Comparison of plasma chemistries for dry etching of Ta2O5

Inductively coupled plasma etching of Ta2O5 was performed in a variety of different chemistries, including SF, with additions of O-2, Ar, CH4 or H-2; Cl-2/Ar; N-2/Ar; and CH4/H-2/Ar. Etch rates up to similar to 1200 Angstrom min(-1) were achieved with either SF6- or Cl-2-based chemistries. Under these conditions the etch rates for Si were approximately four to seven times faster, although equirate etching was achieved at low source powers and low halogen gas percentages in the plasma chemistry. The etched Ta2O5 surfaces were smooth (root mean square roughness less than or equal to 0.5 nm) over a broad range of conditions of source power, chuck power, and process pressure. The etch rates with N-2/Ar and CH4/H-2/Ar were an order of magnitude lower than with SF6 or Cl-2. There; was no effect of postdeposition annealing on the Ta2O5 etch rates, at least up to 800 degrees C. (C) 2000 American Vacuum Society. [S0734-2101(00)00704-1].