Endurance characteristics and degradation mechanism of polysilicon thin film transistor EEPROMs with electron cyclotron resonance NaO-plasma gate oxide

Abstract

Endurance characteristics and degradation mechanism of polysilicon thin film transistor (poly-Si TFT) EEPROMs with electron cyclotron resonance (ECR) N2O-plasma oxide have been investigated. The ECR N2O-plasma oxide has Qbd up to 10 C/cm(2) due to the smooth interface and strong Si-N bonds. The poly-Si TFT EEPROMs have a larger threshold voltage shift of 2.5 V even after 10(5) program and erase (P/E) cycles. The threshold voltage of the programmed device decreases until 10(4) P/E cycles, but after then increases, while that of the erased device increases after 10(3) P/E cycles. The degradation is ascribed to electron trapping in the oxide and the generation of traps and interface states at the tunnel oxide/active poly-Si interface.