Flip-Chip Bonding of SiC Chips onto Alumina Substrate for High-Temperature Applications

This paper studies the flip-chip bonding of silicon carbide (SiC) chips onto an alumina ceramic substrate for applications at up to 600 degrees C high temperatures. A daisy chain interconnect is formed by bonding SiC dummy chips with sputtered Ti/TaSi2/Pt thin film conductor pads to alumina substrate with screen-printed gold conductor pads using gold stud bumps either placed on the SiC or alumina. The package is subjected to a thermal aging process in the air at 600 degrees C for up to eight days. Die shear tests show that the average shear force per bump is 13.3 gram force (gf) for the package with bumps formed on the SiC chip and 17.8 gf for the package with bumps formed on the alumina substrate. No significant dependence of die shear force on thermal aging days is observed. The daisy chain interconnect formed with 36 bumps in the flip-chip package is measured, when continuous, to be about 20 Omega. The resistance decreases slightly and steadily with the thermal aging days.