Silicon etching characteristics for tetramethylammonium hydroxide-based solution with additives

In this reported work, the anisotropic etching properties of single-crystal silicon with tetramethylammonium hydroxide (TMAH) solution are examined in detail. The variations in the Si etching rate and surface morphology at different etching temperatures and TMAH concentrations are evaluated. The effect of isopropyl alcohol (IPA) additive is also examined. As the TMAH concentration (10-25 wt%) decreased, the etching rate increased from 10 to 70 μm/h at temperatures between 70 and 90°C. On the other hand, the etched surface roughness became degraded as the hillock density and corner undercut ratio increased. The additive of IPA affected the morphology of the etched surface to be flat. In addition, the IPA additive improved the etched surface significantly by decreasing the hillock density on the surface.