Preferential Chemical Etchant
Original Publication Date: 1983-Oct-01
Included in the Prior Art Database: 2005-Feb-07
A chemical system is described which consistently results in reliable preferential etching of (100) silicon crystals. Preferential etching is a simple and fast technique to evaluate the structural perfection of a single crystal. For silicon crystals such techniques are widely used to select dislocation-free crystal sections for further processing and also to delineate process-induced defects in silicon wafers. There are several preferential etches currently available for (100) silicon crystals. Use of these etches, however, usually produces contradictory results. A more reliable preferential etch for (100) silicon crystals is therefore highly desirable. It has been found that a mixture of CrO3 (chromium trioxide) dissolved in water at HF (hydrofluoric acid 48%) produces a superior etch.