CAREER: Intermetallic Interfacial Thermal Transport for Advanced Electronics Manufacturing

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Intermetallic-semiconductor interfaces are used widely in electronics and additive manufacturing. Thermal transport across these interfaces affects heat dissipation, and a better understanding of these thermal properties is needed to reduce electronic operating temperatures. Directly manufacturing heat removal devices onto semiconductor substrates can lead to substantial energy savings and a reduction in toxic electronic waste. The added reliability due to improved cooling will be especially valuable in failure-intolerant applications such as space, defense, and medical devices. This research considers the manufacture of heat removal layers directly onto electronic devices. The thermal transport in intermetallic-semiconductor interfaces versus solid-solution alloy-semiconductor interfaces will be studied. Additional tasks are to improve interfacial conductance through laser exposures and to determine whether increasing mechanical interfacial strength increases thermal transport. This project is integrated with educational activities at the K-12, community college, undergraduate, and graduate levels. A primary outreach activity, titled "Heat Transfer Thru Additive Manufacturing", uses hands-on experiments to teach K-12 students, largely from underrepresented groups, about the three modes of heat transfer. Intermetallics form via direct additive manufacture of high-thermal-conductivity heat-removal devices on semiconductor substrates, as used in microprocessors and power electronics. However, the thermal properties of intermetallics are poorly understood and cannot be predicted from base metal thermal conductivity, unlike solid-solution alloys with Nordheim?s relation. Recent research indicates that silicides (a type of intermetallic) have excellent thermal conductance with silicon, but no other intermetallic-semiconductor interfacial conductances have been reported. This research investigates the nature of intermetallic-semiconductor interfaces versus solid-solution alloy-semiconductor thermal interfaces. Furthermore, the project explores whether defects induced by quenching at 107 ?C/sec can be relieved by multiple laser exposures that grow the intermetallic grain boundaries and relieve defects. The relation between interfacial mechanical properties and interfacial thermal conductance are also examined. Samples are prepared by selective laser melting of specially designed alloys to form intermetallics on the semiconductor surface. Thermal characterization is performed with a frequency-domain thermoreflectance tool. The relationship between mechanical properties and thermal conductance has only been examined for a few systems, so this research expands knowledge of different intermetallic-semiconductor systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.