Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/8633
標題: 非晶矽薄膜電晶體在不同頻率電漿處理下之特性 研究
Study on the Characteristics of Amorphous Silicon Thin Film Transistors under different RF Plasma Treatment
作者: 賴葳
wei, Lai
關鍵字: 非晶矽薄膜電晶體
a-Si TFTs
電漿,
Plasma
出版社: 電機工程學系所
引用: 參考文獻 [1] .Fan,Ching-Lin, Yang,Tsung-Hsien,“Effects of NH3 plasma pretreatment before crystallization on low-temperature-processed poly-si thin-film transistors”, Journal of the Electrochemical Society, August 2006,v 153, n 8, p H161-H165 [2] Y. Byun, D. Beer, M. Yang, T. Gu, “A novel amorphous silicon thin film transistor for AMLCDs”, Device Research Conference, 1995. Digest. 1995 53rd Annual, pp.160-161, 1995. [3] Y. Hishikawa, K. Watanabe, S. Tsuda, M. Ohnishi, and Y. Kuwano, “Raman Study on Silicon Network of Hydrogenated Amorphous Silicon Film Deposited by a Glow Discharge”, Jpn. J. Appl. Phys. vol.24, no.5, pp. 385-389, 1985. [4] R. A. Street and M. J. Thompson, “Electronic States at the Hydrogenated Amorphous Silicon/Silicon Nitride Interface”, Appl. Phys. Lett, vol.45, pp.769-771, 1984. [5] K. Hiranaka, T. Yoshimura, and T. Yamaguchi, “Effect of the Deposition Sequence on Amorphous Silicon Thin Film Transistors”, Jpn. J. Appl. Phys. 28, no.11, pp.2197-2200, 1989. [6] H. Uchida, K. Takechi, S. Nishida and S. Kaneko, “High-Mobility and High-Stability a-Si:H Thin Film Transistors With Smooth SiNx/a-Si Interface”, Jpn. J. Appl. Phys. 30, pp.3691-3694, 1991. [7] L. L. Kazmerski, “Polycrystalline and Amorphous Silicon Thin Film and Devices” ,Academic Press, 1980. [8] D. L. Staebler and C. R. Wronski, “Optically induced conductivity changes in discharge-produced hydrogenated amorphous silicon”, J. Appl. Phys. 51, pp.3262-3268, 1980. [9] M. Stutzmann, W. B. Jackson, and C. C. Tsai, “Kinetics of the Staebler-Wronski effect in hydrogenated amorphous silicon”, Appl. Phys. Lett.45(10), vol.15, pp.1075-1077, 1984. [10] B. Pivac, I. Kovacevic, I. Zulim, V. Gradisnik, “Effect of Light Soaking on Amorphous Silicon”, IEEE, pp.884-887, 2000. [11] 簡耀黌,“以PECVD 成長微晶矽薄膜電晶體”,中原大學電機工程系 碩士論文,民國九十六年一月 [12] 莊達人,“VLSI製造技術”,高立出版社 ,民國九十五年六月再版 [13] Masahiko Ando, Masatoshi Wakagi, Tetsuroh Minemura “Comparison of the performance and reliability of wet-etched and dry-etched a-Si:H TFT''s”, IEEE Transactions on Electron Devices, v 45, n 2, p 560-563, Feb 1998. [14] Serage M. GrdelRab , Amir M. Miri , and Savvas G. Chamberlain, “Comparison of the performance and reliability of wet-etched and dry-etched a-Si:H TFT''s”, IEEE Transactions on Electron Devices, v 45, n 2, p 560-563, Feb 1998. [15] Jiun-lin Yeh and Si-Chen Lee, “High field effect mobility deuterated amorphous silicon thin-film transistors based on the substitution of hydrogen with deuterium”, IEEE Electron Device Letters, v 20, n 8, p 415-417, August 1999. [16] Kan Yuan Lee , Yean Kuen Fang , Chii Wen Chen , Mong Song Liang , and Sou Gow Wuu, “High performance polysilicon thin film transistors by H2O plasma hydrogenation”, Thin Solid Films, v 305, n 1-2, p 327-329, Aug 15 1997. [17] Chung Yi , Shi-Woo Rhee , Sae-Hwan Park and Jin-Ho Ju, “Effect of back-channel plasma etching on the leakage current of a-Si:H thin film transistors”, Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers, v 39, n 3 A, p 1051-1053, 2000. [18] Byung Cheon Lim, Young Jin Chio, Jong Hyun Choi and Jin Jang, “Hydrogenated Amorphous Silicon Thin Film Transistor Fabricated on Plasma Treated Silicon Nitride”,IEEE trans. Electron Devices, vol.47, No.2, pp.367,2000. [19] Chuan Yu Wu, Cheng Hsing Chen, Yung Chia Kuan and Kuo Sheng Sun, “High Stable a-si:H TFTs Prepared with Optimum SiNx Film by PECVD Using Taguchi Method”, IDW, pp.1085-1088, 2005. [20] S. W. Lee, K. S. Cho, B. K. Choo, and J. Jang, Member, “Copper Gate Hydrogenated Amorphous Silicon TFT With Thin Buffer layer,” IEEE Electron Device Lett, vol.23, No.6, pp.324-326, 2002. [21] J. H. Choi, C. S. Kim, B. C. Lim, and J. Jang, “A Novel Thin Film Transistor Using Double Amorphous Silicon Active Layer,” IEEE trans. Electron Devices, vol.45, No.9, pp.2074-2076, 1998. [22] D. B. Thomasson and T. N. Jackson, “High Mobility Tri-Layer a-Si:H Thin-Film Transistors with Ultrathin Active Layer,” IEEE Electron Device Lett, vol.18, No.8, pp.397-399, 1997. [23] J. B. Choi, D. C. Yun, Y. I. Park, J. H. Kim, “Properties of hydrogenated amorphous silicon thin film transistors fabricated at 150℃,” Journal of Non-Crystalline Solids 266-269, pp.1315-1319. 2000. [24] J. L. Lin, W. J. Sah, and S. C. Lee, “Amorphous-Silicon Thin-Film Transistors with Very High Field-Effect Mobility,” IEEE Electron Device Lett, vol.12, No.3, pp.120-121, 1991.
摘要: 後通道蝕刻的底部閘極非晶矽薄膜電晶體,雖然有製程步驟簡單的優點,但是因為通道曝露於乾式蝕刻的高能量電漿環境下,將會破壞通道內非晶矽的鍵結,造成底部閘極薄膜電晶體的開電流較小、漏電偏高和可靠度變差的影響,造成整個液晶顯示器光學上的表現變差,這也是為什麼我們極需要研究與探討電漿處理對後通道蝕刻底部閘極薄膜電晶體電性改善的機制。 在本論文中,我們使用完成三道光罩之非對稱式非晶矽薄膜電晶體在裸露出的主動層,運用13.56MHz 和40.68MHz 不同的射頻頻率和NH3、Ar、H2、CF4 不同的氣體電漿源,進行不同製程壓力和混合氣體電漿條件的實驗,然後再比較其處理前與處理後之開電流、漏電流、轉導、臨界電壓,各種電性參數的改善程度。由實驗得之,在製程壓力1Torr 下,運用40.68MHz 射頻頻率產生的NH3 電漿,不管在各項電特性表現都比其他種氣體電漿源來的好,主要是NH3 電漿會解離出N 離子和H 離子,填補主動層內的懸浮鍵(形成N-H 鍵、Si-N 鍵或是Si-H 鍵),使得主動層內鍵結變強,讓主動層內能態 生成以及介電層與主動層接觸表面或介電層內電荷捕捉陷阱的缺陷減少。在NH3 與Ar 混合氣體電漿處理實驗中,通入Ar 氣體比例是很重要的,在不同射頻頻率下,會造成Ar 到底是直接離子轟擊主動層還是幫助NH3 解離,這對薄膜電晶體電性上的改善,會完全不一樣。此外單純通入Ar 氣體,因為它是惰性氣體,對主動層沒有任何修補作用,所以等於是對主動層做離子轟擊,在電漿處理初始階段會讓主動層表面變得平坦化,這對轉導的改善是很明顯的,但也隨著電漿處理時間的增加,改善幅度越來越小。 底部閘極後通道蝕刻式非晶矽薄膜電晶體的結構,一般為5 道光罩製程,然而底部閘極後通道蝕刻非晶矽薄膜電晶體,具有可降低光罩數至4 道的優點,假如電漿參數處理得當,那對業界製造底部閘極後通道蝕刻式非晶矽薄膜電晶體的元件,會有降低成本、提高良率和增加產能提供正面幫助。
Although the BCE-type TFTs of bottom-gate have the advantage of more easier procedure, but the channel is exposed to the dry etching of high energy plasma, which would destroy the a-Si:H bonding in the channel causing lower on current、higher leakage current and worse reliability, and also decrease the optical performance of the display. Therefore we need to research and study the improving mechanism of the BCE-type TFTs after the different plasma treatment conditions. In this thesis, we take the asymmetrical a-Si:H TFTs which have completed three masks processes and the active layer is exposed.And then then they are applied by different RF power (13.56MHz and 40.68MHz) for plasma treatment. We use different gas sources (NH3、Ar、H2、CF4). Process pressure and ratio of mixed gases to improve device’s performance, and then compare the electric at characteristics of Ion、Ioff、Gm、Vth between before-process and after-process. From experiment results, under 40.68MHz RF power at the 1 torr pressure, the electrical characteristics of NH3 plasma treatment are significantly improved as compared with other gas plasma conditions.Because the NH3 plasma will create the N ion and H ion to fill the dangling bond (form N-H bonding、S-H bonding or S-N bonding), it makes the active layer strong and reduces the state creation in the active layer and the interface of dielectric layer and active layer. About the mixing ratio of Ar in the NH3 plasma treatment experiment, Ar ratio is very important to improve device’s performance. At the different RF power, and mixing ratio of Ar, this ion plasma will directly bombardment the active layer or helpfully ion the gas to affect TFTs’ electric characteristics. In addition, when we used Ar gas only, it is no assistance to fix the defect in the active layer of TFTs owing to the inert property of Ar. The significant improve ment of the Gm is due to that Ar plasma directly bombards the surface of the active layer and makes surface flattened. When increasing the treatment time of Ar plasma, the Gm improvement will reduce. The BCE-type of bottom-gate asymmetrical a-Si:H TFTs usual have five-masks process, but it has the possibility the use four-masks to fabricate.If we achieve the optimal condition at the plasma treatment process, it will have the profit of cost down, increasing throughput and yield.
URI: http://hdl.handle.net/11455/8633
其他識別: U0005-2407200915280800
文章連結: http://www.airitilibrary.com/Publication/alDetailedMesh1?DocID=U0005-2407200915280800
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