High temperature resistant joint technology for SiC power devices using transient liquid phase sintering process

Abstract

A high temperature resistant joint technology for bonding SiC power devices is developed using a transient liquid phase sintering (TLPS) process with a paste containing Cu and Sn powders with the size less than 15μm. The SiC devices are bonded to the Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> /Cu/Ni(P) substrate with the TLPS process at 260°C in a N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> atmosphere for 20 minutes. The microstructure of the bond is mainly composed of Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> Sn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> and Cu phases, which is not molten up to 415°C. The joint strength at 300°C after sintering is 38MPa. During high temperature aging, the Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> Sn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> phase transforms to Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn, which is not molten up to 676°C. The joint strength increases with aging time due to the phase transition from Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> Sn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> to Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn and further sintering of Sn and Cu during high temperature aging. The joint strength at 300°C after aging at 300°C for 500h reaches approximate 50MPa. After thermal cycling test at -40~250 °C for 500 cycles, the joint strength is approximate 20MPa, which is 3 times higher than the joint strength standard.