Abstract
In this work, we investigated an approach of hot-wire assisted ALD (HWALD), utilizing a hot (up to 2000 8C) tungsten (W) wire. Tungsten films were deposited by this method using alternating pulses of WF6 gas and atomic hydrogen (at-H). The latter was generated by catalytic dissociation of molecular hydrogen (H2) upon the hot-wire. The W films were grown on a 100-nm thick thermal SiO2. The growth process was monitored in real time by an in-situ spectroscopic ellipsometer (SE). The real-time SE monitoring revealed the coexistence of three processes: CVD, etching, and ALD of the W film. WF6 could back-stream diffuse to the hot-wire, resulting in WF6 decomposition and generation of a flux of fluorine (F). The latter caused etching of the grown W film and the filament, and provided extra tungsten supply, which might cause CVD. Higher pressure and higher carrier gas flow rate were found to largely suppress the back-stream diffusion of WF6, which efficiently limited CVD. By controlling the dose of WF6 and process pressure, the etching had also been minimized. X-ray photoelectron spectroscopy of optimized HWALD grown W revealed 99 at% of W; concentrations of oxygen and fluorine were lower than 1%, below the detection limit.
Original language | English |
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Pages (from-to) | 1607-1614 |
Number of pages | 8 |
Journal | Physica status solidi A |
Volume | 212 |
Issue number | 7 |
Early online date | 25 May 2015 |
DOIs | |
Publication status | Published - Jul 2015 |
Keywords
- Tungsten
- Thin Films
- in-situ spectroscopic ellipsometer
- Etching
- atomic layer depositionetchinghot wirein-situ spectroscopic ellipsometerthin filmstungsten
- Atomic Layer Deposition
- hot wire
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