The feasibility of etching Cu/low- k interconnects by using a low global warming potential C F3 I plasma was studied. Low-damage etching was done and porous SiOC (p-SiOC, k<2.6) film with low roughness was produced. Exposing p-SiOC film to C F3 I plasma was found to suppress the decrease in the C H3 group and the increase in the k value compared to those of conventional C F4 and C4 F6 plasmas. These effects are due to the low UV intensity and small amount of F radicals of C F3 I plasma. The authors also found that the etching profile of C F3 I plasma was comparable with that of C F4 plasma. Since the etching selectivity (p-SiOCArF photoresist) of C F3 I plasma is higher than that of C F4 plasma, the remaining photoresist thickness increases after etching, thus suppressing line edge roughness (LER). The decreased LER mitigated degradation of IV and time dependent dielectric breakdown characteristics in Cu interconnects. They also found that the roughness on the bottom surface of the p-SiOC trench was reduced. These benefits are due to C F3 I plasma's low reactivity with the carbon in photoresists and p-SiOC films. Based on these findings, they believe that the environmentally friendly C F3 I gas has great promise as a p-SiOC etching material.
|Number of pages||6|
|Journal||Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films|
|Publication status||Published - 2008|
ASJC Scopus subject areas
- Condensed Matter Physics
- Surfaces and Interfaces
- Surfaces, Coatings and Films