Mechanical properties and reliability of aluminum nitride thin films

Österlund, Elmeri; Kinnunen, Jere; Rontu, Ville; Torkkeli, Altti; Paulasto‐Kröckel, Mervi

doi:10.1016/j.jallcom.2018.09.062

Cited by 41 publications

(25 citation statements)

References 63 publications

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“…Similar results that thicker AlN films exhibit a higher fracture strength were obtained in the study in Ref. 25. Figure 4(b) shows the S-N curves of AlN (1 μm)/SUS430/AlN (1 μm) and AlN (1 μm)/ SUS304/AlN (1 μm).…”

Section: Fatigue Propertiessupporting

confidence: 86%

“…However, considering the error range, the Young's moduli of the AlN films deposited on both SUS430 and SUS304 show similar variations. Compared with that of the AlN film deposited on the silicon substrate by pulsed direct current reactive sputtering, (25) the Young's moduli of the deposited AlN films in this study are lower.…”

Section: Methodscontrasting

confidence: 57%

“…This is attributed to the high fracture strength of the sputtered AlN thin films. (25) In addition, no fracture occurred in these films after suffering a maximum cyclic stress of 1.28 GPa for 10 4 cycles. (25) However, surface defects were observed on the SUS430 layer.…”

Section: Fatigue Failurementioning

confidence: 85%

“…(25) In addition, no fracture occurred in these films after suffering a maximum cyclic stress of 1.28 GPa for 10 4 cycles. (25) However, surface defects were observed on the SUS430 layer. Figures 5(d)-5(g) show the defects observed on the heterolayered foils vibrating at different stress levels.…”

Section: Fatigue Failurementioning

confidence: 85%

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Mechanical Fatigue Analysis of AlN/SUS430/AlN Heterolayered Foils in Micromachined Devices

Zheng¹,

Minh²,

Nguyen³

et al. 2020

Sensors and Materials

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The combination of piezoelectric aluminum nitride (AlN) films with flexible substrates made of stainless steel (SUS) foils has been applied in low-frequency and robust microdevices, especially in piezoelectric vibration energy harvesters (PVEHs). To find guides in the design of PVEHs, the fatigue properties of micromachined specimens fabricated using SUS430 foils and AlN/SUS430/AlN heterolayered foils were investigated in this work. In particular, the thickness dependence of AlN films on the fatigue behavior of AlN/SUS430/AlN heterolayered foils was investigated. AlN films with different thicknesses of 1 and 2 μm were deposited on 50-μm-thick SUS430 substrates. The specimens for fatigue tests were prepared as cantilevers by microfabrication processes. First, Young's moduli were measured. Fatigue tests were subsequently conducted by resonant bending. The fatigue behavior is discussed in this paper on the basis of both the stress-number of cycle (S-N) curves and the fatigue failures on the surfaces of the cantilevers. The fatigue limits of SUS430 (50 μm), AlN (1 μm)/ SUS430 (50 μm)/AlN (1 μm), and AlN (2 μm)/SUS430 (50 μm)/AlN (2 μm) were estimated to be 264, 291, and 368 MPa, respectively. The larger stiffness of the foils with a heterolayered AlN/SUS430/AlN structure indicated their larger fatigue limit than the SUS430 foil. Fatigue failure in the form of cracks was observed on the surface of SUS430 for AlN (1 μm)/SUS430/ AlN (1 μm) when vibrating at the maximum stress of 488 MPa for 2.9 × 10 7 cycles. Surface defects of intrusions and slip bands rather than cracks were observed on the SUS430 substrate for the heterolayered AlN (2 μm)/SUS430/AlN (2 μm) structure when vibrated at the maximum stress of 605 MPa for 2.9 × 10 7 cycles, resulting in its higher fatigue limit than that of AlN (1 μm)/SUS430/AlN (1 μm). No surface defects on AlN films were observed after undergoing the aforementioned long-cycle vibration.

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Section: Fatigue Propertiessupporting

confidence: 86%

Section: Methodscontrasting

confidence: 57%

Section: Fatigue Failurementioning

confidence: 85%

Section: Fatigue Failurementioning

confidence: 85%

See 2 more Smart Citations

Mechanical Fatigue Analysis of AlN/SUS430/AlN Heterolayered Foils in Micromachined Devices

Zheng¹,

Minh²,

Nguyen³

et al. 2020

Sensors and Materials

View full text Add to dashboard Cite

show abstract

“…At this level, the determination of the Young's modulus requires very different procedures to the traditional uniaxial tensile tests of bulk samples. Several techniques, including nanoindentation [3][4][5], bulge test [6][7][8], electrostatic pull-in experiments [9,10], or resonantbased methods [11,12] have been developed for this purpose. However, they often require complex experimental setups and extraction procedures that complicate the replicability of the experimental results.…”

Section: Introductionmentioning

confidence: 99%

Estimation of the Young’s Modulus of Nanometer-Thick Films Using Residual Stress-Driven Bilayer Cantilevers

et al. 2022

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Precise prediction of mechanical behavior of thin films at the nanoscale requires techniques that consider size effects and fabrication-related issues. Here, we propose a test methodology to estimate the Young’s modulus of nanometer-thick films using micromachined bilayer cantilevers. The bilayer cantilevers which comprise a well-known reference layer and a tested film deflect due to the relief of the residual stresses generated during the fabrication process. The mechanical relationship between the measured residual stresses and the corresponding deflections was used to characterize the tested film. Residual stresses and deflections were related using analytical and finite element models that consider intrinsic stress gradients and the use of adherence layers. The proposed methodology was applied to low pressure chemical vapor deposited silicon nitride tested films with thicknesses ranging from 46 nm to 288 nm. The estimated Young’s modulus values varying between 213.9 GPa and 288.3 GPa were consistent with nanoindentation and alternative residual stress-driven techniques. In addition, the dependence of the results on the thickness and the intrinsic stress gradient of the materials was confirmed. The proposed methodology is simple and can be used to characterize diverse materials deposited under different fabrication conditions.

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Hexagonal Boron Nitride for Next‐Generation Photonics and Electronics

et al. 2022

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Hexagonal boron nitride (h-BN), a member of 2D materials, has an analogous crystal structure to graphene, yet, is an insulator having an indirect bandgap of ≈6 eV. [16] h-BN has been explored as the "ideal" substrate and excellent encapsulant [17] for other 2D materials including graphene and transition metal dichalcogenides (TMDs) due to its excellent insulating property, atomically flat surface free of dangling bonds, [18] and charged impurities, and high thermal conductivity. [19,20] Encapsulating other 2D materials with h-BN effectively protects them from local electrical and chemical environment, enabling them to manifest their theoretically expected "intrinsic" properties. In addition, h-BN has been utilized as passive components in 2D vdW electronic devices, such as gate dielectrics and tunneling barriers.Recently, h-BN is attracting intensive research interests, motivated by the variety of outstanding properties, it shows across the fields of quantum optics, [21] electronics, and optoelectronics. [22] For example, despite its indirect-bandgap nature, h-BN showed deep-ultraviolet (DUV) emission with exceptionally high internal quantum efficiency (IQE) comparable to or even higher than single-crystalline direct-bandgap semiconductors. Defects in h-BN are efficient [21,23] and stable sources for single-photon emission over a wide range of wavelengths, from near-infrared (NIR) [24] to nearultraviolet (NUV), [25] at room temperature. The giant lightmatter interaction and strong band-edge absorption offered by h-BN enable the realization of solar-blind DUV photo detection by using h-BN as the active layer where DUV photons are effectively absorbed and create electrical carriers. h-BN has also been adopted as active media for low energy electronic devices, including nonvolatile resistive switching (RS) memory and radio-frequency (RF) devices, in addition to passive components for field-effect transistors (FETs), effective diffusion barriers, and low-k interlayer dielectrics (ILDs).This article aims to review the most recent discoveries of extraordinary properties of h-BN and advancements in emerging photonic and electronic applications. Although there are several well-written review articles on h-BN, [26][27][28][29] this review article focuses on the most recent theoretical discoveries, such as the stacking sequences of h-BN and related optical properties, and the elucidation on how an indirect-bandgap h-BN exhibits strong emission as efficient as a direct-bandgap Hexagonal boron nitride (h-BN), an insulating 2D layered material, has recently attracted tremendous interest motivated by the extraordinary properties it shows across the fields of optoelectronics, quantum optics, and electronics, being exotic material platforms for various applications. At an early stage of h-BN research, it is explored as an ideal substrate and insulating layers for other 2D materials due to its atomically flat surface that is free of dangling bonds and charged impurities, and its high thermal conductivity. Recent discoveries of st...

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Mechanical properties and reliability of aluminum nitride thin films

Cited by 41 publications

References 63 publications

Mechanical Fatigue Analysis of AlN/SUS430/AlN Heterolayered Foils in Micromachined Devices

Mechanical Fatigue Analysis of AlN/SUS430/AlN Heterolayered Foils in Micromachined Devices

Estimation of the Young’s Modulus of Nanometer-Thick Films Using Residual Stress-Driven Bilayer Cantilevers

Hexagonal Boron Nitride for Next‐Generation Photonics and Electronics

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