Cross sectional view                                   Top View

Fig. 3.8 : V-groove etching in (100) silicon showing the exposed {111} sidewalls

An anisotropic wet etch on a silicon wafer creates a cavity with a trapezoidal cross-section as shown in Fig. 3.8. The bottom of the cavity is a <100> plane, and the sides are <111> planes. The white material is an etch mask, and the grey material is silicon. The angle between (111) planes and (100) surface is 54.7° as calculated before and the etching stops at (111) planes at this angle resulting a V-groove.