A four level silicon microstructure fabrication by DRIE

Abstract

We present a four level Si microstructure fabrication process with depths ranging from 70–400 μm. All four levels are etched from the same side, by using four hard masks (, Al, AZ4562 photo resist, and Al). The choice of the hard masks and their relative selectivity will be discussed. Also two different deep reactive ion etching (DRIE) processes, performed in two different machines, are compared and evaluated. The process evaluation and discussions are based on the vertical walls deviation from a right angle, the surface roughness and the resolution. In the end, a solution is proposed to remove spikes and grassing which appeared during both DRIE processes, and the impact of removing them from the surfaces is discussed.