Two thermal, low pressure nitridation processes are achieved on silicon(111), using two different nitridant gases, and studiedinsituby x‐ray photoelectron spectroscopy (XPS) and low energy electron diffraction (LEED). The results show two different growth rates but the same evolution of the electronic and surface crystallographic stucture. A correlation is established between XPS and LEED measurements, associating the characteristic ‘‘quadruplet’’ patterns with the presence of intermediate nitrides. On the contrary, such compounds are absent when the LEED displays ‘‘8×8’’ patterns. Complementary results by reflection high energy electron diffraction (RHEED) and scanning electron microscopy (SEM), permit us to conclude that our thickest films, up to 40 Å, are stoichiometric Si3N4, poorly crystallized in the β phase, presenting no surface rugosity.