Abstract
An environmental friendly gas, C5F10O, has been proposed for etching low-k SiOCH films using dual frequency (60MHz/2MHz) capacitively coupled plasma. The main ion produced is CF3+, as compared to CF+ produced by the conventional c-C4F8 gas. The advantage of CF3+ over CF+ is the much higher etching rate. With the new etching gas, a high etching rate of about 1000 nm/min with a vertical profile pattern can be achieved. The damage to SiOCH films induced by light, radicals and ions were systematically evaluated. It was found that the most severe damage was caused by ions, followed by VUV. The resist materials can be selectively removed with respect to SiOCH with less damage by employing an O2/Ar surface wave excited plasma. An advanced plasma etching technology with controlled radicals has thus been introduced.
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