We have completed a comparison of SiO2film thicknesses obtained with the three dominant measurement techniques used in the Integrated Circuit industry: ellipsometry, capacitance‐voltage (C‐V) measurements and high resolution transmisission electron microscopy (HRTEM). This work is directed at evaluating metrology capability that might support NIST‐ traceable Reference Materials for very thin dielectric films. Particular care was taken in the design of the sample set to allow redundancy and enable estimates of oxide layer consistency. Ellipsometry measurements were analyzed using a variety of models of the film structure, and C‐V results were analyzed using three different quantum‐mechanical based algorithms to account for quantized states in the substrate and depletion effects in the polysilicon capacitor electrode. HRTEM results were supplemented with Electron Energy‐Loss Spectroscopy. A range of thicknesses was found with each of the methods, but with some overlap of values. HRTEM and STEM values showed less consistency between wafers than the C‐V data for the capacitors used and were seen to be more influenced by local variations such as interface non‐uniformities. Sources of variation and estimates of uncertainty for the analyses are presented. Implications of these results for Reference Materials are discussed. © 2003 American Institute of Physics