DELAMINATION STUDIES IN Cu-ULTRA LOW-k STACK

摘要

One of the major challenges with ultra low-k materials is to eliminate delamination during the chemical mechanical planarization process due to their poor mechanical integrity. Two patterned Cu samples containing different ultra low-k films (A and B) having k values ≤2.0 have been investigated. 2-cm~2 coupons of the samples were polished on a bench-top polisher with either upper oscillation or upper rotation setup. Experiments were performed at different machine parameters with alumina based Cu slurry and IC1000 polishing pad. In every set of testing of A and B samples, a similar patterned Cu sample with TEOS as interlayer dielectric had been used for a direct comparison. Both the dynamic coefficient of friction (COF) and energy of contact high-frequency acoustic emission (AE) were continuously monitored during the tests. COF is found to be less for TEOS sample for down force 3 PSI or less whereas AE shows very high values with higher noise for low-k samples at all conditions. As all Cu removes, AE signals for TEOS and low-k films are similar. Monitoring AE signal along with COF data could be used as an in situ metrology tool for monitoring of Cu damascene process with ultra low-k materials.