IC devices including inductors or transformers formed based on BPRs are disclosed. An example IC device includes semiconductor structures of one or more transistors, an electrically conductive layer, a support structure comprising a semiconductor material, and an inductor. The inductor includes an electrical conductor constituted by a power rail buried in the support structure. The inductor also includes a magnetic core coupled to the electrical conductor. The magnetic core includes magnetic rails buried in the support structure, magnetic TSVs buried in the support structure, and a magnetic plate at the backside of the support structure. The magnetic core includes a magnetic material, such as Fe, NiFe, CoZrTa, etc. In some embodiments, the IC device includes another power rail that is buried in the support structure and constitutes another electrical conductor coupled to the magnetic core. The two power rails and magnetic core can constitute a transformer.