Metal versus rare-gas ion irradiation during Ti{sub 1-x}Al{sub x}N film growth by hybrid high power pulsed magnetron/dc magnetron co-sputtering using synchronized pulsed substrate bias
- Department of Physics (IFM), Linkoeping University, SE-581 83 Linkoeping (Sweden)
Metastable NaCl-structure Ti{sub 1-x}Al{sub x}N is employed as a model system to probe the effects of metal versus rare-gas ion irradiation during film growth using reactive high-power pulsed magnetron sputtering (HIPIMS) of Al and dc magnetron sputtering of Ti. The alloy film composition is chosen to be x = 0.61, near the kinetic solubility limit at the growth temperature of 500 Degree-Sign C. Three sets of experiments are carried out: a -60 V substrate bias is applied either continuously, in synchronous with the full HIPIMS pulse, or in synchronous only with the metal-rich-plasma portion of the HIPIMS pulse. Alloy films grown under continuous dc bias exhibit a thickness-invariant small-grain, two-phase nanostructure (wurtzite AlN and cubic Ti{sub 1-x}Al{sub x}N) with random orientation, due primarily to intense Ar{sup +} irradiation leading to Ar incorporation (0.2 at. %), high compressive stress (-4.6 GPa), and material loss by resputtering. Synchronizing the bias with the full HIPIMS pulse results in films that exhibit much lower stress levels (-1.8 GPa) with no measureable Ar incorporation, larger grains elongated in the growth direction, a very small volume fraction of wurtzite AlN, and random orientation. By synchronizing the bias with the metal-plasma phase of the HIPIMS pulses, energetic Ar{sup +} ion bombardment is greatly reduced in favor of irradiation predominantly by Al{sup +} ions. The resulting films are single phase with a dense competitive columnar structure, strong 111 orientation, no measureable trapped Ar concentration, and even lower stress (-0.9 GPa). Thus, switching from Ar{sup +} to Al{sup +} bombardment, while maintaining the same integrated incident ion/metal ratio, eliminates phase separation, minimizes renucleation during growth, and reduces the high concentration of residual point defects, which give rise to compressive stress.
- OSTI ID:
- 22099112
- Journal Information:
- Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films, Vol. 30, Issue 6; Other Information: (c) 2012 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0734-2101
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM IONS
ALUMINIUM NITRIDES
ARGON IONS
CRYSTAL GROWTH
CUBIC LATTICES
GRAIN ORIENTATION
ION BEAMS
MAGNETRONS
METALS
NANOSTRUCTURES
PLASMA
POINT DEFECTS
PRESSURE RANGE GIGA PA
PULSES
SODIUM CHLORIDES
SOLUBILITY
SPUTTERING
SUBSTRATES
THIN FILMS
TITANIUM COMPOUNDS