Title :
Water-related threshold voltage instability of polysilicon TFTs
Author :
Okuyama, K. ; Kubota, K. ; Hashimoto, T. ; Ikeda, S. ; Koike, A.
Author_Institution :
Process Eng. Dev. Dept., Hitachi Ltd., Tokyo, Japan
Abstract :
Negative bias-temperature (NBT) instability of polysilicon thin film transistors (TFTs) has been studied. We found water is strongly related to this phenomenon and can result in a threshold voltage shift of 1 V or more within a short time under NBT stress. This paper shows the results supporting this fact and proves, by using thin LPCVD SiN films, the suppression of water penetration and/or content in the oxides is essential in reducing this instability to an acceptable level. A qualitative model is presented to explain the role of water and experimental results.<>
Keywords :
elemental semiconductors; humidity; insulated gate field effect transistors; moisture; semiconductor device models; silicon; stability; thin film transistors; Si-SiO/sub 2/-BPSG-SiN; Si-SiO2-B2O3-P2O5-SiO2-SiN; model; negative bias-temperature instability; polysilicon TFTs; thin LPCVD SiN films; thin film transistors; threshold voltage instability; water penetration suppression; water-related instability; Crystallization; Degradation; Insulation; MOSFETs; Semiconductor device modeling; Silicon compounds; Stress; Testing; Thin film transistors; Threshold voltage;
Conference_Titel :
Electron Devices Meeting, 1993. IEDM '93. Technical Digest., International
Conference_Location :
Washington, DC, USA
Print_ISBN :
0-7803-1450-6
DOI :
10.1109/IEDM.1993.347295
