Thin film multichip packaging for high temperature digital electronics

Abstract

Digital silicon carbide integrated circuits provide enhanced functionality for electronics in geothermal, aircraft and other high temperature applications. A multilayer thin film substrate technology has been developed to interconnect multiple SiC devices along with passive components. The conductor is vacuum deposited Ti/Ti:W/Au followed by an electroplated Au. A PECVD silicon nitride is used for the interlayer dielectric. Adhesion testing of the conductor and the dielectric was performed as deposited and after aging at 320°C. The electrical characteristics of the dielectric as a function of temperature were measured. Thermocompression flip chip bonding of Au stud bumped SiC die was used for electrical connection of the digital die to the thin film substrate metallization. Since polymer underfills are not compatible with 300°C operation, AlN was used as the base ceramic substrate to minimize the coefficient of thermal expansion mismatch between the SiC die and the substrate. Initial die shear results are presented.