Evidence of mechanical Film Breakdown and ESCA Analysis of a Film on Thermally Aged Cobalt Hardened Gold

Electron spectroscopy for chemical analysis (ESCA) has been used to determine the chemical formulation of thermally grown films on cobalt hardened-gold electroplate (150°C/8000 h). K2S04 (or SO3) ~ 60-Å, thickness has been identified overlaying a 50-Å-thick CoO layer on cobalt hardened gold. It was found that the dielectric breakdown voltage of this complex film depends on contact force. At Iow contact forces (~10
^-2
N), electronic (as opposed to thermal) dielectric breakdown events are observed at a critical voltage of ~ 3.5 V. I-V characteristics are typically nonohmic. Mechanical film breakdown is evidenced by ohmic I-V characteristics. A statistically important number of mechanical breakthrough events are observed at 0.2-N contact force.