Optimisation & Regulation of Groundbreaking Antioxidant Nanopastes and Void-control by Organics In Die-attachments

To address the global climate crisis and achieve carbon neutrality, power electronics using wide bandgap (WBG) and ultra-wide bandgap (UWBG) semiconductors are urgently needed to replace current Si devices for higher energy efficiency. However, existing die-attach technologies derived from Si devices tend to fail at high temperatures (>175°C), slowing the development of WBG/UWBG devices. Here, we propose a novel antioxidant Cu sintering nanopaste, using reducing organics and precise void control in die attachments (DA), to produce DA with superior properties and reliability performance compared to state-of-the-art sintering pastes. This two-year project will involve multiple disciplines, including physics, chemistry, materials science, engineering, and computer science, employing methods such as multi-scale simulations, antioxidant Cu nanopaste synthesis, advanced materials characterisation for 3D microstructure construction of DA, sintering process development, and cutting-edge reliability evaluation techniques. Crucially, first-principles calculations and molecular dynamics simulations will be combined to model the evolution and diffusion/bonding behaviour of organic additives at sintering necks at the atomic level, guiding the formulation design of Cu nanopastes. In addition, a hybrid finite element method (FEM), coupled with void characteristics, microstructure, and multi-field effects (electric, thermal, and mechanical), will be developed for the accurate lifetime prediction (accuracy: >90%) of Cu sintering joints in WBG devices. The aim is to create an antioxidant Cu nanopaste capable of directly sintering a reliable DA with a shear strength of over 25 MPa at low temperatures (<250°C), in air and without the need for pressure or a protective atmosphere. This work could significantly advance the replacement of conventional Si power electronics with WBG and UWBG devices, greatly improving energy efficiency and reducing fuel consumption and CO2 emissions.