Orientation imaging of macro-sized polysilicon grains on wafers using spatially resolved acoustic spectroscopy

Patel, Rikesh; Li, Wenqi; Smith, Richard J.; Sharples, S. D.; Clark, Matt

doi:10.1016/j.scriptamat.2017.07.003

Cited by 14 publications

(6 citation statements)

References 19 publications

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“…Practically, the process of directly determining the orientation (the inverse problem) is difficult to solve, so a fitting algorithm is used instead [12]. The outcome of the implemented algorithm can be used to create inverse pole figures-there have been a number of past publications comparing obtained crystallographic grain orientation information using the SRAS technique against electron backscatter diffraction (EBSD) [13][14][15][16][17]. If the interrogation area is larger than the crystallographic grain size, then the predominant velocity in the area is measured-the material texture is imaged instead [9,10].…”

Section: Spatially Resolved Acoustic Spectroscopymentioning

confidence: 99%

“…To obtain the SAW phase velocities, the mask is rotated in order to propagate the generated surface waves in different directions-the detection laser also follows with the rotating pattern. Using the described generation and detection lasers, this setup has been used to image the microstructure of titanium, nickel, steel and aluminium based alloys [13][14][15]20], as well as non-metallic materials such as polycrystalline silicon samples (once a metallic coating is applied) [16].…”

Section: Spatially Resolved Acoustic Spectroscopymentioning

confidence: 99%

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Imaging Material Texture of As-Deposited Selective Laser Melted Parts Using Spatially Resolved Acoustic Spectroscopy

et al. 2018

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Additive manufacturing (AM) is a production technology where material is accumulated to create a structure, often through added shaped layers. The major advantage of additive manufacturing is in creating unique and complex parts for use in areas where conventional manufacturing reaches its limitations. However, the current class of AM systems produce parts that contain structural defects (e.g., cracks and pores) which is not compatible with certification in high value industries. The probable complexity of an AM design increases the difficulty of using many non-destructive evaluation (NDE) techniques to inspect AM parts—however, a unique opportunity exists to interrogate a part during production using a rapid surface based technique. Spatially resolved acoustic spectroscopy (SRAS) is a laser ultrasound inspection technique used to image material microstructure of metals and alloys. SRAS generates and detects `controlled’ surface acoustic waves (SAWs) using lasers, which makes it a non-contact and non-destructive technique. The technique is also sensitive to surface and subsurface voids. Work until now has been on imaging the texture information of selective laser melted (SLM) parts once prepared (i.e., polished with R a < 0 . 1 μ m)—the challenge for performing laser ultrasonics in-process is measuring waves on the rough surfaces present on as-deposited parts. This paper presents the results of a prototype SRAS system, developed using the rough surface ultrasound detector known as speckle knife edge detector (SKED)—texture images using this setup of an as-deposited Ti64 SLM sample, with a surface roughness of S a ≈ 6 μ m, were obtained.

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Section: Spatially Resolved Acoustic Spectroscopymentioning

confidence: 99%

Section: Spatially Resolved Acoustic Spectroscopymentioning

confidence: 99%

Imaging Material Texture of As-Deposited Selective Laser Melted Parts Using Spatially Resolved Acoustic Spectroscopy

et al. 2018

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“…Seismological applications of surface waves [ 7 ] include the detection of subsurface anomalies such as tunnels [ 8 ] and mineral deposits [ 9 ] as well as investigations of the evolution of planetary crusts [ 10 , 11 ]. Current applications in materials science include the non-destructive testing of polycrystalline materials [ 12 ] such as silicon for solar cells [ 13 ]. Large engineered structures made of metals [ 14 , 15 ] and concrete [ 16 ] are also inspected for crack formation and growth using surface waves in order to prevent catastrophic failures.…”

Section: Introductionmentioning

confidence: 99%

Multiple Rayleigh waves guided by the planar surface of a continuously twisted structurally chiral material

Mackay

Lakhtakia

2020

Proc. R. Soc. A.

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The Stroh formalism was adapted for Rayleigh-wave propagation guided by the planar traction-free surface of a continuously twisted structurally chiral material (CTSCM), which is an anisotropic solid that is periodically non-homogeneous in the direction normal to the planar surface. Numerical studies reveal that this surface can support either one or two Rayleigh waves at a fixed frequency, depending on the structural period and orientation of the CTSCM. In the case of two Rayleigh waves, each wave possesses a different wavenumber. The Rayleigh wave with the larger wavenumber is more localized to the surface and has a phase speed that changes less as the angular frequency varies in comparison with the Rayleigh wave with the smaller wavenumber.

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“…In addition, it generates a separate optical map of the surface being inspected. Previously, SRAS has been used to measure the grain orientation of large-grained materials such as nickel, titanium and silicon [8][9][10] . As an NDT technique, SRAS is uniquely placed to address many of the challenges instigated by SLM.…”

Section: Introductionmentioning

confidence: 99%

Spatially Resolved Acoustic Spectroscopy Towards Online Inspection of Additive Manufacturing

Pieris¹,

Patel²,

Dryburgh³

et al. 2019

insight

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High-integrity engineering applications such as aerospace will not permit the incorporation of components containing any structural defects. The current generation of additive manufacturing (AM) platforms yield components with relatively high levels of defects. The in-line inspection of components built using AM can provide closed-loop feedback and vary build parameters during fabrication to minimise defects. This article reviews the capability of spatially resolved acoustic spectroscopy (SRAS) to be used as an inspection tool for detecting defects and characterising microstructure in parts induced by variations in build parameters. The authors first correlated changes to surface acoustic wave velocity and an increase in defects to variations in build laser power, then identified changes to the component microstructure caused by variations in build laser scan strategy. This was carried out using the detected probe light intensity and the measured surface acoustic velocity.

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Orientation imaging of macro-sized polysilicon grains on wafers using spatially resolved acoustic spectroscopy

Cited by 14 publications

References 19 publications

Imaging Material Texture of As-Deposited Selective Laser Melted Parts Using Spatially Resolved Acoustic Spectroscopy

Imaging Material Texture of As-Deposited Selective Laser Melted Parts Using Spatially Resolved Acoustic Spectroscopy

Multiple Rayleigh waves guided by the planar surface of a continuously twisted structurally chiral material

Spatially Resolved Acoustic Spectroscopy Towards Online Inspection of Additive Manufacturing

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