It has been reported that single crystal silicon transistors whose gate oxides were grown in N2O or treated to a post oxidation anneal in N2O demonstrated better resiliency under electrical stress. However, normal oxidation in single crystal silicon processing to form gate oxides is incompatible with the low temperature processes required for polysilicon TFTs designed for AMLCDs. In this work, we have used our previously reported process for a double layer gate oxidation, the bottom layer being a grown oxide formed in a low temperature, high density oxygen plasma and the top layer being a deposited oxide, to build the first low temperature polysilicon TFTs with a nitrogen passivated oxide/polysilicon interface. Our devices were constructed with the bottom 10 nm layer of gate oxide being grown in either an N2O or an O2 plasma, followed by a deposition of 100 nm of SiO2 by PECVD. The devices were then subjected to prolonged periods of stress at Vds equals Vgs equals 20 V. While having similar pre-stress device characteristics, the devices made with the oxide grown in the N2O plasma demonstrated a greater degree of stability than those with an oxide grown in an oxide grown in an O2 plasma.
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