An electronic system includes a first integrated-circuit chip and a second integrated-circuit chip. A first substrate wafer is positioned between the first and second integrated-circuit chips and configured with a first connection network to make electrical connection to the first integrated-circuit chip. A second substrate wafer, configured with a second connection network to make electrical connection to the second integrated-circuit chip, is positioned facing the first substrate wafer. The connection networks of the first and second substrate wafers are electrically connected through connection structures. A third substrate wafer, including a third connection network, is thermally in contact with the first integrated-circuit chip and electrically connected to the first connection network of the first substrate wafer through further connection structures. The further connection structure may be formed using another substrate wafer.