Elastic Moduli of Polymer Thin Films: A High-throughput Metrology

Thin polymer films are playing an increasing role in technological applications such as lithographic resist layers, barrier layers, electronic packaging, and optical coatings. As a result, it is becoming apparent that confined polymers can display subtle or even dramatic differences in their physical properties when compared to the same polymers in the bulk state. Understanding these differences is critical to the performance and stability of these devices and systems. In particular, the mechanical properties of thin films are of paramount importance since these properties often impact many of the reliability issues encountered while integrating thin polymer films into new devices. Thus, there is a growing need for measurement techniques that probe the mechanical properties of these materials, not in the bulk state, but rather in their application form, that is, in thin film geometries. This article highlights an innovative high-throughput (HT) method by which the elastic moduli of thin polymer films/coatings can be measured both rapidly and quantitatively. This platform is ideally suited for integration into combinatorial and high-throughput (C&HT) workflows that utilize gradient specimens to generate two-dimensional maps of the mechanical properties of polymer films that vary spatially. Results on several model systems are reviewed that demonstrate the broad applicability of this technique to a wide range of film thickness (30 nm to 50mm) and modulus (5MPa to 10GPa).