Elastic and fracture properties of free-standing amorphous ALD Al2O3 thin films measured with bulge test

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Researchers

Research units

  • University of Helsinki
  • Åbo Akademi University

Abstract

We have investigated elastic and fracture properties of amorphous Al2O3 thin films deposited by atomic layer deposition (ALD) with bulge test technique using a free-standing thin film membrane and extended applicability of bulge test technique. Elastic modulus was determined to be 115 GPa for a 50 nm thick film and 170 GPa for a 15 nm thick film. Residual stress was 142 MPa in the 50 nm Al2O3 film while it was 116 MPa in the 15 nm Al2O3 film. Density was 3.11 g cm(-3) for the 50 nm film and 3.28 g cm(-3) for the 15 nm film. Fracture strength at 100 hPa s(-1) pressure ramp rate was 1.72 GPa for the 50 nm film while for the 15 nm film it was 4.21 GPa, almost 2.5-fold. Fracture strength was observed to be positively strain-rate dependent. Weibull moduli of these films were very high being around 50. The effective volume of a circular film in bulge test was determined from a FEM model enabling future comparison of fracture strength data between different techniques.

Details

Original languageEnglish
Article number046411
Number of pages10
JournalMaterials Research Express
Volume5
Issue number4
Publication statusPublished - Apr 2018
MoE publication typeA1 Journal article-refereed

    Research areas

  • atomic layer deposition, bulge testing, mechanical properties, membrane, fracture strength, ATOMIC LAYER DEPOSITION, ALUMINUM-OXIDE, THERMOMECHANICAL PROPERTIES, SILICA, STRESS, STRENGTH, MODULUS, MASK

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