PECVD silicon-rich nitride and low stress nitride films mechanical characterization using membrane point load deflection

Bagolini, Alvise; Picciotto, A.; Crivellari, M.; Conci, P.; Bellutti, P.

doi:10.1088/0960-1317/26/2/025004

Cited by 5 publications

(3 citation statements)

References 24 publications

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“…Concerning the material properties, silicon nitride is a good candidate to replace polysilicon. Silicon nitride is already involved in CMUT fabrication [ 28 ] and its material properties (similar Poisson’s ratio and higher Young modulus: around 0.25 and 300 GPa, respectively, [ 29 ]) could improve, according to Equation (16), the amplitude of the detected signal by a factor of ≈1.4 compared to polysilicon.…”

Section: Sensor Sensitivity: Acoustic–mechanical and Mechanical–elmentioning

confidence: 99%

CMUT-Based Sensor for Acoustic Emission Application: Experimental and Theoretical Contributions to Sensitivity Optimization

Boubenia

Moal

Bourbon

et al. 2021

Sensors

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The paper deals with a capacitive micromachined ultrasonic transducer (CMUT)-based sensor dedicated to the detection of acoustic emissions from damaged structures. This work aims to explore different ways to improve the signal-to-noise ratio and the sensitivity of such sensors focusing on the design and packaging of the sensor, electrical connections, signal processing, coupling conditions, design of the elementary cells and operating conditions. In the first part, the CMUT-R100 sensor prototype is presented and electromechanically characterized. It is mainly composed of a CMUT-chip manufactured using the MUMPS process, including 40 circular 100 µm radius cells and covering a frequency band from 310 kHz to 420 kHz, and work on the packaging, electrical connections and signal processing allowed the signal-to-noise ratio to be increased from 17 dB to 37 dB. In the second part, the sensitivity of the sensor is studied by considering two contributions: the acoustic-mechanical one is dependent on the coupling conditions of the layered sensor structure and the mechanical-electrical one is dependent on the conversion of the mechanical vibration to electrical charges. The acoustic-mechanical sensitivity is experimentally and numerically addressed highlighting the care to be taken in implementation of the silicon chip in the brass housing. Insertion losses of about 50% are experimentally observed on an acoustic test between unpackaged and packaged silicon chip configurations. The mechanical-electrical sensitivity is analytically described leading to a closed-form amplitude of the detected signal under dynamic excitation. Thus, the influence of geometrical parameters, material properties and operating conditions on sensitivity enhancement is clearly established: such as smaller electrostatic air gap, and larger thickness, Young’s modulus and DC bias voltage.

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Section: Sensor Sensitivity: Acoustic–mechanical and Mechanical–elmentioning

confidence: 99%

CMUT-Based Sensor for Acoustic Emission Application: Experimental and Theoretical Contributions to Sensitivity Optimization

Boubenia

Moal

Bourbon

et al. 2021

Sensors

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“…A SEM picture showing the top view of a grating target with 1 µm wide grooves is shown in figure 1b. Further details on suspended membrane microfabrication can be found in references [8,9].…”

Section: Jinst 12 C03040mentioning

confidence: 99%

Nano and micro structured targets to modulate the spatial profile of laser driven proton beams

et al. 2017

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A: Nano and micro structured thin (µm-scale) foils were designed, fabricated and irradiated with the high intensity laser system operating at LLC (Lund Laser Centre, Sweden) in order to systematically study and improve the main proton beam parameters.Nano-spheres deposited on the front (laser irradiated) surface of a flat Mylar foil enabled a small enhancement of the maximum energy and number of the accelerated protons. Nano-spheres on the rear side allowed to modify the proton beam spatial profile. In particular, with nanospheres deposited on the rear of the target, the proton beam spatial homogeneity was clearly enhanced.Silicon nitride thin foils having micro grating structures (with different step dimensions) on the rear surface were also used as targets to influence the divergence of the proton beam and drastically change its shape through a sort of stretching effect.The target fabrication process used for the different target types is described, and representative experimental results are shown and discussed along with supporting 3D particle-in-cell simulations.

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“…The Young's moduli of silicon nitride and silicon oxide are 250 GPa and 70 GPa, respectively and the Poisson's ratio of both materials is assumed to be 0.3 [35]. The values of Young's modulus used in the modeling are typical of silicon nitride and oxide, but it is important to note that the modulus can change with stoichiometry for PECVD films [36]. A film thickness range from 0.1 to 1.3 μm is considered.…”

Section: Mechanical Modelmentioning

confidence: 99%

Design, analysis, and characterization of stress-engineered 3D microstructures comprised of PECVD silicon oxide and nitride

Turner

2016

J. Micromech. Microeng.

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Microelectromechanical systems (MEMS) are typically 2D or quasi-3D structures fabricated using surface and bulk micromachining processes. In this work, an approach for 3D structure fabrication based on stress engineering is demonstrated. Specifically, sub-mm 3D spherical cage-like structures are realized through the deformation of bilayers of residually-stressed silicon oxide and silicon nitride with micrometer-scale thicknesses. Analytical and finite models to predict the shape of stress-engineered structures based on geometry and residual stress are described and used for structure design. A systematic experimental study was performed to quantify residual stresses in silicon nitride films made by plasma-enhanced chemical vapor deposition (PECVD). The measurements show that the residual stress of PECVD silicon nitride can be tuned over a wide range of tensile stresses through the control of deposition parameters, such as flow rate and power. Stress engineered 3D cage-like structures comprised of PECVD silicon nitride and oxide films were fabricated. 3D structures with a range of curvatures were demonstrated. The measured geometry of the fabricated structures are in good agreement with predictions from analytical and finite element models.

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PECVD silicon-rich nitride and low stress nitride films mechanical characterization using membrane point load deflection

Cited by 5 publications

References 24 publications

CMUT-Based Sensor for Acoustic Emission Application: Experimental and Theoretical Contributions to Sensitivity Optimization

CMUT-Based Sensor for Acoustic Emission Application: Experimental and Theoretical Contributions to Sensitivity Optimization

Nano and micro structured targets to modulate the spatial profile of laser driven proton beams

Design, analysis, and characterization of stress-engineered 3D microstructures comprised of PECVD silicon oxide and nitride

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