US Patent 9209034 Plasma etching method and plasma etching apparatus

In a plasma etching method for etching a metal layer of a substrate to be processed through a hard mask by using a plasma etching apparatus, a first step in which a first etching gas comprising a mixed gas of O2, CF4 and HBr is used as an etching gas, and a second step in which a second etching gas comprising a mixed gas of O2 and CF4 is used as an etching gas, are continuously and alternately repeated a plurality of times. At this time, a first high-frequency power of a first frequency and a second high-frequency power of a second frequency, which is lower than the first frequency, are applied to a lower electrode, and the first high-frequency power is applied in a pulse form.