Lithium fluoride (LiF) films are deposited by thermal evaporation on silicon substrates, The substrate temperature and deposition rate’s influence on the morphology and structure of the films are investigated, It is shown that it is necessary to work with a low deposition rate to have crack-free layers. Also, the substrate temperature has a great influence on coating morphology : the grain size increases with temperature. At the same time, the crystallization state increases up to 300 degrees C. For higher temperatures, recrystallization seems to appear. The grain size increases as well as the grain boundary size.