US Patent 7211197 Etching method and plasma processing method

A processing gas constituted of CH2F2, O2 and Ar is introduced into a processing chamber 102 of a plasma processing apparatus 100. The flow rate ratio of the constituents of the processing gas is set at CH2F2/O2/Ar=20 sccm/10 sccm/100 sccm. The pressure inside the processing chamber 102 is set at 50 mTorr. 500 W high frequency power with its frequency set at 13.56 MHz is applied to a lower electrode. 108 on which a wafer W is placed. The processing gas is raised to plasma and thus, an SiNx layer 206 formed on a Cu layer 204 is etched. The exposed Cu layer 204 is hardly oxidized and C and F are not injected into it.