Nano-cluster formation in halogen etching on Cl/Si(1 1 1)-7 × 7

To furnish semiconductor surfaces at device fabrication, control of micro-structures is expected of the most importance in the near-future. Highly sensitive measurement of desorption from Cl-adsorbed Si(1 1 1) surface indicated that a diffusive process plays an important role on the surface. The desorption barrier was estimated to be 2.2 eV from temperature-dependence of time-course in isothermal desorption, suggesting the desorption site contains distortion. Defects, which may be steps or clusters, are the dominant sites where the associative reaction occurs. In STM images, clusters were observed at step edges, as well as growth of pits and defects. From comparison of the desorption with high temperature STM images, a cluster pins the step movement to form step bunches. Interaction between clusters through the step movements makes clusters aligned. Ordered structures can be obtained when velocity of the surface diffusion matches the rate of the chloride desorption.