Semiconductor device, package structure and method of fabricating the same

A method, comprising:

• forming first conductive features and second conductive features disposed on and electrically connected to a semiconductor die, wherein the first conductive features and the second conductive features are vertically overlapped with the semiconductor die and are made of nickel;
• forming a first metallic layer on the first conductive features and forming a second metallic layer on the second conductive features, wherein the first metallic layer and the second metallic layer are vertically overlapped with the semiconductor die, and a bottom surface of the first metallic layer is horizontally aligned with a bottom surface of the second metallic layer, and a top surface of the first metallic layer is horizontally aligned with a top surface of the second metallic layer;
• providing an interconnection die comprising through substrate vias, conductive pads disposed on the through substrate vias, and nickel-containing connection structures electrically connected to the conductive pads, wherein the through substrate vias, the conductive pads and the nickel-containing connection structures are vertically overlapped with one another;
• after forming the nickel-containing connection structures on the interconnection die, bonding the interconnection die to the semiconductor die by joining the first conductive features to the nickel-containing connection structures through a plurality of bump structures, wherein the plurality of bump structures contains tin, and performing a reflow process to melt the first metallic layer so that a metallic element is formed in the plurality of bump structures, and wherein after the reflow process, a bottom surface of the plurality of bump structures is aligned with a bottom surface of the second metallic layer;
• forming through vias directly on the second metallic layer, and over the second conductive features;
• forming an underfill structure laterally surrounding and contacting the first conductive features, the nickel-containing connection structures of the interconnection die and the plurality of bump structures, wherein the underfill structure is vertically non-overlapped with the through substrate vias of the interconnection die;
• and
• after forming the through vias, forming an insulating encapsulant covering and contacting a portion of the second metallic layer that is vertically overlapped with the semiconductor die, and wherein the insulating encapsulant is laterally surrounding the through vias.

A method, comprising:

• forming first conductive features and second conductive features over a substrate, wherein the first conductive features and the second conductive features have aligned top surfaces;
• forming a precious metal layer on the top surfaces of the first conductive features and the second conductive features;
• providing an interconnection die, comprising a die substrate, through substrate vias embedded in the die substrate, and connection structures disposed on the through substrate vias;
• and
• performing a reflow process to join a plurality of bump structures to the connection structures and the first conductive features, wherein during the reflow process, the plurality of bump structures and the precious metal layer are sandwiched between two nickel-containing interfaces of the connection structures and the first conductive features, and after the reflow process, a first intermetallic compound consisting of AuSn4 and Ni3Sn4 is formed between the first conductive features and the plurality of bump structures, a second intermetallic compound consisting of Ni3Sn4 is formed between the connection structures and the plurality of bump structures, and the plurality of bump structures have a greater thickness than the first intermetallic compound and the second intermetallic compound, the precious metal layer on the first conductive features is melted during the reflow process and dissolved into the plurality of bump structures so that metal elements originating from the precious metal layer are located in the plurality of bump structures and physically separated from the first intermetallic compound and the second intermetallic compound, while the precious metal layer is retained on the second conductive features, and the metal elements are vertically overlapped with the through substrate vias of the interconnection die;
• forming through vias on the precious metal layer over the second conductive features;
• forming an insulating encapsulant surrounding the interconnection die and the through vias;
• and
• performing a thinning step to remove portions of the insulating encapsulant to reveal a top surface of the through vias and a top surface of the through substrate vias of the interconnection die, wherein the top surface of the through vias, the top surface of the through substrate vias and a top surface of the insulating encapsulant are coplanar and levelled with one another after the thinning step.