Erbium silicide thin films are grown on Si(100) substrates under high vacuum by single deposition of Er or co-deposition of Er and Si, followed by annealing. Electron microscopy revealed for both preparations the existence of at least three new types of structural phases of erbium suicide. One has a tetragonal ThSi2 type structure; the other two are orthorhombic superstructures of the first one resulting from ordering of vacancies on the Si sublattice, which leads to a composition of ErSi2-x(0 < x < 0.5).