Deposition kinetics and microstructural evolution in sputtered ta films: a real-time/in-situ study

摘要

Ta films were grown using sputter gas (Ar) pressures ranging from 1.7 to 20 mTorr. This produced growth environments where incoming adatom kinetic energies ranged from over 100 eV to less than 1 eV. Film development was monitored in-situ using a x-ray diffraction set-up that allowed complete diffraction patterns to be rapidly collected without interrupting the growth process. Traditional x-ray diffraction methods, transmission electron microscopy (TEM), and transmission electron diffraction (TED) were used to examine film microstructure after growth. It was found that lower Ar pressures, which allow higher adatom kinetic energies, produced films that disphayed significant grain growth, texturing, and a smooth surface morphology. Those films grown at increasingly higher Ar pressures displayed smaller grain sizes, less texturing, and increasingly porous microstructures. To further explore this effect, the Ar pressure was varied during deposition for several films. The in-situ probe allowed the effects of each pressure increment to be analyzed and compared with previous x-ray and microscopy results. It was found that the microstructure of any particular film layer depended more on the deposition conditions during its formation rather than the structure or crystallography of previous layers.