Influence of the angle between etched (near) Si{111} surfaces and the substrate orientation on the underetch rate during anisotropic wet-chemical etching of silicon

Anisotropic wet-chemical etching of silicon in alkaline solutions is a key technology in the fabrication of sensors and actuators. In earlier work it was found that not only the etchant and temperature determine the exact ani sotropy of etched silicon; the angle between the silicon surface and the ma sk was also shown to play an important role-In this paper this phenomenon w as quantified for several etching conditions. Also, the etch rates of Si{10 0} and Si{110} were determined under these conditions, together with the ac tivation energies of these orientations. Finally, the anisotropy ratios (et ch depth/underetch) of the etched samples were determined.