Reliability analysis method for low-k interconnect dielectrics breakdown in integrated circuits

The shrinking line-to-line spacing in interconnect systems for advanced integrated circuit technology and the use of lower dielectric constant materials create the need for tools to evaluate the interconnect dielectric reliability. A multi-temperature, dual-ramp-rate voltage-ramp-to-breakdown methodology is presented and used here to extract important dielectric-breakdown parameters accurately for minimum-spaced metal lines. It is demonstrated that correction for the true minimum line-to-line spacing distributions become critically important and that the minimum spacing can be extracted electrically and compares favorably to electron microscopy cross sections. The spacing-corrected breakdown field distributions, at various temperatures, for the organosilicate material tested, indicated a very low apparent zero-field activation energy (0.14±0.02eV) and an apparent field-acceleration parameter γ=4.1±0.3cm∕MV that has little or no temperature dependence. Constant-voltage time-dependent-dielectric-breakdown measurements were found to agree well with these observations.