Concepts for embedded cooling of vertical current wide band-gap semiconductor devices

Abstract

Wide band-gap (WBG) power semiconductor devices are being researched in order to meet future high power density electronic packaging targets for a range of power conversion applications. All power devices may be classified based on the current flow direction, namely lateral versus vertical, and for both types, the device junction temperature is determined, in part, by the package thermal resistance. For electrified vehicle applications, where vertical current device architectures are preferred, the vertical configuration leads to current rates that are higher than those found in a lateral device, and this in turn leads to large heat fluxes (∼1 kW/cm2) for large bare dies (∼1 cm2). Considering the challenges associated with the vertical current WBG device structure, three embedded cooling concepts are described. One strategy is selected for initial investigation, where a multi-layer straight microchannel chip-scale cooler is fabricated and thermal-fluid performance characteristics of the device are experimentally plus numerically evaluated. Performance limitations of the design are highlighted, and ongoing work focused on fabrication of a design that exploits jet impingement plus fluid flow through an optimized microchannel topology is described. Discussion regarding device electrical performance and the separation of the vertical current field from the coolant flow is provided.