Study of ashing for low-k dielectrics using the N2/O2 ferrite-core inductively coupled plasmas

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 A/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.