Application of triton X-100 surfactant for silicon anisotropic etching in KOH-based solutions

The results of etching of silicon surfaces with different crystallographic orientations in KOH solutions containing a nonionic surfactant Triton X-100 are presented in this paper. The etch rate ratio R(100)/R(110) >1, typical of KOH + IPA and TMAH + Triton X-100 mixtures, is achieved. The surface morphology of Si(hkl) wafers is closely investigated by SEM and AFM. The very low roughness of (110) and its vicinal (hh1) planes is observed and measured. In addition, the relatively smooth (h11) surfaces are obtained in the solution with Triton X-100 surfactant, as compared to the KOH solutions containing alcohols. Due to good smoothness of the studied surfaces, the KOH solution with Triton X-100 seems to be especially interesting for bulk micromachining employing non-standard (hkl) planes. The examples of mesas and trenches fabricated by anisotropic etching in the KOH solution containing Triton X-100 surfactant are presented. Keywords: silicon anisotropic etching;Triton X-100; potassium hydroxide; Si(hkl) surfaces