SELECTIVE ION-BEAM ETCHING OF AL2O3 FILMS

Preferential etching of sputter-deposited Al2O3 films and photoresist were investigated using a reactive ion beam etching system. Fluorohydrocarbon gases served as etching gases. When CH2F2 and CH3F gases were used, a problem of polymer film deposition occurred during etching of Al2O3 films. This problem could be overcome by using CHF3 gas. Based on these results, selective etching of Al2O3 films and photoresist were examined using CH2F2 + CHF3 and CH3F + CHF3 gases. Selectivity of more than 20 could be realized with these gas mixtures. This was because the etching rate of photoresist was reduced remarkably.