A method of plasma etching one or more features in a silicon substrate includes performing a main etch using a cyclical etch process in which a deposition step and an etch step are alternately repeated, and performing an over etch to complete the plasma etching of the features. The over etch includes one or more etch steps of a first kind and one or more etch steps of a second kind, each of the etch steps of the first and second kind include etching by ion bombardment of the silicon substrate. The ion bombardment during the one or more etch steps of the second kind has an inward inclination with respect to ion bombardment during the one or more etch steps of the first kind.