Improvement of Stress Anisotropy in Circular Planar MagnetronSputter Deposited Molybdenum Films with Annealing

As part of the programme to develop a free-standing thin-film filter for soft x-ray optics applications, stress anisotropy in molybdenum films deposited by dc circular planar magnetron sputtering has been studied by off-normal x-ray diffraction as a function of sputtering argon gas pressure over a range of 0.8-1.5 Pa. The stresses are found to be more compressive in the center area than in the edge area, and more compressive in the tangential direction than in the radial direction. The highest stress anisotropy exists in the film deposited at 1.5 Pa gas pressure. Annealing the films in vacuum is effective in reducing both the tensile stress and stress anisotropy in the tensile stressed films.