Techniques for fabricating a cored or coreless semiconductor package having one or more magnetic bilayer structures embedded therein are described. A magnetic bilayer structure includes a magnetic layer and a dielectric layer. For one technique, fabricating a cored or coreless semiconductor package includes: depositing a seed layer on a build-up layer; forming a raised pad structure and a trace on the seed layer; removing one or more uncovered portions of the seed layer to uncover top surfaces of one or more portions of the build-up layer; applying a magnetic bilayer structure on the raised pad structure, the trace, any unremoved portion of the seed layer, and the top surfaces of the one or more portions of the build-up layer, the magnetic bilayer structure comprises a magnetic layer and a dielectric layer; and forming a conductive structure on the raised pad structure. Other techniques are also described.