Abbreviated tomography techniques for quick correction of slides in 3-Dimensional NAND Flash architectures

A high stack structure is being developed to increase the 3D NAND Flash storage capacity. However, problems such as bowing, incomplete etching, and twisting occur during the channel hole etching process. For the analysis of these process problems, cross-sectional analysis of devices with high stacks is essential.However, it is difficult to uniformly measure the top and bottom layers of the source line contact and V-NAND string area. Therefore, distortion occurs through cross section analysis. The reasons include the focused ion beam incident beam angle relative to the sample coordinate system, beam current profile, and differential milling.The listed physical parameters can be adjusted in a way to obtain distortion-improved, uniform, and perpendicular image data; however, this time-consuming task is a hindrance when trying to increase the reliability of the analysis.In order to address this problem, we propose an efficient processing technique, abbreviated tomography, which is an efficient data reconstruction method.In this study, 248 images were prepared to set up the tomography algorithm data set. The data was reconstructed in a significantly reduced time using the abbreviated tomography technique. Although it took an average of 5 h to obtain 248 new 2D images, we were able to reconstruct the data in 4 min using the abbreviated tomography technique. This abbreviated tomography algorithm can be used as an efficient reconstruction tool for studying structure at the most basic level.