Package and fabrication method thereof

A package, comprising:

• a substrate;
• a first semiconductor device bonded to the substrate;
• a first underfill layer disposed between the substrate and the first semiconductor device;
• a second semiconductor device bonded to the substrate, wherein the second semiconductor device is electrically connected to the first semiconductor device by the substrate, and the second semiconductor device comprises a photonic integrated circuit;
• a second underfill layer disposed between the substrate and the second semiconductor device;
• and
• a supporting structure attached on the substrate by a first adhesive layer, wherein the first adhesive layer is laterally located between the first underfill layer and the second underfill layer.