電晶體通道寬度對低溫複晶矽薄膜元件可靠度影響之研究

Study of Channel-width-dependent Reliability Behavior of LTPS TFTs

梁馨宜(Hsing-Yi Liang)

指導教授 ： 金雅琴 ； 林崇榮

國立清華大學/電機資訊學院/電子工程研究所/碩士(2007年)

摘要

循序性側向結晶技術能有效增大複晶矽的晶粒尺寸及控制晶粒邊界的位置，以提升低溫複晶矽薄膜電晶體的性能。然而，由於循序性側向結晶和一般雷射結晶技術，所成長之晶粒型態不同，循序性側向結晶製程形成與通道長度方向平行之晶粒邊界，將影響元件之可靠度。本論文將探討hot carrier stress對於循序性側向結晶技術之複晶矽薄膜電晶體所造成的影響。由實驗結果顯示，經stress作用後，元件特性的衰退現象和其通道寬度有關。針對此結果，本篇論文提出一全新的衰退機制及電路模型來模擬其衰退行為，以充分預估元件特性在電路操作下的變化。

關鍵字

低溫複晶矽薄膜 ； 可靠度

並列摘要

Sequential lateral solidification (SLS) technology developed for crystallizing amorphous Si enlarges grain size and controls the position of grain boundaries effectively. However, thin-film transistors made by SLS suffer reliability issues possibly due to the innate sub-grain boundaries parallel to the drain current direction as a result of this unique solidification process. In this thesis, we observed channel-width-dependent degradation on these devices after hot carrier stress. A degradation model was proposed and verified by comparing the measured characteristic with the simulated behavior on the proposed sub-circuit, which successfully explains the degraded transistor behavior and its width dependence.

並列關鍵字

LTPS ； TFT ； reliability

參考文獻

[2] F. Hayashi, et. al., “A high performance polysilicon TFT sing RTA and plasma hydrogenation applicable to highly stable SRAMs of 16Mbit and beyond,” in Symp. On VLSI Technology, pp.36-37, 1992.

[3] J.H. Lee, et. al., “A new poly-Si TFT current-mirror pixel for Active Matrix Organic Light Emitting Diode,” EEE Electron Device Lett., vol. 27, no.10, pp. 830-833, 2006.

[4] T. Noma, et. al.,“Crystal forms by solid-state recrystallization of amorphous Si films on SiO2,” Appl. Phys. Lett., vol. 59, no. 6, pp.653-655, 1991.

[5] S. W. Lee, et. al.,“Low temperature poly-Si thin-film transistor fabrication by metal-induced lateral crystallization,” IEEE Electron Device Lett., vol. 17, no. 4, pp. 160-162, 1996.

[6] C. Hayzelden and J. L. Batstone, “Silicide formation and silicide-mediated crystallization of nickel-implanted amorphous silicon thin films,” J. Appl. Phys., vol. 73, no.12, pp. 8279-8289, 1993.