Deep reactive ion etching of in situ boron doped LPCVD Ge0.7Si0.3 using SF6 and O2 plasma

This paper reports on deep reactive ion etching (DRIE) of in situ highly boron doped low pressure chemical vapor deposited Ge0.7Si0.3 alloy in SF6 and O2 plasma. The effect of RF power, SF6 flow, O2 flow and temperature on the etch rate of Ge0.7Si0.3 films with a boron concentration of 2.1 × 1021 atoms/cm3 is investigated. Optimized conditions for a combination of a vertical etch profile and a high selectivity towards PECVD oxide are reported. The effect of boron doping concentration on the etch rate is also investigated. The etch rate is found to decrease with an increase in the dopant concentration. The developed SF6 and O2 based DRIE recipes are applied to fabricate GeSi microresonators.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Fabrication of microelectromechanical resonator is demonstrated by DRIE of boron doped Ge0.7Si0.3. ► Etch profile control by oxygen flow for doped Ge0.7Si0.3. ► Increased etch selectivity towards oxide with an increase in temperature. ► Suppressed etch rate with increased boron concentration in Ge0.7Si0.3 alloy.