Wet etching of deep trenches on silicon with three-dimensional (3D) controllability

Trenches on silicon have found important applications in microelectromechanic system, microfluidic devices, photonic devices, capacitor memory devices and etc. Etching trenches with controllability of 3D geometry receives growing interests from academia as well as industry. In this paper we introduce a novel wet etching method, named metal assisted chemical etching, as a promising trench etching technology with 3D geometry variation. Both vertical and tapered etching results are presented. Slanted trenches from few-micron scale to sub-micron scale are also demonstrated with complex 3D features. Etchant composition, temperature and catalyst type are identified as key parameters in tuning 3D geometry of trenches by MaCE. Compared to currently available etching technology such as wet etching and reactive ion etching, the presented data in this paper demonstrate the merit of flexible 3D geometry capability, high-aspect ratio capability and low cost, which uniquely belongs to MaCE.