  We present an R&D activity focused on the development of novel modules for
the upgrade of the ATLAS pixel system at the High Luminosity LHC (HL-LHC). The
modules consist of n-in-p pixel sensors, 100 or 200 $\mu$m thick, produced at
VTT (Finland) with an active edge technology, which considerably reduces the
dead area at the periphery of the device. The sensors are interconnected with
solder bump-bonding to the ATLAS FE-I3 and FE-I4 read-out chips, and
characterized with radioactive sources and beam tests at the CERN-SPS and DESY.
The results of these measurements will be discussed for devices before and
after irradiation up to a fluence of $5\times 10^{15}$ \neqcm. We will also
report on the R&D activity to obtain Inter Chip Vias (ICVs) on the ATLAS
read-out chip in collaboration with the Fraunhofer Institute EMFT. This step is
meant to prove the feasibility of the signal transport to the newly created
readout pads on the backside of the chips allowing for four side buttable
devices without the presently used cantilever for wire bonding. The read-out
chips with ICVs will be interconnected to thin pixel sensors, 75 $\mu$m and 150
$\mu$m thick, with the Solid Liquid Interdiffusion (SLID) technology, which is
an alternative to the standard solder bump-bonding.
