Impact of LKD5109™ low-k to cap/liner interfaces in single damascene process and performance

The importance of interface quality in the single damascene integration process of LKD5109? porous low-k films is investigated. A strong correlation is observed between chemical mechanical planarization (CMP) performance and LKD/cap layer interfacial fracture energies. The use of FF02? as cap layer material (an on-purpose developed spin-on organic hard-mask) on LKD leads to superior interfacial adhesion and metal continuity yield as compared to the use of chemical vapour deposition SiC:H cap films. The adhesion quality of LKD/liner films appears less critical than LKD/cap layer adhesion as far as CMP performance is concerned. Electrical line-to-line performance is not always directly correlated with adhesion but rather, more generally speaking, with interface quality (i.e., presence of defects/dangling bonds or moisture). The introduction of surface pre-treatments to enhance interfacial adhesion leads to degradation in both leakage current and breakdown field behaviour because of damage induced at the interface.