Aluminum oxide from trimethylaluminum and water by atomic layer deposition: The temperature dependence of residual stress, elastic modulus, hardness and adhesion

Oili M.E. Ylivaara, Xuwen Liu, Lauri Kilpi, Jussi Lyytinen, Dieter Schneider, Mikko Laitinen, Jaakko Julin, Saima Ali, Sakari Sintonen, Maria Berdova, Eero Haimi, Timo Sajavaara, Helena Ronkainen, Harri Lipsanen, Jari Koskinen, Simo Pekka Hannula, Riikka L. Puurunen

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

Use of atomic layer deposition (ALD) in microelectromechanical systems (MEMS) has increased as ALD enables conformal growth on 3-dimensional structures at relatively low temperatures. For MEMS device design and fabrication, the understanding of stress and mechanical properties such as elastic modulus, hardness and adhesion of thin film is crucial. In this work a comprehensive characterization of the stress, elastic modulus, hardness and adhesion of ALD aluminum oxide (Al2O3) films grown at 110-300 C from trimethylaluminum and water is presented. Film stress was analyzed by wafer curvature measurements, elastic modulus by nanoindentation and surface-acoustic wave measurements, hardness by nanoindentation and adhesion by microscratch test and scanning nanowear. The films were also analyzed by ellipsometry, optical reflectometry, X-ray reflectivity and time-of-flight elastic recoil detection for refractive index, thickness, density and impurities. The ALD Al 2O3 films were under tensile stress in the scale of hundreds of MPa. The magnitude of the stress decreased strongly with increasing ALD temperature. The stress was stable during storage in air. Elastic modulus and hardness of ALD Al2O3 saturated to a fairly constant value for growth at 150 to 300 C, while ALD at 110 C gave softer films with lower modulus. ALD Al2O3 films adhered strongly on cleaned silicon with SiOx termination.

Original languageEnglish
Pages (from-to)124-135
Number of pages12
JournalThin Solid Films
Volume552
Early online date6 Dec 2013
DOIs
Publication statusPublished - 2014
MoE publication typeA1 Journal article-refereed

Fingerprint

Atomic layer deposition
Aluminum Oxide
atomic layer epitaxy
residual stress
Residual stresses
modulus of elasticity
adhesion
Adhesion
hardness
aluminum oxides
Elastic moduli
Hardness
Aluminum
temperature dependence
Oxides
Water
water
Temperature
Nanoindentation
nanoindentation

Keywords

  • Adhesion
  • Aluminum oxide
  • Atomic layer deposition
  • Elastic modulus
  • Hardness
  • Residual stress

Cite this

Ylivaara, Oili M.E. ; Liu, Xuwen ; Kilpi, Lauri ; Lyytinen, Jussi ; Schneider, Dieter ; Laitinen, Mikko ; Julin, Jaakko ; Ali, Saima ; Sintonen, Sakari ; Berdova, Maria ; Haimi, Eero ; Sajavaara, Timo ; Ronkainen, Helena ; Lipsanen, Harri ; Koskinen, Jari ; Hannula, Simo Pekka ; Puurunen, Riikka L. / Aluminum oxide from trimethylaluminum and water by atomic layer deposition : The temperature dependence of residual stress, elastic modulus, hardness and adhesion. In: Thin Solid Films. 2014 ; Vol. 552. pp. 124-135.
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abstract = "Use of atomic layer deposition (ALD) in microelectromechanical systems (MEMS) has increased as ALD enables conformal growth on 3-dimensional structures at relatively low temperatures. For MEMS device design and fabrication, the understanding of stress and mechanical properties such as elastic modulus, hardness and adhesion of thin film is crucial. In this work a comprehensive characterization of the stress, elastic modulus, hardness and adhesion of ALD aluminum oxide (Al2O3) films grown at 110-300 C from trimethylaluminum and water is presented. Film stress was analyzed by wafer curvature measurements, elastic modulus by nanoindentation and surface-acoustic wave measurements, hardness by nanoindentation and adhesion by microscratch test and scanning nanowear. The films were also analyzed by ellipsometry, optical reflectometry, X-ray reflectivity and time-of-flight elastic recoil detection for refractive index, thickness, density and impurities. The ALD Al 2O3 films were under tensile stress in the scale of hundreds of MPa. The magnitude of the stress decreased strongly with increasing ALD temperature. The stress was stable during storage in air. Elastic modulus and hardness of ALD Al2O3 saturated to a fairly constant value for growth at 150 to 300 C, while ALD at 110 C gave softer films with lower modulus. ALD Al2O3 films adhered strongly on cleaned silicon with SiOx termination.",
keywords = "Adhesion, Aluminum oxide, Atomic layer deposition, Elastic modulus, Hardness, Residual stress",
author = "Ylivaara, {Oili M.E.} and Xuwen Liu and Lauri Kilpi and Jussi Lyytinen and Dieter Schneider and Mikko Laitinen and Jaakko Julin and Saima Ali and Sakari Sintonen and Maria Berdova and Eero Haimi and Timo Sajavaara and Helena Ronkainen and Harri Lipsanen and Jari Koskinen and Hannula, {Simo Pekka} and Puurunen, {Riikka L.}",
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Ylivaara, OME, Liu, X, Kilpi, L, Lyytinen, J, Schneider, D, Laitinen, M, Julin, J, Ali, S, Sintonen, S, Berdova, M, Haimi, E, Sajavaara, T, Ronkainen, H, Lipsanen, H, Koskinen, J, Hannula, SP & Puurunen, RL 2014, 'Aluminum oxide from trimethylaluminum and water by atomic layer deposition: The temperature dependence of residual stress, elastic modulus, hardness and adhesion', Thin Solid Films, vol. 552, pp. 124-135. https://doi.org/10.1016/j.tsf.2013.11.112

Aluminum oxide from trimethylaluminum and water by atomic layer deposition : The temperature dependence of residual stress, elastic modulus, hardness and adhesion. / Ylivaara, Oili M.E.; Liu, Xuwen; Kilpi, Lauri; Lyytinen, Jussi; Schneider, Dieter; Laitinen, Mikko; Julin, Jaakko; Ali, Saima; Sintonen, Sakari; Berdova, Maria; Haimi, Eero; Sajavaara, Timo; Ronkainen, Helena; Lipsanen, Harri; Koskinen, Jari; Hannula, Simo Pekka; Puurunen, Riikka L.

In: Thin Solid Films, Vol. 552, 2014, p. 124-135.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Aluminum oxide from trimethylaluminum and water by atomic layer deposition

T2 - The temperature dependence of residual stress, elastic modulus, hardness and adhesion

AU - Ylivaara, Oili M.E.

AU - Liu, Xuwen

AU - Kilpi, Lauri

AU - Lyytinen, Jussi

AU - Schneider, Dieter

AU - Laitinen, Mikko

AU - Julin, Jaakko

AU - Ali, Saima

AU - Sintonen, Sakari

AU - Berdova, Maria

AU - Haimi, Eero

AU - Sajavaara, Timo

AU - Ronkainen, Helena

AU - Lipsanen, Harri

AU - Koskinen, Jari

AU - Hannula, Simo Pekka

AU - Puurunen, Riikka L.

N1 - Project 74717 MECHALD

PY - 2014

Y1 - 2014

N2 - Use of atomic layer deposition (ALD) in microelectromechanical systems (MEMS) has increased as ALD enables conformal growth on 3-dimensional structures at relatively low temperatures. For MEMS device design and fabrication, the understanding of stress and mechanical properties such as elastic modulus, hardness and adhesion of thin film is crucial. In this work a comprehensive characterization of the stress, elastic modulus, hardness and adhesion of ALD aluminum oxide (Al2O3) films grown at 110-300 C from trimethylaluminum and water is presented. Film stress was analyzed by wafer curvature measurements, elastic modulus by nanoindentation and surface-acoustic wave measurements, hardness by nanoindentation and adhesion by microscratch test and scanning nanowear. The films were also analyzed by ellipsometry, optical reflectometry, X-ray reflectivity and time-of-flight elastic recoil detection for refractive index, thickness, density and impurities. The ALD Al 2O3 films were under tensile stress in the scale of hundreds of MPa. The magnitude of the stress decreased strongly with increasing ALD temperature. The stress was stable during storage in air. Elastic modulus and hardness of ALD Al2O3 saturated to a fairly constant value for growth at 150 to 300 C, while ALD at 110 C gave softer films with lower modulus. ALD Al2O3 films adhered strongly on cleaned silicon with SiOx termination.

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KW - Adhesion

KW - Aluminum oxide

KW - Atomic layer deposition

KW - Elastic modulus

KW - Hardness

KW - Residual stress

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U2 - 10.1016/j.tsf.2013.11.112

DO - 10.1016/j.tsf.2013.11.112

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