Package structure and manufacturing method thereof

A manufacturing method of a packaging structure, comprising:

• providing a preliminary structure, comprising:
• a first die, comprising a silicon substrate and a through silicon conductor penetrating the silicon substrate;
• an encapsulant, covering the first die;
• and
• a redistribution circuit structure, located on the encapsulant and electrically connected to the first die, wherein a groove is present on an upper surface of the redistribution circuit structure, and the upper surface comprises a first area and a second area located on opposite sides of the groove;
• disposing a second die on the preliminary structure, and electrically connecting the second die to the redistribution circuit structure;
• disposing a third die on the preliminary structure, and electrically connecting the third die to the redistribution circuit structure, wherein the third die has an optical signal transmission area;
• and
• forming a filler between the second die and the redistribution circuit structure and between the third die and the redistribution circuit structure, wherein the filler directly contacts the first area, and the filler is away from the second area.