The dopant diffusion barrier property of a chemically grown oxide (CGO) film has been characterized in polysilicon. The CGO film was grown by immersion of an amorphous Si film in a mixture of H2O2, NH4OH, and H2O liquids, heated to 55 degrees C. The 4.7 A CGO film behaves as a superior dopant diffusion barrier compared to a 12.7 A thermally grown oxide (TGO) film. Composition analysis shows the CGO film has 0.4 atom % N while the TGO has no detectable N. The superior barrier property of the thinner CGO film is attributed to N incorporation.