Epitaxial growth of μm-sized Cu pyramids on silicon

Abstract

Triangular and quadratic Cu pyramids were epitaxially grown on Si(111) and Si(100) substrates, respectively, by pulsed laser deposition at elevated substrate temperatures above 200°C as well as by post-annealing of closed Cu layers prepared at room temperature. In both cases, three-dimensional pyramids with edge lengths of up to 9 µm were obtained, as observed by scanning electron microscopy and atomic force microscopy. Although the macroscopic shape is a pyramid, microscopically the islands consist of columnar grains (with lateral sizes of only about 50 nm at 260°C). The size and shape of the pyramids can be controlled by the substrate used, the amount of material deposited, and the temperature during deposition or annealing. Additionally, first hints were found that the pyramids can be aligned by structuring the substrate. The formation of such large pyramids is explained by a fast diffusion of Cu atoms on Si over distances of some µm and a high jump probability to higher pyramid layers.

Shape and Orientation Controlled Hydrothermal Synthesis of Silicide and Metal Dichalcogenide on a Silicon Substrate

“…Square, hexagonal, and triangular patterns have been achieved on the silicon substrates with orientations of (100), (110), and (111), respectively, by growing Cu film followed by high-temperature annealing using a CVD method. 45 It is a result of the fact that the formation energy of Cu silicide with the shapes of square, hexagon, and triangle is the lowest on (100), (110), and (111) silicon substrates, respectively. Besides the lowest formation energy, Kukushkin et al explained that the elastic energy of lattice and interaction of defects also play significant role in the nucleation of a new phase.…”

“…Furthermore, the silicon substrate has a strong effect on the orientation of the formed silicide. Square, hexagonal, and triangular patterns have been achieved on the silicon substrates with orientations of (100), (110), and (111), respectively, by growing Cu film followed by high-temperature annealing using a CVD method . It is a result of the fact that the formation energy of Cu silicide with the shapes of square, hexagon, and triangle is the lowest on (100), (110), and (111) silicon substrates, respectively.…”