A high-bandwidth package-on-package (HBPoP) structure includes a first package structure and a second package structure disposed over the first package structure. The first package structure includes a first package substrate, a semiconductor die, an interposer, and a molding material. The first package substrate is formed of a silicon and/or ceramic material. The semiconductor die is disposed over the first package substrate. The interposer is disposed over the semiconductor die and is formed of a silicon and/or ceramic material. The molding material is disposed between the first package substrate and the interposer and surrounds the semiconductor die.