Processing forms an integrated circuit structure having first and second layers on opposite sides of an insulator, and an interconnect structure extending through the insulator between the first layer and the second layer. The interconnect structure is formed in an opening extending through the insulator between the first layer and the second layer and has an electrical conductor in the opening extending between the first layer and the second layer and a thermally conductive electrical insulator liner along sidewalls of the opening extending between the first layer and the second layer. The electrical conductor is positioned to conduct electrical signals between the first layer and the second layer, and the thermally conductive electrical insulator liner is positioned to transfer heat between the first layer and the second layer.