Semiconductor package with improved pillar bump process and structure

摘要

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.

主权项

1. A device, comprising:
a semiconductor substrate; a plurality of contact pads positioned on a front face of the substrate; a first plurality of pillars positioned directly over, and in electrical contact with respective ones of the plurality of contact pads, the first plurality of pillars being solid structures that are not hollow; a layer of molding compound positioned on the front face of the substrate, surrounding and enclosing side surfaces of each of the first plurality of pillars and having an upper surface that is coplanar with front faces of each of the first plurality of pillars, the layer of molding compound being formed from a flowable material; a second plurality of pillars, each positioned over a respective one of the first plurality of pillars, the second plurality of pillars having an upper surface that is spaced apart from the upper surface of the layer of molding compound by side surfaces, a substantial portion of the side surfaces being free of a solid material between adjacent pillars of the second plurality of pillars, the second plurality of pillars being solid structures that are not hollow; a plurality of solder bumps, each positioned directly over a respective one of the second plurality of pillars and in electrical contact with respective ones of the first plurality of pillars; and a passivation layer positioned over the layer of molding compound and abutting the side surfaces of the second plurality of pillars while maintaining the substantial portion of the side surfaces free of a solid material between adjacent pillars.