6.3 Thermal Management Techniques Employing Thermal Vias 121 There are several ways to place thermal vias to decrease the tempera- ture of the upper planes in a 3-D IC. These techniques can include thermal via insertion within certain regions, and dispersion of the thermal vias across the planes with thermal via planning, discussed in Sections 6.3.1 and 6.3.2, respectively. In addition to thermal vias, thermal wires can be employed to transfer heat, as described in Section 6.3.3. 6.3.1 Region-Constrained Thermal Via Insertion In Chapter 5, available space among the cells on each plane is reserved for allocating decoupling capacitors to mitigate simultaneous switch- ing noise. In the same context, the available space can also be used to mitigate thermal problems by allocating thermal vias within these regions. The generation of these regions, however, assumes that sophis- ticated placement tools can produce free area among the placed cells. Thermal via insertion is applied as a subsequent step before routing the signal nets. Thermal via insertion can satisfy a variety of design