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Film and surface stress during Al2O3 thermal atomic layer etching using in situ wafer curvature measurements.

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Title: Film and surface stress during Al2O3 thermal atomic layer etching using in situ wafer curvature measurements.
Authors: Vanfleet, Ryan B.1 (AUTHOR), Bright, Victor M.2 (AUTHOR), George, Steven M.1 (AUTHOR) Steven.George@Colorado.edu
Source: Journal of Vacuum Science & Technology: Part A-Vacuums, Surfaces & Films. May2026, Vol. 44 Issue 3, p1-9. 9p.
Subjects: Aluminum oxide, Atomic layer deposition, Interfacial stresses, Fluorination, Ligand exchange reactions, Surface forces
Abstract: In situ wafer curvature measurements were employed to monitor film and surface stress during Al2O3 thermal atomic layer etching (ALE). The Al2O3 thermal ALE was performed using fluorination and ligand-exchange reactions using sequential hydrogen fluoride (HF) and trimethylaluminum [TMA, Al(CH3)3] exposures at temperatures from 250 to 300 °C. The initial Al2O3 films were grown using Al2O3 atomic layer deposition (ALD) with TMA and H2O as the reactants. These Al2O3 ALD films are known to be under tensile stress. The progressive decrease in stress-thickness versus Al2O3 thermal ALE cycles was consistent with the linear removal of the Al2O3 ALD film that contains tensile stress. The results indicated that ALE can be used as a layer removal method to determine the stress distribution in a thin film. The reduction of the stress-thickness by Al2O3 thermal ALE at 250, 275, and 300 °C was consistent with the Al2O3 etch rates at these temperatures. Surface stresses corresponding to the fluorination and ligand-exchange reactions were also monitored during Al2O3 thermal ALE. The TMA reaction resulted in an average negative stress-thickness change of −0.50 ± 0.07 N/m that was consistent with a compressive surface stress. This negative stress-thickness change was attributed to repulsive interactions between surface methyl groups. The subsequent HF reaction then produced a positive stress-thickness change by releasing the compressive stress from the TMA reaction. The fluorination of the initial Al2O3 ALD film by HF led to a negative stress-thickness change that was consistent with a gain in compressive stress. The amount of this negative stress-thickness change depended on the thickness of the initial Al2O3 ALD film. The average negative stress-thickness change of −0.52 ± 0.08 N/m after >8 Al2O3 ALD cycles suggested that the fluorination depth during HF exposure to Al2O3 was approximately 9–10 Å. [ABSTRACT FROM AUTHOR]
Copyright of Journal of Vacuum Science & Technology: Part A-Vacuums, Surfaces & Films is the property of American Institute of Physics and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
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DbLabel: Engineering Source
An: 194305131
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  Data: Film and surface stress during Al<subscript>2</subscript>O<subscript>3</subscript> thermal atomic layer etching using in situ wafer curvature measurements.
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  Data: <searchLink fieldCode="AR" term="%22Vanfleet%2C+Ryan+B%2E%22">Vanfleet, Ryan B.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Bright%2C+Victor+M%2E%22">Bright, Victor M.</searchLink><relatesTo>2</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22George%2C+Steven+M%2E%22">George, Steven M.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> Steven.George@Colorado.edu</i>
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  Data: <searchLink fieldCode="JN" term="%22Journal+of+Vacuum+Science+%26+Technology%3A+Part+A-Vacuums%2C+Surfaces+%26+Films%22">Journal of Vacuum Science & Technology: Part A-Vacuums, Surfaces & Films</searchLink>. May2026, Vol. 44 Issue 3, p1-9. 9p.
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  Data: <searchLink fieldCode="DE" term="%22Aluminum+oxide%22">Aluminum oxide</searchLink><br /><searchLink fieldCode="DE" term="%22Atomic+layer+deposition%22">Atomic layer deposition</searchLink><br /><searchLink fieldCode="DE" term="%22Interfacial+stresses%22">Interfacial stresses</searchLink><br /><searchLink fieldCode="DE" term="%22Fluorination%22">Fluorination</searchLink><br /><searchLink fieldCode="DE" term="%22Ligand+exchange+reactions%22">Ligand exchange reactions</searchLink><br /><searchLink fieldCode="DE" term="%22Surface+forces%22">Surface forces</searchLink>
– Name: Abstract
  Label: Abstract
  Group: Ab
  Data: In situ wafer curvature measurements were employed to monitor film and surface stress during Al2O3 thermal atomic layer etching (ALE). The Al2O3 thermal ALE was performed using fluorination and ligand-exchange reactions using sequential hydrogen fluoride (HF) and trimethylaluminum [TMA, Al(CH3)3] exposures at temperatures from 250 to 300 °C. The initial Al2O3 films were grown using Al2O3 atomic layer deposition (ALD) with TMA and H2O as the reactants. These Al2O3 ALD films are known to be under tensile stress. The progressive decrease in stress-thickness versus Al2O3 thermal ALE cycles was consistent with the linear removal of the Al2O3 ALD film that contains tensile stress. The results indicated that ALE can be used as a layer removal method to determine the stress distribution in a thin film. The reduction of the stress-thickness by Al2O3 thermal ALE at 250, 275, and 300 °C was consistent with the Al2O3 etch rates at these temperatures. Surface stresses corresponding to the fluorination and ligand-exchange reactions were also monitored during Al2O3 thermal ALE. The TMA reaction resulted in an average negative stress-thickness change of −0.50 ± 0.07 N/m that was consistent with a compressive surface stress. This negative stress-thickness change was attributed to repulsive interactions between surface methyl groups. The subsequent HF reaction then produced a positive stress-thickness change by releasing the compressive stress from the TMA reaction. The fluorination of the initial Al2O3 ALD film by HF led to a negative stress-thickness change that was consistent with a gain in compressive stress. The amount of this negative stress-thickness change depended on the thickness of the initial Al2O3 ALD film. The average negative stress-thickness change of −0.52 ± 0.08 N/m after >8 Al2O3 ALD cycles suggested that the fluorination depth during HF exposure to Al2O3 was approximately 9–10 Å. [ABSTRACT FROM AUTHOR]
– Name: AbstractSuppliedCopyright
  Label:
  Group: Ab
  Data: <i>Copyright of Journal of Vacuum Science & Technology: Part A-Vacuums, Surfaces & Films is the property of American Institute of Physics and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.)
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RecordInfo BibRecord:
  BibEntity:
    Identifiers:
      – Type: doi
        Value: 10.1116/6.0005425
    Languages:
      – Code: eng
        Text: English
    PhysicalDescription:
      Pagination:
        PageCount: 9
        StartPage: 1
    Subjects:
      – SubjectFull: Aluminum oxide
        Type: general
      – SubjectFull: Atomic layer deposition
        Type: general
      – SubjectFull: Interfacial stresses
        Type: general
      – SubjectFull: Fluorination
        Type: general
      – SubjectFull: Ligand exchange reactions
        Type: general
      – SubjectFull: Surface forces
        Type: general
    Titles:
      – TitleFull: Film and surface stress during Al2O3 thermal atomic layer etching using in situ wafer curvature measurements.
        Type: main
  BibRelationships:
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      – PersonEntity:
          Name:
            NameFull: Vanfleet, Ryan B.
      – PersonEntity:
          Name:
            NameFull: Bright, Victor M.
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          Name:
            NameFull: George, Steven M.
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          Dates:
            – D: 01
              M: 05
              Text: May2026
              Type: published
              Y: 2026
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              Value: 07342101
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              Value: 44
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              Value: 3
          Titles:
            – TitleFull: Journal of Vacuum Science & Technology: Part A-Vacuums, Surfaces & Films
              Type: main
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