Advancing semiconductor characterization: utilizing 3D reconstruction techniques with AFM electrical modes

Abstract

As semiconductor devices continue to increase in complexity and scale down in size, conventional characterization methods struggle to provide high-resolution insights into dopant profiles and device structures. To overcome these limitations, this thesis investigates an innovative technique that leverages the capabilities of atomic force microscopy (AFM), specifically, scanning capacitance microscopy (SCM), augmented with novel pre- and post-processing methods for three-dimensional electrical imaging of semiconductor devices. While AFM-based techniques have been widely used to characterize the physical properties of semiconductor surfaces, their utility is usually confined to surface-level data. SCM and scanning spreading resistance microscopy (SSRM) typically rely on scans of perfectly smooth surfaces to extract electrical information, yet they do not inherently provide depth-resolved profiles. This work introduces a novel methodology that integrates bevel polishing to expose multiple planar layers of an array of the device simultaneously, enabling electrical characterization across varying depths. Additionally, image reconstruction software, adapted from tools extensively used in the medical imaging field, is employed to merge adjacent sequential scans into an accurate 3D representation of the device’s internal dopant structure. This approach addresses traditionally lacking dopant information for highly 3D integrated device designs and helps to facilitate future device development with improved dopant imaging. Author Keywords: Atomic Force Microscopy (AFM), Scanning Capacitance Microscopy (SCM), Scanning Spreading Resistance Microscopy (SSRM), Spreading Resistance Profiling (SRP), Semiconductor Failure Analysis, 3D Tomography, Bevel Polishing, Dopant Profiling, Image Reconstruction, Microelectronic Characterization