CMP technology for 32-45nm node Cu/Low-k integration

The effect CMP pressure had on the via resistance yield of 2-level porous low-k/Cu damascene interconnects was investigated. This yield was found to strongly depend on both the CMP pressure and moduli of via low-k films. We found that high-modulus low-k films (9.8 GPa) and low-pressure CMP (< 1.5 psi) were essential for fabricating reliable low-k/Cu interconnects for the 45-nm technology node. We also investigated the dependence of ultra low-k (ULK, k=1.6-1.8) film delamination on the pattern during CMP for the 32-nm technology node. A CMP mask that had various kinds of dummy-patterns was developed to quantitatively characterize ULK film delamination. As a result, we found dummy pattern supported the poor mechanical strength of ULK films (modulus < 2 GPa) and obtained excellent electrical properties for Cu/ULK damascene interconnects on 300-mm wafers.