The ability to predict and optimize the effects of the process parameters during silicon dry etching is vital for the fabrication of emerging hyperintegration technologies, as well as many microclectromechanical systems and integrated circuit devices. This article outlines the establishment of reactive ion etching protocols for fabrication of high aspect ratio trenches with minimum scalloping and undercut, employing the Bosch process. High aspect ratio submicron trench array patterns were transferred into silicon substrates using a Unaxis Versalock deep reactive ion etch tool equipped with a time multiplexed plasma etch/passivation cycle scheme which uses an inductively coupled plasma etcher. Through careful optimization of Bosch etch process conditions, successful etching of high aspect ratio (20:1) 170 nm trench features was achieved. (c) 2007 American Vacuum Society.