A circuit arrangement and method in one aspect utilize thermal-only through vias, extending between the opposing faces of stacked semiconductor dies, to increase the thermal conductivity of a multi-layer semiconductor stack. The thermal vias are provided in addition to data-carrying through vias, which communicate data signals between circuit layers, and power-carrying through vias, which are coupled to a power distribution network for the circuit layers, such that the thermal conductivity is increased above that which may be provided by the data-carrying and power-carrying through vias in the stack. A circuit arrangement and method in another aspect organize the circuit layers in a multi-layer semiconductor stack based upon current density so as to reduce power distribution losses in the stack.