We have studied the characteristics of photoresist (PR) ashing using N-2/O-2 plasmas in ferrite-core inductively coupled plasma etcher. By varying the O-2/(O-2+N-2) gas flow ratio, we have changed the PR ash rate and the low-k material etch rate, obtaining the PR ash rate and the PR to low-k materials etch selectivity, respectively, of 15,000 angstrom/min and 180. Fourier transform infrared spectroscopy and HF etch test coincidentally indicated that the ash damage to the low-k material decreased with decreasing the O-2/(O-2+N-2) gas flow ratio. (c) 2005 Elsevier B.V. All rights reserved.