REACTION PROCESSES FOR LOW TEMPERATURE (<1500C) PLASMA ENHANCED DEPOSITION OF HYDROGENATED AMORPHOUS SILICON THIN FILM TRANSISTORS ON TRANSPARENT PLASTIC SUBSTRATES

摘要

This article presents mechanisms for lowtemperature (<150 deg C) if plasma enhanced chemical vapordeposition of silicon and silicon nitride thin films that lead tosufficient electronic quality for thin film transistor (TFT)fabrication and operation. For silicon deposition, hydrogenabstraction and etching, and silicon disproportionationreactions are identified that can lead to optimized hydrogenconcentration and bonding environments at <150 deg C.Nitrogen dilution of SiH4/NH3 mixtures during silicon nitridedeposition at low temperatures helps promote N-H bonding,leading to reduced charge trapping. Good quality amorphoussilicon TFT's fabricated with a maximum processingtemperature of 110 deg C are demonstrated on flexibletransparent plastic substrates. Transistors formed with the sameprocess on glass and plastic show linear mobilities of 0.33 and0.12 cm~2/Vs, respectively, with I_(ON)/I_(OFF) ratios>10~6.