High-resolution dry etch patterning of PZT for piezoelectric MEMS devices

Dry etch patterning of lead zirconate titanate with self-aligned top and bottom platinum electrodes was demonstrated using a combination of reactive ion etching of PZT and argon ion milling of Pt. Monochlorotetrafluoroethane (HC₂ClF₄) etch gas and a Pt etch mask were employed for PZT patterning. PZT etch rates in the range 13-110 nm/min were measured as a function of rf discharge power for alumina, graphite, and ardel electrode shields in a conventional parallel plate reactor. The top and bottom platinum films were patterned by argon ion milling with a photoresist etch mask which was applied at the outset of the process and left in place throughout patterning. Etched profiles of Pt(200 nm)/PZT(500 nm)/Pt(150 nm) multilayer films were characterized by SEM and exhibited submicron definition