Impact of Chemical and Epitaxial Treatment on Surface Defects on Silicon Wafers

Defects on polished as well as hot SC1 treated silicon wafers were investigated with an Atomic Force Microscope (AFM) and Surface Scanning Inspection Systems (SSIS). Measurement with two SSIS of different type allows to identify most of the surface defects as non particulate scatterers. AFM of these defects reveals tiny pits or groups of pits. An almost linear relation is found between the geometrical lateral defect dimension and their average size in units of LSE (Latex Sphere Equivalent; an effective measure for the scattering cross section) as reported by one of the SSIS for the defects on wafers treated with hot SC1. Growth rates of about 40 nmLSE/h are observed for the defects during subsequent treatments of wafers with hot SC1. The LSE-size distribution of as-grown defects with a peak at about 105 and 110 nmLSE is obtained for two types of wafer by modeling the defect evolution during hot SC1 treatment. The number of surface flaws ≥ 0.12 µmLSE on a substrate is reduced by two orders of magnitude for epitaxial layers as thin as 1.5 µm.