ABSTRACT
Isotropic etching is a process in which etching advances normal to solid surfaces with a uniform etching rate at any place on the solid surface except on masking materials. When the wafer is etched in ideally isotropic manner from a pinhole of the mask, the etched profile becomes hemispherical concave. In a chemical isotropic etching system, etching rates are strongly enhanced by stirring motion of etching solutions. The isotropic etching system is based on the fact that the chemical reaction between the etchant and the silicon surface is so aggressive that the etching rate is not dominated by the reaction but by material transfer via diffusion in the solution. The isotropic etching system is usually utilized for the purpose of selectively removing materials from a wafer surface by the difference in the properties of the materials coexisting on the wafer.
