  Deep reactive ion etching (DRIE) with the Bosch process is one of the key
procedures used to manufacture micron-sized structures for MEMS and
microfluidic applications in silicon and, hence, of increasing importance for
miniaturization in biomedical research. While guaranteeing high aspect ratio
structures and providing high design flexibility, the etching procedure suffers
from reactive ion etching lag and often relies on complex oxide masks to enable
deep etching. In this work, we introduce an optimized Bosch process that
reduces the etch lag to below 1.5 %. Furthermore, we improved a three-step
Bosch process, allowing the fabrication of structures with 6 micrometre
thickness at depths up to 180 micrometre while maintaining their stability.
