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

Channel length (L-ch) 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 L-ch device, however, threshold voltage shift (Delta V-T) is greater. Charge pumping data reveal that electron trapping in gate oxide above channel region is responsible for Delta V-T. Simulation results show that longer L-ch device exhibits enhanced vertical electric field (E-y), i.e., enhanced hot-electron injection, in channel region due to the alleviation of Kirk effect. Results presented in this letter reveal that enhanced Delta V-T driven by enhanced channel E-y may become a serious reliability concern in DEMOS transistors with longer L-ch.