Hot-Carrier acceleration factors for low power management in DC-AC stressed 40nm NMOS node at high temperature

Abstract

Channel Hot-Carrier degradation presents a renewed interest in the last NMOS nodes where the device reliability of bulk silicon (core) 40nm and Input/Output (IO) device is difficult to achieve at high temperature as a function of supply voltage VDD and back bias VBS. A three mode interface trap generation is proposed based on the energy acquisition involved in distinct interactions in all the VGS, VDS (VBS) conditions as a single IDS lifetime dependence is observed with VGD > 0. This gives a new age(t) function useful for accurate DC to AC transfers. Positive temperature activation is explained by the rise of ionization rate with electron-electron scattering (medium IDS) and multi vibrational excitation (higher IDS) which increase the H desorption by thermal emission. The use of forward VBS has shown no gain under CHC for both device types. The main limitation occurs under reverse VBS = −VDD in IO where the smaller temperature activation partially compensates the larger damage. In that case a security margin can be established giving a limit of VBS = −VDD/2 for design reliability.