scholarly journals High frequency guided wave defect imaging in monocrystalline silicon wafers

2019 ◽  
Author(s):  
Mathieu Simon ◽  
Bernard Masserey ◽  
Jean-Luc Robyr ◽  
Paul Fromme
Keyword(s):  
High Frequency ◽  
Guided Wave ◽  
Silicon Wafers ◽  
Monocrystalline Silicon ◽  
Defect Imaging

scholarly journals High frequency guided wave propagation in monocrystalline silicon wafers

2017 ◽  
Author(s):  
Marco Pizzolato ◽  
Bernard Masserey ◽  
Jean-Luc Robyr ◽  
Paul Fromme
Keyword(s):  
Wave Propagation ◽  
High Frequency ◽  
Guided Wave ◽  
Silicon Wafers ◽  
Monocrystalline Silicon ◽  
Guided Wave Propagation

High Frequency Guided Wave Propagation and Scattering in Silicon Wafers

2021 ◽  
pp. 1-18
Author(s):  
Jean-Luc Robyr ◽  
Mathieu Simon ◽  
Bernard Masserey ◽  
Paul Fromme
Keyword(s):  
Wave Propagation ◽  
Wave Field ◽  
High Frequency ◽  
Surface Defects ◽  
Wave Mode ◽  
Guided Wave ◽  
Silicon Wafers ◽  
Monocrystalline Silicon ◽  
Custom Made

Abstract Thin monocrystalline silicon wafers are employed for the manufacture of solar cells with high conversion efficiency. Micro-cracks can be induced by the wafer cutting process, leading to breakage of the fragile wafers. High frequency guided waves allow for the monitoring of wafers and detection and characterization of surface defects. The material anisotropy of the monocrystalline silicon leads to variations of the guided wave characteristics, depending on the guided wave mode and propagation direction relative to the crystal orientation. Selective excitation of the first anti-symmetric A0 wave mode at 5 MHz center frequency was achieved experimentally using a custom-made wedge transducer. Strong wave pulses with limited beam skewing and widening were measured using non-contact laser interferometer measurements. This allowed the accurate characterization of the Lamb wave propagation and scattering at small artificial surface defects with a size of less than 100 µm. The surface extent of the defects of varying size was characterized using an optical microscope. The scattered guided wave field was evaluated, and characteristic parameters extracted and correlated to the defect size, allowing in principle detection of small defects. Further investigations are required to explain the systematic asymmetry of the guided wave field in the vicinity of the indents.

scholarly journals Defect detection in monocrystalline silicon wafers using high frequency guided waves

2019 ◽  
Author(s):  
Bernard Masserey ◽  
Mathieu Simon ◽  
Jean-Luc Robyr ◽  
Paul Fromme
Keyword(s):  
Defect Detection ◽  
High Frequency ◽  
Guided Waves ◽  
Silicon Wafers ◽  
Monocrystalline Silicon

Experimental investigation into polishing of monocrystalline silicon wafer using double-disc chemical assisted magnetorheological finishing process

2021 ◽  
pp. 095440622098384
Author(s):  
Mayank Srivastava ◽  
Pulak M Pandey
Keyword(s):  
Surface Roughness ◽  
Silicon Wafer ◽  
Flow Rate ◽  
Silicon Wafers ◽  
Monocrystalline Silicon ◽  
Slurry Flow ◽  
Magnetorheological Finishing ◽  
Finishing Process ◽  
Process Factors ◽  
Slurry Flow Rate

In the present work, a novel hybrid finishing process that combines the two preferred methods in industries, namely, chemical-mechanical polishing (CMP) and magneto-rheological finishing (MRF), has been used to polish monocrystalline silicon wafers. The experiments were carried out on an indigenously developed double-disc chemical assisted magnetorheological finishing (DDCAMRF) experimental setup. The central composite design (CCD) was used to plan the experiments in order to estimate the effect of various process factors, namely polishing speed, slurry flow rate, percentage CIP concentration, and working gap on the surface roughness ([Formula: see text]) by DDCAMRF process. The analysis of variance was carried out to determine and analyze the contribution of significant factors affecting the surface roughness of polished silicon wafer. The statistical investigation revealed that percentage CIP concentration with a contribution of 30.6% has the maximum influence on the process performance followed by working gap (21.4%), slurry flow rate (14.4%), and polishing speed (1.65%). The surface roughness of polished silicon wafers was measured by the 3 D optical profilometer. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were carried out to understand the surface morphology of polished silicon wafer. It was found that the surface roughness of silicon wafer improved with the increase in polishing speed and slurry flow rate, whereas it was deteriorated with the increase in percentage CIP concentration and working gap.

Laser-Generated Ultrasonic Technique for Inspecting Delamination in CFRP

2006 ◽  
Vol 321-323 ◽  
pp. 968-971
Author(s):  
Won Su Park ◽  
Sang Woo Choi ◽  
Joon Hyun Lee ◽  
Kyeong Cheol Seo ◽  
Joon Hyung Byun
Keyword(s):  
High Frequency ◽  
Ultrasonic Method ◽  
Piezoelectric Sensor ◽  
Frequency Component ◽  
Guided Wave ◽  
Center Frequency ◽  
High Frequency Component ◽  
Ultrasonic Technique ◽  
Non Destructive Evaluation ◽  
Non Destructive

For improving quality of a carbon fiber reinforced composite material (CFRP) by preventing defects such as delamination and void, it should be inspected in fabrication process. Novel non-contacting evaluation technique is required because the transducer should be contacted on the CFRP in conventional ultrasonic technique during the non-destructive evaluation and these conventional contact techniques can not be applied in a novel fiber placement system. For the non-destructive evaluation of delamination in CFRP, various methods for the generation and reception of laser-generated ultrasound are applied using piezoelectric transducer, air-coupled transducer, wavelet transform technique etc. The high frequency component of laser-generated guided wave received with piezoelectric sensor disappeared after propagating through delamination region. Air-coupled transducer was tried to be adopted in reception of laser-generated guided wave generated by using linear slit array in order to generate high frequency guided wave with a frequency of 1.1 MHz. Nevertheless, it was failed to receive high frequency guided wave in using air-coupled transducer and linear slit array. Transmitted laser-generated ultrasonic wave was received on back-wall and its frequency was analyzed to establish inspecting technique to detect delamination by non-contact ultrasonic method. In a frequency spectrum analysis, intensity ratio of low frequency and center frequency was approvable parameter to detect delamination.

A high-frequency GaAs optical guided-wave electrooptic interferometric modulator

1985 ◽  
Vol 21 (1) ◽  
pp. 18-21 ◽  
Author(s):  
J. Donnelly ◽  
N. DeMeo ◽  
G. Ferrante ◽  
K. Nichols
Keyword(s):  
High Frequency ◽  
Guided Wave

scholarly journals High Frequency Ultrasonic Wave Propagation in  Anisotropic Materials

2021 ◽  
Author(s):  
◽  
Andrew Paul Dawson
Keyword(s):  
Wave Propagation ◽  
Ultrasonic Wave ◽  
High Frequency ◽  
Guided Wave ◽  
Ultrasonic Waves ◽  
Tissue Characterisation ◽  
Ultrasonic Wave Propagation ◽  
Matching Layer ◽  
Fibrous Tissues ◽  
Wave Modes

<p>The influence of highly regular, anisotropic, microstructured materials on high frequency ultrasonic wave propagation was investigated in this work. Microstructure, often only treated as a source of scattering, significantly influences high frequency ultrasonic waves, resulting in unexpected guided wave modes. Tissues, such as skin or muscle, are treated as homogeneous by current medical ultrasound systems, but actually consist of highly anisotropic micron-sized fibres. As these systems increase towards 100 MHz, these fibres will significantly influence propagating waves leading to guided wave modes. The effect of these modes on image quality must be considered. However, before studies can be undertaken on fibrous tissues, wave propagation in more ideal structures must be first understood. After the construction of a suitable high frequency ultrasound experimental system, finite element modelling and experimental characterisation of high frequency (20-200 MHz) ultrasonic waves in ideal, collinear, nanostructured alumina was carried out. These results revealed interesting waveguiding phenomena, and also identified the potential and significant advantages of using a microstructured material as an alternative acoustic matching layer in ultrasonic transducer design. Tailorable acoustic impedances were achieved from 4-17 MRayl, covering the impedance range of 7-12 MRayl most commonly required by transducer matching layers. Attenuation coefficients as low as 3.5 dBmm-1 were measured at 100 MHz, which is excellent when compared with 500 dBmm-1 that was measured for a state of the art loaded epoxy matching layer at the same frequency. Reception of ultrasound without the restriction of critical angles was also achieved, and no dispersion was observed in these structures (unlike current matching layers) until at least 200 MHz. In addition, to make a significant step forward towards high frequency tissue characterisation, novel microstructured poly(vinyl alcohol) tissue-mimicking phantoms were also developed. These phantoms possessed acoustic and microstructural properties representative of fibrous tissues, much more realistic than currently used homogeneous phantoms. The attenuation coefficient measured along the direction of PVA alignment in an example phantom was 8 dBmm-1 at 30 MHz, in excellent agreement with healthy human myocardium. This method will allow the fabrication of more realistic and repeatable phantoms for future high frequency tissue characterisation studies.</p>

Damage-free polishing of monocrystalline silicon wafers without chemical additives

2008 ◽  
Vol 59 (11) ◽  
pp. 1178-1181 ◽  
Author(s):  
A.Q. Biddut ◽  
L.C. Zhang ◽  
Y.M. Ali ◽  
Z. Liu
Keyword(s):  
Silicon Wafers ◽  
Monocrystalline Silicon ◽  
Chemical Additives
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