A semiconductor device assembly and method can include a single semiconductor layer or stacked semiconductor layers, for example semiconductor wafers or wafer sections (semiconductor dice). On each semiconductor layer, a diamond layer formed therethrough can aid in the routing and dissipation of heat. The diamond layer can include a first portion on the back of the semiconductor layer, and one or more second portions which extend vertically into the semiconductor layer, for example completely through the semiconductor layer. Thermal contact can then be made to the diamond layer to conduct heat away from the one or more semiconductor layers. A conductive via can be formed through the diamond layers to provide signal routing and heat dissipation capabilities.