Handbook of Silicon Based MEMS Materials and Technologies

23.5. DRIE Applications

Silicon DRIE steps can have very different roles in the process, and their optimization depends on disparate requirements. Shallow etching is usually associated with good linewidth control (undercut elimination), sidewall smoothness, and sidewall angle control. Deep or through-wafer etching is mostly concerned with rate and mask selectivity, and to a lesser degree with sidewall angle and quality. Intermediate applications can have any mix of requirements. All of these are affected by the device design, through size and shape dependent non-idealities and loading.

Silicon DRIE steps can be positioned anywhere in the process flow, but typically deep or through-wafer etches are done at the very end of the process because ...