Study of metal additives to alumina substrate for high temperature and pressure application

In this work, we present systematical characterizations of iron doped alumina substrates produced by solid state sintering of ball milled powders. It was found that the doped samples have higher fracture toughness, lower thermal conductivity, smaller coefficient of thermal expansion and higher relative dielectric constant than undoped ones. A reduction in thermal conductivity could arguably give extra protection to the package chip in a high temperature application environment and can be attributed to an increase in phonon scattering. Furthermore, the decrease in coefficient of thermal expansion also helps to reduce thermal induced stress between the substrates and device chip. The observed improvement in fracture toughness cannot be explained by the common toughening mechanism, such as crack bridging or due to the increase in crystallite size, and is the subject of further investigation.