Phase formation of metal‐rich Pd silicides was studied in palladium–amorphous‐silicon thin‐film interactions by means of4He+‐ion backscattering, Auger spectrometry, electron microprobe, and x‐ray diffractometry. In the initial stage of compound formation, where both unreacted Si and Pd layers ar present, the Pd2Si phase has been observed. At increasing annealing temperature in SiO2/Si(a)/Pd systems, where the metal‐film thickness was larger than that of amorphous‐Si film, phases richer and richer in metal have been detected, following exactly the phase diagram reported in literature. The Pd‐richest phase was identified as Pd4Si and is stable up to 650 °C in the presence of unreacted Pd. A crystallographic characterization of this new thin‐film end phase was performed on the basis of a triclinic unit cell.