US Patent 11854997 Method of forming semiconductor device

A method includes encapsulating a device die in an encapsulating material, forming a first dielectric layer over the device die and the encapsulating material, forming first redistribution lines extending into the first dielectric layer to electrically couple to the device die, forming an alignment mark over the first dielectric layer, wherein the alignment mark includes a plurality of elongated strips, forming a second dielectric layer over the first redistribution lines and the alignment mark, and forming second redistribution lines extending into the second dielectric layer to electrically couple to the first redistribution lines. The second redistribution lines are formed using the alignment mark for alignment.