An embodiment method for forming a semiconductor package includes attaching a first die to a first carrier, depositing a first isolation material around the first die, and after depositing the first isolation material, bonding a second die to the first die. Bonding the second die to the first die includes forming a dielectric-to-dielectric bond. The method further includes removing the first carrier and forming fan-out redistribution layers (RDLs) on an opposing side of the first die as the second die. The fan-out RDLs are electrically connected to the first die and the second die.

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.

An embodiment is a structure including a first semiconductor device and a second semiconductor device, a first set of conductive connectors mechanically and electrically bonding the first semiconductor device and the second semiconductor device, a first underfill between the first and second semiconductor devices and surrounding the first set of conductive connectors, a first encapsulant on at least sidewalls of the first and second semiconductor devices and the first underfill, and a second set of conductive connectors electrically coupled to the first semiconductor device, the second set of conductive connectors being on an opposite side of the first semiconductor device as the first set of conductive connectors.

A multi-clip structure includes a first clip for die bonding and a second clip for die bonding. The multi-clip structure further includes a retaining tape fixed to the first clip and to the second clip to hold the first clip and the second clip together.

An embodiment is a structure including a first semiconductor device and a second semiconductor device, a first set of conductive connectors mechanically and electrically bonding the first semiconductor device and the second semiconductor device, a first underfill between the first and second semiconductor devices and surrounding the first set of conductive connectors, a first encapsulant on at least sidewalls of the first and second semiconductor devices and the first underfill, and a second set of conductive connectors electrically coupled to the first semiconductor device, the second set of conductive connectors being on an opposite side of the first semiconductor device as the first set of conductive connectors.

An embodiment method for forming a semiconductor package includes attaching a first die to a first carrier, depositing a first isolation material around the first die, and after depositing the first isolation material, bonding a second die to the first die. Bonding the second die to the first die includes forming a dielectric-to-dielectric bond. The method further includes removing the first carrier and forming fan-out redistribution layers (RDLs) on an opposing side of the first die as the second die. The fan-out RDLs are electrically connected to the first die and the second die.

An embodiment is a structure including a first semiconductor device and a second semiconductor device, a first set of conductive connectors mechanically and electrically bonding the first semiconductor device and the second semiconductor device, a first underfill between the first and second semiconductor devices and surrounding the first set of conductive connectors, a first encapsulant on at least sidewalls of the first and second semiconductor devices and the first underfill, and a second set of conductive connectors electrically coupled to the first semiconductor device, the second set of conductive connectors being on an opposite side of the first semiconductor device as the first set of conductive connectors.

An embodiment method for forming a semiconductor package includes attaching a first die to a first carrier, depositing a first isolation material around the first die, and after depositing the first isolation material, bonding a second die to the first die. Bonding the second die to the first die includes forming a dielectric-to-dielectric bond. The method further includes removing the first carrier and forming fan-out redistribution layers (RDLs) on an opposing side of the first die as the second die. The fan-out RDLs are electrically connected to the first die and the second die.

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 structure includes a metal pad, a passivation layer having a portion covering edge portions of the metal pad, and a dummy metal plate over the passivation layer. The dummy metal plate has a plurality of through-openings therein. The dummy metal plate has a zigzagged edge. A dielectric layer has a first portion overlying the dummy metal plate, second portions filling the first plurality of through-openings, and a third portion contacting the first zigzagged edge.