Characteristics of low temperature poly-Si TFT device and circuits fabricated with disilane

Abstract

Various fabrication techniques have been employed in order to optimize the performance of poly-Si TFTs device and circuits. We have prepared poly-Si active film by LPCVD and PECVD using monosilane and disilane recrystallized by the low temperature process of ELA and the high temperature process of SPC. The poly-Si TFTs with ELA active films exhibit higher field effect mobility and lower threshold voltages than those with SPC active film due to low intragranular trap state density. The poly-Si TFTs with active film deposited using Si2H6 exhibit higher mobility and sub-threshold slope than those with active film deposited using SiH4 due to larger poly-Si grain size and lower grain boundary trap state density. The oscillation frequency of a 23-stage CMOS inverter chain and the current driving capability of a CMOS transmission gate indicate that the low temperature processed circuits with active film deposited using Si2H6 and annealed by ELA method exhibit remarkable performances.