New experimental findings on constant voltage and current soft-breakdown in ultra-thin oxides

Abstract

This paper compares constant current stress (CCS) and constant voltage stress (CVS) soft breakdown (SBD) measurement results in ultra-thin oxides (3.5 nm and 2.5 nm) and finds that a number of important correlation issues arise. The discrepancies between CCS and CVS SBD include the following: SBD event percentage is greater in CCS than CVS; CCS SBD region extends to higher stress currents; post-SBD noise is much greater in CCS than CVS. To understand these discrepancies the effect of available source power on CCS and CVS SBD is examined. In both 3.5 nm and 2.5 nm oxides it is found that the available source power has significant impact on SBD results.