The memory characteristics of submicron feature-size PZT capacitors with PtOx top electrode by using dry-etching

Abstract

Dry etching and its effect on the characteristics of submicron feature-size PbZr1−xTixO3 (PZT) capacitors with PtOx top electrode were investigated. The photoresist (PR)-masked PtOx films were etched by an Ar/(20%)Cl2/O2 helicon wave plasma. A fence-free pattern with a significantly high etch rate and sidewall slope was obtained by the addition of O2 into the etching gas mixture, due to the chemical instability of PtOx and the formation of a PtO2 passivation layer to suppress redeposition of the etch by-products on the etched surface. The patterned PtOx electrode can be further used as a hard mask for etching the PZT film, subsequently, with the gas mixture of Ar, CF4 and O2. A high etching rate of PZT and a good etching selectivity to PtOx can be obtained at 30% O2 addition into the Ar/(50%)CF4 plasma. The etched capacitors have a steep, 72°, sidewall angle with a clean surface. Moreover, the addition of O2 into the etching gas can well preserve the properties and the fatigue endurance of PtOx/PZT capacitors.