Progress in dry etching processes [reactive ion etching (RIE) and electron cyclotron resonance etching, (ECRE)] is described, concerning etch geometry and fidelity of pattern transfer by using advanced techniques to produce masks of photoresist and or . In contrast to capacitively coupled hydrogen/methane discharges, in which the etch rate of is significantly lower than that of , in ECR discharges by the simple variation of the gas composition, the etch rate of can be driven to values comparable with . The different on‐line monitoring techniques are compared. It is shown that optical emission spectroscopy can be applied successfully even with sample areas of about 2 cm2 at etch rates of 50 nm/min.