Title :
An analytical method of evaluating variation of the threshold voltage shift caused by the negative-bias temperature stress in poly-Si TFTs
Author :
Maeda, Shigenobu ; Maegawa, Shigeto ; Ipposhi, Takashi ; Kuriyama, Hirotada ; Ashida, Motoi ; Inoue, Yasuo ; Miyoshi, Hirokazu ; Yasuoka, Akihiko
Author_Institution :
ULSI Lab., Mitsubishi Electr. Corp., Hyogo, Japan
fDate :
1/1/1998 12:00:00 AM
Abstract :
The variation of the threshold voltage shift (Vth shift) caused by negative-bias temperature stress (-BT stress) in poly-crystalline silicon thin-film transistors (poly-Si TFTs) was investigated. Based on the chemical reaction caused by -BT stress at the poly-Si/SiO2 interface and the poly-Si grain boundary, an analytical method of evaluating the variation of both the Vth shift and the initial Vth was proposed. It was shown from this analysis that the enlargement of the poly-Si grain, using Si2 H6 gas could be a solution for efficient reduction of the easily hydrogenated dangling bonds which resulted in the Vth shift and suppression of the Vth shift and its variation. Moreover, it was suggested that there are two kinds of the dangling bonds; one is hydrogenated by hydrogenation and can be dehydrogenated by -BT stress; the other is not hydrogenated and the variation of its density is much smaller than the former
Keywords :
dangling bonds; elemental semiconductors; silicon; thin film transistors; Si-SiO2; Si2H6 gas; chemical reaction; dangling bonds; grain boundary; hydrogenation; negative-bias temperature stress; poly-Si/SiO2 interface; polycrystalline silicon thin-film transistor; polysilicon TFT; threshold voltage shift; Chemical analysis; Crystallization; Electrodes; Grain boundaries; Random access memory; Silicon; Stress; Temperature; Thin film transistors; Threshold voltage;
Journal_Title :
Electron Devices, IEEE Transactions on
