Transient Capacitance Spectroscopy of Copper-Ion-Drifted Methylsilsesquiazane-Methylsilsesquioxane Interlayer Dielectrics

Abstract

The evidence of copper (Cu) ion drift in low-dielectric-constant (low-k) interlayer films was obtained for the first time by transient capacitance measurements. The charge states of the electronic states related to Cu+ ions drifted into the low-k layer of Cu/low-k/SiO2/Si metal–insulator–semiconductor capacitors were altered by photo?electron injection from the p-Si substrate by applying a positive bias to the Cu layer under UV light illumination. A decrease in the time-dependent transient capacitance C(t) was attributed to the thermal emission of electrons from Cu-related electronic states. The trap level of the Cu-related electronic states was estimated to be approximately 0.9 eV below the conduction band edge in the bandgap of the low-k material.