Enhanced reliability for gate dielectric of low-temperature polysilicon thin-film transistors by NO-plasma nitridation

Polysilicon thin-film transistors (poly-Si TFTs) fabricated solely by low-temperature processes (under 600°C) are treated with nitridation using NO plasma. Their properties are investigated at room temperature under high-field stress. It is found that the plasma is effective in improving the gate-oxide hardness against stress-induced damage, with the nitrided device showing a smaller shift in threshold voltage, a smaller decrease in peak transconductance and a smaller increase in subthreshold slope after the stress. This result shows that plasma nitridation has positive effects on the reliability of low-temperature-fabricated poly-Si TFTs, which play an important role nowadays in low-cost flat-panel display systems on glass.