Mizuho Morita

Absolute flatness of three silicon plane mirrors have been measured by a three-intersection method based on the three-flat method using a near-infrared interferometer. The interferometer was constructed using a near-infrared laser diode with a 1,310-nm wavelength light where the silicon plane mirror is transparent. The height differences at the coordinate values between the absolute line profiles by the three-intersection method have been evaluated. The height differences of the three flats were 4.5 nm or less. The three-intersection method using the near-infrared interferometer was useful for measuring the absolute flatness of the silicon plane mirrors.

We propose the metal-assisted chemical etching of Ge surfaces in water mediated by dissolved oxygen molecules (O₂). First, we demonstrate that Ge surfaces around deposited metallic particles (Ag and Pt) are preferentially etched in water. When a Ge(100) surface is used, most etch pits are in the shape of inverted pyramids. The mechanism of this anisotropic etching is proposed to be the enhanced formation of soluble oxide (GeO₂) around metals by the catalytic activity of metallic particles, reducing dissolved O₂ in water to H₂O molecules. Secondly, we apply this metal-assisted chemical etching to the nanoscale patterning of Ge in water using a cantilever probe in an atomic force microscopy setup. We investigate the dependences of probe material, dissolved oxygen concentration, and pressing force in water on the etched depth of Ge(100) surfaces. We find that the enhanced etching of Ge surfaces occurs only when both a metal-coated probe and saturated-dissolved-oxygen water are used. In this study, we present the possibility of a novel lithography method for Ge in which neither chemical solutions nor resist resins are needed.

A photoetching method with -fluoropyridinium salts is proposed in this study. Si is etched by applying -fluoropyridinium salts to its surface and exposing the surface to light. The etched surface that uses liquid -fluoropyridinium salts is smoother than when solid -fluoropyridinium salts are used. The etching depth increases with exposure time. H-terminated hydrophobic Si is easier to etch than OH-terminated hydrophilic Si. is produced by photoetching. This suggests that -fluoropiridinium salts receive excited electrons from Si and supply Si with active F species.