Embodiments include a package substrate and semiconductor packages. A package substrate includes a first cavity in a top surface, first conductive pads on a first surface of the first cavity, a second cavity in a bottom surface, second conductive pads on a second surface of the second cavity, where the first surface is above the second surface, and a third cavity in the first and second cavities, where the third cavity vertically extends from the top surface to the bottom surface. The third cavity overlaps a first portion of the first cavity and a second portion of the second cavity. The package substrate may include conductive lines coupled to the first and second conductive pads, a first die in the first cavity, a second die in the second cavity, and interconnects in the third cavity that directly couple first die to the second die.