Integrated circuits with magnetic core inductors and methods of fabrications thereof

A method of forming a semiconductor device, the method comprising:

• forming a first inductor coil within and/or over a substrate, the first inductor coil formed adjacent a top side of the substrate;
• forming first trenches within the substrate adjacent the first inductor coil;
• filling the first trenches with a magnetic fill material;
• attaching a carrier to the top side of the substrate;
• and
• encapsulating the substrate and the first inductor coil with a magnetic mold compound, wherein the first inductor coil comprises a central region surrounded by the first inductor coil and a peripheral region surrounding the first inductor coil, wherein forming the first trenches comprises forming a first hole within the central region and a second hole within the peripheral region.

A method of forming a semiconductor device comprising:

• forming metal lines of a first inductor coil within and/or over a substrate, the metal lines disposed adjacent a top side of the substrate than an opposite back side;
• forming first trenches within the substrate adjacent the first inductor coil;
• at least partially filling the first trenches with a magnetic fill material;
• and
• forming a magnetic material under a first portion of the substrate at the back side, wherein at least a part of a magnetic core region of the first inductor coil comprises the magnetic material and the magnetic fill material, wherein the magnetic material comprises a structured layer formed under the first inductor coil, wherein, at the back side, a second portion of the substrate is not covered by the magnetic material.