Fabrication of 2D ordered arrays of cobalt silicide nanodots on (001)Si substrates

Two-dimensional (2D) periodic arrays of Co metal and Co silicide nanodots were successfully fabricated on (0 0 1)Si substrate by using the polystyrene (PS) nanosphere lithography (NSL) technique and thermal annealing. The epitaxial CoSi 2 was found to start growing in samples after annealing at 500 °C. The sizes of the Co silicide nanodots were observed to shrink with annealing temperature. From the analysis of the selected-area electron diffraction (SAED) patterns, the crystallographic relationship between the epitaxial CoSi 2 nanodots and (0 0 1)Si substrates was identified to be [0 0 1]CoSi 2 //[0 0 1]Si and (2 0 0)CoSi 2 //(4 0 0)Si. By combining the planview and cross-sectional TEM examination, the epitaxial CoSi 2 nanodots formed on (0 0 1)Si were found to be heavily faceted and the shape of the faceted epitaxial CoSi 2 nanodot was identified to be inverse pyramidal. The observed results present the exciting prospect that with appropriate controls, the PS NSL technique promises to offer an effective and economical patterning method for the growth of a variety of large-area periodic arrays of uniform metal and silicide nanostructures on different types of silicon substrates.