Flip-chip bonded silicon carbide MOSFETs as a low parasitic alternative to wire-bonding

Abstract

This paper presents flip-chip bonding as an alternative to wire-bonding for commercially available silicon carbide (SiC) MOSFETs. A process was developed for the wire-bondless attachment of a SiC power MOSFET onto a substrate. The gate and source bond pads of commercially available MOSFETs are typically made of aluminum to aid the wire bonding process. The process for obtaining a finish suitable for soldering or sintering on these pads is described in this paper. An additional concern during the flip-chip bonding of a MOSFET is the possible shorting of the source and gate pads. The gate and source terminals of the power MOSFET are typically in very close proximity with each other on the die, making the flip-chip process susceptible to the formation of conductive bridges when soldering or sintering. A procedure for addressing this concern is presented. The performance benefits of the flip-chip scheme are analyzed and compared with the traditional wire bonding process through die shear and pull tests.