Study on compensation method for vertical trench using anisotropic wet etching

This paper investigates anisotropic wet etching characteristics of (110)-oriented silicon wafers in KOH etchant for obtaining vertical trench. To obtain a near rectangled trench instead of parallelogrammic trench with concave corners of 70° and 110°, a new compensation method was proposed. With this design, a trench with all sidewalls vertical was obtained by an over etching of silicon. Due to different widths of the trench, the over etching rate in releasing inclined crystal plane {111} varies from 0.32μm/min to 0.43μm/min.