Time-Dependent Dielectric Breakdown of Interlevel Dielectrics for Copper Metallization

Abstract

Bias-temperature stressing of Cu/dielectric/Si capacitors demonstrated that time-dependent dielectric breakdown (TDDB) lifetime strongly depends on dielectric materials. Phosphosilicate glass (PSG) films had much higher immunity from TDDB than thermally grown SiO2. This higher immunity of PSG films is attributed to their greater suppression of Cu diffusion. They provide good protection against Cu contamination of devices. The lifetime (τ) of plasma-enhanced chemical-vapor-deposited TEOS (PECVD–TEOS) films was found to be related to the electric field (E) by using Peek's law (E∝τ-1/4). Using this law, the lifetime becomes rapidly longer than does the previous expectation when the electric field reduces. This suggests PECVD–TEOS films have the potential to be used as interlevel dielectrics for Cu metallization.