Magnetic field sensor with coil structure and method of fabrication

A magnetic field sensor comprising:

• an active silicon substrate having a processing circuit formed therein, the active silicon substrate having an electrically conductive layer and an electrically insulating layer overlying the electrically conductive layer;
• a magnetic sense element formed over the electrically insulating layer of the active silicon substrate;
• and
• a coil structure surrounding the magnetic sense element comprising:
• first coil segments formed in the electrically conductive layer of the active silicon substrate such that the magnetic sense element is separated from the first coil segments by the electrically insulating layer;
• conductive vias extending through a protective layer overlying the magnetic sense element, the conductive vias being electrically coupled with the first coil segments;
• and
• second coil segments formed over the protective layer, the second coil segments being electrically coupled with the conductive vias to produce the coil structure.

A method comprising:

• forming first coil segments in an electrically conductive layer of an active silicon substrate;
• forming a magnetic sense element over an electrically insulating layer of the active silicon substrate, the magnetic sense element being separated from the first coil segments in the electrically conductive layer by the electrically insulating layer;
• forming a protective layer over the magnetic sense element;
• forming first conductive vias extending through the protective layer and the electrically insulating layer to electrically couple with the first coil segments;
• forming a second conductive via extending through the protective layer to electrically couple with a contact pad of the magnetic sense element;
• forming a third conductive via extending through the protective layer and the electrically insulating layer to electrically couple with an electrical contact in the electrically conductive layer of the active silicon substrate, wherein the electrical contact is electrically coupled to a processing circuit in the active silicon substrate;
• and
• forming second coil segments over the protective layer, the second coil segments electrically coupling with the first conductive vias to produce a coil structure of the first coil segments, the first conductive vias, and the second coil segments, and the coil structure surrounding the magnetic sense element.