Dry etching of SrBi2Ta2O9: Comparison of inductively coupled plasma chemistries

A systematic study of the etch characteristics of SrBi2Ta2O9 (SBT) thin films in inductively coupled plasmas (ICPs) has been performed with various chemistries of Cl2/Ar, Cl2/O2/Ar, Cl2/NF3/Ar, and Cl2/NF3/O2/Ar. Etch rate was dependent on plasma chemistries and parameters. Addition of O2 stabilized the perovskite structure of SBT film and suppressed the etch rate, but NF3 enhanced the etch rate substantially mainly due to reactive fluorine radicals. Maximum etch rates obtained were: 740 å/min with Cl2/Ar, 320 å/min with Cl2/O2/Ar, 1,500 å/min with Cl2/NF3/Ar, and 1,600 å/min with Cl2/NF3/O2/Ar at 5 mTorr, 700 W. ICP power and 150 W. rf chuck power. Electrical properties of the SBT films were quite dependent on plasma chemistries employed; Cl2/NF3/O2/Ar showed the least damage in the films and resulted in the best P-E hysteresis loop having remnant polarization (2Pr)=12.3 ΜC/cms2 and coercive field (Ec)=41.9 V/cm.