Low-pressure inductively coupled plasma etching of benzocyclobutene with SF6/O2 plasma chemistry

Highly anisotropic features of benzocyclobutene, a promising low stress layer for microelectromechanical systems, were achieved by inductively coupled plasma (ICP) etching with fluorine/oxygen based chemistry. The effects of chamber pressure, platen power, ICP power, and SF6/O2 relative concentration were studied on etch rate, selectivity, and sidewall morphology. Highly anisotropic features were achieved with sidewall slopes ∼88° for almost all conditions. Grass-like residue, due to redeposition of etch material, was observed under certain conditions and is shown to be dependent on pressure, ICP power, and feature dimensions.