US Patent 9013037 Semiconductor package with improved pillar bump process and structure

A flip chip structure formed on a semiconductor substrate includes a first plurality of copper pillars positioned directly over, and in electrical contact with respective ones of a plurality of contact pads on the front face of the semiconductor substrate. A layer of molding compound is positioned on the front face of the substrate, surrounding and enclosing each of the first plurality of pillars and having a front face that is coplanar with front faces of each of the copper pillars. Each of a second plurality of copper pillars is positioned on the front face of one of the first plurality of copper pillars, and a solder bump is positioned on a front face of each of the second plurality of pillars.