Progress in the semiconductor/diamond heterogeneous integrations: Technical methods, interfacial phonon transport, and thermal characterizations

Excellent physical properties of wide and ultrawide bandgap semiconductor materials have significantly advanced the miniaturization of high-power devices, radio frequency devices, and light-emitting diodes. However, the heat generated per unit volume shows a rapid increase with the increase of power and the reduction of heat dissipation area, which puts forward new requirements for thermal management technology. Diamond, one of the members of ultrawide bandgap semiconductors, has a significant application value in the field of thermal management due to its extremely internal thermal conductivity, in addition to its potential as a more advanced electronic device. However, the thermal boundary resistance at the semiconductor interface accounts for a large portion of the total device thermal resistance when using diamond as a heat spreader, severely hindering the further development of thermal management technology. Over the past decades, researchers have made many attempts in the integration process, physical mechanism, and thermal characterization to deeply reveal the potential influence mechanism of thermal boundary conductivity (TBC), which has contributed significantly to the advancement of diamond heat spreader technology. However, these advances and reports are isolated, and due to experimental errors or theories, there are discrepancies between experiments and simulations in TBC at the same interface reported by different researchers. It is necessary to summarize the recent studies on TBC and distill the guiding general laws. This review attempts to link the three elements of material design and optimization, including structure, process, and intrinsic properties, to the thermal management design of interfaces from the perspective of material science and to form a guide for TBC regulation. First, a detailed summary and comparison of diamond heat spreader and semiconductor material integration processes is presented, and some emerging process technologies are introduced. Subsequently, the theoretical models and test technology advances on thermal boundary resistance are summarized. Based on these elements, implementable strategies for thermal property control of bonded interfaces are analyzed in detail. Finally, the challenges and directions for the future development of interfacial thermal property control are outlined. Providing systematic solutions has become an inevitable path for the semiconductor industry in the future, as traditional Moore's Law growth is difficult to sustain. This paper provides a comprehensive summary and outlook of the current stage of interfacial control for diamond heat spreaders.