This paper is a comprehensive summary and analysis of a SEMATECH funded project to study the limits of optical critical dimension scatterometry. The project was focused on two primary elements: 1) the comparison, stability, and validity of industry models and 2) a comprehensive analysis of process stacks to evaluate the ultimate sensitivity and limits of OCD. Modeling methods are a requirement for the interpretation and quantitative analysis of scatterometry data. The four models evaluated show good agreement over a range of targets and geometries for zero order specular reflection as well as higher order diffraction. A number of process stacks and geometries representing semiconductor manufacturing nodes from the 45 nm node to the 18 nm node were simulated using several measurement modalities including angle-resolved scatterometry and spectrally-resolved scatterometry, measuring various combinations of intensity and polarization. It is apparent in the results that large differences are observed between those methods that rely upon unpolarized and single polarization measurements.
Proceedings Title: Proceedings of SPIE
Conference Dates: February 1, 2007
Conference Location: San Jose, CA
Conference Title: Metrology, Inspection, and Process Control for Microlithography XXI
Pub Type: Conferences
electromagnetic scattering, optical critical dimension scatterometry, optical modeling, sensitivity and limits, zero order specular reflection