Enabling record-high heat flux in wide-bandgap electronics via in-chip microfluidic cooling on diamond substrates

As electronic devices continue to scale toward higher integration and power density, localized heat fluxes can exceed 1 kW/cm2, far surpassing the capabilities of conventional cooling technologies. Efficient thermal management, particularly of highly localized hotspots, has thus become a critical bottleneck for device reliability and performance. To address this challenge, we propose a near-junction thermal management strategy that integrates high-thermal-conductivity polycrystalline diamond substrates with in-chip microfluidic cooling. This hybrid approach simultaneously enhances both lateral heat spreading and vertical convective dissipation. The cooling structure was fabricated using microfabrication techniques, including thin-film heater patterning, laser-micromachined microchannels, and adhesive bonding of a fluidic manifold. Under a maximum junction temperature of 120°C, the system achieved a record-high background heat flux of 4099 W/cm2, a record-low total thermal resistance of 0.019 cm2 K/W, and hotspot heat fluxes reaching 73.5 kW/cm2. Compared to the highest previously reported heat flux (1723 W/cm2) and the lowest previously reported total thermal resistance (0.024 cm2 K/W) from prior works in the literature, this work achieves a 2.38-fold increase in heat flux and a 20.8% reduction in total thermal resistance. This work demonstrates a promising pathway for addressing extreme thermal challenges in wide-bandgap semiconductors, paving the way for more reliable and high-power electronics through advanced material and cooling integration.