Tailoring etch directionality in a deep reactive ion etching tool

Abstract

Silicon deep reactive ion etching is a process that produces projected two-dimensional shapes due to the inability to control the direction of the energetic ions arriving at the surface of a wafer. The resulting etched profiles present sidewalls which are nominally 90° to the wafer surface. However, we have developed and demonstrated a new technique that allows us to control the angle that trenches make with respect to the wafer surface. This scheme exploits the charging of buried dielectric layers to achieve ion steering and thus control the direction of the etch. The measured angle variation was controlled between −32° and +32° with respect to a line orthogonal to the wafer surface. We report and describe this new technique to control etch angle.