Three-dimensional integrated circuit structures and methods of forming the same

A three-dimensional integrated circuit (3DIC) structure, comprising:

• a semiconductor package disposed over and electrically connected to a first package substrate, wherein the semiconductor package comprises at least one semiconductor die having a first side close to the first package substrate and a second side away from the first package substrate;
• a passive device disposed over and electrically connected to the first package substrate, wherein the passive device and the semiconductor package are disposed laterally on the first package substrate;
• a molded underfill layer disposed aside the semiconductor package and the passive device and having a top surface not lower than the second side of the semiconductor die;
• and
• a clamp component configured to clamp the semiconductor package to a second package substrate below the first package substrate,
• wherein the semiconductor package is bonded to the first package substrate through a plurality of first bumps, the first package substrate is bonded to the second package substrate through a plurality of second bumps, and a dimension of the plurality of first bumps is less than a dimension of the plurality of second bumps, and
• wherein a capillary underfill layer surrounds the plurality of second bumps.

A three-dimensional integrated circuit (3DIC) structure, comprising:

• a semiconductor package, disposed over and electrically connected to a first package substrate through a plurality of first bumps, wherein the semiconductor package comprises semiconductor dies and an encapsulation layer aside and between the semiconductor dies;
• a heat spreader, mounted on the semiconductor package and exposing a portion of the encapsulation layer;
• and
• a molded underfill layer, surrounding the plurality of first bumps, a sidewall of the semiconductor package and a vertical side surface of the heat spreader.