Fan-out interconnect structure and method for forming same

A method for integrated circuit packaging comprising:

• forming a sacrificial layer over a top surface of a die, the die comprising:
• a substrate;
• an interconnect structure over the substrate;
• a metal pad at the top surface of the die and over the interconnect structure;
• and
• a first polymer layer over the metal pad, wherein the sacrificial layer is disposed over and extends through the first polymer layer;
• forming a molding compound over the sacrificial layer and the die, wherein the sacrificial layer is disposed between the molding compound and the die, and wherein the molding compound extends along sidewalls of the die and covers a top surface of the sacrificial layer;
• exposing the sacrificial layer by grinding the molding compound;
• exposing the first polymer layer by planarizing a portion of the sacrificial layer disposed over the first polymer layer so that top surfaces of the sacrificial layer and the first polymer layer are substantially co-planar;
• removing a portion of the sacrificial layer extending through the first polymer layer;
• and
• forming a redistribution layer (RDL) over the first polymer layer, a via portion of the RDL extending through the first polymer layer and an additional polymer layer disposed over the first polymer layer, wherein the RDL is electrically connected to the metal pad, and wherein the via portion of the RDL is wider at a bottom of the additional polymer layer than at a top of the first polymer layer.

A method for integrated circuit packaging comprising:

• forming a first polymer layer over a die, the die comprising a contact pad at a top surface;
• patterning a first opening in the first polymer layer to expose the contact pad;
• forming a sacrificial film layer over the first polymer layer, wherein the sacrificial film layer extends in the first opening;
• forming a molding compound over the sacrificial film layer and the die relative the top surface of the die, the molding compound extending along sidewalls of the die and covers the sacrificial film layer;
• exposing the first polymer layer by removing portions of the sacrificial film layer over the first polymer layer so that top surfaces of the sacrificial layer and the first polymer layer are substantially level;
• removing the sacrificial film layer to expose the contact pad;
• forming a second polymer layer over the first polymer layer;
• patterning the second polymer layer to form a second opening extending through the second polymer layer, the second opening being directly over the first opening;
• and
• forming a redistribution layer (RDL) over the die and electrically connected to the contact pad, wherein a via portion of the RDL extends through the first opening, the second opening, and contacts a top surface of the first polymer layer exposed by the second opening.