Technology evolution in the data storage industry is driven by the continuous scaling down of devices and by an increasing complexity of the critical elements in the devices. Focused ion beam - scanning electron microscope (SEM) tomography can enable characterization of a device over its entire volume, while maintaining the resolution of the SEM. This study introduces the quantitative 3D tomography technique developed in the data storage industry to specifically address the industrial process development needs. In the detail section, the methodology of 3D reconstruction is introduced, key parameters are reviewed, and the steps for a successful 3D tomographic reconstruction are described. The study presents typical applications of 3D analysis for device design and process development to illustrate the benefits and unique learning opportunities. By reconstructing all slice-view 2D images quantitatively, 3D device structures and related 3D metrology data can be obtained.