In situ phase evolution study in magnetron sputtered tantalum thin films

The design and construction of a planar magnetron sputter deposition system with a beryllium chamber has been accomplished to perform in situ X-ray diffraction growth study of refractory coatings. The deposition system sits on top of a laboratory θ-2θ X-ray diffractometer. A 2D array detector was interfaced for observation of the Debye rings during growth. Integration along the 2θ and χ directions allows fast phase and texture determination. Two sputter depositions of tantalum films onto glass substrate in argon gas are reported, one was deposited at 25 mm target-detector distance, 3.9 Pa argon gas, and the other at 108 mm target-detector distance and 1.3 Pa argon gas. The first film grew to 250 nm in 39 min at an average growth rate of 6.4 nm/min. It consisted of 45 nm of interface layer, which showed no crystalline structure, followed by 15-nm growth of β-tantalum, followed by 190-nm growth of α-tantalum. From the full-width-half-maximum of the χ-plot, it was determined that β-tantalum was <0 0 2> textured, and α-tantalum was <1 1 0> textured and grew more textured with deposition time. The second film grew to 36 nm in 22 min at an average growth rate of 1.6 nm/min. It consisted of 31 nm of layer, which showed no crystalline structure, followed by 5 nm of surface layer of β- and α-tantalum. Ex situ grazing incidence X-ray diffraction performed on the film surface confirmed the in situ results. Ex situ pole figure analysis showed: <1 1 0> fiber texture in α-tantalum, and highly <0 0 2> texture in β-tantalum