Atomic scale deformation in the solid surface Induced by nanoparticle impacts

摘要

Nanoparticle impacts on an ultra-smooth surface always occur in nano-machining processes, such as polishing of a monocrystalline silicon wafer, which is an important process in the manufacture of semiconductors. A fundamental understanding of nanoparticle impacts on a solid surface is important to control and prevent the deformation of the surface. In this study, a cylindrical liquid jet containing de-ionized water and SiO_2 nanoparticles impacts obliquely on a single crystal silicon surface at a speed of 50 m s~(-1). The microstructure of the impacted surface was examined using a high resolution transmission electron microscope, an atomic force microscope, etc. Some crystal defects, lattice distortion, grain refinement and rotation of grains in the surface layer of the silicon wafer after exposure for 30 s have been observed. However, when the exposure time is extended to 10 min, an amorphous layer containing crystal grains is exhibited in the subsurface, and many craters, scratches and atom pileups can be found in the surface.