In this paper, the electrostatic-discharge (ESD) protection capabilities of the protection devices fabricated on a silicon-on-diamond (SOD) structure and a conventional Si substrate are compared. The results showed that the ESD protection capability of the SOD substrate is higher than that of the silicon-on-insulator (SOI) substrate. We also evaluate the ESD protection device suitable for the SOD structure. In addition, we propose the three-dimensional (3D) stacking structure suitable for a power supply on a chip (power-SoC) and the best location for the implementation of the ESD protection device based on the results of device simulations.