Thickness mapping of high-k dielectrics at the nanoscale

Contact potential difference measurements by Kelvin probe force microscopy (KPFM) together with corona charging was applied for contactless equivalent oxide thickness (EOT) mapping with nanometer range lateral resolution. Characterization was performed under ambient conditions and compared to a conventional macroscale method based on Kelvin probe measurements. The presented method is directly applicable for dielectrics with homogeneous thicknesses. For other dielectric layers, the implemented laboratory setup suffers from imprecise KPFM sample positioning. If such samples have microscopically non-flat surfaces a proposed data evaluation procedure overcomes that issue which is demonstrated for nanoscale EOT maps of HfO2 and HfSixOy samples.