Packaging architecture with coaxial pillars for high-speed interconnects

An IC package, comprising:

• a package substrate;
• an interposer coupled to the package substrate, the interposer comprising:
• a first IC die;
• a dielectric material;
• a first plurality of conductive pillars through the dielectric material, the first plurality of conductive pillars between the first IC die and the package substrate;
• a second plurality of conductive pillars through the dielectric material;
• and
• an electromagnetic shield at least partially surrounding the conductive pillars of the first plurality of conductive pillars and the second plurality of conductive pillars, the electromagnetic shield separated from the conductive pillars by the dielectric material;
• and
• a second IC die coupled to the interposer on a side opposite to the package substrate,
• wherein:
• the electromagnetic shield is a conductive structure,
• the first plurality of conductive pillars conductively couples the first IC die and the package substrate, and
• the second plurality of conductive pillars conductively couples the second IC die and the package substrate.

A method for fabricating a microelectronic assembly, the method comprising:

• providing a package substrate;
• providing an interposer comprising conductive pillars, a dielectric material and an electromagnetic shield;
• providing an IC die;
• coupling the IC die to the interposer;
• and
• coupling the interposer to the package substrate,
• wherein:
• the conductive pillars extend through the interposer providing a conductive pathway between the IC die and the package substrate,
• the conductive pillars are surrounded by the dielectric material, and
• the dielectric material is surrounded by the electromagnetic shield.