Stress in sputtered Mo thin films: The effect of the discharge voltage

The present study reports on internal stress in planar magnetron sputtered Mo films. Characteristic compressive-to-tensile stress transition curves were measured. The transition pressure is observed to shift to higher values when the discharge power to the cathode is increased. Gas density measurements in the plasma region proved that at least part of the observed shift of the stress curves originates from a localized gas heating effect. At low argon pressures the stress in the Mo films appeared to be a function of the discharge voltage, independent of the discharge power. The discharge voltage is directly linked to the energy of the fast neutrals, backscattered from the target in the direction of the growing film. It will be shown that the resultant film stress can be attributed to the level of energetic, neutral bombardment during deposition.