Investigation of effects of metalization on heat spreading in bump-bonded 3D systems

In three-dimensional integrated circuits (3DICs) aggressive wafer-thinning can lead to large thermal gradients, including spikes in individual device temperatures. In this paper we have simulated the impact of highly directionalized metallization on the transistor temperatures of a two-tier bump-bonded 3D system for various thicknesses of the top tier. A 90 µm × 90 µm area of active devices in the top tier dissipates power at 250 W/cm², creating a hotspot. The maximum difference between temperatures in-line and out-of-line with the directional wiring is 4.5% for the 20 µm thick case and 17.3% for the 1 µm thick case.