An under bump metallurgy (UBM) and redistribution layer (RDL) routing structure includes an RDL formed over a die. The RDL comprises a first conductive portion and a second conductive portion. The first conductive portion and the second conductive portion are at a same level in the RDL. The first conductive portion of the RDL is separated from the second conductive portion of the RDL by insulating material of the RDL. A UBM layer is formed over the RDL. The UBM layer includes a conductive UBM trace and a conductive UBM pad. The UBM trace electrically couples the first conductive portion of the RDL to the second conductive portion of the RDL. The UBM pad is electrically coupled to the second conductive portion of the RDL. A conductive connector is formed over and electrically coupled to the UBM pad.

A package structure and a method for forming a package structure are provided. The package structure includes a chip-containing structure bonded to a redistribution structure through multiple first solder bumps. The package structure also includes a memory-containing structure bonded to an interposer chip. The interposer chip is bonded to the redistribution structure through multiple second solder bumps. The package structure further includes a substrate, and the redistribution structure is over the substrate.