4. 3-D Nanostructure Fabrication by Focused-Ion Beam, Electron- and Laser Beam

In this chapter, we describe three-dimensional (3-D) nanostructure fabrication techniques using focused-ion-beam (FIB)-induced chemical vapor deposition (CVD), electron-beam (EB)-induced CVD, and femtosecond laser (fs-laser) techniques. We first describe 30 keV Ga⁺ FIB-induced CVD using a phenanthrene (C₁₄H₁₀) source gas as the precursor. A diamond-like amorphous carbon film is deposited during this process; it has a Young's modulus exceeding 600 GPa, making it potentially highly desirable for various applications. A three-dimensional pattern generator system has been developed to make arbitrary three-dimensional nanostructures. We also discuss microstructure plastic art, which is a new field that has been made possible by microbeam technology, and we present examples of such art, including a micro wine glass with an external diameter of 2.75 μm and a height of 12 μm. We then discuss free-space nanowiring and show by using a mixture of C₁₄H₁₀ and W ( CO)₆ that the electrical properties indicate an increase in metal content results in a lower resistivity. We also demonstrate that a Morpho butterfly scale quasistructure fabricated by FIB-induced CVD has almost the same optical characteristics as a real Morpho butterfly scale. We then discuss three-dimensional nanostructure fabrication using EB-induced CVD. Because of the nanometer resolution, EB-induced CVD is now indispensable for mask repair techniques for the 193 nm node. According to real-time observations by transmission electron microscopy, the W clusters, as the initial growth stage, are formed first followed by the W layer which forms as W clusters coalesce due to EB irradiation. We go on to discuss photonic crystals and Smith–Purcell electron optics as examples of three-dimensional nanostructure applications using EB-induced CVD. Finally, we describe femtosecond-laser-assisted micro/nano fabrication which has been recognized as a promising technique to fabricate three-dimensional structures inside transparent materials. The spatial resolution can reach submicrometer levels and even tens of nanometers owing to suppression of the involved heat diffusion and nonlinear adsorption. We discuss three-dimensional femtosecond laser nanofabrication using the direct laser writing technique and multiple beam interference lithography and describe the fabrication of photonic crystals in a photoresist.