Journal of Vacuum Science & Technology A, Vol.20, No.2, 530-535, 2002
Sputter-etching characteristics of barium-strontium-titanate and bismuth-strontium-tantalate using a surface-wave high-density plasma reactor
The etching of barium-strontium-titanate (BST) and bismuth-strontium-tantalate (SBT) deposited using a pulsed laser deposition technique has been investigated using a nonreactive (argon) surface-wave high-density plasma source. The etch rate of the rf-biased thin films was determined as a function of the self-bias voltage, of the magnetic field intensity and of the gas pressure. It was found that high etch rates with a good selectivity over resist can be achieved without any plasma chemistry. provided the plasma is operated in the very low pressure regime (i.e., below 1 mTorr). For SBT, etch rates as high as 3000 Angstrom/min with a selectivity of 0.2 over HPR-504 photoresist were obtained with self-bias voltages lower than 150 V. It is also found that even though BST and SBT present similar sputter-etching characteristics, SBT is etched about two times faster than BST as a result of the difference in the atomic density of each material.