Fabrication of self-supported Si nano-structure with STM

A self-supported Si nano-structure was fabricated on a Si diaphragm using STM induced anodization and anisotropic Si etching. The width and the thickness of the nano-structure were both approximately 200 nm. For the fabrication of the nano-structure, a very thin double-layered diaphragm which consist of a top Si layer (160 nm) and buried-SiO₂ layer (100) was employed. This diaphragm was prepared by etching a SIMOX wafer in TMAH solution from the back side. The top Si layer was protected from the etchant with the buried-SiO₂, and used for Si nano-structure. Oxide line pattern was delineated by STM induced anodization of a hydrogen-terminated Si surface. This top Si-layer having anodized-pattern was selectively etched in a hydrazine solution. Anodized oxide patterns act as masks to form Si nano-structures during the etching process. The buried-SiO₂ layer was then etched out to release the nano-structure. A supercritical drying method was used for drying the nano-structure after etching the buried-SiO₂ layer in buffered HF. The widths of the anodized-oxide were observed to be approximately 30 nm by a TEM investigation. Since the Si (100) layer is wet etched anisotropicaly, the width of the structure was enlarged approximately 200 nm.