Structural properties of reactively sputtered W-Si-N thin films
- INFN-Laboratori Nazionali di Legnaro, Viale Universita 2, I-35020 Legnaro (PD), Italy and SENSOR Lab, CNR-INFM, Via Valotti 9, I-25133 Brescia (Italy)
Tungsten-silicon-nitrogen, W-Si-N, ternary thin films have been reactively sputter deposited from W{sub 5}Si{sub 3} and WSi{sub 2} targets using several nitrogen partial pressures. The films have been thermal annealed in the 600-1000 deg. C temperature range and a wide region of the W-Si-N ternary phase diagram has been explored by changing the N{sub 2}/Ar ratio during the deposition. Multitechnique approach was adopted for the analysis of the samples. Composition has been determined via ion beam analysis; chemical states were investigated using x-ray photoelectron spectroscopy (XPS); crystalline structure was studied using transmission electron microscopy (TEM) and x-ray diffraction (XRD) and surface morphology by scanning electron microscope. The films deposited in pure argon atmosphere are tungsten rich and approach the target contents as N{sub 2}/Ar ratio is varied during deposition. Tungsten enrichment in the films is caused by resputtering of silicon which can be inhibited by the formation of silicon nitride, allowing films with Si/W ratio closer to the target compositions. The higher capability to form nitrides with silicon than with tungsten favors enhancement of nitrogen content in samples deposited from the silicon rich target (WSi{sub 2}). The samples with excess nitrogen content have shown losses of this element after thermal treatment. XPS measurements show a break of W-N bonds caused by thermal instability of tungsten nitrides. TEM and XRD revealed the segregation of tungsten in form of metallic or silicide nanoclusters in samples with low nitrogen content (W{sub 58}Si{sub 21}N{sub 21} and W{sub 24}Si{sub 42}N{sub 34}). High amounts of nitrogen were revealed to be highly effective in inhibiting metallic cluster coalescence. Measurements of electrical resistivity of as deposited films were performed using four point probe technique. They were found to lie in the range between 0.4 and 79 m{omega} cm depending on sample composition.
- OSTI ID:
- 21057470
- Journal Information:
- Journal of Applied Physics, Vol. 102, Issue 3; Other Information: DOI: 10.1063/1.2761828; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ANNEALING
ARGON
CHEMICAL STATE
ELECTRIC CONDUCTIVITY
ION BEAMS
NANOSTRUCTURES
PARTIAL PRESSURE
PHASE DIAGRAMS
SCANNING ELECTRON MICROSCOPY
SEGREGATION
SILICON NITRIDES
SPUTTERING
TEMPERATURE RANGE 0400-1000 K
TEMPERATURE RANGE 1000-4000 K
THIN FILMS
TRANSMISSION ELECTRON MICROSCOPY
TUNGSTEN NITRIDES
TUNGSTEN SILICIDES
X-RAY DIFFRACTION
X-RAY PHOTOELECTRON SPECTROSCOPY