Title :
Characteristics of high mobility polysilicon thin-film transistors using very thin sputter-deposited SiO2 films
Author :
Yamauchi, Noriyoshi ; Kakuda, Nobuhiko ; Hisaki, Tomoko
Author_Institution :
NTT Interdisciplinary Res. Labs., Tokyo, Japan
fDate :
10/1/1994 12:00:00 AM
Abstract :
Polysilicon thin-film transistors with various gate oxide thicknesses ranging from 94 to 7 nm using sputter-deposited SiO2 films were fabricated and their electrical characteristics were studied to explore the possibilities of enhancing the TFT characteristics by scaling down the gate oxide thickness. It was found that the threshold voltage and the subthreshold slope decrease linearly as the gate oxide thickness is reduced while the field effect mobilities stay constant. The breakdown electric field of the gate oxide increases as the gate oxide thickness decreases and is over 10 MV/cm when the thickness is less than 20 nm. The polysilicon TFT with the 7-nm gate oxide, the thinnest in this work, showed excellent characteristics: threshold voltage of 0.44 V, subthreshold slope of 110 mV/dec, field effect mobility of 97 cm2/Vs
Keywords :
electric breakdown of solids; elemental semiconductors; high electron mobility transistors; silicon; sputtered coatings; thin film transistors; 0.44 V; Si-SiO2; breakdown electric field; electrical characteristics; field effect mobilities; gate oxide thicknesses; high mobility polysilicon thin-film transistors; sputter-deposited SiO2 films; subthreshold slope; threshold voltage; Circuits; Electric breakdown; Electric variables; Liquid crystal displays; Optical arrays; Silicon; Sputtering; Substrates; Thin film transistors; Threshold voltage;
Journal_Title :
Electron Devices, IEEE Transactions on