Effect of ion irradiation during deposition on the structure of alumina thin films grown by plasma assisted chemical vapour deposition

Kyrylov, O.; Kurapov, D.; Schneider, Jochen M.

doi:10.1007/s00339-004-2998-y

Cited by 43 publications

(29 citation statements)

References 20 publications

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“…As a consequence, phase control of alumina thin films in general, and low-temperature growth of ␣-Al 2 O 3 in particular, has been studied intensely during the last decade. [1][2][3][4][5][6] Irradiation of the growth surface by energetic ions is known to be important in thin film growth, especially at low growth temperatures. For example, properties such as microstructure, 7 defect density, 8 and crystal structure 9,10 can effectively be modified by energetic bombardment.…”

Section: Introductionmentioning

confidence: 99%

Energy distributions of positive and negative ions during magnetron sputtering of an Al target in Ar∕O2 mixtures

Andersson

Wallin

Münger

et al. 2006

Journal of Applied Physics

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The ion flux obtained during reactive magnetron sputtering of an Al target in Ar/ O 2 gas mixtures was studied by energy-resolved mass spectrometry, as a function of the total and O 2 partial pressures. The positive ions of film-forming species exhibited bimodal energy distributions, both for direct current and radio frequency discharges, with the higher energy ions most likely originating from sputtered neutrals. For the negative oxygen ions a high-energy peak was observed, corresponding to ions formed at the target surface and accelerated towards the substrate over the sheath potential. As the total pressure was increased the high-energy peaks diminished due to gas-phase scattering. Based on these results, the role of energetic bombardment for the phase constituent of alumina thin films are discussed.

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Section: Introductionmentioning

confidence: 99%

Energy distributions of positive and negative ions during magnetron sputtering of an Al target in Ar∕O2 mixtures

Andersson

Wallin

Münger

et al. 2006

Journal of Applied Physics

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show abstract

“…Consequently, many low-temperature growth studies, aimed at forming the α phase, have been made during the last decade. Notably, α-Al 2 O 3 films were achieved at 760 °C by pulsed DC reactive magnetron sputtering, 1 at 580 °C using plasma assisted chemical vapor deposition, 2 and at 280 °C by non-reactive RF magnetron sputtering from an Al 2 O 3 target using chromia (Cr 2 O 3 ) nucleation layers. 3,4 In this article, the method of a chromia "template" is applied to reactive magnetron sputtering, with the aim to understand and control alumina growth at low temperatures.…”

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confidence: 99%

Phase control of Al2O3 thin films grown at low temperatures

et al. 2006

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Low-temperature growth (500°C) of α-Al 2 O 3 thin films by reactive magnetron sputtering was achieved for the first time. The films were grown onto Cr 2 O 3 nucleation layers and the effects of the total and O 2 partial pressures were investigated. At 0.33 Pa total pressure and ≥16 mPa O 2 partial pressure α-Al 2 O 3 films formed, while at lower O 2 pressure or higher total pressure (0.67 Pa), only γ phase was detected in the films (which were all stoichiometric). Based on these results we suggest that α phase formation was promoted by a high energetic bombardment of the growth surface.2 Alumina (Al 2 O 3 ) thin films are widely used as, e.g., wear-resistant or diffusion barrier coatings. In such high-temperature applications the hard and thermally stable α phase is usually desired. However, synthesis of this phase is not straight-forward. The existence of several metastable phases complicates growth of α-Al 2 O 3 , especially when low temperature growth is required (to limit the thermal load of the substrate). Consequently, many low-temperature growth studies, aimed at forming the α phase, have been made during the last decade. Notably, α-Al 2 O 3 films were achieved at 760 °C by pulsed DC reactive magnetron sputtering, 1 at 580 °C using plasma assisted chemical vapor deposition, 2 and at 280 °C by non-reactive RF magnetron sputtering from an Al 2 O 3 target using chromia (Cr 2 O 3 ) nucleation layers. 3,4 In this article, the method of a chromia "template" is applied to reactive magnetron sputtering, with the aim to understand and control alumina growth at low temperatures. To this end the crystalline structure and chemical composition of the grown films were studied as functions of O 2 partial pressure and Ar+O 2 total pressure. Moreover, in order to study the effect of water, which is known to be important in alumina growth, 5 films were deposited both at ultra high vacuum (UHV) and in a background of ~10 -4 Pa H 2 O.

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“…Consequently, phase control of alumina thin films and, in particular, low-temperature growth of ␣-Al 2 O 3 has been studied intensely during the last decade. [1][2][3][4][5] A thin film is formed through chemical bonding between the species incident onto the substrate. Thus, knowledge of the contents of the deposition flux is of importance in order to understand and control the growth.…”

mentioning

confidence: 99%

Molecular content of the deposition flux during reactive Ar∕O2 magnetron sputtering of Al

Andersson

Wallin

Münger

et al. 2006

Applied Physics Letters

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The deposition flux obtained during reactive radio frequency magnetron sputtering of an Al target in Ar∕O2 gas mixtures was studied by mass spectrometry. The results show significant amounts of molecular AlO+ (up to 10% of the Al+ flux) in the ionic flux incident onto the substrate. In the presence of ∼10−4Pa H2O additional OH+ and AlOH+ were detected, amounting to up to about 100% and 30% of the Al+ flux, respectively. Since the ions represent a small fraction of the total deposition flux, an estimation of the neutral content was also made. These calculations show that, due to the higher ionization probability of Al, the amount of neutral AlO in the deposition flux is of the order of, or even higher than, the amount of Al. These findings might be of great aid when explaining the alumina thin film growth process.

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Effect of ion irradiation during deposition on the structure of alumina thin films grown by plasma assisted chemical vapour deposition

Cited by 43 publications

References 20 publications

Energy distributions of positive and negative ions during magnetron sputtering of an Al target in Ar∕O2 mixtures

Energy distributions of positive and negative ions during magnetron sputtering of an Al target in Ar∕O2 mixtures

Phase control of Al2O3 thin films grown at low temperatures

Molecular content of the deposition flux during reactive Ar∕O2 magnetron sputtering of Al

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