Formation of single-crystalline silicon nanostructures by self-assembling growth with molecular beam epitaxy

Dry etching techniques for patterning of silicon nanostructures suffer from unintentional process induced degradation. Local deposition by serial writing techniques does not enable high through-put and reproducibility. To overcome these problems we propose two parallel, self-assembling growth processes, both based on local molecular beam epitaxy MBE.: MBE with micro-shadow masks and MBE on nonplanar, prepatterned substrates. Depending on growth parameters ultrasharp, single-crystalline tips or wedges with crystallographic 111.andror 311.sidewalls are grown. As shown by scanning electron micrographs the tip radius amounts to less than 5 nm. These structures exhibit high thermal stability and simple process technology. A physical model, based on an energetic as well as a kinetic approach is proposed which consistently explains the observed grown features. q1998 Elsevier Science B.V. All rights reserved.