Nondestructive structural evaluation of high-aspect-ratio-etched holes by tender x-ray ptychography with computed tomography

Abstract

Nondestructive evaluation of high-aspect-ratio (HAR) structures in advanced memory devices is essential yet remains challenging at the nanoscale. In this study, we demonstrate tender x-ray ptychography for the characterization of HAR-etched hole structures with depths of approximately 10 μm. Reconstructed two-dimensional projection images, with a spatial resolution of 38.5 nm, reveal features such as necking at the amorphous carbon mask and tapered hole profiles. Furthermore, a three-dimensional (3D) electron density map was reconstructed using ptychographic x-ray computed tomography, achieving a spatial resolution of 67.5 nm. This approach enables direct visualization of etch-rate variations associated with aspect-ratio-dependent etching. These results establish a powerful nondestructive methodology for three-dimensional nanoscale evaluation of HAR structures, with significant potential for applications in advanced memory device development.