Reliability evaluations of ECP tools and chemistries

Microstructural considerations were studied in a tool qualification for ECP in a dual-damascene 110nm Cu/low-k BEOL process. Wafer Level tests (HTS, Isothermal EM) using standard SM/SIV and EM test structures were used to compare two ECP tools and chemistries, and sensitivities were further investigated with materials analysis consisting of Elemental (TOF-SIMS), EBSD (texture analysis) and grain-size analysis. It is found that the differences in the relative grain-size, and impurity content both contributed to the improvement of the TTF for EM and SM/SIV. Interpretation of the SIV data used a proportional hazards model, incorporating basic elements of stochastic geometry to find a scaling form which can be used to extract the relative change in Cu mobility.