Channel length dependence of hot-carrier-induced degradation in n-type drain extended metal-oxide-semiconductor transistors

Abstract

Channel length (Lch) dependence of hot-carrier-induced degradation in n-type drain extended metal-oxide-semiconductor (DEMOS) transistors stressed under high drain voltage and high gate voltage is investigated. On-resistance degradation is reduced in longer Lch device, however, threshold voltage shift (ΔVT) is greater. Charge pumping data reveal that electron trapping in gate oxide above channel region is responsible for ΔVT. Simulation results show that longer Lch device exhibits enhanced vertical electric field (Ey), i.e., enhanced hot-electron injection, in channel region due to the alleviation of Kirk effect. Results presented in this letter reveal that enhanced ΔVT driven by enhanced channel Ey may become a serious reliability concern in DEMOS transistors with longer Lch.