Semiconductor package using cavity substrate and manufacturing methods

A semiconductor package includes a cavity substrate, a semiconductor die, and an encapsulant. The cavity substrate includes a redistribution structure and a cavity layer on an upper surface of the redistribution structure. The redistribution structure includes pads on the upper surface, a lower surface, and sidewalls adjacent the upper surface and the lower surface. The cavity layer includes an upper surface, a lower surface, sidewalls adjacent the upper surface and the lower surface, and a cavity that exposes pads of the redistribution structure. The semiconductor die is positioned in the cavity. The semiconductor die includes a first surface, a second surface, sidewalls adjacent the first surface and the second surface, and attachment structures that are operatively coupled to the exposed pads. The encapsulant encapsulates the semiconductor die in the cavity and covers sidewalls of the redistribution structure.