Silver glass die attach adhesives for power semiconductor devices

The authors examine mechanisms of adhesion between gold or silver backside chips and metallized substrates commonly used in individual power hybrid applications. EDS (energy dispersive spectroscopy) analyses and SEM (scanning electron microscopy) observations indicate that adhesion is due to silver diffusion in the different metal layers, whereas for alumina the bond is chemical. The bond for the Au- or Ag-backside/silicon-die/silver-glass/Ag-plated copper systems is probably due to interdiffusion mechanisms. An optimized process for power chips has been developed; it is demonstrated that the presence of voids is dependent on the drying temperature