Thermostable electroless plating optimized for Ag sinter die-attach realizing high TJ device packaging

In terms of die-attach for high TT device, metallization on the backside of the bare chip and the substrate surface affect the high-temperature reliability of the joint due to the accelerated atomic diffusions. We evaluated two types of electroless plated metallization schemes which are Ni/Ag and Ni/Pd/Pt/Ag, respectively. High temperature storage of 250 degrees C for 500 h was used to test the high temperature reliability of the two metallization schemes. After the high temperature storage, an unidentified compound has generated between Ni and Ag layer in the typical electroless Ni/Ag metallization. However, by introducing a Pt diffusion barrier layer in the multi-layer metals of electroless Ni/Ag metallization, the multilayer interface remains stable and no newly formed interfacial phase can be observed after annealing. This result implies the longitude diffusion of atoms can be suppressed and the interfacial reliability can be improved by introducing the electroless-plated Pt diffusion barrier layer.