A method for fabricating stable and low-stress tantalum films, suitable for absorbers of x-ray masks, by dc-bias, rf magnetron sputtering is presented. The superiority of Xe over Ar as a working gas is demonstrated. The stress-vs-bias-voltage curve has a plateau, where the film stresses are low and constant over the bias voltage ranging from −15 to 20 V. The plateau stresses vary linearly with both the working Xe pressure and the substrate temperature with slopes of 1.2×1010 dyn/cm2 Pa and 8.6×106 dyn/cm2 deg, respectively. By control of the pressure and the temperature, stresses of (3±2)×108 dyn/cm2 are achieved. The Ta film which is stable under a heat treatment up to 300 °C is obtainable when it is deposited at 220 °C and then annealed at 220 °C for 1 h. The density of the films is (15.0±0.5) g/cm3. By x-ray diffraction the films are found to be in a mixture of the α-Ta phase and the β-Ta phase. Ta patterns of 0.15 μm in width were fabricated.

No abstract

No abstract

No abstract