In this study, we investigated the etching mechanism of $RuO_2$ thin film in $Cl_2$ and $O_2/Cl_2$ electron cyclotron resonance plasma. This work can give good information of acquiring optimal condition in the process of G-bit DRAM devices.
To study accurately, we investigated the etch rate of $RuO_2$ film with processing parameters, incident ion flux and bombarding energy, and O* and Cl* radical concentration.
In $O_2/Cl_2$ plasma, it was $O_2:Cl_2=5:5$ (flow rate ratio) that show maximum etch rate which was 7 times higher than pure $O_2$ or $Cl_2$ plasma.
The etch rate was greatly dependent on O* radical concentration and incident ion bombarding energy. Even though there were enough O* radicals, $RuO_2$ was not etched without ion bombardment. So we found that the etching mechanism of $RuO_2$ film in $O_2/Cl_2$ plasma was ion induced etching.
In $Cl_2$ plasma, the characteristic of $RuO_2$ film was found to be ion sputter etching and the etch rate was greatly dependent on the incident ion flux and bombarding energy.