Heat sink formed of multiple metal layers on backside of integrated circuit die

An integrated circuit die includes a substrate having a front surface and a back surface, wherein the substrate front surface has electrical circuits formed thereon, and the substrate back surface has a plurality of metal layers formed thereon. The plurality of metal layers comprises at least one layer having a thickness of greater than about ten micrometers. The outermost metal layer may be mechanically and thermally bonded to a package using a die attach layer comprising a thermally conductive reflowable material. The invention advantageously facilitates the dissipation of heat from the integrated circuit die.