Nano fabrication of silicon fins
We describe the formation of silicon micro- and nano-fins, with (111)-plane sidewall facets, for selective sidewall epitaxy of III-Nitride semiconductors. The fins were produced by wet etching (110)-oriented silicon wafers. Silicon dioxide was deposited using plasma enhanced chemical vapor deposition for producing a hard mask. The silicon dioxide was patterned using photo- and electron-beam lithography for micro and nano-fins, respectively, followed by wet etching in hydrofluoric acid. Wet etching to produce silicon fins was carried out using tetramethyl ammonium hydroxide (TMAH) diluted with isopropyl alcohol (IPA), as well as silicon doped TMAH/IPA solution with surfactant (Triton-X-100). Atomic force microscopy and scanning electron microscopy were used to determine the morphology including surface roughness of the area between fins and etching rate of silicon. We tuned the etching time, temperature, percentage of IPA, drops of Triton-X-100 in order to get the best surface on both (111) and (110) planes.