A detailed analysis of the pre-breakdown current fluctuations in thin oxide MOS capacitors

The on-off fluctuations of the tunnel current preceding the breakdown of thin oxide MOS capacitors are analyzed using a low noise measurement system controlled by a personal computer. An automated procedure has been implemented which is capable of interrupting the stress a few seconds before breakdown, in order to perform the electrical characterization of the structure in pre-breakdown conditions. The relationships with other phenomena preceding breakdown (stress induced leakage current, SILC, and soft breakdown, SBD) are discussed.