Merged epitaxial lateral overgrowth (MELO) of silicon was combined with an SiO2 etch stop to form a novel 9-μm-thick and 250-μm x 1000-μm single-crystal silicon membrane for micromechanical sensors. When epitaxial lateral overgrowth (ELO) silicon merges on SiO2 islands, it forms a local silicon-on-insulator (SOI) film of moderate doping concentration. The SiO2 island then acts as a near-perfect etch stop in a KOH- or ethylenediamine-based solution. The silicon diaphragm thickness over a 3-in wafer had a standard deviation of 0.5 μm and is precisely controlled by the epitaxial silicon growth rate (A 0.1 μm/min) rather than by conventional etching techniques. Diodes fabricated in the substrate and over MELO regions have nearly identical reverse-bias currents indicating good quality silicon in the membrane.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering