ESD-induced oxide breakdown on self-protecting GG-nMOSFET in 0.1-μm CMOS technology

Historically, the failure mode of the nMOS/lateral n-p-n (L_npn) bipolar junction transistor (BJT) due to electrostatic discharge (ESD) is source-to-drain filamentation, as the temperature exceeds the melting temperature of silicon. However, as the gate-oxide thickness shrinks, the ESD failure changes over to oxide breakdown. In this paper, transmission line pulse (TLP) testing is combined with measurements of various leakage currents and numerical simulations of the electric field to examine the failure mode of an advanced 0.1-μm CMOS technology, which is shown to be through gate-oxide breakdown. It is also shown by I_D-V_G and I_G-V_G measurements that the application of nondestructive ESD pulses causes gradual degradation of the oxide well before failure is reached, under the (leakage current) failure criteria used. Finally, the latent effects of stress-induced oxide degradation on the failure current I_f of the nMOS/L_npn are studied, and it is shown that as the device ages from an oxide perspective, its ESD protection capabilities decrease.