Comparison of mechanical properties and composition of magnetron sputter and plasma enhanced atomic layer deposition aluminum nitride films

Perttu Sippola, Alexander Pyymäki Perros, Oili Ylivaara, Helena Ronkainen, Jaakko Julin, Xuwen Liu, Timo Sajavaara, Jarkko Etula, Harri Lipsanen, Riikka L. Puurunen

Research output: Contribution to journalArticleScientificpeer-review

1 Citation (Scopus)

Abstract

A comparative study of mechanical properties and elemental and structural composition was made for aluminum nitride thin films deposited with reactive magnetron sputtering and plasma enhanced atomic layer deposition (PEALD). The sputtered films were deposited on Si (100), Mo (110), and Al (111) oriented substrates to study the effect of substrate texture on film properties. For the PEALD trimethylaluminum–ammonia films, the effects of process parameters, such as temperature, bias voltage, and plasma gas (ammonia versus N2/H2), on the AlN properties were studied. All the AlN films had a nominal thickness of 100 nm. Time-of-flight elastic recoil detection analysis showed the sputtered films to have lower impurity concentration with an Al/N ratio of 0.95, while the Al/N ratio for the PEALD films was 0.81–0.90. The mass densities were ∼3.10 and ∼2.70 g/cm3 for sputtered and PEALD AlN, respectively. The sputtered films were found to have higher degrees of preferential crystallinity, whereas the PEALD films were more polycrystalline as determined by x-ray diffraction. Nanoindentation experiments showed the elastic modulus and hardness to be 250 and 22 GPa, respectively, for sputtered AlN on the (110) substrate, whereas with PEALD AlN, values of 180 and 19 GPa, respectively, were obtained. The sputtered films were under tensile residual stress (61–421 MPa), whereas the PEALD films had a residual stress ranging from tensile to compressive (846 to −47 MPa), and high plasma bias resulted in compressive films. The adhesion of both films was good on Si, although sputtered films showed more inconsistent critical load behavior. Also, the substrate underneath the sputtered AlN did not withstand high wear forces as with the PEALD AlN. The coefficient of friction was determined to be ∼0.2 for both AlN types, and their wear characteristics were almost identical.
Original languageEnglish
Article number051508
Number of pages12
JournalJournal of Vacuum Science and Technology A: Vacuum, Surfaces and Films
Volume36
Issue number5
DOIs
Publication statusPublished - 30 Jul 2018
MoE publication typeA1 Journal article-refereed

Fingerprint

Aluminum nitride
Atomic layer deposition
aluminum nitrides
atomic layer epitaxy
mechanical properties
Plasmas
Mechanical properties
Chemical analysis
Substrates
aluminum nitride
residual stress
Residual stresses
Wear of materials
Plasma Gases
Reactive sputtering
Nanoindentation
Bias voltage
nanoindentation
tensile stress
Ammonia

Keywords

  • ALD
  • Atomic Layer Deposition
  • sputtering
  • aluminum nitride
  • AlN
  • mechanical properties

Cite this

Sippola, Perttu ; Pyymäki Perros, Alexander ; Ylivaara, Oili ; Ronkainen, Helena ; Julin, Jaakko ; Liu, Xuwen ; Sajavaara, Timo ; Etula, Jarkko ; Lipsanen, Harri ; Puurunen, Riikka L. / Comparison of mechanical properties and composition of magnetron sputter and plasma enhanced atomic layer deposition aluminum nitride films. In: Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films. 2018 ; Vol. 36, No. 5.
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abstract = "A comparative study of mechanical properties and elemental and structural composition was made for aluminum nitride thin films deposited with reactive magnetron sputtering and plasma enhanced atomic layer deposition (PEALD). The sputtered films were deposited on Si (100), Mo (110), and Al (111) oriented substrates to study the effect of substrate texture on film properties. For the PEALD trimethylaluminum–ammonia films, the effects of process parameters, such as temperature, bias voltage, and plasma gas (ammonia versus N2/H2), on the AlN properties were studied. All the AlN films had a nominal thickness of 100 nm. Time-of-flight elastic recoil detection analysis showed the sputtered films to have lower impurity concentration with an Al/N ratio of 0.95, while the Al/N ratio for the PEALD films was 0.81–0.90. The mass densities were ∼3.10 and ∼2.70 g/cm3 for sputtered and PEALD AlN, respectively. The sputtered films were found to have higher degrees of preferential crystallinity, whereas the PEALD films were more polycrystalline as determined by x-ray diffraction. Nanoindentation experiments showed the elastic modulus and hardness to be 250 and 22 GPa, respectively, for sputtered AlN on the (110) substrate, whereas with PEALD AlN, values of 180 and 19 GPa, respectively, were obtained. The sputtered films were under tensile residual stress (61–421 MPa), whereas the PEALD films had a residual stress ranging from tensile to compressive (846 to −47 MPa), and high plasma bias resulted in compressive films. The adhesion of both films was good on Si, although sputtered films showed more inconsistent critical load behavior. Also, the substrate underneath the sputtered AlN did not withstand high wear forces as with the PEALD AlN. The coefficient of friction was determined to be ∼0.2 for both AlN types, and their wear characteristics were almost identical.",
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Comparison of mechanical properties and composition of magnetron sputter and plasma enhanced atomic layer deposition aluminum nitride films. / Sippola, Perttu; Pyymäki Perros, Alexander; Ylivaara, Oili; Ronkainen, Helena; Julin, Jaakko; Liu, Xuwen; Sajavaara, Timo; Etula, Jarkko; Lipsanen, Harri; Puurunen, Riikka L.

In: Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films, Vol. 36, No. 5, 051508, 30.07.2018.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Comparison of mechanical properties and composition of magnetron sputter and plasma enhanced atomic layer deposition aluminum nitride films

AU - Sippola, Perttu

AU - Pyymäki Perros, Alexander

AU - Ylivaara, Oili

AU - Ronkainen, Helena

AU - Julin, Jaakko

AU - Liu, Xuwen

AU - Sajavaara, Timo

AU - Etula, Jarkko

AU - Lipsanen, Harri

AU - Puurunen, Riikka L.

PY - 2018/7/30

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N2 - A comparative study of mechanical properties and elemental and structural composition was made for aluminum nitride thin films deposited with reactive magnetron sputtering and plasma enhanced atomic layer deposition (PEALD). The sputtered films were deposited on Si (100), Mo (110), and Al (111) oriented substrates to study the effect of substrate texture on film properties. For the PEALD trimethylaluminum–ammonia films, the effects of process parameters, such as temperature, bias voltage, and plasma gas (ammonia versus N2/H2), on the AlN properties were studied. All the AlN films had a nominal thickness of 100 nm. Time-of-flight elastic recoil detection analysis showed the sputtered films to have lower impurity concentration with an Al/N ratio of 0.95, while the Al/N ratio for the PEALD films was 0.81–0.90. The mass densities were ∼3.10 and ∼2.70 g/cm3 for sputtered and PEALD AlN, respectively. The sputtered films were found to have higher degrees of preferential crystallinity, whereas the PEALD films were more polycrystalline as determined by x-ray diffraction. Nanoindentation experiments showed the elastic modulus and hardness to be 250 and 22 GPa, respectively, for sputtered AlN on the (110) substrate, whereas with PEALD AlN, values of 180 and 19 GPa, respectively, were obtained. The sputtered films were under tensile residual stress (61–421 MPa), whereas the PEALD films had a residual stress ranging from tensile to compressive (846 to −47 MPa), and high plasma bias resulted in compressive films. The adhesion of both films was good on Si, although sputtered films showed more inconsistent critical load behavior. Also, the substrate underneath the sputtered AlN did not withstand high wear forces as with the PEALD AlN. The coefficient of friction was determined to be ∼0.2 for both AlN types, and their wear characteristics were almost identical.

AB - A comparative study of mechanical properties and elemental and structural composition was made for aluminum nitride thin films deposited with reactive magnetron sputtering and plasma enhanced atomic layer deposition (PEALD). The sputtered films were deposited on Si (100), Mo (110), and Al (111) oriented substrates to study the effect of substrate texture on film properties. For the PEALD trimethylaluminum–ammonia films, the effects of process parameters, such as temperature, bias voltage, and plasma gas (ammonia versus N2/H2), on the AlN properties were studied. All the AlN films had a nominal thickness of 100 nm. Time-of-flight elastic recoil detection analysis showed the sputtered films to have lower impurity concentration with an Al/N ratio of 0.95, while the Al/N ratio for the PEALD films was 0.81–0.90. The mass densities were ∼3.10 and ∼2.70 g/cm3 for sputtered and PEALD AlN, respectively. The sputtered films were found to have higher degrees of preferential crystallinity, whereas the PEALD films were more polycrystalline as determined by x-ray diffraction. Nanoindentation experiments showed the elastic modulus and hardness to be 250 and 22 GPa, respectively, for sputtered AlN on the (110) substrate, whereas with PEALD AlN, values of 180 and 19 GPa, respectively, were obtained. The sputtered films were under tensile residual stress (61–421 MPa), whereas the PEALD films had a residual stress ranging from tensile to compressive (846 to −47 MPa), and high plasma bias resulted in compressive films. The adhesion of both films was good on Si, although sputtered films showed more inconsistent critical load behavior. Also, the substrate underneath the sputtered AlN did not withstand high wear forces as with the PEALD AlN. The coefficient of friction was determined to be ∼0.2 for both AlN types, and their wear characteristics were almost identical.

KW - ALD

KW - Atomic Layer Deposition

KW - sputtering

KW - aluminum nitride

KW - AlN

KW - mechanical properties

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U2 - 10.1116/1.5038856

DO - 10.1116/1.5038856

M3 - Article

VL - 36

JO - Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films

JF - Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films

SN - 0734-2101

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M1 - 051508

ER -