Levelling monocrystalline silicon surfaces - by anisotropic etching with basic etchant

摘要

Prodn. of level surfaces on monocrystalline Si semiconductor substrates in which the surface consists of a (100) crystal plane with a depression, comprises first coating at least part of the bottom surface of the depression with an SiO2 layer. The uncoated parts are then subjected to anisotropic etching with a basic etching medium until they are level with the coated surface, after which the SiO2 layer is removed. The whole assembly can then be isotropically etched (to remove any indentations formed by anisotropic etching of the bottom of the depression when only partly coated with SiO2). The process is based on the fact that the (100) crystal plane is etched away 50 times faster than the (111) plane, so that the substrate surface can be etched without significantly etching away the walls of the depression.