統不用在真空系統下運作，因此可以降低我們的成本，並且可以大範圍面積的製作。

隨著莫爾定律的演進，氧化層的厚度也越來越薄，當傳統二氧化矽厚氧化層度薄到1.4奈米時會導致不可避免得漏電流飆高，造成電性上的影響。因此我們採用高介電係數材料二氧化鋯來當我們的氧化層，藉此我們可以獲得較薄的等效氧化層厚度(4.05奈米)，以及較高的驅動電流，卻又不會造成漏電的上升。氮電漿處理可以調變二氧化鋯薄膜的物理及電特性。較好的二氧化鋯薄膜應用在我們的非晶銦鎵鋅氧薄膜電晶體上可以得到更好的電性。

中性粒子束是一種對於未來奈米元件很有前途的一項技術，因為其無損傷及有機和無機材料表面修補，我們利用中性粒子束在我們的鎵鋅氧薄膜和二氧化鋯薄膜，讓我們的電晶體可以得到更好的電性。

我們成功的藉由大氣壓電漿輔助化學氣相沉積製作出以二氧化鋯當氧化層的非晶銦鎵鋅氧薄膜電晶體，它的電子遷移率有12.26 cm2/(V•S)，臨界電壓 1.77 伏特，次臨界擺幅 124 mV/decade，開關電流比 4.2×10^5。而經中性電子束氧電漿處理過的二氧化鋯當氧化層的非晶銦鎵鋅氧薄膜電晶體表現出更佳的電性，它擁有更高的電子遷移率52.22 cm2/V•S，臨界電壓 2.86伏特，更小的次臨界擺幅 74 mV/decade，更高的開關電流比 8.2×10^5。

Amorphous InGaZnO (a-IGZO) Thin Film Transistor (TFTs) has been studied extensively for their perspective applications in next generation active-matrix displays such as liquid crystal displays and flat-panel displays, due to its better field-effect mobility, smaller subthreshold swing (SS) and better electrical characteristics.

In this investigation, we used atmospheric-pressure PECVD (AP-PECVD) to deposit our IGZO active layer. With AP-PECVD, we could deposit IGZO thin film without vacuum system, thus, it could lower our cost, improved the throughput, and applied to large area manufacturing.

As the scaling to Moore’s law, it is terrible that gate oxide is too thin (1.4nm) which caused an intolerable gate leakage due to direct tunneling current. We use the high- material ZrO2 as our oxide to achieve the thinner EOT (4.05nm) and high on current but not degrade the leakage current. Furthermore, the post N2 plasma treatment on ZrO2 oxide can modify the physical and electrical properties, such as RMS, leakage current, the formation of interfacial layer, et al. We could use the modified ZrO2 thin film which shows better electrical properties as the a-IGZO TFT oxide. Thus, the a-IGZO TFT will exhibits better electrical characteristics.

Neutral beam is a promising candidate for the practical fabrication technology for future nano-devices because of damage-free and surface modification of inorganic/organic materials. We use neutral beams in our IGZO and ZrO2 thin films. Thus, our transistors will exhibits better electrical characteristics.

Successfully, we fabricated a-IGZO TFT with AP-PECVD using ZrO2 high-k dielectric. It exhibits comparable mobility of 12.26 cm2/V•S, VT of 1.77 V, subthreshold swing of 124 mV/decade, Ion/Ioff is 4.2×10^5. With the post O2 plasma treatment on ZrO2 oxide by neutral beams, the a-IGZO TFT exhibits higher mobility of 52.22 cm2/V•S, VT of 2.86 V, lower subthreshold swing of 74 mV/decade, higher Ion/Ioff of 8.2×10^5.

Contents
Abstract (Chinese) i
Abstract (English) iii
Acknowledgement v
Table Captions ixx
Figure Captions x

Chapter 1 Introduction 1
1.1 Overview of thin film transistors 1
1.2 Amorphous In-Ga-Zn oxide (a-IGZO) active channel layer 2
1.2.1 Transparent conductive oxide (TCO) film 2
1.2.2 Reasons for amorphous In-Ga-Zn-O (a-IGZO) thin film 2
1.2.3 Issue for amorphous In-Ga-Zn-O (a-IGZO) thin film 3
1.3 High-κ gate dielectric 4
1.3.1 Background of high-κ gate dielectric material 4
1.3.2 Reasons for using high-κ gate dielectric material 5
1.3.3 High-κ gate dielectric material options 8
1.4 Background of atmospheric pressure plasma-enhanced chemical vapor deposition (AP-PECVD) 9
1.5 Plasma treatment by neutral beam system (NBS) 10
1.5.1 Back ground of plasma treatment 10
1.5.2 Neutral beam system 11
1.6 Motivation 12
Chapter 2 Experiment 25
2.1 The ZrO2 capacitor fabricated process 25
2.1.1 ZrO2 capacitor without O2 plasma treatment 25
2.1.2 ZrO2 capacitor with O2 plasma treatment by neutral beam system 25
2.2 Experiment details of IGZO TFT 26
2.2.1 In-Ga-Zn-O TFTs without O2 plasma treatment 26
2.2.2 In-Ga-Zn-O TFTs with O2 plasma treatment on channel layer 27
2.2.3 In-Ga-Zn-O TFTs with O2 plasma treatment on channel layer 27
Chapter 3 Results and Discussions 34
3.1 The C-V and I-V characteristics of ZrO2 capacitors 34
3.2 IGZO TFTs with O2 plasma treatment on IGZO channel 34
3.2.1 The electrical characteristic of IGZO TFTs 34
3.2.2 The secondary ion mass spectrometer analysis of IGZO thin films 35
3.2.3 The auger electron spectroscopy analysis of IGZO thin films 35
3.2.4 The X-ray diffraction analysis of IGZO thin films 36
3.2.5 The X-ray photoelectron spectroscopy analysis of IGZO thin films 36
3.2.6 The atomic force microscope and scanning electros microscopy analysis of IGZO thin films 37
3.2.7 Transmittance analysis of IGZO thin films 37
3.2.8 The Hall measurement of IGZO thin films 37
3.3 IGZO TFTs with O2 plasma treatment on IGZO channel and ZrO2 oxide 38
3.3.1 The electrical characteristic of IGZO TFTs 38
3.3.2 The X-ray diffraction analysis of ZrO2 thin films 39
3.3.3 The X-ray photoelectron spectroscopy analysis of ZrO2 thin films 39
3.3.4 The atomic force microscope analysis of ZrO2 thin films 40
Chapter 4 Conclusions and Future Work 54
4.1 Conclusions 54
4.2 Future work 54

Reference 56

Chapter1
[1.1] D. B. Thomason, et al., “Fully self-aligned tri-layer a-Si:H thin-film transistors with deposited doped contact layer”, IEEE Electron Device Letters, Vol. 19, p. 124-126, 1998.
[1.2] E.Fortunato, et al., “Oxide Semiconductor Thin-Film Transistors: A Review of Recent Advances,” Adv. Mater., vol. 24, pp. 2945-2986, June, 2012.
[1.3] H. Yabuta, et al., “High-mobility thin-film transistor with amorphous InGaZnO4 channel fabricated by room temperature rf-magnetron sputtering”, Appl. Phys. Lett., Vol. 89, pp. 2123-2125, 2006.
[1.4] A. Suresh, et al., “Room temperature pulsed laser deposited indium gallium zinc oxide channel based transparent thin film transistors,” Applied Physics Letters, vol. 90, pp. 123512-123512-3, 2007.
[1.5] K. Ellmer, “Resistivity of polycrystalline zinc oxide films: current status and physical limit,” Journal of Physics D: Applied Physics, vol. 34, p. 3097, 2001.
[1.6] G. Adamopoulos, et al., “Electronic properties of ZnO Field-Effect Transistors Fabricated by Spray Pyrolysis in Ambient Air,” Appl. Phys. Lett., vol. 95, pp. 133507-133507-3, September, 2009.
[1.7] H.-C. Cheng, et al., “Transparent ZnO Thin Film Transistor Fabricated by Sol-gel and Chemical Bath Deposition Combination Method,” Appl. Phys. Lett, vol. 90, pp. 012113-012113-3, January, 2007.
[1.8] C. Avis, J. Jang, “A High Performance Inkjet Printed Zinc Tin Oxide Transparent Thin-Film Transistor Manufactured at the Maximum Process Temperature of 300˚C and Its Stability Test,” Electrochemical and Solid-State Letters, vol. 14, pp. J9-J11, 2011.
[1.9] S. K. Park, et al., “High Performance Solution-Processed and Lithographically Patterned Zinc--Tin Oxide Thin-Film Transistors with Good Operational Stability,” Electrochemical and Solid-State Letters, vol. 12, pp. H256-H258, 2009.
[1.10] Y.-L. Wang, et al., “Room Temperature Deposited Indium Zinc Oxide Thin Film Transistors,” Appl. Phys. Lett., vol. 90, pp. 232103-232103-3, June, 2007.
[1.11] C. Chang-Ken, et al., “The Influence of Channel Compositions on the Electrical Properties of Solution-Processed Indium-Zinc Oxide Thin-Film Transistors,” Display technology, Journal of, vol. 5, pp. 509-514, December, 2009.
[1.12] L. Jae Sang, et al., “High-Performance a-IGZO TFT With ZrO2 Gate Dielectric Fabricated at Room Temperature,” Electron Device Letters, IEEE, vol. 31, pp. 225-227, March, 2010.
[1.13] C. J. Chiu, et al., “High-Performance a-IGZO Thin-Film Transistor Using Ta2O5 Gate Dielectric,” Electron Device Letters, IEEE, vol. 31, pp. 1245-1247, November, 2010.
[1.14] T. Hirao, et al., “Bottom-Gate Zinc Oxide Thin-Film Transistors (ZnO TFTs) for AM-LCDs”, IEEE Trans. Electron Devices, Vol. 55, pp. 3136-3142, 2008
[1.15] W. Lim, et al., “Room-Temperature-Deposited Indium-Zinc Oxide Thin Films with Controlled Conductivity”, Electrochem Solid-State Lett., Vol. 10, pp. 267-269, 2007.
[1.16] K. Nomura, et al., “Room-Temperature Fabrication of Transparent Flexible Thin- Film Transistors using Amorphous Oxide Semiconductors”, Nature, 432, pp. 488-492, October, 2004.
[1.17] H.Q. Chiang, et al., “High mobility transparent thin-film transistors with amorphous zinc tin oxide channel layer”, Appl. Phys. Lett., Vol. 86, pp. 3503-3505, 2005.
[1.18] H. H. Hsieh, et al., “Amorphous ZnO transparent thin-film transistors fabricated by fully lithographic and etching processes”, Appl. Phys. Lett., Vol. 91, pp. 3502-3504, 2007.
[1.19] Paul A. Packan, “Pushing the Limits”, Science vol. 285, pp.2079-2081, 1999.
[1.20] A. I. Kingon, et al., “Alternative dielectrics to silicon dioxide for memory and logic devices”, Nature, 406, pp. 1032-1038, August, 2000.
[1.21] G. S. Higashi, et al., “Recent Progress in Gate Dielectric Scaling”, Appl. Materials. Vol. 1, pp.271-272, 2004.
[1.22] J. Robertson, “High Dielectric Constant Oxides,” Eur. Phys. J. Appl. Phys., vol. 28, pp. 265-291, December, 2004.
[1.23] R. W. Murto, et al., “Challenges in Gate Stack Engineering,” Solid-State Technol., vol. 46, p. 43, October, 2003.
[1.24] A. Tsumura, et al., “Macromolecular electronic device; Field effect transistor with a polythiophene thin film,” Appl. Phys. Lett., vol. 49, p.1210, 1986.
[1.25] L. Kang, et al., “Electrical Characteristics of Highly Reliable Ultrathin Hafnium Oxide Gate Dielectric,” Electron Devices Letters, IEEE, vol. 21, pp. 181-183, April, 2000.
[1.26] H. Kim, et al., “Crystallization Kinetics and Microstructure-dependent Leakage Current Behavior of Ultrathin HfO2 Dielectrics: In Situ Annealing Studies,” Appl. Phys. Lett., vol. 84, pp. 2064-2066, March, 2004.
[1.27] H. Lee, et al., “Electrical Characteristics of a Dy-doped HfO2 Gate Dielectric,” Appl. Phys. Lett., vol. 79, pp. 2615-2617, October, 2001.
[1.28] C. Chaneliere, et al., “Tantalum Pentoxide (Ta2O5) Thin Films for Advanced Dielectric Applications,” Materials Science and Engineering: Reports, vol. 22, pp. 269-322, May, 1998.
[1.29] L. A. Ragnarsson, et al., “Electrical Characterization of Al2O3 n-Channel MOSFETs with Aluminum Gates,” Electron Devices Lett. IEEE, vol. 22, pp. 490-492, October, 2001.
[1.30] S. Guha, et al., “High-Quality Aluminum Oxide Gate Dielectrics by Ultra-High-Vacuum Reactive Atomic-Beam Deposition,” J. Appl. Phys., vol. 90, pp. 512-514, March, 2001.
[1.31] M. Gurvitch, et al., “Study of Thermally Oxidized Yttrium Films on Silicon,” Appl. Phys. Lett., vol. 51, pp. 919-921, July, 1987.
[1.32] J. Kwo, et al., “Properties of High  Gate Dielectrics Gd2O3 and Y2O3 for Si,” J. Appl. Phys., vol. 89, pp. 3920-3927, April, 2001.
[1.33] W. J. Qi, et al., “Performance of MOSFETs with Ultrathin ZrO2 and Zr Silicate Gate Dielectrics,” VLSI Technology. Digest of Technical Papers. 2000 Symposium on, pp. 40-41, June, 2000.
[1.34] M. Copel, et al., “Structure and Stability of Ultrathin Zirconium Oxide Layers on Si(001),” Appl. Phys. Lett., vol. 76, pp. 436-438, November, 2000.
[1.35] T. S. Jeon, et al., “Thermal Stability of Ultrathin ZrO2 Films Prepared by Chemical Vapor Deposition on Si(100),” Appl. Phys. Lett., vol. 78, pp. 368-370, January, 2001.
[1.36] P. O. Rocío, et al., “High-k organic, inorganic, and hybrid dielectric for low-voltage organic field-effect transistors,” Chem. Rev. vol. 110, pp. 205-239, 2010.
[1.37] T. S. Jean, et al., “Thermal Stability of Ultrathin ZrO2 Films Prepared by Chemical Bapor,” Appl. Phys. Lett., vol. 78, pp. 368-370, January, 2001.
[1.38] J. Robertson, “Band Structures and Band Offsets of High Dielectrics on Si,” Applied Surface Science, vol. 190, pp. 2-10, May, 2002.
[1.39] L. Xifeng, et al., “Low-temperature solution-processed zirconium oxide gate insulators for thin-film transistors,” IEEE Transactions on Electron Devices, vol. 60, No. 10, pp. 3413-3416, 2013.
[1.40] J. S. Lee, S. Chang, et al., “High-Performance a-IGZO TFT With ZrO2 Gate Dielectric Fabricated at Room Temperature,” IEEE Electron Device Letters, vol. 31, No. 3, pp. 225-227, 2010.
[1.41] K. M. Chang, et al., “Enhancement of the light-scattering ability of Ga-doped ZnO thin filmsusing SiOx nano-films prepared by atmospheric pressure plasma deposition system,” Thin Solid Films, vol. 548, pp. 460-464. October, 2013.
[1.42] X. F. Li, et al., “Influence of Plasma Treatment on Optical and Electrical Properties of a-InGaZnO Films,” J. Vac. Sci. Technol. A, vol. 31, pp. 031505- 031505-5, March, 2013.
[1.43] H. F. Pu, et al., “Investigation of Oxygen Plasma Treatment on the Device Performance of Solution-processed a-IGZO Thin Film Transistors,” Applied Surface Science, vol. 283, pp. 723-726, October, 2013.
[1.44] J. H. Kang, et al., “Mobility Enhancement in Amorphous InGaZnO Thin-Film Transistors by Ar Plasma Treatment,” Appl. Phys. Lett., vol. 102, pp. 222103-222103-3, June, 2013.
[1.45] K. C. Liu, et al., “Defect passivation by O2 plasma treatment on high-k dielectric HfO2 films at room temperature,” Thin Solid Films., vol. 519, pp. 5110-5113, January, 2011.
[1.46] H. Wang, et al., “Oxygen plasma assisted high performance solution-processed Al2Ox gate insulator for combustion-processed InGaZnOx thin film transistors,” Appl. Phys. Vol. 117, January, 2015.
[1.47] S. Noda, et al., “50nm gate electrode patterning using a neutral-beam etching system,” J. Vac. Sci. Technol. A, vol. 22, p. 1506, July, 2004.
[1.48] S. Samukawa, et al., “Pulse-time modulated plasma discharge for highly selective, highly anisotropic and charge-free etching,” Plasma Source Sci. Technol. 5, pp. 132-138, January, 1996.
[1.49] S. Samukawa, et al., “Pulse-time-modulated electron cyclotron resonance plasma discharge for highly selective, highly anisotropic, and charge-free etching,” J. Vac. Sci. A, vol. 14, p. 3049, August, 1996.
[1.50] T. Kubota, et al., “A 7-nm nanocolumn structure fabricated by using a ferritin iron-core mask and low-energy CI neutral beams,” Apply. Phys. Lett., vol. 84, p. 1555, January, 2004.
[1.51] S. Samukawa, et al., “Ultimate top-down etching processes for future nanoscale device: advanced neutral-beam etching,” Appl. Phys., vol. 45, no. 4A, pp. 2395-2407, April, 2006.
[1.52] A. Suresh, et al., “Transparent, high mobility InGaZnO thin films deposited by PLD,” Thin Solid Film, vol. 561, no. 7, pp. 1326-1329, February, 2007.
[1.53] A. Suresh, et al., “Room temperature pulsed laser deposited indium gallium zinc oxide channel based transparent thin film transistors,” Appl. Phys. Lett., vol. 90, no. 12, pp. 123 512-1-123 512-3, March, 2007.
[1.54] E. M. C. Fortunato, et al., “High mobility indium free amorphous oxide thin film transistors,” Appl. Phys. Lett., vol. 92, no. 22, pp. 222 103-1-222 103-3, May, 2008.
[1.55] J. Park, et al., “High-performance amorphous gallium indium zinc oxide thin-film transistors through N2O plasma passivation,” Appl. Phys. Lett., vol. 93, no. 5, pp. 053 505-1-053 505-3, August, 2008.
[1.56] J. H. Na, et al., “High field-effect mobility amorphous InGaZnO transistors with aluminum electrodes,” Appl. Phys. Lett., vol. 93, no. 6, pp. 063 501-1-063 501-3, August, 2008.
[1.57] Nomura, et al., “Room-temperature fabrication of transparent flexible thin-film transistors using amorphous oxide semiconductors,” Nature, vol. 432, no. 7016, pp. 488-492, Nov, 2004.
[1.58] P. K. Nayak, et al., “High performance solution-deposited amorphous indium gallium zinc oxide thin film transistors by oxygen plasma treatment,” Appl. Phys. Lett., vol. 100, p. 202106, May, 2012.

Chapter2
[2.1] K. M. Chang, et al., “ Transparent conductive indium-doped zinc oxide films prepared by atmospheric pressure plasma jet,” Elsevier, vol. 519, pp. 5114-5117, , May, 2011.




Chapter3
[1.59] K. C. Liu, et al., “Defect passivation by O2 plasma treatment on high-k dielectric HfO2 films at room temperature,” Elsevier, vol. 519, pp. 5110-5113, January, 2011.
[1.60] B. C. Huang, et al., “Effect of the induced electron traps by oxygen plasma treatment on transfer characteristics of organic thin film transistors,” Appl. Phys. Lett., vol. 99, p. 113301, September, 2011.
[1.61] H. Pu, et al., “Investigation of oxygen plasma treatment on the device performance of solution-processed a-IGZO thin film transistors,” Elsevier, vol. 283, pp. 722-726, July, 2013.
[1.62] S. W. Tsao, et al., “Hydrogen-induced improvements in electrical characteristics of a-IGZO thin-film transistors,” Solid-State Electron, vol. 54, no. 12, pp. 1497–1499, December, 2010.
[1.63] G. J. Lee, et al., “High Performance, Transparent a-IGZO TFTs on a Flexible Thin Glass Substrate,” Semiconductor Science and Technology, vol. 29, pp. 035003-03508, January, 2014
[1.64] Y. J. Mi, et al., “A simple One-Step Solution Deposition Process for Constructing High-Performance Amorphous Zirconium Oxide Thin Film,” RSC, Advanced, vol. 4, pp. 6060-6067, December, 2013.
[1.65] H. Wang, et al., “Oxygen plasma assisted high performance solution-processed Al2Ox gate insulator for combustion-processed InGaZnOx thin film transistors,” Appl. Phys. Lett., vol. 117, p. 035703, January, 2015.
[1.66] Y. Jeong, et al., “Optimization of a solution-processed SiO2 gate insulator by plasma treatment for zinc thin film transistors,” Appl. Mater. Interfaces., vol. 10, pp. 2061-2070, December, 2015.