Impact of low-potential plasma on long-term stability in low-k via etching

We have developed an ESC (electrostatic chuck) damage-less plasma-cleaning technique for a UHF-ECR dielectric etching apparatus. The degradation of the surface of the ESC in wafer-less plasma-cleaning was suppressed by lowering the ion energy incident on the ESC surface. We have confirmed long-term stability of the etching performance and a long MTBC (mean time between wet cleaning) of over 400 hrs in low-k via etching. We have also estimated that the ESC lifetime was over 12,000 hr.