Simulation and experimental study of maskless convex corner compensation in TMAH water solution

Maskless etching with convex corner compensation in the form of a 〈1 0 0〉 oriented beam is investigated using both experiments and simulations. The maskless convex corner compensation technique is defined as a combination of masked and maskless anisotropic etching of {1 0 0} silicon in 25 wt% TMAH water solution at a temperature of 80 °C. This technique enables fabrication of three-level micromachined silicon structures with compensated convex corners at the bottom of the etched structure. All crystallographic planes that appear during etching are determined and their etch rates are used to calculate the etch rate value in an arbitrary crystallographic direction necessary for simulation by an interpolation procedure. A 3D simulation of the profile evolution of the etched structure during masked and maskless etching of silicon based on the level set method is presented. All crystallographic planes of the etched silicon structures determined in the experiment are recognized in the corresponding simulated etching profiles obtained by the level set method.