A method includes bonding a first device die and a second device die to an interconnect die. The interconnect die includes a first portion over and bonded to the first device die, and a second portion over and bonded to the second device die. The interconnect die electrically connects the first device die to the second device die. The method further includes encapsulating the interconnect die in an encapsulating material, and forming a plurality of redistribution lines over the interconnect die.