Complimentary Optical Metrology Techniques Used for Characterization of High-K Gate Dielectrics

Abstract

We report on the use of two different optical metrology techniques for characterization of high‐k gate dielectrics. Spectroscopic Ellipsometry (SE) is a standard in‐line metrology technique used to extract film information such as thickness and optical constants. However, with the gate dielectric being extremely thin (∼3nm), SE encounters certain inherent limitations when it comes to the data analysis. As a result, SE requires a secondary technique to fully characterize the thin films. Therefore, the ability of Second Harmonic Generation (SHG) to serve as a complimentary optical technique is reviewed. This non‐linear optical technique probes the high‐k/silicon interface and demonstrates sensitivity towards certain process‐induced conditions such as chemical composition, phase separation, defect trap states, and interfacial roughness.