화학공학소재연구정보센터
Thin Solid Films, Vol.518, No.22, 6465-6468, 2010
Comparison of dry etching of PMMA and polycarbonate in diffusion pump-based 02 capacitively coupled plasma and inductively coupled plasma
We report a comparison of dry etching of polymethyl methacrylate (PMMA) and polycarbonate (PC) in 02 capacitively coupled plasma (CCP) and inductively coupled plasma (ICP). A diffusion pump was used as high vacuum pump in both cases. Experimental variables were process pressure (30-180 mTorr), CCP power (25 150 W) and ICP power (0-350 W). Gas flow rate was fixed at 5 sccm. An optimized process pressure range of 40-60 mTorr was found for the maximum etch rate of PMMA and PC in both CCP and ICP etch modes. ICP etching produced the highest etch rate of 0.9 mu m/min for PMMA at 40 mTorr, 100 W CCP and 300 W ICP power, while 100 W CCP only plasma produced 0.46 mu m/min for PMMA at the same condition. For polycarbonate, the highest etch rates were 0.45 and 0.27 mu m/min, respectively. RMS surface roughnesses of PMMA and PC were about 2-3 nm after etching. Etch selectivity of PMMA over photoresist was 1-2 and that of PC was less than 1. When ICP power increased from 0 to 350 W, etch rates of PMMA and PC increased linearly from 0.47 to 1.18 mu m/min and from 0.18 to 0.6 mu m/min, while the negative self bias slightly reduced from 364 to 352 V. Increase of CCP power raised both self bias and PMMA etch rate. PMMA etch rates were about 3 times higher than those of PC at the same CCP conditions. SEM data showed that there was some undercutting of PMMA and PC after etching at 300 W ICP, 100 W CCP and 40 mTorr. The results also showed that the etched surface of PMMA was rough and that of PC was relatively smooth. (C) 2010 Elsevier B.V. All rights reserved.