NIST researchers develop and distribute crucial optical dispersion model to the semiconductor industry. (News Briefs).

NIST researchers have recently derived a unique Generalized Tauz-Lorentz (GTL) dispersion model that can successfully model spectroscopic ellipsometry data for high-k thin films in the spectral range of 1.5 eV to 6.3 eV. This model can be used to determine accurately film thickness and optical properties. Furthermore, the model and measurements were shown to provide a nondestructive method to assess film qualities such as surface roughness and degree of crystallinity. This GTL model has been implemented in a user-friendly windows-based software which was recently transferred to International SEMATECH for further dissemination to the industry. The spectroscopic ellipsometry measurements enabled by this work will provide crucial data for identifying, developing, and ultimately manufacturing high-k gate dielectrics.

One of the most important parts of the search for a new gate dielectric is the ability to measure accurately and control the film thickness. The thickness measurement method that integrated circuit (IC) manufacturers most frequently use is nondestructive, non-contact ellipsometry. However, this technique requires an optical model to characterize the film properties in order to extract an accurate film thickness. To address this industry need, NIST researchers have been acquiring films from IC industry leaders and university research groups to investigate the optical properties and develop models required for measuring the thickness of these new materials.

CONTACT: Nhan Nguyen, [phone]; nhan. [e-mail].