A silicon wafer was implanted by a high dose of cobalt ions. Afterwards it was annealedinsituwhile grazing incidence x‐ray diffraction measurements in a temperature range up to 690 °C were carried out. The formation of cobalt disilicide (CoSi2) precipitates starts during implantation. The annealing dependence of the precipitate growth, of strain relaxation, and of improvements of the silicide crystallinity was determined. We got an activation energy of (0.47±0.08) eV for the observed annealing process. The result is a buried cobalt disilicide layer with very rough interfaces. The film quality can be improved by a subsequent annealing at about 1000 °C.