Impact of pre-barrier sputter etch in porous MSQ-based Cu interconnects

摘要

The impact of pre-barrier sputter etch (PSE) on line-to-line leakage, yield, and reliability was studied in porous methyl silsesquioxane dual-damascene copper interconnect structures. Increased PSE was shown to improve line-to-line leakage, as a result of the redeposition of a dense dielectric layer onto the sidewall. A silicon-nitride (SiNx) liner showed similar impact on reducing line-to-line leakage. Although PSE improved leakage, increased PSE was shown to degrade CMP process capability as a result of corner rounding. Based on these results, we conclude that an alternative solution, such as a deposited dielectric liner, is needed to achieve acceptable leakage for porous MSQ-based Cu interconnects.