Microelectromechanical systems (MEMS): fabrication, design and applications

Abstract Microelectromechanical Systems (MEMS) are often used in transceiver modules, especially for telecommunication and radar applications. In this paper, we present recent progress in the development on a MEMS-on-LTCC process. We focus on the Low Temperature Co-fired Ceramic (LTCC) substrate issues and we present a successful solution for overcoming the substrate challenges through surface pre-treatment using a chemical mechanical surface polishing (CMP) process which allows us to reach the required smoothness for the fabrication of MEMS devices. We discuss various process parameters such as slurry type, rotating pad and rotation speed, and show their impact on the final surface finish. With an optimized process, the maximum roughness was decreased from more than 10μm to less than 0.5 μm over a 640 × 640 μm2 LTCC sample. Also, we present the various MEMS process steps starting with the deposition and patterning of various layers to a prototype switch highlighting the validated steps and the challenges encountered. A brief discussion of the perspectives for the integration of MEMS and LTCC technologies is also presented.

Download Full-text

Mechanical Properties of Ultrananocrystalline Diamond Thin Films for MEMS Applications

MRS Proceedings ◽

10.1557/proc-741-j9.2 ◽

2002 ◽

Vol 741 ◽

Cited By ~ 5

Author(s):

H.D. Espinosa ◽

B. Peng ◽

K.-H. Kim ◽

B.C. Prorok ◽

N. Moldovan ◽

...

Keyword(s):

Thin Films ◽

Mechanical Properties ◽

Elastic Moduli ◽

Microelectromechanical Systems ◽

Nanosized Particles ◽

Good Reproducibility ◽

Fracture Properties ◽

Ultrananocrystalline Diamond ◽

Mems Fabrication ◽

Membrane Deflection

ABSTRACTMicrocantilever deflection and the membrane deflection experiment (MDE) were used to examine the elastic and fracture properties of ultrananocrystalline diamond (UNCD) thin films in relation to their application to microelectromechanical systems (MEMS). Freestanding microcantilevers and membranes were fabricated using standard MEMS fabrication techniques adapted to our UNCD film technology. Elastic moduli measured by both methods described above are in agreement, with the values being in the range 930 and 970 GPa with both techniques showing good reproducibility. The MDE test showed fracture strength to vary from 3.95 to 5.03 GPa when seeding was performed with ultrasonic agitation of nanosized particles.

Download Full-text

Additive manufacturing as an emerging technology for fabrication of microelectromechanical systems (MEMS)

Journal of Micromanufacturing ◽

10.1177/2516598419843688 ◽

2019 ◽

Vol 2 (2) ◽

pp. 175-197 ◽

Cited By ~ 6

Author(s):

Sanjay Kumar ◽

Pulak Bhushan ◽

Mohit Pandey ◽

Shantanu Bhattacharya

Keyword(s):

Additive Manufacturing ◽

3D Printing ◽

Microelectromechanical Systems ◽

Manufacturing Sector ◽

Process Improvements ◽

Recent Success ◽

Mems Fabrication ◽

Recent Developments ◽

Potential Applications ◽

Printing Processes

The recent success of additive manufacturing processes (also called, 3D printing) in the manufacturing sector has led to a shift in the focus from simple prototyping to real production-grade technology. The enhanced capabilities of 3D printing processes to build intricate geometric shapes with high precision and resolution have led to their increased use in fabrication of microelectromechanical systems (MEMS). The 3D printing technology has offered tremendous flexibility to users for fabricating custom-built components. Over the past few decades, different types of 3D printing technologies have been developed. This article provides a comprehensive review of the recent developments and significant achievements in most widely used 3D printing technologies for MEMS fabrication, their working methodology, advantages, limitations, and potential applications. Furthermore, some of the emerging hybrid 3D printing technologies are discussed, and the current challenges associated with the 3D printing processes are addressed. Finally, future directions for process improvements in 3D printing techniques are presented.

Download Full-text

Capillary Induced Stiction and Adhesion of MEMS Materials

World Tribology Congress III, Volume 2 ◽

10.1115/wtc2005-63203 ◽

2005 ◽

Author(s):

Yan Xin Zhuang ◽

Aric K. Menon

Keyword(s):

Surface Energy ◽

Microelectromechanical Systems ◽

Film Coating ◽

Native Oxide ◽

Polar Component ◽

Silicon Compounds ◽

Force Microscopy ◽

Nano Scale ◽

Mems Fabrication ◽

Adhesive Forces

Adhesion and stiction are serious problems in microelectromechanical systems (MEMS) fabrication and application. The wettability, surface energies, and nano-scale adhesive forces of commonly used MEMS materials have been examined by contact angle meter and atomic force microscopy. Silicon and silicon compounds have higher surface energy than that of PMMA and SU-8 due to larger polar component of surface energy. The nano-scale adhesive forces of PMMA and SU-8 are 3–4 times smaller than that of as-received silicon with native oxide. It has been shown that the materials with higher surface energy have higher adhesive forces. One efficient way to avoid stiction in silicon microstructures is to deposit a thin fluorocarbon film coating.

Download Full-text

Heat Transfer Implications in the First MEMS Fabricated Thermal Transpiration-Driven Vacuum Pump for Gases

10.1115/imece2000-1440 ◽

2000 ◽

Author(s):

Stephen E. Vargo ◽

Amanda A. Green ◽

E. P. Muntz

Keyword(s):

Microelectromechanical Systems ◽

Rarefied Gas ◽

Experimental Testing ◽

Flow Analysis ◽

Vacuum Pump ◽

Transitional Flow ◽

Deep Reactive Ion Etching ◽

Thermal Transpiration ◽

Numerical Predictions ◽

Mems Fabrication

Abstract The success of NASA’s future space missions and the development of portable, commercial instrument packages will depend greatly on miniaturized components enabled by the use of microelectromechanical systems (MEMS). Both of these application markets for miniaturized instruments are governed by the use of MEMS components that satisfy stringent power, mass, volume, contamination and integration requirements. An attractive MEMS vacuum pump for instruments requiring vacuum conditions is the Knudsen Compressor, which operates based on the rarefied gas dynamics phenomenon of thermal transpiration. Thermal transpiration describes the regime where gas flows can be induced in a system by maintaining temperature differences across porous materials under rarefied conditions. This pumping mechanism provides two overwhelmingly attractive features as a miniature vacuum pump — no moving parts and no working fluids or lubricants. Due to favorable power, volume and mass estimates a Knudsen Compressor fabricated using MEMS fabrication techniques (lithography, deep reactive ion etching) and new materials (silicon, aerogel) has been completed. The experimental testing of this MEMS Knudsen Compressor device’s thermal and pumping performance are outlined in this manuscript. Good agreement between experiments and numerical predictions using a transitional flow analysis have also been obtained although simple simulations based on the aerogel’s structure are difficult to perform.

Download Full-text

Thermomechanics of High-Pressure MEMS Sensors

ASME 2007 InterPACK Conference, Volume 2 ◽

10.1115/ipack2007-33501 ◽

2007 ◽

Cited By ~ 2

Author(s):

Ryszard J. Pryputniewicz

Keyword(s):

High Pressure ◽

High Performance ◽

Microelectromechanical Systems ◽

Hybrid Approach ◽

Mems Sensors ◽

Temperature Changes ◽

Sensing Technology ◽

Piezoresistive Sensor ◽

Mems Fabrication ◽

Increasing Demand

Increasing demand for high performance, stable, and affordable sensors for applications in process control industry has led to development of a miniature pressure sensor. This development, made possible by recent advances in microelectromechanical systems (MEMS) fabrication, utilizes polysilicon-sensing technology. The unique polysilicon piezoresistive sensor (PPS) measures differential pressure (DP) based on deformations of a multilayer/multimaterial diaphragm, which is about 2 μm thick. Deformations of a diaphragm, subjected to changes in pressure, are sensed by the piezoresistive bridge elements. Determination of the loading pressures from strains of the piezoresistors is based on computations relying on a number of material specific and process dependent coefficients that, because of their nature, can vary, which may lead to uncertainties in displayed results, especially when temperature changes also. To establish an independent means for measurements of the thermomechanical (TM) deformations of the PPS diaphragms and to validate the coefficients used, a hybrid methodology, based on measurements using optoelectronic laser interferometric microscope (OELIM) and finite element method (FEM) computations coupled with uncertainty analysis provided by unique closed form formulations, was developed. This methodology allows highly accurate and precise measurements of TM deformations of diaphragms, as well as their computational modeling/simulations, and is a basis for “design by analysis” approach to efficient and effective developments of new MEMS sensors. In this paper the hybrid approach is described and its use is illustrated by representative examples addressing high-pressure MEMS sensors.

Download Full-text

3D Printed MEMS Technology—Recent Developments and Applications

Micromachines ◽

10.3390/mi11040434 ◽

2020 ◽

Vol 11 (4) ◽

pp. 434 ◽

Cited By ~ 6

Author(s):

Tomasz Blachowicz ◽

Andrea Ehrmann

Keyword(s):

3D Printing ◽

Microelectromechanical Systems ◽

Measurement Technology ◽

Mems Fabrication ◽

Recent Developments ◽

Mems Technology ◽

New Ideas ◽

3D Printed ◽

New Applications ◽

The Internet Of Things

Microelectromechanical systems (MEMS) are of high interest for recent electronic applications. Their applications range from medicine to measurement technology, from microfluidics to the Internet of Things (IoT). In many cases, MEMS elements serve as sensors or actuators, e.g., in recent mobile phones, but also in future autonomously driving cars. Most MEMS elements are based on silicon, which is not deformed plastically under a load, as opposed to metals. While highly sophisticated solutions were already found for diverse MEMS sensors, actuators, and other elements, MEMS fabrication is less standardized than pure microelectronics, which sometimes blocks new ideas. One of the possibilities to overcome this problem may be the 3D printing approach. While most 3D printing technologies do not offer sufficient resolution for MEMS production, and many of the common 3D printing materials cannot be used for this application, there are still niches in which the 3D printing of MEMS enables producing new structures and thus creating elements for new applications, or the faster and less expensive production of common systems. Here, we give an overview of the most recent developments and applications in 3D printing of MEMS.

Download Full-text

MEMS Actuators for Optical Microendoscopy

Micromachines ◽

10.3390/mi10020085 ◽

2019 ◽

Vol 10 (2) ◽

pp. 85 ◽

Cited By ~ 5

Author(s):

Zhen Qiu ◽

Wibool Piyawattanametha

Keyword(s):

High Performance ◽

Microelectromechanical Systems ◽

Fabrication Technology ◽

Optical Components ◽

Research Institutes ◽

Mems Fabrication ◽

Batch Fabrication ◽

Mems Actuators ◽

Mems Technology ◽

Manufacturing Methods

Growing demands for affordable, portable, and reliable optical microendoscopic imaging devices are attracting research institutes and industries to find new manufacturing methods. However, the integration of microscopic components into these subsystems is one of today’s challenges in manufacturing and packaging. Together with this kind of miniaturization more and more functional parts have to be accommodated in ever smaller spaces. Therefore, solving this challenge with the use of microelectromechanical systems (MEMS) fabrication technology has opened the promising opportunities in enabling a wide variety of novel optical microendoscopy to be miniaturized. MEMS fabrication technology enables abilities to apply batch fabrication methods with high-precision and to include a wide variety of optical functionalities to the optical components. As a result, MEMS technology has enabled greater accessibility to advance optical microendoscopy technology to provide high-resolution and high-performance imaging matching with traditional table-top microscopy. In this review the latest advancements of MEMS actuators for optical microendoscopy will be discussed in detail.

Download Full-text

Ultrafast Self-Assembly of Microscale Particles by Open-Channel Flow

MRS Proceedings ◽

10.1557/proc-1196-c02-05 ◽

2009 ◽

Vol 1196 ◽

Author(s):

Sun Choi ◽

Albert P. Pisano ◽

Tarek I. Zohdi

Keyword(s):

Self Assembly ◽

Open Channel ◽

Microelectromechanical Systems ◽

Complementary Metal Oxide Semiconductor ◽

Metal Oxide Semiconductor ◽

Oxide Semiconductor ◽

Particle Assembly ◽

Mems Fabrication ◽

Easy Integration ◽

Particle Assemblies

AbstractWe developed an ultrafast microfluidic approach to self-assemble microparticles in threedimensions by taking advantage of simple photolithography and capillary action of microparticle-dispersed suspensions. The experimental verifications of the assembly of various sizes of silica microspheres and silica gel microspheres within thin and long open microchannels by using this approach have been demonstrated. We anticipate that the presented technique will be widely used in semiconductor and Bio-MEMS (microelectromechanical Systems) fields because it offers a fast way to control 3D, microscale particle assemblies and also has superb compatibility with photolithography, which can lead to an easy integration of particle assembly with existing CMOS (complementary metal-oxide-semiconductor) and MEMS fabrication processes.

Download Full-text

Four-Probe Bridges for In-Line Determination of Thickness and Sidewall Etch Angle of Surface Micromachined Thin Films

Applied Sciences ◽

10.3390/app8122424 ◽

2018 ◽

Vol 8 (12) ◽

pp. 2424 ◽

Cited By ~ 1

Author(s):

Haiyun Liu ◽

Zhen Zhang ◽

Jiaqi Chen

Keyword(s):

Thin Films ◽

Extraction Method ◽

Microelectromechanical Systems ◽

Low Cost ◽

Fast Response ◽

Thickness Measurement ◽

Test Structure ◽

Fabrication Process ◽

Geometrical Parameters ◽

Mems Fabrication

Geometrical parameters, such as the thickness and the sidewall etch angle of microelectromechanical systems (MEMS) thin films, are important information for device design and simulation, material property extraction, and quality control in a fabrication process line. This paper presents an in-line test microstructure for measuring geometrical parameters of surface micromachined thin films. The structure consists of four-probe bridges with continuous step structures and deposited at three different angles. The extraction method takes advantage of the resistances of the step structures to determine the thickness and the sidewall etch angle of the phosphosilicate glass (PSG) layer and the thickness of the polysilicon layer. The sheet resistance and the width of the test structure are required for the extraction method and can also be measured by using the test structure. Thicknesses of (2.080 ± 0.011) µm, (2.142 ± 0.012) µm, (1.614 ± 0.014) µm and (2.892 ± 0.012) µm are obtained for the Poly 1 layer, the Oxide 1 layer, the Poly 2 layer and the stacked layer of Oxide 1-Oxide 2, respectively. The sidewall etch angles for the Oxide 1 layer and the stacked layer of Oxide 1-Oxide 2 are obtained as (77.51 ± 0.61)° and (76.17 ± 0.91)°, respectively. In comparison to previously reported thickness measurement approaches, the proposed method is nondestructive, and makes use of four-point probe technique which is featured with electrical input and output configuration, simple operation, low cost, fast response, good repeatability and ease of integration. Therefore, this method is more suited to in-line monitoring the MEMS fabrication process.

Download Full-text