Study on hydrogenation of polysilicon thin film transistors by ion implantation

• Published in: IEEE transactions on electron devices Vol. 42; no. 6; pp. 1134 - 1140
• Main Authors: Min Cao, Tiemin Zhao, Saraswat, K.C., Plummer, J.D.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01-06-1995; Institute of Electrical and Electronics Engineers
• Subjects: Annealing; Applied sciences; Electronics; Exact sciences and technology; Hydrogen; Implants; Ion implantation; Leakage current; Microelectronic fabrication (materials and surfaces technology); Plasma immersion ion implantation; Plasma materials processing; Plasma temperature; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Thin film transistors; Threshold voltage; Microelectronic fabrication; Ion implantation; Polycrystal; Temperature effect; Silicon; Thin film transistor; Experimental study; Thermal annealing; Hydrogenation; Electrical characteristic
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/16.387248

Hydrogenation of polysilicon (poly-Si) thin film transistors (TFT's) by ion implantation has been systematically studied. Poly-Si TFT performance was dramatically improved by hydrogen ion implantation followed by a forming gas anneal (FGA). The threshold voltage, channel mobility, subthreshold swing, leakage current, and ON/OFF current ratio have been studied as functions of ion implantation dose and FGA temperature. Under the optimized conditions (H/sup +/ dose of 5/spl times/10/sup 15/ cm/sup -2/ and FGA temperature at 375/spl deg/C), NMOS poly-Si TFT's fabricated by a low temperature 600/spl deg/C process have a mobility of /spl sim/27 cm /sup 2//V/spl middot/s, a threshold voltage of /spl sim/2 V, a subthreshold swing of /spl sim/0.9 V/decade, and an OFF-state leakage current of /spl sim/7 pA//spl mu/m at V/sub DS/=10 V. The avalanche induced kink effect was found to be reduced after hydrogenation.< >