It is well known that pursuing the miniaturization of devices to lower the cost and increase high-speed performance are extremely important goals for dynamic random access memory (DRAM). Therefore, electron tomography has a high potential for application to novel generation DRAMs. In this article, several real-case examples of electron tomography on 90 nm technology DRAM, including barrier layer step coverage, via fill process observations and defect analysis are reported. These cases were demonstrated to show the applications of bright field-transmission electron microscope (BF-TEM) and HADDF- scanning transmission electron microscope (STEM) tomography to analyze barrier layer step coverage, defects, and W fill quality in advanced DRAM. By appropriate use of BF-TEM or HAADF STEM tomography, optimal information for failure analysis, root cause clarification, and subsequent process improvements can be obtained. Electron tomography holds significant advantages in comparison to traditional TEM imaging for appropriate cases.