EQUILIBRIUM SHAPE OF COSI2 HUT CLUSTERS ON SI(100)

CoSi2 clusters of constant height on a Si(100) surface grow in a squar e shape at first, but at a critical size a shape transition to cluster s with large aspect ratios occurs. With each cluster connected to an i mplanted layer of cobalt by a thermally induced defect that serves as a diffusion channel, clusters can grow independently with a continuous supply of cobalt. When the cobalt supply is limited, clusters grow up to a specific volume and then have time to adjust their height, assum ing their minimum-energy shape. Although calculations indicate that th is should be a square pyramid, experiments indicate that a more elonga ted cluster corresponds to equilibrium. (C) 1998 American Vacuum Socie ty.