Design and Optimization of 100 V GaN Multi-chip Power Micromodule Based on AlN DBC Substrate

The paper presents concept and the results of development of novel GaN multi-chip power micromodule. The GaN multi-chip power micromodule was based on AlN direct bonded copper substrate with through-plated copper vias which have reduced inductances of the gate and power loops of GaN transistors. AlN direct bonded copper substrate provided reduced thermal resistance of GaN multi-chip power micromodule. GaN multi-chip power micromodule is intended for use as part of high-density, low-power switching mode DCDC converters operating at frequencies above 0.5 MHz. The presented GaN multi-chip power micromodule included two dies of power e-mode GaN high electron mobility transistors, a packaged Si driver, an AlN direct bonded copper substrate and SMD passive components. GaN multi-chip power micromodule had two independent channels, each of which provided a current of up to 7 A, and operating voltage of at least 100 V. GaN multi-chip power micromodule had dimensions of 10.5×9 mm. The design of AlN direct bonded copper substrate layout was verified with steady state current analysis and parasitic extraction using Ansys. It was shown that proposed GaN multichip power micromodule design had the gate loop parasitic inductance about 1.1 nH, with a mismatch of less than 4% between channels, while total power loop parasitic inductance did not exceed 0.5 nH.