Merged epitaxial lateral overgrowth (MELO) of silicon was combined with an SiO 2 etch stop to form a 9-μm-thick and 250-μm × 1000-μm single-crystal Si membrane for micromechanical sensors. When epitaxial lateral overgrowth (ELO) silicon merges on SiO 2 islands, it forms a local silicon-on-insulator (SOI) film of moderate doping concentration. The SiO 2 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 has a standard deviation of 0.5 μm and is precisely controlled by the epitaxial silicon growth rate (≈ 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.
|Number of pages||3|
|Journal||Electron device letters|
|Publication status||Published - 1991 Nov 1|
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