  Context. Brown dwarfs represent a sizable fraction of the stellar content of
our Galaxy and populate the transition between the stellar and planetary mass
regime. There is however no agreement on the processes responsible for their
formation. Aims. We have conducted a large survey of the young, nearby cluster
IC 348, to uncover its low-mass brown dwarf population and study the cluster
properties in the substellar regime. Methods. Deep optical and near-IR images
taken with MegaCam and WIRCam at the Canada-France-Hawaii Telescope (CFHT) were
used to select photometric candidate members. A spectroscopic follow-up of a
large fraction of the candidates was conducted to assess their youth and
membership. Results. We confirmed spectroscopically 16 new members of the IC
348 cluster, including 13 brown dwarfs, contributing significantly to the
substellar census of the cluster, where only 30 brown dwarfs were previously
known. Five of the new members have a L0 spectral type, the latest-type objects
found to date in this cluster. At 3 Myr, evolutionary models estimate these
brown dwarfs to have a mass of ~13 Jupiter masses. Combining the new members
with previous census of the cluster, we constructed the IMF complete down to 13
Jupiter masses. Conclusions. The IMF of IC 348 is well fitted by a log-normal
function, and we do not see evidence for variations of the mass function down
to planetary masses when compared to other young clusters.
