Ghoneim, M.T. and Hussain, M.M., 2017. Highly Manufacturable Deep (Sub‐Millimeter) Etching Enabled High Aspect Ratio Complex Geometry Lego‐Like Silicon Electronics. Small, 13(16).

Abstract

Formation of high aspect ratio Lego-like silicon electronics can enable hybrid integration of 
diverse range of electronics on soft materials enabling free-form (physically flexible, 
stretchable, and reconfigurable) electronics. In that regard, micromachining, used in 
complementary metal oxide semiconductor (CMOS) technology, microelectromechanical 
systems (MEMS), dynamic random access memory (DRAM) capacitors, and through silicon 
vias (TSVs) for 3D integrated circuits (3D-ICs), can play effective role.[1, 2] Many bulk 
micromachining techniques have been demonstrated in the past for making high aspect 
ratio structures.[3–7] The techniques generally utilize a hard mask (eg, metal) material to 
withstand abrasive deep reactive ion etching (DRIE).[4] Klaassen et al. reported a bilayer of 
silicon oxide and photoresist (PR) used as mask to form 300 µm deep trenches.[6] …