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Detailed Program
Paper Number : LD-I05
Time Frame : 14:20~14:45
Presentation Date : Thurseday, 27, November
Session Name : LED and Display Matrials
Session Chair 1# : Inhwan Lee
Session Chair 2# : Yasushi Nanishi
High Mobility and Highly Stable Aluminum-doped Indium Zinc Tin Oxide Thin-Film Transistors Compatible with Back-Channel Etch Process
Sung Haeng Cho
Electronics and Telecommunications Research Institute (ETRI),
We report highly stable and high mobility aluminum-doped indium zinc tin oxide (AIZTO) thin-film transistors (TFT) with field effect mobility larger than 30 cm2/Vs of which process is compatible with the current a-Si :H TFT process. Metal oxide semiconductror thin-film transistors (MOS-TFTs) have attracted great attention as a large area electronics such as a backplane for high-resolution TFT-LCD or AMOLED displays due to their excellent performances such as high mobility, current stability and low off current. MOS TFTs have the advantages of good uniformity, low process temperaure, and low fabrication cost compared with LTPS TFTs, but, the convention metal oxide semiconductors such indium gallium zinc oxide (IGZO) or analogues of zinc oxide (ZnO) are vulnerable to strong acidic solutions of metal etchants or dry etchants in plasma which necessarilly need etch stopper (ES) layer on the backchannel to protect it from source/drain (SD) metal etchant in the bottom gate, staggered configuration. It increases the number of mask in TFT process and adds process complexity. Futhermore, ES-TFTs have a limitation to decrease the channel length below the reolution of photolithography due to the design margin for layer-to layer overlap which also increases overlap area between gate and SD which is origin f large parasitic capacitance in ES-TFTs. On the other hand, in back-channel etch (BCE) TFT process, at least 2 masks can be omitted in compared with ES-TFT process if halftone mask is employed and the parasitic capacitance and the channel length can be made as small as possible which will help to realize the low RC delay in bus line and large aperture ratio in high-resolution display. We developed the new metal oxide semiconductor robust against etch-back process and report here that the high mobility oxide TFTs exceeding 30 cm2/Vs can be fabricated in BCE process without back-channel damage with Molybdenum source/drain metal. For comparitive study, ES-TFT and BCE-TFTs are fabricated using the same oxide semiconductor and their electrical performances and stabilities againt bias and current stress are reported in this study.
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