Towards a versatile DRIE: silicon pit structures combined with electrochemical etch stop

A novel approach to increasing the versatility of deep reactive ion etching (DRIE) and electrochemical etching (ECE) by combining both techniques is presented. The goal of this work is to release membrane based sensors as well as sensor arrays of different sizes on a single wafer with a well defined etch stop. The combination of a grid like mask pattern featuring uniform size etch openings for DRIE with a reliable ECE technique allows for processing of dense arrays of silicon membranes with feature sizes ranging from 0.01 mm² to 2.2 mm². Our method enables processing of standard CMOS wafers and obviates the need for expensive SOI wafers.