An integrated circuit has a thermal routing structure above a top interconnect level. The top interconnect level includes interconnects connected to lower interconnect levels, and does not include bond pads, probe pads, input/output pads, or a redistribution layer to bump bond pads. The thermal routing structure extends over a portion, but not all, of a plane of the integrated circuit containing the top interconnect level. The thermal routing structure includes a layer of nanoparticles in which adjacent nanoparticles are attached to each other. The layer of nanoparticles is free of an organic binder material. The thermal routing structure has a thermal conductivity higher than the metal in the top interconnect level. The layer of nanoparticles is formed by an additive process.