Design and characterization of a novel ICP plasma tool for high speed and high accuracy drie processing

Advanced deep reactive ion etching (DRIE) with high etch rates (30 mum/min) is achieved by using an etching system with a novel ICP (inductively coupled plasma) source and substrate holder (chuck). Waferstepper dual side lithography (front- to backwater overlay 500 nm) is used to fabricate electrical overlay test structures in order to measure the non-perpendicularity of the etch profile (angular deviation) and the post etch dimension in a through wafer etch process. Compared with a conventional configuration, the angular deviation is reduced from 0.6 deg to a very low value of 0.2 deg. Furthermore, the accuracy of through wafer etched features is improved from 0.7 % to 0.1 % (one sigma).