A chip package includes an interposer comprising a silicon substrate, multiple metal vias passing through the silicon substrate, a first interconnection metal layer over the silicon substrate, a second interconnection metal layer over the silicon substrate, and an insulating dielectric layer over the silicon substrate and between the first and second interconnection metal layers; a field-programmable-gate-array (FPGA) integrated-circuit (IC) chip over the interposer; multiple first metal bumps between the interposer and the FPGA IC chip; a first underfill between the interposer and the FPGA IC chip, wherein the first underfill encloses the first metal bumps; a non-volatile memory (NVM) IC chip over the interposer; multiple second metal bumps between the interposer and the NVM IC chip; and a second underfill between the interposer and the NVM IC chip, wherein the second underfill encloses the second metal bumps.