Breakdown characteristics of interconnect dielectrics

Abstract

The shrinking of line-to-line spacing in interconnect systems for advanced IC technology and the use of new 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 organo-silicate materials tested, indicated a very low apparent zero-field activation energy (0.14/spl plusmn/0.02 eV) and an apparent field acceleration parameter /spl gamma/ = 4.1/spl plusmn/0.3 cm/MV that has little or no temperature dependence. Constant-voltage time-dependent-dielectric-breakdown (TDDB) measurements were found to agree well with these observations.