Metrology of DSA process using TEM tomography

Directed self-assembly (DSA) of block copolymers (BCPs) is a rising technique for sub-20 nm patterning. To fully harness DSA capabilities for patterning, a detailed understanding of the three dimensional (3D) structure of BCPs is needed. By combining sequential infiltration synthesis (SIS) and scanning transmission electron microscopy (STEM) tomography, we have characterized the 3D structure of self-assembled and DSA BCPs films with high precision and resolution. SIS is an emerging technique for enhancing pattern transfer in BCPs through the selective growth of inorganic material in polar BCP domains. Here, Al2O3 SIS was used to enhance the imaging contrast and enable tomographic characterization of BCPs with high fidelity. Moreover, by utilizing SIS for both 3D characterization and hard mask fabrication, we were able to characterize the BCP morphology as well as the alumina nanostructures that would be used for pattern transfer.