Experimental extraction of degradation parameters after constant voltage stress and substrate hot electron injection on ultrathin oxides

I. Introduction By reducing the gate-oxide thickness (T OX), the proportion of injected tunneling carriers increases during stress so that MOSFET's parameters are slightly changed. In thicker oxides (T OX >3.5nm), Stress Induced Leakage Current (SILC) was a good marker of oxide degradation. In thinner oxide, gate oxide leakage current appears in depletion regime, SILC is recalled as Low Voltage Stress Induced Leakage Current (LVSILC) [1]. In this work, we have investigated ultra-thin oxide reliability in MOSFET's in order to identify the critical parameter of the degradation. A few parameters as the gate bias (V G), the oxide voltage (V OX), the field oxide (F OX), the injected current (I INJ), the injected charge density (Q INJ), the carriers energy (E) can influence defects generation. In a constant voltage stress (CVS) V G , F OX , I INJ , and E are definitely correlated. Also it is useful to compare both uniform CVS and substrate hot electron injection (SHEI) in which case F OX , I INJ and E are independent. Actually, a lateral n + /p injector allows imposing the injected current I INJ independently of V G , furthermore E is correlated to the substrate bias V B .