Anisotropic etching of silicon. a model diffusion-controlled reaction

In conventional isotropic etching of metals, it has been found that narrower slots take longer to etch than wider ones. This has been attributed largely to the restricted access of fresh etchant to the metal surface. Spent etchant remains at the metal surface and forms a physical etch-retarding barrier. Anisotropic etching of single crystals differs from isotropic etching, in that it is orientation dependent, and different crystal planes are etching at different rates under identical conditions. This investigation examines anisotropic etching of (110) silicon for different slot widths and compares it with the already available information on isotropic etching of metals [1].