Thermoelectric Self-Cooling on Germanium Chip

Abstract

Growing interest in germanium solid-state devices is raising concern over the effects of on-chip, micro-scaled, high flux hot spot on the reliability and performance of germanium chips. Current thermal management technology offers few choices for such on-chip hot spot remediation. However, the good thermo-electric properties of single crystal germanium support the development of a novel thermal management approach, relying on thermoelectric self-cooling by an electric current flowing in a thin planar layer on the back of the germanium chip. Use of metal-on-germanium fabrication techniques can yield a very low thermal contact resistance at the micro cooler/chip interface and the current flow can transfer the energy absorbed from a hot spot to the edge of the chip, thus substantially reducing the detrimental effect of thermoelectric heating on the temperature of the active circuitry. In this paper three-dimensional thermo-electric simulations are used to investigate the self-cooling of hot spots on a germanium chip for a wide range of input current, doping concentration, hot spot heat flux, micro cooler size, and germanium chip thickness. Results suggest that localized thermoelectric self-cooling on the germanium chip can significantly reduce the temperature rise resulting from micro-scaled high-flux hot spots.