Package structure and method of forming the same

A package structure, comprising:

• a first die and a second die;
• a first via, laterally aside the first die;
• a second via, laterally aside the second die;
• a first adhesion promoter layer laterally surrounding the first via;
• a second adhesion promoter layer laterally surrounding the second via;
• a first encapsulant, laterally encapsulating the first die, the first adhesion promoter layer and the first via;
• a second encapsulant, laterally encapsulating the second die, the second adhesion promoter layer and the second via;
• a first redistribution layer (RDL) structure, between the first die and the second die and electrically connected to the first via and the second via;
• a first polymer layer, under the first via;
• a second polymer layer of the first RDL structure, under the second via;
• wherein sidewalls of the second via are in physical contact with the second adhesion promoter layer, and a bottom portion of the second via is in physical contact with the second polymer layer,
• wherein the second encapsulant comprises a portion aside the second via and under the second adhesion promoter layer, and the portion of the second encapsulant is sandwiched between the second adhesion promoter layer and the second polymer layer.

A method of forming a package structure, comprising:

• forming a first polymer;
• attaching a first die on the first polymer;
• forming a first via laterally aside the first die and on the first polymer;
• forming a first adhesion promoter layer on sidewalls of the first via;
• forming a first encapsulant, laterally encapsulating the first die, the first adhesion promoter layer and the first via;
• forming a first redistribution layer (RDL) structure on the first die, the first via, the first adhesion promoter layer, and the first encapsulant;
• attaching a second die on the first RDL structure;
• forming a second via laterally aside the second die;
• forming a second adhesion promoter layer on sidewalls of the second via;
• forming an second encapsulant, laterally encapsulating the second die, the second adhesion promoter layer and the second via, wherein the second adhesion promoter layer is sandwiched between the second via and the second encapsulant, wherein the sidewalls of the second via are covered by the second adhesion promoter layer, while a bottom surface of the second via is uncovered by the second adhesion promoter layer, wherein the second encapsulant comprises a portion aside the second via and under the second adhesion promoter layer, and the portion of the second encapsulant is sandwiched between the second adhesion promoter layer and a second polymer layer of the first RDL structure.