PMMA microstructures deep etch process

A PMMA-based reactive ion etching (RIE) process for the fabrication of high aspect ratio microstructures is described in this paper. Although the resolution of this process is lower than that of the LIGA process, this process provides a simpler way to get higher height and high aspect ratio microstructures. In the process, Ni material is selected as mask and patterned using photochemical etching. The self-bias, which is determined by different etching parameters such as etching power and gas pressure etc, is very important. By optimizing the etching parameters, vertical PMMA profile and 5:1 aspect ratio structures can be obtained. The micro-mask effect and high power etching damage are also demonstrated and discussed in this paper.