Gate oxide evaluation under very fast transmission line pulse (VFTLP) CDM-type stress

Abstract

Gate oxide breakdown is analyzed under very fast transmission line pulsed (VFTLP) stress, using different pulse - rise times and -widths. The switching of oxide behavior pre- and post- breakdown occurs in tenths of a nanosecond and it shows reproducible voltage and current characteristics. The total stress and time-dependent-dielectric-breakdown (TDDB) during pulsed stress-method are evaluated using the following two procedures: 1) by adding up the total pulsed stress time, and 2) by extrapolation of the pulsed stress time to a constant voltage stress (CVS)-type measurements. It is shown that the latter method allows for a better comparison of identical oxides TDDB under various stress conditions. A methodology to characterize gate oxide breakdown using a single pulse is finally discussed. This is important to assess the gate-oxide failure condition during a charged device model (CDM)-type electrostatic discharge (ESD).