Packages and manufacturing method thereof

A method includes forming a build-up package substrate, which includes forming a first plurality of redistribution lines (RDLs) and a second plurality of RDLs, forming a first plurality of through-vias on the first plurality of RDLs, bonding an interconnect die to the second plurality of RDLs, encapsulating the interconnect die and the first plurality of through-vias in a first encapsulant, and forming a third plurality of RDLs over the first encapsulant. The third plurality of RDLs are electrically connected to the first plurality of through-vias. An organic package substrate is bonded to the build-up package substrate. The build-up package substrate and the organic package substrate in combination form a compound organic package substrate. A first package component and a second package component are bonded to the compound organic package substrate, and are electrically interconnected through the interconnect die.