非晶相銦鎵鋅氧化物薄膜電晶體之電性及穩定度研究

非晶相銦鎵鋅氧化物 (a-IGZO)中有許多的能隙缺陷會造成元件之不穩定，如電晶體在正偏壓測試下會有臨界電壓正偏的現象，在負偏壓測試下會有臨界電壓負偏的現象。了解a-IGZO 穩定度將對未來的使用更有幫助。在本篇論文中探討了水對於IGZO 薄膜電晶體的電性影響以及穩定度研究，亦分析在不同環境下之穩定度測試並探討其物理機制。發現在空氣中的水分子會吸附於IGZO表面造成元件電性變差，而且在正偏壓測試下會與一般正偏趨勢相反，會呈現臨界電壓負偏的現象，在負偏壓也是相反的趨勢，即負偏壓測試下臨界電壓正偏的現象。為避免水的效應，加強鈍化層可以大幅改善。第二章中，利用雙閘極結構，以上閘極或下閘極操作薄膜電晶體即可分辨上層或下層通道之好壞。運用下閘極操作電晶體時，加以使用不同上閘極偏壓，改變載子移動之路徑，輔以電腦軟體輔助說明，能夠探討a-IGZO 通道中不同區域之品質好壞，運用此方式可以詳細分析且改善製程條件。除此之外，利用上閘極不同偏壓將載子轉移至較佳之通道區域，是除了改善製程外，另外能再次提升薄膜電晶體之載子遷移率之方式。不同氧流量沉積之IGZO，呈現不同的能隙缺陷，影響後續薄膜電晶體之電性及穩定度。第三章中，製作雙層通道之IGZO元件，在濺鍍a-IGZO通道時，改變氧流量製成上下兩層不同氧流量的通道，運用低氧電性好，高氧在照光穩定度好的特性，將能改善元件電性及穩定度。

關鍵字

薄膜電晶體；非晶相銦鎵鋅氧化物；水效應；雙層通道；穩定度測試

並列摘要

The high density of defect states in a-IGZO causes device instability. The a-IGZO thin film transistors (TFTs) reportedly suffer from positive threshold voltage (VT) shift after positive bias stress (PBS) and negative VT shift after negative bias stress (NBS). Therefore, realize the a-IGZO characteristic for external factor is critical for the InGaZnO applications. In this work, we studied the water effect of InGaZnO and the VT instability of a-IGZO TFTs was investigated in different environment. The water molecules in air adsorb at IGZO/SiO2 interface. This effect affects the electrical property and the instability of devices. Make the negative threshold voltage shift after positive bias stress and positive VT shift after negative bias stress. To avoid this effect, the good passivation layer is needed. The electrical characterization of the double gate a-IGZO TFT structure is used to analyze the device. It shows the better electrical property performance using bottom gate sweep than top gate sweep. This is due to the fact that the back-channel-etching (BCE) type TFT which back surface is vulnerable to plasma damage when dry-etch process are used for S/D deposition. Bottom gate sweep with different top gate bias affect the mobility and subthreshold swing (SS). It is the way to control the carriers flow. This method also provides the good way to analyze the quality of the region. Double gate structure can enhance the performance by controlling the carriers in the good quality region. The density of defect state in a-IGZO degrades the device performance and cause the device instability. The oxygen proportion of a-IGZO is one of the factors to affect the density of defect state in a-IGZO. The low oxygen proportion IGZO devices show the better electrical property and worse instability. On the other hand, high oxygen proportion IGZO devices show the worse electrical property and better instability. It is a method to make dual channel TFTs better.

並列關鍵字

Thin film transistors ； Amorphous InGaZnO ； Water effect ； Dual channel ； Reliability test

參考文獻

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[3] Y. G. Mo, M. Kim, and H. D. Kim, “Amorphous-oxide TFT backplane for large-sized AMOLED TVs,” Jsid, vol. 19, no. 1, pp. 16–20 (2011).

[4] K. H. Cherenack, N. S. Munzenrieder, and G. Troster, “Impact of mechanical bending on ZnO and IGZO thin-film transistors,” IEEE Electron Device Lett., vol. 31, no. 11, pp. 1254–1256 (2010).

[5] J. S. Park, T. W. Kim, D. Stryakhilev, J. S. Lee, S. G. An, Y. S. Pyo, D. B. Lee, Y. G. Mo, D. U. Jin, and H. K. Chung, “Flexible full color organic light-emitting diode display on polyimide plastic substrate driven by amorphous indium gallium zinc oxide thin-film transistors,” Appl. Phys. Lett., vol. 95, no. 1, pp. 51–53 (2009).

[6] H. Yabuta, M. Sano, K. Abe, T. Aiba, T. Den, H. Kumomi, K. Nomura, T. Kamiya, and H. Hosono, “High-mobility thin-film transistor with amorphous InGaZnO4 channel fabricated by room temperature rf-magnetron sputtering,” Appl. Phys. Lett., vol. 89, no. 11, pp. 1–4 (2006).

國際替代計量

非晶相銦鎵鋅氧化物薄膜電晶體之電性及穩定度研究

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