In-plane inductors in IC packages

An integrated circuit (IC) package substrate, comprising:

• a magnetic material embedded within one or more dielectric materials, wherein the one or more dielectric materials is between a bottom of the magnetic material and a bottom side of the IC package substrate, and the one or more dielectric materials is between a top of the magnetic material and a top side of the IC package substrate, opposite the bottom side of the IC package substrate;
• and
• a metallization level comprising a first metal feature embedded within the magnetic material, and a second metal feature at an interface of the magnetic material and the one or more dielectric materials, wherein:
• the second metal feature completely surrounds the first metal feature, and extends along a perimeter of the magnetic material;
• and
• the second metal feature has a first sidewall in contact with at least one of the one or more dielectric materials and a second sidewall, opposite the first sidewall, in contact with the magnetic material, wherein:
• a sidewall of the first metal feature has a non-vertical first slope between a top of the first metal feature proximal to the top side of the IC package substrate that has a smaller lateral linewidth and a bottom of the first metal feature proximal to the bottom side of the IC package substrate that has a larger lateral linewidth;
• the second sidewall has the non-vertical first slope;
• and
• the first sidewall is more vertical than the second sidewall, and more vertical than the sidewall of the first metal feature.