Phosphorus (P) protrusion into thin-oxide film from heavily P-doped Si (100) upon annealing was investigated using X-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM). After annealing at 750 degrees C, the P was segregated at the SiO2/Si interface and its concentration decayed exponentially toward both the thin-oxide film and the substrate. The chemical state of protruded-P in the oxide was nearly elemental. After annealing, the AFM images of the sample surface showed that some of the plateaus grew in height while maintaining their lateral shape. The total increment volume of the grown plateaus corresponded roughly to the volume of protruded-P in the oxide film estimated by XPS. (c) 2007 Elsevier B.V. All rights reserved.