Height control of silicon nano-whiskers embedded in ultra thin silicon nitride layers by rapid thermal annealing

Two steps are necessary to produce nanometre sized silicon whiskers rising out of ultra thin silicon nitride layers: (i) production of under-stoichiometric silicon nitride surface layers by ion implanting of silicon wafer material, (ii) growth of silicon whiskers by the formation of silicon nitride bonds in the surface region through rapid thermal electron beam annealing. Depending on the implantation and annealing conditions, whiskers of different height and width can be produced. As an example, 25 nm high whiskers were formed by implanting 10 keV N-15(2)+ ions into silicon (fluence 5 x 10(16) cm(-2)) followed by rapid thermal electron beam annealing at 900 degreesC for 15 s. In atomic force microscope studies, it was observed that the structures became more pronounced with increased temperature. Resonant nuclear reaction analysis revealed the absence of nitrogen in the whiskers and the stoichiometry of the silicon nitride layer formed by implantation. (C) 2001 Elsevier Science B.V. All rights reserved.