Novel dissoluble hardmask for damage-less Cu/low-k interconnect fabrication

A Cu/low-k dual-damascene process using a novel dissoluble hardmask material, AlO, is developed to suppress ashing-damage to porous/nonporous low-k SiOC. In this process, ArF-resist patterns are firstly transferred to a very thin, typically 30-nm-thick, AlO hardmask layer. After removing the resist, SiOC is patterned using the hardmask. The hardmask remaining after the etching is spontaneously removed during post-etch wet-cleaning. The line-to-line capacitance of 280-nm-pitch, 4-level interconnects using this process is reduced by 10% from that using a conventional resist-mask process.