A method includes encapsulating a device in an encapsulating material, planarizing the encapsulating material and the device, and forming a conductive feature over the encapsulating material and the device. The formation of the conductive feature includes depositing a first conductive material to from a first seed layer, depositing a second conductive material different from the first conductive material over the first seed layer to form a second seed layer, plating a metal region over the second seed layer, performing a first etching on the second seed layer, performing a second etching on the first seed layer, and after the first seed layer is etched, performing a third etching on the second seed layer and the metal region.

A method includes encapsulating a device in an encapsulating material, planarizing the encapsulating material and the device, and forming a conductive feature over the encapsulating material and the device. The formation of the conductive feature includes depositing a first conductive material to from a first seed layer, depositing a second conductive material different from the first conductive material over the first seed layer to form a second seed layer, plating a metal region over the second seed layer, performing a first etching on the second seed layer, performing a second etching on the first seed layer, and after the first seed layer is etched, performing a third etching on the second seed layer and the metal region.

In an embodiment, a package structure including an electro-optical circuit board, a fanout package disposed over the electro-optical circuit board is provided. The electro-optical circuit board includes an optical waveguide. The fanout package includes a first optical input/output portion, a second optical input/output portion and a plurality of electrical input/output terminals electrically connected to the electro-optical circuit board. The first optical input/output portion is optically coupled to the second optical input/output portion through the optical waveguide of the electro-optical circuit board.

In an embodiment, a package structure including an electro-optical circuit board, a fanout package disposed over the electro-optical circuit board is provided. The electro-optical circuit board includes an optical waveguide. The fanout package includes a first optical input/output portion, a second optical input/output portion and a plurality of electrical input/output terminals electrically connected to the electro-optical circuit board. The first optical input/output portion is optically coupled to the second optical input/output portion through the optical waveguide of the electro-optical circuit board.

In an embodiment, a device includes: a back-side redistribution structure including: a metallization pattern on a first dielectric layer; and a second dielectric layer on the metallization pattern; a through via extending through the first dielectric layer to contact the metallization pattern; an integrated circuit die adjacent the through via on the first dielectric layer; a molding compound on the first dielectric layer, the molding compound encapsulating the through via and the integrated circuit die; a conductive connector extending through the second dielectric layer to contact the metallization pattern, the conductive connector being electrically connected to the through via; and an intermetallic compound at the interface of the conductive connector and the metallization pattern, the intermetallic compound extending only partially into the metallization pattern.

In an embodiment, a device includes: a back-side redistribution structure including: a metallization pattern on a first dielectric layer; and a second dielectric layer on the metallization pattern; a through via extending through the first dielectric layer to contact the metallization pattern; an integrated circuit die adjacent the through via on the first dielectric layer; a molding compound on the first dielectric layer, the molding compound encapsulating the through via and the integrated circuit die; a conductive connector extending through the second dielectric layer to contact the metallization pattern, the conductive connector being electrically connected to the through via; and an intermetallic compound at the interface of the conductive connector and the metallization pattern, the intermetallic compound extending only partially into the metallization pattern.

In an embodiment, a device includes: a package component including: a first integrated circuit die; an encapsulant at least partially surrounding the first integrated circuit die; a redistribution structure on the encapsulant, the redistribution structure physically and electrically coupling the first integrated circuit die; a first module socket attached to the redistribution structure; an interposer attached to the redistribution structure adjacent the first module socket, the outermost extent of the interposer extending beyond the outermost extent of the redistribution structure; and an external connector attached to the interposer.

In an embodiment, a device includes: a package component including: a first integrated circuit die; an encapsulant at least partially surrounding the first integrated circuit die; a redistribution structure on the encapsulant, the redistribution structure physically and electrically coupling the first integrated circuit die; a first module socket attached to the redistribution structure; an interposer attached to the redistribution structure adjacent the first module socket, the outermost extent of the interposer extending beyond the outermost extent of the redistribution structure; and an external connector attached to the interposer.

In an embodiment, a device includes: a bottom integrated circuit die having a first front side and a first back side; a top integrated circuit die having a second front side and a second back side, the second back side being bonded to the first front side, the top integrated circuit die being free from through substrate vias (TSVs); a dielectric layer surrounding the top integrated circuit die, the dielectric layer being disposed on the first front side, the dielectric layer and the bottom integrated circuit die being laterally coterminous; and a through via extending through the dielectric layer, the through via being electrically coupled to the bottom integrated circuit die, surfaces of the through via, the dielectric layer, and the top integrated circuit die being planar.

In an embodiment, a device includes: a bottom integrated circuit die having a first front side and a first back side; a top integrated circuit die having a second front side and a second back side, the second back side being bonded to the first front side, the top integrated circuit die being free from through substrate vias (TSVs); a dielectric layer surrounding the top integrated circuit die, the dielectric layer being disposed on the first front side, the dielectric layer and the bottom integrated circuit die being laterally coterminous; and a through via extending through the dielectric layer, the through via being electrically coupled to the bottom integrated circuit die, surfaces of the through via, the dielectric layer, and the top integrated circuit die being planar.