Performance Modification of SiC MEMS

2009 ◽  
Vol 615-617 ◽  
pp. 621-624 ◽  
Author(s):  
Florentina Niebelschütz ◽  
Klemens Brueckner ◽  
Volker Cimalla ◽  
Matthias A. Hein ◽  
Jörg Pezoldt
Keyword(s):  
Residual Stress ◽  
Resonant Frequency ◽  
Epitaxial Growth ◽  
Quality Factor ◽  
Growth Conditions ◽  
Mems Devices ◽  
Quality Factors ◽  
Resonant Frequencies ◽  
Raman Analysis

The adjustment of the properties of 3C-SiC based MEMS devices, i.e. the quality factor and resonant frequency, was achieved by changing the residual stress and the 3C-SiC material quality of the SiC-layers grown on Si(111) by manipulating the nucleation conditions and growth conditions with Ge deposition prior to the carbonization and epitaxial growth. Previous Raman analysis of the SiC-layers and measured resonant frequencies and quality factors of the processed MEMS show a dependence on the Ge amount at the interface of the Si/SiC heterostructure, which allows to adjust the MEMS properties to the requirements needed for certain applications.

Analysis of a circular microstrip antenna on isotropic or uniaxially anisotropic substrate using neurospectral approach

2013 ◽  
Vol 33 (1/2) ◽  
pp. 567-580 ◽  
Author(s):  
Sami Bedra ◽  
Siham Benkouda ◽  
Tarek Fortaki
Keyword(s):  
Resonant Frequency ◽  
Quality Factor ◽  
Microstrip Antenna ◽  
Numerical Results ◽  
Spectral Domain ◽  
Quality Factors ◽  
Resonant Frequencies ◽  
Content Type ◽  
Anisotropic Substrate ◽  
Circular Microstrip Antenna

Purpose – The paper aims to propose an artificial neural network (ANN) in conjunction with spectral domain formulation for fast and accurate determination of the resonant frequency and quality factor of circular microstrip antenna printed on isotropic or anisotropic substrate. This neurospectral approach reduces the problem complexity. Design/methodology/approach – The moment method implemented in the spectral domain provides good accuracy but its computational cost is high due to the evaluation of the slowly decaying integrals and the iterative nature of the solution process. The paper introduces the electromagnetic knowledge combined with ANN in the analysis of circular microstrip antenna on isotropic or uniaxially anisotropic substrate to reduce the complexity of the spectral approach and to minimize the CPU time necessary to obtain the numerical results. Findings – The resonant frequency results obtained from the neural model are in very good agreement with the experimental and theoretical results available in the literature. Finally, numerical results for the substrate anisotropy effect on the resonant frequency, quality factor and radiation pattern are also presented. Originality/value – The paper develops fast and accurate model based on ANN technique to calculate the resonant frequencies and quality factors of circular microstrip antennas. ANN is used to model the relationship between the parameters of the microstrip antenna and the resonant frequencies and quality factors obtained from the spectral domain approach. This relatively simple model allows designers to predict accurately the resonant frequencies and quality factors for a given design without having to develop or run the spectral method codes themselves. The main advantages of the method are: less computing time than the spectral model, results with accuracy equivalent to that of full-wave models and cost effectiveness, since the client can use a simple PC for implementation. Another advantage of the proposed ANN model is that it takes into account the uniaxial anisotropy in the substrate without increasing the network size. This is done by combining ANN with electromagnetic knowledge.

Property Modification of 3C-SiC MEMS on Ge-Modified Si(100) Substrates

2010 ◽  
Vol 645-648 ◽  
pp. 861-864 ◽  
Author(s):  
Florentina Niebelschütz ◽  
Wei Hong Zhao ◽  
Klemens Brueckner ◽  
Katja Tonisch ◽  
Matthias Linß ◽  
...  
Keyword(s):  
Residual Stress ◽  
Young’S Modulus ◽  
Microelectromechanical Systems ◽  
Young's Modulus ◽  
Growth Conditions ◽  
Quality Factors ◽  
Growth Changes ◽  
Property Modification ◽  
Good Agreement

The manipulation of nucleation and growth conditions with Ge deposition prior to the carbonization and epitaxial growth changes the residual stress and the material quality of 3C-SiC(100)-layers grown on Si(100). This enables the modification of quality factor and resonant frequency of microelectromechanical systems (MEMS) based on 3C-SiC-layers. Measured resonant frequencies and quality factors of the magnetomotively actuated MEMS exhibit a dependence on the Ge amount at the interface of the Si/SiC heterostructure. This offers a degree of freedom to adjust the MEMS properties within a certain range to the requirements necessary for specific applications. The observed dependencies of the Young’s modulus are in good agreement with the trends of residual stress and Young’s modulus, which were determined on as grown 3C-SiC(100):Ge samples by fourier transform infrared (FTIR) spectroscopy and nanoindentation.

A Microcontroller Approach to Measuring Transmissibility of MEMS Devices

2015 ◽  
Vol 2015 (DPC) ◽  
pp. 001564-001593
Author(s):  
Chong Li ◽  
Yixuan Wu ◽  
Haoyue Yang ◽  
Luke L. Jenkins ◽  
Robert N. Dean ◽  
...  
Keyword(s):  
Resonant Frequency ◽  
Quality Factor ◽  
Real Time ◽  
High Speed ◽  
Mechanical Quality Factor ◽  
Quantization Noise ◽  
Mems Devices ◽  
Input And Output ◽  
Mechanical Quality ◽  
Mems Device

The transmissibility reveals two very useful characteristics of a micro-electro-mechanical systems (MEMS) device, the resonant frequency and the mechanical quality factor. Real time knowledge on these two important factors can enhance application performance or avoid potential problems from environmental disturbances due to fabrication tolerances and the resulting operational differences in otherwise identical devices. Expensive laboratory equipment is typically used to measure the transmissibility. However, these test systems are not readily adaptable to field use. Therefore, it is important to be able to measure the transmissibility using a real time technique with a simplified test setup. This study proposes a technique that can compute the transmissibility in real time using a low cost microcontroller. This technique utilizes two laser vibrometers to detect the input and output motions of the proof mass in a MEMS device, which are fed to high speed 500 KHz analog to digital converters (ADC) in the microcontroller. A filtering step is performed to decrease noise. After the sampling and pre-filtering, a Fast Fourier Transform (FFT) is performed to convert the time-domain signals to frequency domain signals. The amplitude of the output signal at each frequency is divided by the amplitude of the corresponding input signal at each frequency to obtain the transmissibility. To overcome the difficulties resulting from measurement and quantization noise, a recursive calculating algorithm and a de-quantization filter are introduced. The recursive calculating process guarantees that the system updates the results continually, which results in a transmissibility plot covering the entire bandwidth. The de-quantization filter considers the validity of the data and performs the transmissibility division step accordingly. A cantilevered structure was chosen as the device-under-test to verify and evaluate this technique. The cantilevered device was attached to an electromechanical shaker system for vibratory stimulation. Two laser vibrometers were used to detect the input and output motion and this data was fed into a microcontroller. The microcontroller was STM32F407, which is 32-bit and 168 MHz controller. The tests demonstrated that this technique can measure the transmissibility and therefore the resonant frequency and mechanical quality factor accurately compared to a professional signal analyzer.

Deposition of epitaxial transition metal carbide films and superlattices by simultaneous direct current metal magnetron sputtering and C60 evaporation

2001 ◽  
Vol 16 (3) ◽  
pp. 633-643 ◽  
Author(s):  
H. Högberg ◽  
J. Birch ◽  
M. P. Johansson ◽  
L. Hultman ◽  
U. Jansson
Keyword(s):  
Epitaxial Growth ◽  
Deposition Process ◽  
Growth Conditions ◽  
Growth Behavior ◽  
Transition Metal Carbide ◽  
Structural Quality ◽  
Metal Carbide ◽  
General Observation ◽  
Better Than

Thin epitaxial TiC and VC films and superlattices have been deposited on MgO(001) by simultaneous sputtering of the metals and evaporation of C60. It was found that epitaxial growth conditions for TiC could be maintained down to a temperature of 100 °C, while the epitaxial growth of VC required 200 °C. Epitaxial VC films were completely relaxed at all growth temperatures, while a change from a relaxed to a strained growth behavior was observed for TiC films. The structural quality of the TiC films was better than for the VC films. A general observation was that a plasma-assisted deposition process yields films with a higher quality and allows epitaxial growth at lower temperatures than for a pure coevaporation process.

FTIR Ellipsometry Analysis of the Internal Stress in SiC/Si MEMS

2007 ◽  
Vol 556-557 ◽  
pp. 363-366 ◽  
Author(s):  
Jörg Pezoldt ◽  
Christian Förster ◽  
Volker Cimalla ◽  
Florentina Will ◽  
Ralf Stephan ◽  
...  
Keyword(s):  
Residual Stress ◽  
Internal Stress ◽  
Thin Layers ◽  
Quality Factors ◽  
Resonant Frequencies ◽  
Suitable Technique

The resonant frequencies and quality factors of MEMS and NEMS depend critically on the layer quality and the residual stress in the SiC/Si heterostructure. It is demonstrated, that FTIRellipsometry is a suitable technique for monitoring the inhomogeneous residual stress inside SiC/Si heterostructures containing thin layers and their variation with during processing.

Dual-Band Bandpass Filter Optimized for High Q-Factor

2021 ◽  
Vol 36 (4) ◽  
pp. 398-410
Author(s):  
Walid Fahmy ◽  
Asmaa Farahat ◽  
Khalid Hussein ◽  
Abd-El-Hadi Ammar
Keyword(s):  
Quality Factor ◽  
Bandpass Filter ◽  
High Quality Factor ◽  
Dual Band ◽  
Optimized Design ◽  
Hybrid Architecture ◽  
Quality Factors ◽  
High Quality ◽  
Resonant Frequencies ◽  
Simulation Results

High quality factor bandpass filters based on a number of cascaded resonators of dual-resonance mechanism are proposed in the present paper. Each resonator is constructed as two overlapped coplanar waveguide (CPW) resonant structures. The cascaded resonators mediate microwave coupling between two isolated corner-shaped CPW feeders only at the resonant frequencies leading to a bandpass filter of high quality factor. The two resonant frequencies and the separation between them can be fine-tuned by the dimensions of the structure. The effects of the dimensional parameters of the resonator and the feeding CPW regions on the resonant frequencies and the performance of the bandpass filter are investigated. The effect of the loss tangent of the dielectric substrate material on the quality factors at the two resonant frequencies is studied. Three prototypes of the proposed filter are fabricated and experimentally studied for more understanding of the underlying physical principles of operation and for verifying some of the simulation results. The experimental results show good agreement when compared with the corresponding simulation results. It is shown that, at low enough absolute temperature, the proposed structure can operate as superconducting microwave resonator when made from the appropriate materials. Also, it is shown that an optimized design of the proposed bandpass filter, based on superconducting CPWR structure, can achieve quality factors high enough to form a quantum data bus for hybrid architecture of quantum information systems.

scholarly journals Effect of Axial Force on the Performance of Micromachined Vibratory Rate Gyroscopes

Sensors ◽  
2010 ◽  
Vol 11 (1) ◽  
pp. 296-309 ◽  
Author(s):  
Zhanqiang Hou ◽  
Dingbang Xiao ◽  
Xuezhong Wu ◽  
Peitao Dong ◽  
Zhihua Chen ◽  
...  
Keyword(s):  
Resonant Frequency ◽  
Axial Force ◽  
Great Influence ◽  
Quality Factors ◽  
Resonant Frequencies ◽  
Vibratory Gyroscopes ◽  
Thermal Expansion Coefficients ◽  
Micromachined Gyroscope ◽  
Experimental Values ◽  
Increasing Temperature

It is reported in the published literature that the resonant frequency of a silicon micromachined gyroscope decreases linearly with increasing temperature. However, when the axial force is considerable, the resonant frequency might increase as the temperature increases. The axial force is mainly induced by thermal stress due to the mismatch between the thermal expansion coefficients of the structure and substrate. In this paper, two types of micromachined suspended vibratory gyroscopes with slanted beams were proposed to evaluate the effect of the axial force. One type was suspended with a clamped-free (C-F) beam and the other one was suspended with a clamped-clamped (C-C) beam. Their drive modes are the bending of the slanted beam, and their sense modes are the torsion of the slanted beam. The relationships between the resonant frequencies of the two types were developed. The prototypes were packaged by vacuum under 0.1 mbar and an analytical solution for the axial force effect on the resonant frequency was obtained. The temperature dependent performances of the operated mode responses of the micromachined gyroscopes were measured. The experimental values of the temperature coefficients of resonant frequencies (TCF) due to axial force were 101.5 ppm/°C for the drive mode and 21.6 ppm/°C for the sense mode. The axial force has a great influence on the modal frequency of the micromachined gyroscopes suspended with a C-C beam, especially for the flexure mode. The quality factors of the operated modes decreased with increasing temperature, and changed drastically when the micromachined gyroscopes worked at higher temperatures.

Control of Stress with Growth Conditions and Mechanical Parameters Determination of 3C-SiC Heteroepitaxial Thin Films

2000 ◽  
Vol 657 ◽  
Author(s):  
C. Gourbeyre ◽  
T. Chassagne ◽  
M. Le Berre ◽  
G. Ferro ◽  
C. Malhaire ◽  
...  
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Residual Stress ◽  
Epitaxial Growth ◽  
Buffer Layer ◽  
Growth Conditions ◽  
Mean Value ◽  
Nano Indentation ◽  
Deposited Films

ABSTRACTWe report here on the influence of the epitaxial growth conditions on the residual stress of heteroepitaxial 3C-SiC grown on silicon using atmospheric-pressure chemical vapour deposition (APCVD) and on the determination of its mechanical properties. 3C-SiC films were grown on (100) Si substrates in a vertical reactor by APCVD. SiH4 and C3H8 are used as precursor gases and H2 as carrier gas. The growth procedure involves the formation of a carburization buffer layer at 1150°C under a mixture of H 2 and C3H8. The epitaxial growth occurs then at 1350°C by adding SiH 4.For as-deposited films the measurement techniques implemented are substrate curvature measurements, AFM, and nano-indentation. For micromachined self-suspended SiC membranes, load deflection measurements were used. The substrate curvature measurement leads to the determination of the residual stress in the deposited SiC film. We show that we can achieve 3C-SiC layers with a compressive or a tensile state having equivalent crystallinity. Whereas thermal mismatch just accounts for tensile stresses, we demonstrate that 3C-SiC thin films may have compressive stresses by using specific conditions for the formation of the buffer layer. The early stage of growth is indeed of major importance.Regarding the mechanical properties, the 3C-SiC Young's modulus was determined using nano-indentation. Its mean value reaches 378 GPa comparable to the calculated value of 307 GPa. As test structures, we have processed self-suspended SiC membranes. Load deflection measurements enable the determination of the Young's modulus and the residual stress of the self-suspended films. For self-suspended SiC membranes, the absolute value of the residual stress in the SiC thin films decreases compared to the as-deposited films and takes a mean value of 170 MPa in a tensile state.

Microelectromechanical Systems Cantilever Resonators: Pressure-Dependent Gas Film Damping

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Chu Rainer Kwang-Hua
Keyword(s):  
Quality Factor ◽  
Knudsen Number ◽  
Microelectromechanical Systems ◽  
Unit Length ◽  
Mems Devices ◽  
Dynamical Friction ◽  
Quality Factors ◽  
Wafer Level ◽  
Unsteady Fluid ◽  
Parameter Per Unit Length

Abstract Under near-vacuum conditions, the fluid frictional dissipation or approximately the inverse of the quality factor of a microcantilever once the intrinsic dissipation can be neglected is proportional to the low pressure. We shall investigate the dynamic behavior of micro-electromechanical systems (MEMS) devices via the calculation of the quality factor or frictional damping forces resulting from surrounding gases. Here, we illustrated some specific examples relevant to the computation of the quality factor or dynamical friction for an oscillating microcantilever in air via measurements of the paper of Okada et al. (Okada, H., Itoh, T., and Suga, T., 2008, Wafer Level Sealing Characterization Method Using Si Micro Cantilevers,” Sens. Actuators A, 147(2), pp. 359–364) considering the quality factors of the CM (a label for a microcantilever: 500 × 90 × 5 μm3 Si microcantilever (the measured resonance frequency: 23.7 kHz) and the paper of Kara et al. (Kara, V., Yakhot, V., and Ekinci, K. L., 2017, Generalized Knudsen Number for Unsteady Fluid Flow, Phys. Rev. Lett., 118(7), p. 074505) in rarefied gases regime. We present the corrected quality factor or dynamical friction over the whole range of the Knudsen number considering the CM part by Okada et al. Our new plot considering the quality factor which is proportional to the inverse of the dissipative friction parameter per unit length, pressure as well as the Knudsen number over the whole range should be useful to researchers in this field.

scholarly journals Simple Non-Destructive Method of Ultrathin Film Material Properties and Generated Internal Stress Determination Using Microcantilevers Immersed in Air

Coatings ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 486 ◽  
Author(s):  
Ivo Stachiv ◽  
Lifeng Gan
Keyword(s):  
Internal Stress ◽  
Quality Factor ◽  
Ultrathin Films ◽  
Material Properties ◽  
Ultrathin Film ◽  
Film Deposition ◽  
Film Material ◽  
Quality Factors ◽  
Resonant Frequencies ◽  
Film Density

Recent progress in nanotechnology has enabled to design the advanced functional micro-/nanostructures utilizing the unique properties of ultrathin films. To ensure these structures can reach the expected functionality, it is necessary to know the density, generated internal stress and the material properties of prepared films. Since these films have thicknesses of several tens of nm, their material properties, including density, significantly deviate from the known bulk values. As such, determination of ultrathin film material properties requires usage of highly sophisticated devices that are often expensive, difficult to operate, and time consuming. Here, we demonstrate the extraordinary capability of a microcantilever commonly used in a conventional atomic force microscope to simultaneously measure multiple material properties and internal stress of ultrathin films. This procedure is based on detecting changes in the static deflection, flexural and torsional resonant frequencies, and the corresponding quality factors of the microcantilever vibrating in air before and after film deposition. In contrast to a microcantilever in vacuum, where the quality factor depends on the combination of multiple different mechanical energy losses, in air the quality factor is dominated just by known air damping, which can be precisely controlled by changing the air pressure. Easily accessible expressions required to calculate the ultrathin film density, the Poisson’s ratio, and the Young’s and shear moduli from measured changes in the microcantilever resonant frequencies, and quality factors are derived. We also show that the impact of uncertainties on determined material properties is only minor. The validity and potential of the present procedure in material testing is demonstrated by (i) extracting the Young’s modulus of atomic-layer-deposited TiO2 films coated on a SU-8 microcantilever from observed changes in frequency response and without requirement of knowing the film density, and (ii) comparing the shear modulus and density of Si3N4 films coated on the silicon microcantilever obtained numerically and by present method.

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