In-situ measurement of ion angular distribution in bulk titanium DRIE for modeling the etch profile

The bulk titanium deep reactive ion etching (DRIE) enabled high aspect ratio structures and devices are promising for harsh and in vivo environments applications. An etching model is necessary for better profile control to acquire needed performance, in which a correct ion angular distribution (IAD) in chlorine plasma is crucial. In this paper, an overhang SU-8 structure is proposed to experimentally in-situ measure the IAD by analyzing the etching profiles. With these data, a profile evolution model is developed to predict the titanium DRIE process.