The Fabrication of Three-Dimensional Structures in p-Type Silicon Wafer with Epitaxial Layer Using Electrochemical Etching

摘要

This paper presents a new fabrication technique for the three-dimensional structures in a p-type silicon wafer with epitaxial layer using electrochemical etching. This new technique is based on the experimental result for trench formation in p-type silicon. The wall width increased with increasing substrate resistivity providing the trench structure with a thick wall and under some conditions we could observe both macropore formation and electropolishing depending on the substrate resistivity. Utilizing this result, we successfully fabricated freestanding beam structures using a p-type silicon wafer which consisted of two different regions: an epitaxial layer with high resistivity leading to a trench structure being created by macropore formation and a bulk substrate with low resistivity leading to a large hollow below the trench structure being created by electropolishing.