Feasibility of an Ag-alloy film as a thin-film transistor liquid-crystal display source/drain material

Journal of Electronic Materials, Jun 2002 by Jeong, C O, Roh, N S, Kim, S G, Park, H S, Et al

Figure 7 shows the transfer characteristics of an a-Si:H TFT using APC as a source/drain material. The subthreshold slope and on/off current ratio obtained from the transfer curve at a drain voltage (VD) of 10 V are 0.9 V/dec and ~10^sup 6^, respectively. The off-- state leakage current is ~10^sup -13^ A at V^sub d^ = 10 V and a gate voltage (V^sub g^) of -5 V The fabricated a-Si:H TFT exhibited a threshold voltage of 4 V The on-state current shows a small drain current of 1.6 pA at VG = 20 V because of the decreasing ratio of WAL by overetching during patterning of the S/D metals.

CONCLUSIONS

Inverted-staggered back-channel-etch a-Si:H TFTs using APC as a source/drain material has been demonstrated. A lower source/drain line resistivity of 2.0 (mu)(Omega)-cm was obtained, which compares to that of AINd metals. The APC films showed improved resistance to agglomeration on annealing compared to pure Ag and exhibited excellent contact with the n a-Si layer. Additionally, the Ag/Si structure was stable at 700 deg C, indicating no diffusion barrier is needed for Ag/Si contacts. Thus, a structure of single layers of gate-Ag alloys and S/D Ag alloys is adaptable to large-size TFT-LCD panels. Such process simplification will achieve cost reductions and productivity improvements of monitors, televisions, and notebook PCs.

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C.O. JEONG,1 N.S. ROH,1 S.G. KIM,1 H.S. PARK,1 C.W. KIM,1

D.S. SAKONG,1 J.H. SEOK,1 K.H. CHUNG,1 WH. LEE,2 DONGWEN GAN,3

PAUL S. HO,3 B.S. CHO,4 B.J. KANG,4 HA YANG,4 Y.K. KO,4 and J.G. LEE 4,5

1.-R&D Team, AMLCD Division, Samsung Electronics Co., Ltd., Kiheung-Eup, Yongin-City, Kyunggi-Do, Korea. 2.-Department of Advanced Materials Engineering, Sejong University, Seoul 143-747, Korea. 3.-Microelectronics Research Center, University of Texas, Austin, TX 78712. 4.School of Metallurgical and Materials Engineering, Kookmin University, Seoul 136-702, Korea. 5.-E-mail: lgab@kookmin.ac.kr