According to one embodiment, a semiconductor device is provided. The semiconductor device includes a first semiconductor module, a redistribution layer (RDL) module and a second semiconductor module. The RDL module is disposed on the first semiconductor module. The RDL module includes a plurality of polymer layers and a plurality of vias. The polymer layers are stacked on the first semiconductor module. The vias are disposed within the polymer layers. The second semiconductor module is disposed on the RDL module. A height difference of a top surface of at least one of the polymer layers ranges from 0 um to 1 um; or an angle between a sidewall and a bottom surface of at least one of the vias ranges from 90 to 95; or a glass transition temperature (Tg) of at least one of the polymer layers is larger than 260 C.

A wafer level fan out semiconductor device and a manufacturing method thereof are provided. A first sealing part is formed on lateral surfaces of a semiconductor die. A plurality of redistribution layers are formed on surfaces of the semiconductor die and the first sealing part, and solder balls are attached to the redistribution layers. The solder balls are arrayed on the semiconductor die and the first sealing part. In addition, a second sealing part is formed on the semiconductor die, the first sealing part and lower portions of the solder balls. The solder balls are exposed to the outside through the second sealing part. Since the first sealing part and the second sealing part are formed of materials having thermal expansion coefficients which are the same as or similar to each other, warpage occurring to the wafer level fan out semiconductor device can be suppressed.