MEASUREMENTS OF THE ANISOTROPIC ETCHING OF A SINGLE-CRYSTAL SILICON SPHERE IN AQUEOUS CESIUM HYDROXIDE

A mechanically polished single-crystalline silicon sphere with a diameter of 0.25 in is etched in 40% cesium hydroxide solution to study the orientation dependence of the anisotropic etching of silicon in three dimensions. The characteristic structures formed on the surface of the sphere after etching are examined under the scanning electron microscope. The slow-etching planes, {111} and {100}, as well as fast-etching planes, {110}, are identified from the micrographs. Most importantly, the {311} planes are found to be the most significant amongst the higher-order crystal planes.