Scanning probe tomography toward the three-dimensional characterization of confined volumes
Umberto Celano and Wilfried Vandervorst
1 IMEC, Kapeldreef 75, B-3001 Heverlee (Leuven), Belgium
2 KU Leuven, Department of Physics and Astronomy (IKS), Celestijnenlaan200D, 3001 Leuven, Belgium.
Three dimensional (3D) device architectures and novel materials has been already widely introduced to maintain scaling and performance improvement in nowadays microelectronics. Logic switches (transistors) have been the first to move from 2D to 3D in 2011 with the introduction of FinFET in replacement of planar devices. Non-volatile memory has followed in 2014 with the replacement of traditional flash devices with 3D NAND. Finally, the requirements for future technology nodes foresee the introduction of new materials (such as III-V compound semiconductors) fully integrated in 3D structures (trenches) embedded in traditional Si substrates. However, the pervasive introduction of 3D devices poses unparalleled challenges to semiconductor metrology. We present in this work scanning probe microscopy (SPM) tomography as a concept for three-dimensional characterization with nm spatial resolution. Based on a 2D contact-mode SPM using a (biased) conductive tip. In SPM tomography we extend this method to 3D by combining the high lateral-resolution conductance mapping with a controlled material removal during tip scanning. The consecutive planar C-AFM current images are then stacked and interpolated for the formation of the 3D tomogram. In this paper we discuss various application for resistive switching devices, 3D NAND and failure analysis.
