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

Volume

45

Issue

1

fYear

1998

fDate

1/1/1998 12:00:00 AM

Firstpage

165

Lastpage

172

Abstract

The variation of the threshold voltage shift (V_th 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 V_th shift and the initial V_th was proposed. It was shown from this analysis that the enlargement of the poly-Si grain, using Si₂H₆ gas could be a solution for efficient reduction of the easily hydrogenated dangling bonds which resulted in the V_th shift and suppression of the V_th 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;

fLanguage

English

Journal_Title

Electron Devices, IEEE Transactions on

Publisher

ieee

ISSN

0018-9383

Type

jour

DOI

10.1109/16.658826

Filename

658826