Special Issue "Silicon Micromachined Devices: Outlook and Challenges for Future Applications"

A special issue of Micromachines (ISSN 2072-666X).

Deadline for manuscript submissions: closed (30 November 2017) | Viewed by 15145

Special Issue Editors

Dr. Marco De Fazio
E-Mail Website
Guest Editor
STMicroelectronics, 30 Corporate dr STE 300, 01803 Burlington, USA
Interests: MEMS; SiPho; sensors; microfluidics; material science; III/V semiconductors; biosensors
Prof. Dr. Sabina Merlo
E-Mail Website
Guest Editor
Department of Electrical, Computer and Biomedical Engineering, University of the Studies of Pavia, 27100 Pavia, Italy
Interests: MEMS; MOEMS; optical sensors; interferometry; microphotonics; biophotonics; biosensors; lab on a chip
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Special Issue Information

Dear Colleagues,

We are very pleased to introduce this Special Issue on “Silicon Micromachined Devices: Outlook and Challenges for Future Applications.”

Silicon micromachined devices have immensely changed the way we are communicating, working and enjoying everyday life. Silicon micromachined accelerometers, gyroscopes, magnetometers, pressure sensors and microphones, just to name a few, are in everyone’s pocket and we use them every day. Micro actuators such as picoprojectors, micro-motors and print-heads for 3D printing are also emerging to further augment our everyday experience and expand developers’ possibilities in designing new IoT systems, such as virtual and augmented reality goggles, portable projectors and self-driving cars. Microfluidic devices will enable fully integrated Lab-on-Chip for point-of-care diagnostics and also smart thermal management of IT systems.

The key ingredients for this amazing success is the material, silicon, with its mechanical properties and features, together with the fabrication techniques originally developed for mass production of microelectronic integrated circuits.

However, what are the outlook and challenges for future developments and applications of silicon micromachined devices? In this Special Issue, we are inviting emerging and pioneer investigators to contribute research papers, short communications, and review articles that focus on novel methodological, technological and engineering developments in the area of silicon micromachined devices. The main idea is to stimulate contributions from both the academic and the industrial communities working in this exciting field, with the ambitious aim to provide a unique collection of insightful papers. We are looking forward to see academia and industry become ever more connected in order to further exploit silicon micromachined devices for improving our way of life and sustaining economic growth all over the world.

Contributions are solicited on the developments of new silicon micromachined devices and systems, such as sensors and actuators, silicon micromachined photonic devices, innovative design and new applications of silicon micromachined devices, as well as innovative techniques for characterization of silicon micromachined devices.

Prof. Sabina Merlo
Dr. Marco De Fazio
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Micromachines is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Silicon micromachined devices
  • Si-based MEMS
  • Si-based MOEMS
  • Si-based sensors
  • Si-based actuators
  • Silicon micromachined photonic devices
  • Innovative design of silicon micromachined devices
  • Innovative techniques for characterization of silicon micromachined devices
  • Applications of silicon micromachined devices

Published Papers (7 papers)

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Research

Article
Surface Modification of Electroosmotic Silicon Microchannel Using Thermal Dry Oxidation
Micromachines 2018, 9(5), 222; https://doi.org/10.3390/mi9050222 - 07 May 2018
Cited by 4 | Viewed by 1895
Abstract
A simple fabrication method for the surface modification of an electroosmotic silicon microchannel using thermal dry oxidation is presented. The surface modification is done by coating the silicon surface with a silicon dioxide (SiO2) layer using a thermal oxidation process. The [...] Read more.
A simple fabrication method for the surface modification of an electroosmotic silicon microchannel using thermal dry oxidation is presented. The surface modification is done by coating the silicon surface with a silicon dioxide (SiO2) layer using a thermal oxidation process. The process aims not only to improve the surface quality of the channel to be suitable for electroosmotic fluid transport but also to reduce the channel width using a simple technique. Initially, the parallel microchannel array with dimensions of 0.5 mm length and a width ranging from 1.8 µm to 2 µm are created using plasma etching on the 2 cm × 2 cm silicon substrate <100>. The oxidation of the silicon channel in a thermal chamber is then conducted to create the SiO2 layer. The layer properties and the quality of the surface are analyzed using scanning electron microscopy (SEM) and a surface profiler, respectively. The results show that the maximum oxidation growth rate occurs in the first 4 h of oxidation time and the rate decreases over time as the oxide layer becomes thicker. It is also found that the surface roughness is reduced with the increase of the process temperature and the oxide thickness. The scallop effect on the vertical wall due to the plasma etching process also improved with the presence of the oxide layer. After oxidation, the channel width is reduced by ~40%. The demonstrated method is suggested for the fabrication of a uniform channel cross section with high aspect ratio in sub-micro and nanometer scale that will be useful for the electroosmotic (EO) ion manipulation of the biomedical fluid sample. Full article
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Article
Statistical Investigation of the Mechanical and Geometrical Properties of Polysilicon Films through On-Chip Tests
Micromachines 2018, 9(2), 53; https://doi.org/10.3390/mi9020053 - 30 Jan 2018
Cited by 7 | Viewed by 1439
Abstract
In this work, we provide a numerical/experimental investigation of the micromechanics-induced scattered response of a polysilicon on-chip MEMS testing device, whose moving structure is constituted by a slender cantilever supporting a massive perforated plate. The geometry of the cantilever was specifically designed to [...] Read more.
In this work, we provide a numerical/experimental investigation of the micromechanics-induced scattered response of a polysilicon on-chip MEMS testing device, whose moving structure is constituted by a slender cantilever supporting a massive perforated plate. The geometry of the cantilever was specifically designed to emphasize the micromechanical effects, in compliance with the process constraints. To assess the effects of the variability of polysilicon morphology and of geometrical imperfections on the experimentally observed nonlinear sensor response, we adopt statistical Monte Carlo analyses resting on a coupled electromechanical finite element model of the device. For each analysis, the polysilicon morphology was digitally built through a Voronoi tessellation of the moving structure, whose geometry was in turn varied by sampling out of a uniform probability density function the value of the over-etch, considered as the main source of geometrical imperfections. The comparison between the statistics of numerical and experimental results is adopted to assess the relative significance of the uncertainties linked to variations in the micro-fabrication process, and the mechanical film properties due to the polysilicon morphology. Full article
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Article
Investigation on the Quality Factor Limit of the (111) Silicon Based Disk Resonator
Micromachines 2018, 9(1), 25; https://doi.org/10.3390/mi9010025 - 22 Jan 2018
Cited by 10 | Viewed by 2309
Abstract
Quality factor is one of the most important parameters for a MEMS resonator. Most MEMS resonators are dominated by thermoelastic dissipation (TED). This paper demonstrates that the TED in a disk resonator that is made of (111) single-crystal silicon is surpassed by clamping [...] Read more.
Quality factor is one of the most important parameters for a MEMS resonator. Most MEMS resonators are dominated by thermoelastic dissipation (TED). This paper demonstrates that the TED in a disk resonator that is made of (111) single-crystal silicon is surpassed by clamping loss. The stiffness-mass decoupling design method, combined with reducing the beam width, was used to engineer high QTED. Experiments show that Q of the (111) disk resonator have an upper boundary that is determined by the clamping loss caused by the unbalanced out-of-plane displacement. The origin of the out-of-plane displacement is explained by theory and simulation. Full article
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Article
Research of a Novel Ultra-High Pressure Sensor with High-Temperature Resistance
Micromachines 2018, 9(1), 5; https://doi.org/10.3390/mi9010005 - 25 Dec 2017
Cited by 6 | Viewed by 2805
Abstract
Ultra-high pressure measurement has significant applications in various fields such as high pressure synthesis of new materials and ultra-high pressure vessel monitoring. This paper proposes a novel ultra-high pressure sensor combining a truncated-cone structure and a silicon-on-insulator (SOI) piezoresistive element for measuring the [...] Read more.
Ultra-high pressure measurement has significant applications in various fields such as high pressure synthesis of new materials and ultra-high pressure vessel monitoring. This paper proposes a novel ultra-high pressure sensor combining a truncated-cone structure and a silicon-on-insulator (SOI) piezoresistive element for measuring the pressure up to 1.6 GPa. The truncated-cone structure attenuates the measured pressure to a level that can be detected by the SOI piezoresistive element. Four piezoresistors of the SOI piezoresistive element are placed along specific crystal orientation and configured as a Wheatstone bridge to obtain voltage signals. The sensor has an advantage of high-temperature resistance, in that the structure of the piezoresistive element can avoid the leakage current at high temperature and the truncated-cone structure separates the piezoresistive element from the heat environment. Furthermore, the upper surface diameter of the truncated-cone structure is designed to be 2 mm for the application of small scale. The results of static calibration show that the sensor exhibits a good performance in hysteresis and repeatability. The temperature experiment indicates that the sensor can work steadily at high temperature. This study would provide a better insight to the research of ultra-high pressure sensors with larger range and smaller size. Full article
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Article
A Fast Multiobjective Optimization Strategy for Single-Axis Electromagnetic MOEMS Micromirrors
Micromachines 2018, 9(1), 2; https://doi.org/10.3390/mi9010002 - 23 Dec 2017
Cited by 5 | Viewed by 1845
Abstract
Micro-opto-electro-mechanical (MOEMS) micromirrors are an enabling technology for mobile image projectors (pico-projectors). Low size and low power are the crucial pico-projector constraints. In this work, we present a fast method for the optimization of a silicon single-axis electromagnetic torsional micromirror. In this device, [...] Read more.
Micro-opto-electro-mechanical (MOEMS) micromirrors are an enabling technology for mobile image projectors (pico-projectors). Low size and low power are the crucial pico-projector constraints. In this work, we present a fast method for the optimization of a silicon single-axis electromagnetic torsional micromirror. In this device, external permanent magnets provide the required magnetic field, and the actuation torque is generated on a rectangular multi-loop coil microfabricated on the mirror plate. Multiple constraints link the required current through the coil, its area occupancy, the operating frequency, mirror suspension length, and magnets size. With only rather general assumptions about the magnetic field distribution and mechanical behavior, we show that a fully analytical description of the mirror electromagnetic and mechanical behavior is possible, so that the optimization targets (the assembly size, comprising the mirror and magnets, and the actuation current) can be expressed as closed functions of the design parameters. Standard multiobjective optimization algorithms can then be used for extremely fast evaluation of the trade-offs among the various optimization targets and exploration of the Pareto frontier. The error caused by model assumptions are estimated by Finite Element Method (FEM) simulations to be below a few percent points from the exact solution. Full article
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Article
Rotating Circular Micro-Platform with Integrated Waveguides and Latching Arm for Reconfigurable Integrated Optics
Micromachines 2017, 8(12), 354; https://doi.org/10.3390/mi8120354 - 01 Dec 2017
Cited by 10 | Viewed by 2586
Abstract
This work presents a laterally rotating micromachined platform integrated under optical waveguides to control the in-plane propagation direction of light within a die to select one of multiple outputs. The platform is designed to exhibit low constant optical losses throughout the motion range [...] Read more.
This work presents a laterally rotating micromachined platform integrated under optical waveguides to control the in-plane propagation direction of light within a die to select one of multiple outputs. The platform is designed to exhibit low constant optical losses throughout the motion range and is actuated electrostatically using an optimized circular comb drive. An angular motion of ±9.5° using 180 V is demonstrated. To minimize the optical losses between the moving and fixed parts, a gap-closing mechanism is implemented to reduce the initial air gap to submicron values. A latch structure is implemented to hold the platform in place with a resolution of 0.25° over the entire motion range. The platform was integrated with silicon nitride waveguides to create a crossbar switch and preliminary optical measurements are reported. In the bar state, the loss was measured to be 14.8 dB with the gap closed whereas in the cross state it was 12.2 dB. To the authors’ knowledge, this is the first optical switch based on a rotating microelectromechanical device with integrated silicon nitride waveguides reported to date. Full article
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Article
Uncertainty Quantification of Microstructure—Governed Properties of Polysilicon MEMS
Micromachines 2017, 8(8), 248; https://doi.org/10.3390/mi8080248 - 12 Aug 2017
Cited by 10 | Viewed by 1840
Abstract
In this paper, we investigate the stochastic effects of the microstructure of polysilicon films on the overall response of microelectromechanical systems (MEMS). A device for on-chip testing has been purposely designed so as to maximize, in compliance with the production process, its sensitivity [...] Read more.
In this paper, we investigate the stochastic effects of the microstructure of polysilicon films on the overall response of microelectromechanical systems (MEMS). A device for on-chip testing has been purposely designed so as to maximize, in compliance with the production process, its sensitivity to fluctuations of the microstructural properties; as a side effect, its sensitivity to geometrical imperfections linked to the etching process has also been enhanced. A reduced-order, coupled electromechanical model of the device is developed and an identification procedure, based on a genetic algorithm, is finally adopted to tune the parameters ruling microstructural and geometrical uncertainties. Besides an initial geometrical imperfection that can be considered specimen-dependent due to its scattering, the proposed procedure has allowed identifying an average value of the effective polysilicon Young’s modulus amounting to 140 GPa, and of the over-etch depth with respect to the target geometry layout amounting to O = 0.09 μ m. The procedure has been therefore shown to be able to assess how the studied stochastic effects are linked to the scattering of the measured input–output transfer function of the device under standard working conditions. With a continuous trend in miniaturization induced by the mass production of MEMS, this study can provide information on how to handle the foreseen growth of such scattering. Full article
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