Neutron reflectometry, x-ray reflectometry, and spectroscopic ellipsometry characterization of thin SiO2 on Si

We present here a comparison of neutron reflectometry, x-ray reflectometry, and spectroscopic ellipsometry on a thin oxide film. These three probes each independently determine the structure of the film as a function of depth. We find an excellent agreement between the three techniques for measurements of thicknesses and interfacial roughnesses for both the SiO2 and surface contamination layers found in the sample. Realistic models based on interface parameters measured herein indicate that as the SiO2 layers decrease to sizes projected for future generations of electronic devices, both spectroscopic ellipsometry and neutron reflectometry can easily measure SiO2 films to 2 nm thick or less.