In vacuo studies on plasma-enhanced atomic layer deposition of cobalt thin films
| Autor: | Johann W. Bartha, Matthias Albert, Felix Winkler, Johanna Reif, Sebastian Killge, Martin Knaut |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Argon
Materials science Hydrogen Scanning electron microscope 020209 energy Analytical chemistry chemistry.chemical_element 02 engineering and technology Surfaces and Interfaces 021001 nanoscience & nanotechnology Condensed Matter Physics Surfaces Coatings and Films Atomic layer deposition chemistry X-ray photoelectron spectroscopy Sputtering 0202 electrical engineering electronic engineering information engineering Thin film 0210 nano-technology Cobalt |
| Zdroj: | Journal of Vacuum Science & Technology A. 38:012405 |
| ISSN: | 1520-8559 0734-2101 |
| Popis: | Plasma-enhanced atomic layer deposition (PE-ALD) of cobalt (Co) using cyclopentadienylcobalt dicarbonyl [CpCo(CO)2] combined with hydrogen, nitrogen, ammonia, and argon based plasma gases was investigated. The utilized ALD tool was clustered to an ultrahigh vacuum analytic system for direct surface analyses including X-ray photoelectron spectroscopy (XPS). The combination with a nondestructive surface analysis system enabled a sample transfer without vacuum break and thereby a direct qualification and quantification of the chemical surface composition under quasi in situ conditions. The authors studied the influence of process parameters (e.g., pulse times, plasma power, and substrate temperature) on film compositions and film properties. The occurrence and prevention of sputtering effects due to ion bombardment at high plasma powers were discussed. Beyond those results, precise information about the impact of different plasma gas compositions on the resulting film properties was obtained. Cobalt films grown using a hydrogen/nitrogen (H2/N2) plasma as a coreactant showed a stable film composition (CoNx) with a high Co content of 75 at. %. Using scanning electron microscopy and four point probe measurements, a moderate electrical resistivity of about 56 μΩ cm was calculated for a 20 nm film. The high sensitivity of in vacuo XPS measurements allowed investigations of interface reactions for a single PE-ALD pulse as well as investigations of the initial film growth mechanisms. The nucleation of CoNx films during PE-ALD using H2/N2 plasma as a coreactant was investigated on several substrate materials by XPS. After the very first cycle of the PE-ALD process, no Co could be detected on all the investigated substrates. XPS revealed that the plasma pulse was needed to provide active binding sites for the adsorption reaction of precursor molecules due to the formation of Si-Nx or Si-NxOy surfaces. Therefore, the plasma pulse plays an important role in the PE-ALD process of Co on silicon surfaces. The early cycles were characterized by the onset of Co—O bonds. The homogeneous film body on all substrates consisted of Co-nitride compounds. |
| Databáze: | OpenAIRE |
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