Characterization of Titanium Etching in Cl2 / N 2 Plasmas

The effects of etch time, nitrogen and chlorine gas flows, radio frequency power, pressure, and temperature on the etch rate of sputtered titanium films in chlorine-nitrogen plasmas were investigated in this work. The radio frequency power was found to have the greatest effect on the etch rate, followed by the reaction pressure. The increase in Ti etch rate with radio frequency power can be attributed to increased ionization of the gases and increase in ion and eiectron energies in the plasma. The increase in pressure led to a decline in the etch rate, probably due to loss of chlorine through recombination reactions. It was observed that the etch rate increased with increase in chlorine for gas flows below 100 sccm. Addition of nitrogen increased the etch rate to a flow of 10 sccm due to generation of free chlorine radicals, but led to a decrease in etch rate for nitrogen flows beyond 25 sccm due to dilution effect. There was only slight dependence of etch rate on the temperature within the range of this investigation.