High quality 3D shapes by silicon anodization

Abstract

AbstractIn this paper some process considerations and optimizations of anodization for three‐dimensional (3D)‐structuring of silicon are discussed. For the shape controlling of etched form different approaches, such as frontside masking design, local backside doping and surface pre‐structuring are presented. Influences of the opening size and etch depth on the shape of the etching form are investigated. The surface quality of the resulting 3D structures is critically dependent on the specific process parameters and process flow. Best surface quality was obtained for electropolishing in 7 wt.% hydrofluoric acid (HF) at applied current densities of 100–300 mA/cm2. Application of 3D silicon forms for injection moulding is demonstrated and further implementations of the process for optical and fluidic devices are discussed.magnified image 3D silicon shapes fabricated using anodization process with local backside doping design.