A method for forming a package structure is provided, including forming an interconnect structure over a carrier substrate and forming a semiconductor die over a first side of the interconnect structure. A removable film is formed over the semiconductor die. The method includes forming a first stacked die package structure over the first side of the interconnect structure. A top surface of the removable film is higher than a top surface of the first stacked die package structure. The method includes forming a package layer, removing a portion of the package layer to expose a portion of the removable film, removing the removable film to form a recess, forming a lid structure over the semiconductor die and the first stacked die package structure. The lid structure has a main portion and a protruding portion disposed in the recess and extending from the main portion.