Coventor's MEMS Design Blog

MEMS Energy Harvesting Modeling - Holst - IMEC - Coventor

(Go to Modeling and Simulation of Energy Harvester) 

As wireless sensor nodes become smaller, their energy supply is a limiting factor for further miniaturization as integration density is limited by the space requirements of the energy storage system. MEMS based energy harvesters, such as the one shown in this example, are becoming a key enabler for further miniaturization and deployment of energy autonomous sensor nodes.

 

Vibration harvesting taps into energy present in moving structures. Several physical effects can be employed to transform mechanical to electrical energy. Piezoelectric, electrostatic or electrodynamic effects are the most common approaches. In this example we show a piezoelectric vibrational energy harvester, similar to the devices shown in Figure 1, fabricated from silicon by a combination of wet and dry etching techniques. This device is designed to be integrated into a energy harvesting module together with a power transfer circuit, a storage element and a resistive load. 

Figure 1: Various piezoelectric energy harvesters packaged between two glass substrates. Image courtesy of Holst Centre / IMEC The Netherlands.  

 

A 2D scanning MEMS mirror from ASTRI

A contribution from Wei Ma, H. -Y. Chan, Yick Chuen Chan, Chun Cheong Wong, Francis Chee Shuen Lee from ASTRI in HongKong.

Introduction:

This micro-mechanical scanning mirror has drawn wide attention recently as its combination with diode light sources (e.g., laser diodes) provides a promising solution for mini image projectors, which can be integrated in portable electronics. The combination of a large scanning angle at a high resonant frequency but low actuation power is essential for this application.

Resonant 2D scanning mirrors, whose rotation is actuated by vertical electrostatic combs and can enable the out-of-plane rotation both in x- and y- direction by a gimbal structure [1], are very attractive in the application of mini image projectors due to their simple driving mechanism and fabrication process. An electrostatically (ES) actuated 2D scanning mirror is shown in Figure 1.

Figure 1: An electrostatically actuated 2D scanning mirror. Insert: A SEM (scanning electron microscope) picture of the 2D scanning mirror

Modeling:

Coventor's Architect software is employed to build a 3D model of the device. A simplified schematic of the model is shown in Figure 2. Mirror plate, supported by a pair of ‘Beam' components, was modeled using ‘Rigid Plate' component from the Architect parts library. The electrical driving force was applied to the mirror by the component ‘Comb Stator'. A 2D model was realized by adding another set of ‘Rigid Plate', ‘Beam' and ‘Comb Stator', which represent the gimbal structure. 

Figure 2: Schematic of a 2D scanning mirror. 

Simulation:
As it is known that the motion of the mirror is highly nonlinear, Architect is used to simulate the transient frequency response instead of solving complicated ordinary differentiate equation. The mirror response due to a down sweeping frequency of an excitation source is shown in Figure 3.

Figure 3: Transient response of one-axis of the 2D scanning mirror. A frequency down sweep is applied. 

Indeed, the response of the mirror to the down and up sweeping frequency is different and there exists hysteresis. This could be predicted by Architect and the results, as shown in Figure 4, are compared with the experimental one measured from a fabricated 2D mirror. It is shown that the Architect model is a fantastic tool for device simulation and further design optimization. An animation of the transient response of a 2D scanning mirror is shown in Figure 5. 

Figure 4: Comparisons of Architect's results with the experimental one. 

 

Figure 5. An animation of the transient response. 

[1] Wei Ma, H. -Y. Chan, Yick Chuen Chan, Chun Cheong Wong, Francis Chee Shuen Lee, "Design optimization of MEMS 2D scanning mirrors with high resonant frequencies", MEMS 2010, Hong Kong, Jan. 2010, pp. 823-826.

MEMS BUTTERFLY: Give your ideas wings with MEMS+ 2.0

 

AC simulation of the movement of butterfly wings using MEMS+ and Cadence Spectre.

Give your ideas wings with MEMS+ 2.0 . . .

Nature has inspired many designers to create new products that we use in our every day lives. The butterfly seems to be popular among scientists, see Qualcomm's iMOD display and others have designed gyroscopes.

Similarly, Coventor's product development created a test case inspired by the butterfly to demonstrate the new amazing capabilities of the MEMS model library that will be released in MEMS+ 2.0 in June this year. 

The video above gives you a sneak preview of what's going to be possible with our upcoming MEMS+ 2.0 release. 

Fastest computation of MEMS structures in Cadence Spectre 

The video shows the first Eigenmode of a butterfly made of our new flexible plate components. The butterfly test structure was made of circular, quadrilateral and pie shaped flexible plates. Featuring 92 nodes, it was simulated in only 5 seconds with an AC analysis using Cadence Spectre. Constructing the model in MEMS+ 2.0 Innovator took less then 5min. 

MEMS+ 2.0 user interface with access to foundry material and process data, 3D graphical interface for model creation and the MEMS model library. 

Visualization of the connecting nodes of the 3D model. After creation of the 3D geometry the model can be simulated immediately in Cadence Spectre or UltraSim.

Don't be limited by what you do today. Contact Us for more information or sign up to receive a free evaluation license. 

MEMS+ 2.0 is expected to be released in June 2010.

MEMS relays as logic gates. Really?

Even if I didn't say it, that is what I was thinking when I was approached after a talk I gave at the International Solid State Circuits Conference (ISSCC) in the "Fusion of MEMS and Circuits" session last month. The person who approached me was Matthew Spencer, a contributor on a program to use MEMS relays to realize ultra-low-power VLSI circuits [1,2,3]. He was excited about the possibilities of what our new product, MEMS+, could do for him. What exactly are they trying to do with these MEMS switches and logic? What could I have said in my talk to inspire this interest? Was his excitement warranted? I'll try to answer that in the rest of this post.

What are they trying to do for VLSI? 

Matt sent me their papers after I returned from the conference [1,2,3]. And the answer to my title question is "Really!". The work is impressive and is the result of a combined effort at UC Berkeley, MIT, and UCLA. Just as MEMS RF-switches have advantages in high isolation and low insertion loss over solid-state devices, MEMS as logic gates have zero leakage in the off-state and high on-state current compared to other CMOS alternatives for ultra-low-power [1]. The device is a switch plate with a folded flexure design as shown here (posted with permission from the authors):

The switch closes at around a 10 volt gate-to-body voltage difference and closes in about 100 ns. These gates can then be assembled into circuits to create logic functions such as part of an adder that generates the carry bit (posted with permission from the authors): 

A and B are, say, the 4's digit from two binary numbers. Cin is any "carry" from adding the 2's digit. Cout is the carry digit to be sent to the 8's digit. The above example demonstrates a VLSI logic function but in order to create a VLSI logic application, the logic must communicate, and for this the authors demonstrate using the switches for I/O and analog-to-digital/digital-to-analog conversion. 

What did I say in my talk that could help this effort? 

They hope to design logic circuits with 10's to 100's of these gates in the near term. That design process requires simulation, and to simulate these large circuits they need a good model of their switch within their circuit environment of choice, in this case Cadence Virtuoso. Matt had been tasked with creating this model, and over the past year he's gone through quite an "ordeal", as Matt put it, to create a model in Verilog-A. It doesn't model all the physics he'd like and its robustness is suspect but it does allow them to simulate a handful of switches in a minute or so of simulation.

My talk suggested a possible route for Matt to end his ordeal. The first few slides of my talk at the ISSCC conference described the larger vision for MEMS+ as a shared platform for MEMS and IC that integrates into IC and system level design flows. However, as the rest of my talk described, what we've executed most rigorously in this first release of MEMS+ is the straightforward manner of creating a circuit-level model directly from a physical description of the device. The approach relies on hints during design entry of the MEMS device that indicate the physical behavior of that section of the device. One is effectively creating a 3D schematic. The procedure is detailed in the MEMS+ video tutorial on our website. Since MEMS+ goes directly from description to model without lengthy finite-element analysis, the models can be made parametric with respect to design variables so a designer can easily explore changing dimensions or environmental conditions, such as temperature, without recreating the model.

Was the interest warranted?

I was intrigued with this new application for MEMS and MEMS+ and wanted to see just how quickly I could put together something useful with this new tool we in Coventor R&D have worked so hard to create. Given just the papers, which lacked many of the dimensions and material properties, I put together the following quick-and-dirty 3-D schematic of their design in somewhere between 1 and 2 hours of my time:

Most of that time was spent reviewing the papers and mapping that to the appropriate components and design dimensions. Note I carefully made it parametric with respect to the design dimensions such as gate size and drain width so that one could explore changing those dimensions from within the circuit simulation environment. Also note that the electrical interface was carefully defined for the eventual simulation model.

I then imported the model into a the Cadence Virtuoso Library Manager (a 5 minute process), placed an instance of the new symbol, built a little test harness of voltage sources and got my first simulation in about 15 minutes of my time:

 

Above you see the rather boring square symbol for the switch with the 6 electrical pins exposed from the MEMS+ 3D-view (the 7th pin at the top is a mechanical pin for the z position of the gate). Inset below the symbol are some of the properties of the instance. Notice those were automatically created to give access to the MEMS+ 3D-view's design dimensions. Matt had indicated he had his own contact resistance model, so I put a 1K resistor between the contacts and turned off our own contact resistance model. I also put a 1K resistor at the source so there would be a non-floating voltage to measure (not really necessary in retrospect). I swept the gate voltage and observed contact at around 7 volts (not shown). This doesn't match the paper's value of 10 volts, but is good enough (don't forget I didn't know many of the dimensions (something I will leave Matt to do)).

The figure on the right shows a transient simulation for one on/off cycle of 10 volts applied to the gate. This shows the position of the gate over time. You can see around 10us the gate closed, but bounced a number of times before settling. It first made contact at 400 ns, which is in the right ballpark from the paper (100 ns). The simulation took a handful of CPU seconds (maybe 30, I don't quite remember).

Are we done? No. The above model would be good for MEMS design studies. For instance, I could run parameter sweeps on the design dimensions to understand how to optimize the dimensions to get greater contact force or faster switching times. However, the goal here is to simulate many of these switches together, so we'd like to optimize this model for speed at the expense of some of the details such as the bouncing. Matt even indicated that bouncing isn't an issue for them at the moment.

To that end, I spent about 2 or 3 hours tinkering with some of the knobs we provide to trade accuracy for speed. For instance, the switch's gate in the above simulation could move in all 3 translation directions (x,y,z) as well as rotate about the 3 axes. For this study, we don't need to tax the simulator by tracking the motion of all 6 degrees of freedom, so I fixed the plate to only move in z. By doing so, we also know that the gap between gate and body is uniform and so the electrostatic computation need only account for the holes and edges, not a non-uniform gap. I also added a custom contact damper to absorb the bouncing since much of the time spent was in resolving the many bounces:

Which gave the following:

The entire simulation shown took only 0.230 CPU seconds. And this is on a Linux Dell Precision 380 (circa 2005). Some more recent desktop hardware is about 4x faster. The far-right plot shows that once contact was made, the switch between drain and source was closed and the voltage at the source jumped as desired. (The astute observer will notice that the source voltage output is not 10 volts. I was getting significant parasitic actuation between the drain and the floating contact dimple so I lowered the drain voltage for this demo. Of course that force is actually there but I must have guessed contact dimples that were too large. Again, something for Matt to get right).

With a functional logic gate, we are ready to connect these together to build a logic circuit.

The voltage sources and source resistor were removed from the schematic above to create a cell-view for a single logic gate with gate, source, drain, and body terminals. The cell instances were then placed to create the carry generation circuit shown before:

Which, in 3 CPU seconds, on circa 2005 desktop hardware, generates a good carry bit for all the input combinations:

Conclusion

The above showed that with about 7 hours of work, a model capturing the fundamental electromechanical behavior of this switch could be created directly from design parameters and then tweaked for simulation speed within the Cadence Virtuoso environment. Multiple instances of this model could be assembled to simulate a small logic circuit in a few seconds with the Cadence Spectre simulator.

Many of the dimensions were guessed, however the part that made this an "ordeal" for Matt within Verilog-A is clearly not an ordeal for MEMS+.

Much could still be done from here. Obviously the design dimensions must be entered correctly. From that, a useable layout pCell could be created automatically. In addition, other features could be modeled to make this more accurate, such as nonlinear damping, stiction force, and parasitic actuation due to the drain-to-gate voltage.

References

[1] Fred Chen, et. al., "Integrated Circuit Design with NEM Relays," IEEE/ACM ICCAD Nov. 2008
[2] Rhesa Nathanael, et. al., "4-Terminal Relay Technology for Complementary Logic," IEEE IEDM, Dec. 2009
[3] Fred Chen, et. al., "Demonstration of Integrated Micro-Electro-Mechanical Switch Circuits for VLSI Applications," IEEE ISSCC, Feb. 2010. 

 

 

Nonlinear dynamics in MEMS, aka Frequency Hysteresis, Hard Spring Effect, or Duffing Effect

Introduction

The frequency response of a MEMS device under some desired exciation is a key tool in understanding device performance.  Typically it can be assumed that the excitation is sufficiently small that the device remains within its linear regime and therefore the amplitude of the response is proportional to the excitation, regardless of the magnitude of excitation. This is the assumption when using Harmonic Analysis is CoventorWare's Analyzer tool, or AC Analysis in CoventorWare's Architect tool. However, in several MEMS applications, the amplitude of motion is large enough that this assumption is violated either by the strong nonlinearity of the electrostatic force, which varies like 1/(g -x)^2 where g is the gap and x is the displacement, or by the nonlinearity in beam bending.  The figure below shows how the frequency response can vary for large amplitude motion. This figure was taken from a paper by Tilman's [1] for resonant strain gauges.  But similar curves can be found in applications for scanning mirrors [2] published by Schenk and [3] Ataman as well as RF resonators [4]

As the amplitude grows, two effects occur:

1. the device appears to stiffen since the peak frequency gets larger
2. the curve starts to look like a breaking ocean wave.  This describes a hysteresis effect that shows that for frequencies underneath the breaking wave, there are two possible amplitudes of oscillation.  Which one the device oscillates at depends on the path to get there:  One for slowly increasing the frequency and one for decreasing the frequency.   This is not unlike a pull-in/lift-off curve.

Simulation using CoventorWare ARCHITECT 

Since AC analysis is a small signal analysis, it cannot be used to compute a frequency hysteresis curve.  Instead, one must use a transient analysis with a sinusoidal drive frequency of appropriate large amplitude.

An application note and schematics for using Architect for this purpose are available from Coventor's support.

Good example of this type of simulation in CoventorWare ARCHITECT on a MEMS micro-mirror has just been presented at MEMS2010 in Hong Kong by ASTRI.

[1] JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL. 7, NO. 1, MARCH 1998. Nonlinearity and Hysteresis of Resonant Strain Gauges, Chengqun Gui, Rob Legtenberg, Harrie A. C. Tilmans, Jan H. J. Fluitman, and Miko Elwenspoek

[2] IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS, VOL. 6, NO. 5, SEPTEMBER/OCTOBER 2000. Large Deflection Micromechanical Scanning Mirrors for Linear Scans and Pattern Generation. Harald Schenk, Peter Dürr, Thomas Haase, Detlef Kunze, Udo Sobe, Hubert Lakner, and Heinz Kück.

[3] Proceedings of SPIE Vol. 5348 (SPIE, Bellingham, WA, 2004). Nonlinear Frequency Response of Comb-Driven Microscanners. Caglar Ataman, Hakan Urey

[4] Solid-State Sensors, Actuators, and Microsystems Workshop Hilton Head Island, South Carolina, June 4-8, 2006. AMPLITUDE NOISE INDUCED PHASE NOISE IN ELECTROSTATIC MEMS RESONATORS. Manu Agarwal, Kwan K. Park, Bongsang Kim, Matthew A. Hopcroft, Saurabh A. Chandorkar, Rob N. Candler1, Chandra M. Jha, Renata Melamud, Thomas W. Kenny, Boris Murmann

APPLICATION OF MEMS TECHNOLOGY IN CONSUMER ELECTRONIC PRODUCTS

Today, consumer electronic products are mostly wireless mobile devices such as laptops, iPhones and iPods, and gaming controllers. There are several reasons why companies are pleased with the market pull associated with consumer electronics. First of all, the traditional markets for MEMS technology such as automotive and industrial applications has declined over the last year. And secondly, the potential number of MEMS devices that can be supplied to the consumer market is in the billions. This last point is relevant in more than one ways in that because of this potential high volume of MEMS devices, semiconductor manufacturers such as TSMC are all of a sudden interested in production of MEMS.
Let's look at the potential application of MEMS technology in consumer electronic products. The three MEMS devices that will see a rapid growth are Si microphones, accelerometers and RF MEMS. Nokia gave an excellent presentation during the MEMS Executive Congress in November 2008 (downloadable for MEMS Industry Group Members).
Just a year later, the list of MEMS devices that are designed for cell phones is growing, including; Pressure sensors and Gyroscopes for location based services (think GPS), Micromirrors for image projection (think Pico-Projector which still has not proven itself), Microdisplays for ultra low power displays and better picture in sunlight (think Mirasol), some devices inside which the consumer will never see such as Variable capacitors, RF Switches, FBAR, BAW and Oscillators. And micro fuel cells for longer battery life.

 

Image of the Board inside an iPhone pointing out the MEMS accelerometer
When you actually open up a smart phone you will find an accelerometer inside. View the tear down of an iPhone by UBM TechInsights in this video.
If you are interested to learn which MEMS devices are available on the market go to our MEMS product Blog.
Most of our interaction with computing devices has been through a keyboard, a mouse, and a screen or display. Smart phones have removed the actual mouse and keyboard and introduced the touch sensitive screen but MEMS technology is introducing the next level of interaction, motion sensing. Today seven out of ten games for the iPhone use the built-in MEMS accelerometer as a smart controller that allows users to tilt, shake and otherwise use motion to control games. Read this article about Invensense and their success in MEMS gyroscopes.
Wikipedia lists a number of smart phones that use acceleration sensors, look for the consumer electronics heading.
For now the computing growth given to us by Moore's law has driven the development of more compact computing devices and mobile consumer applications. We are just entering the era where these devices will be able to sense what's going on around us and present back to us targeted information.

There is CAD and than there is MEMS CAD

Choosing the right structural analysis method for MEMS simulations

MEMS designers are asked to generate MEMS models for circuit simulators such as SPICE in order for IC-designers to design control and read-out circuits for MEMS devices and optimize the two together. The three options available for creating such MEMS models are:

1. Hand-crafted analytical models
2. Create macro models extracted from Finite Element simulations
3. Discrete element representation using Network Models

These MEMS models need to describe the MEMS behavior accurately in the mechanical domain and electrical domain.
Each method has its advantages and disadvantage:

Analytical hand-crafted models

• Easy model creation - NO (depending on complexity and knowledge)
• Fast simulations - YES (for simple models)
• Accuracy - NO (Idealized models, lots of assumptions)
• Parametric - YES
• Complexity - NO
• Easy integration into IC tools - NO (manually)

FEM based macro-modeling

• Easy model creation - NO (Long simulation time and model validation)
• Fast simulation - YES (only for linear, simple models)
• Accuracy - NO (missing non-linearity, multi-physics)
• Parametric - NO
• Complexity - NO (partitioning in abstract macro-models)
• Easy integration into IC tools - NO (manually)

Network Models

• Easy model creation - YES (the geometry defines the models)
• Fast simulation - YES (fastest models compatible with ICs)
• Accuracy - YES (includes non-linearity, coupled multi-physics)
• Parametric - YES (100% parameterization of models)
• Complexity - YES (unlimited 3-D stacking and layouts)
• Easy integration into IC tools - YES (fully automated)

The diagram below shows the different methods of mechanical structural analysis along with other methods of analysis as described in [1].

Methods of structural analysis
The analytical method (1) is usually limited to simple models for which a closed form solution can be found; for example one dimensional linear deflection of an idealized beam under a point load. Usually these models are not sufficient to be used for MEMS design. These models also lead to misconceptions; it is for example often assumed that the pull-in voltage of a MEMS device occurs at 1/3 of the gap width which is only true for idealized "mass-spring-parallel plate capacitor" system.
The numerical solution of differential equations is usually limited to simple structures.
Also Finite Element based simulators (2) have their limitations and are not compatible with circuit simulators. There are clear disadvantages of using Reduced Order Modeling or Macro-Model extraction techniques since the resulting models are non-parameterized, often limited to structural analysis only and can not model non-linearity very well.
Since the goal is to connect the MEMS models with IC simulators the most natural choice is the "network method (3)" since it can be directly integrated with circuit simulations. In order to use the network method the MEMS device or structure is decomposed into an assembly of discrete structural elements with assumed form of displacement and the complete solution is then obtained by combining these individual approximate displacements in a manner which satisfies the force-equilibrium at the junctions of these elements. Methods based on this approach appear to be suitable for the analysis of complex structures. The theory of matrix structural analysis is ideally suited to numerically solve this type of analysis.
"the theory of matrix structural analysis" by J. S. Przemieniecki (1985).

Process modeling of MEMS + IC DLP Mirror Device

Coventor software tools provide effective solutions for designing "MEMS+IC" devices. SEMulator3D offers the ability to build 3-dimensional models of complex MEMS structures and CMOS circuits as well as visualize the electrical connectivity between circuits and the MEMS devices with which they interact. One of the best known examples of a monolithically integrated CMOS circuit and MEMS device is Texas Instruments Digital MicroMirror Device, wherein MEMS digital light switches are rotated by electrostatic attraction depending on the state of an underlying SRAM cell.

 

Isometric and Cross Section View of single pixel model created with SEMulator3D
The following images show SEM photomicrographs (courtesy of Texas Instruments) and the equivalent SEMulator3D model view.

 

Ion Mill & SEMulator3D model Cross Section

 

DMD with mirror removed (Left: SEM image, right: SEMulator3D model)
Each DMD is addressed by an SRAM memory cell. SEMulator3D can effectively model both the underlying CMOS circuit as well as the MEMS device integrated above it. The following image shows an example 6T SRAM CMOS model - before the micromirror is built.

 

(top left) Exploded view of DLP mirror and memory cell. (bottom left) 6T SRAM. (top right) 3D model of circuitry. (bottom right) top view of MEMS DLP 3D model. 

Once the complete model is built, the SEMulator3D Viewer allows you to visualize the model in terms of its electrical connectivity. As such, you can see to which part of the circuit each address electrode connects - in 3D - with the ability to rotate, zoom, explode and physically manipulate the model to verify that your design is correct.

 

To find out how SEMulator3D works visit www.coventor.com

• L. J. Hornbeck, "Current Status and Future Applications for DMD-Based Projection Displays", in Proceedings of the Fifth International Display Workshop IDW ‘98, Kobe, Japan (1998).
• L.J. Hornbeck, "Digital Light Processing and MEMS: Timely Convergence for a Bright Future." SPIE Micromachining and Micro-fabrication ‘95, Austin, Texas (1995).

 

MEMSCAP PolyMUMPs MEMS Variable Capacitor Design

Variable Capacitor

The PolyMUMPS varactor is a gap-tuning structure, see image below and schematic below. The design consists of a three parallel-plates with the central one suspended by T-shaped arms between two fixed electrodes. One electrode lies on the silicon substrate coated with nitride (poly 0), the second rigidly suspended above the mobile plate (poly 2). Thus the device consist of two variable capacitors in series. One is used for RF applications (e.g. a VCO) and the other is considered as a parasitic. (The one with the smallest capacitance which means the bottom capacitor in this case).

 

3D Solid model in CoventorWare DESIGNER

Hierarchical schematic in CoventorWare ARCHITECT3D of the Variable Capacitor.
For process related questions a much more detailed 3D model and cross sections are often needed.

Process accurate 3D model in SEMulator3D

Voltage controlled oscillator

 

A voltage controlled oscillator (VCO) can be constructed from the variable capacitor. The schematic is shown below and is based on a cross-coupled PMOS architecture with 2 LC tank resonators.

 

VCO with 2 variable MEMS capacitors

Tutorial Overview

The above material and more is covered in a short course and is scheduled for 2 short days and contains 3 exercises. There is an additional excerise, excercise 4 which can be used to extend the course duration
Exercise 1: Model design in Architect

• Material Property Database review
• Process view (Design kit)
• Schematic creation including hierarchical design of the tether arms
• Scene3D simulation result visualization
• Layout export

Exercise 2: Varactor simulation in Architect

• Mechanical Resonance Frequency analysis (including a vary loop)
• DC transfer
• Transient analysis
• Adding an electronic circuit to create a Voltage Controlled Oscillator (VCO)
• Initiate oscillation (holding specific nodes)
• AC analysis to see frequency change with bottom electrode voltage* *

Exercise 3: FEA in Analyser : Considering the top electrode as mobile (fixed on 2 opposite sides only).

• Process modification
• 3D solid generation
• Meshing with partition of arms
• Initial position of middle and top plates in MemMech due to residual stresses (including tiedlink automatically created)
• Capacitance calculation in MemElectro on the deformed shape obtained in MemMech

Exercise 4 additional FEA in Analyzer:

• Memmech mechanical+modal 6 frequencies
• MemElectro as above
• CoSolveEM with detect pull-in on the bottom electrode

Additional resources

1. Dec and Suyama, 1998, IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 46, NO. 12, DECEMBER 1998, Micromachined Electro-Mechanically Tunable Capacitors and Their Applications to RF IC's
2. PolyMUMPs Design Handbook release 11.0
3. Dec and Suyama, 2000, "Microwave MEMS-based Voltage-Controlled Oscillators", IEEE Transactions on Microwave Theory and Techniques, vol 48, no 11
4. To find CoventorWare manuals please go to: Start >All Programs >Coventor >Coventorware2008 >documentation or browse to ...\Coventor\CoventorWare2008\docs

 

MEMS in Taiwan. Motion sensing, motion sensing and motion sensing.

At Semicon Taiwan this week, MEMS is gaining more respect and visitors to the special MEMS pavilion. Next to a selection of MEMS companies with booths is a "MEMS Museum" organized by semi, ITRI and the Nanotechnology and Micro System Association of Taiwan (NMA), showing the history of MEMS in Taiwan but also several consumer devices, 90% of them based on motion sensing; new gaming applications, computer mouse, and 3D remote controls.
For years the Taiwanese MEMS industry has been limited to government funded research projects lead by ITRI. Many universities offer MEMS courses today and generated well-educated MEMS designers and engineers.
Times are changing though.
First things first in Taiwan. Three foundries have been working on MEMS projects for a several years now, TSMC, UMC and APM (Asia Pacific Microstructures). Each one has been working on establishing their own way of doing MEMS. All this is accelerated by demand from established MEMS companies like Analog Devices to move MEMS fabrication to Asia and second source their production. TSMC management even announced that 20% of their total revenue will come from MEMS by 2012, whether this will happen or not isn't important, what this indicates is that the Taiwanese companies are serious.
If the Taiwanese foundries manage to deliver stable MEMS processes in the near future, the local IC Design Houses are sure to follow. And the rest of the MEMS industry might still be looking for the killer application to produce MEMS in high volumes. The Taiwanese have figured it out. All of them are focused on motion sensors, not exclusively of course but the inertial MEMS devices seems to be a driving factor for getting the local Taiwan MEMS eco-system established.