Thin-Film Encapsulation Solution for High-Temperature SiC Power Devices

Wide bandgap semiconductors like silicon carbide (SiC) are capable to operate at temperature above 250 °C. However, current encapsulations cannot work at temperature above 175 °C, making high-temperature (≥250 °C) packaging of SiC devices still a challenge. This article introduces an innovative high-temperature packaging scheme for SiC power devices, utilizing a multilayered Parylene HT/Al<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> composite film (MPACF). By implementing a cross-stacked organic Parylene HT and inorganic Al<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> multilayer structure, the pathway for external moisture and oxygen to reach the SiC chips at elevated temperatures is blocked, reducing the risk of moisture/oxygen contact and circumventing the thermal oxidation process associated with traditional organic packaging materials. After further modifying the interface between the encapsulation material and the substrate with a silane coupling agent, the adhesion strength has been significantly enhanced. The MPACF ensures a high operational temperature and a low coefficient of thermal expansion, effectively safeguarding the SiC devices in the hashed condition. Reliability tests including 1500 cycles of thermal shock ranging from −55 °C to 250 °C and 500 h high-temperature aging at 250 °C have been carried on the encapsulated SiC devices, the adhesion strength of MPACF is well preserved at 5B and the devices exhibited outstanding static characteristics and switching performance.