High aspect ratio etching in polymer for microactuator applications

High aspect ratio line and trench plating molds suitable for microactuator applications were etched in polymer using oxygen plasma in an RF inductive plasma etcher. A high vertical etch rate of ≃2.5 μm/min in a polymer has been achieved for μm wide lines and trenches, with even higher rates being observed for wider trenches due to the usual RIE lag effect. The lateral etch rate can be reduced by adjusting the inductive to bias power ratio, and by lowering the etch temperatures. Under optimum etching conditions, aspect ratios of close to 20:1 in a 2.5 μm line/2.0 μm spacing pattern and of greater than 20:1 in isolated 2.0 μm lines with ≥5 μm. spacing have been achieved.