Micro Regular Octahedron and Truncated Octahedron Cavities on 111 Oriented Silicon Wafer

Octahedron cavities fabricated on <111>-oriented silicon wafer combining with the dry etching of reactive ion etching-inductively coupled plasma (RIE-ICP) and the wet etching of ethylene diamine, pyrocatechol, and water (EDP/EPW) were investigated. The etching characteristics are analyzed depending on different etching conditions, and regular or irregular octahedron cavities can be obtained by self etch stop of smooth {111} crystalline planes. RIE-ICP etching is used to define the depth of cavities, and EDP etching is followed for removing the roughness. The final self-etch-stop profiles of cavities are determined by the dimension of mask patterns, aligning direction and the depth of cavities in the wafer. The results of etched cavities confirmed the condition to determine the final etching profiles.