Thermo-Mechanical Characterization Of Au-In Transient Liquid Phase Bonding Die-Attach

Semiconductor die-attach techniques are critically important in the implementation of high-temperature wide-bandgap power devices. In this paper, thermal and mechanical characteristics of Au-In transient liquid phase (TLP) die-attach are examined for SiC devices. Samples with SiC diodes TLP-bonded to copper-metalized silicon nitride substrates are made using several different values for such fabrication properties as gold and indium thickness, Au/In ratio, and bonding pressure. The samples are then characterized for die-attach voiding, shear strength, and thermal impedance. It is found that the Au-In TLP-bonded samples offer a high average shear strength of 22.0 kgf and a low average thermal impedance of 0.35 K/W from the device junction through the substrate. It is also discovered that some of the fabrication properties have a greater influence on the bond characteristics than others. Overall, TLP bonding remains promising for high-temperature power electronic die-attach. © 2011-2012 IEEE

Reliability Characterization Of Au-In Transient Liquid Phase Bonding Through Electrical Resistivity Measurement

Transient liquid phase (TLP) die-attach bonding is an attractive technique for high-temperature semiconductor device packaging. In this paper, the material reliability of gold-indium (Au-In) TLP bonding is investigated utilizing electrical resistivity measurement as an indicator of material diffusion. Samples were fabricated featuring a TLP reaction, representative of TLP die-attach, by depositing TLP materials on glass substrates with various Au-In compositions, but with identical barrier layers, and were then used for reliability investigation. The samples were annealed at 200 °C and then stressed with thermal cycling. Samples containing high indium content in the TLP bond are shown to have poor reliability due to material diffusion through barrier layers, whereas the samples containing sufficient gold content proved reliable through electrical resistivity measurement, energy-dispersive X-ray spectroscopy, focused ion beam, and scanning electron microscope characterization