Low-k organic film in-situ surface-modification etching technology for the Cu/low-k interconnects

摘要

The 0.36μm pitched (0.18μmΦ) Cu/ organic low-k dual damascene interconnects (DDI) was successfully obtained by in-situ surface modification etching technology. We found that the sidewall of low-k was modified to the fluorinated carbon nitride (FCN) during the plasma etching using N{sub}2-based plasma with highly molecular weight fluorocarbon gas. The fluorocarbon polymer deposites on the sidewall of low-k after etching, however, this polymer is selectively removed by wet-cleaning which causes the FCN surface of low-k. This FCN layer suppresses the Cu diffusion effectively. This stacked structure (Cu/Barrier/FCN/low-k) is very tolerant for the barrier deficit. Using these gas chemistries, the Cu/organic low-k dual damascene interconnects are precisely fabricated, which causes higher via yield and reliability than that in the conventional process.