Integrated circuit assembly including interposer between stacked die and related methods

An integrated circuit (IC) assembly comprising:

• a substrate and a plurality of IC die coupled to the substrate in laterally spaced relation;
• the substrate comprising
• a bottom layer and a top layer coupled thereto and defining a heat exchange fluid chamber therebetween,
• a plurality of dielectric pillars extending within the heat exchange fluid chamber between the bottom layer and the top layer,
• a heat exchange fluid within the heat exchange fluid chamber,
• a wick structure within the heat exchange fluid chamber for moving the heat exchange fluid in a liquid phase into the heat exchange fluid chamber,
• a nanodiamond layer lining the heat exchange fluid chamber,
• a plurality of electrically conductive through-vias extending within respective ones of the plurality of dielectric pillars and being exposed on outer surfaces of the bottom layer and the top layer, and
• an optical waveguide layer above the top layer.

A method for making an integrated circuit (IC) assembly comprising:

• coupling a plurality of IC die on a substrate;
• the substrate comprising
• a bottom layer and a top layer coupled thereto and defining a heat exchange fluid chamber therebetween,
• a plurality of dielectric pillars extending within the heat exchange fluid chamber between the bottom layer and the top layer,
• a heat exchange fluid within the heat exchange fluid chamber,
• a wick structure within the heat exchange fluid chamber for moving the heat exchange fluid in a liquid phase into the heat exchange fluid chamber,
• a plurality of electrically conductive through-vias extending within respective ones of the plurality of dielectric pillars and being exposed on outer surfaces of the bottom layer and the top layer, and
• an optical waveguide layer above the top layer.