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Solid Modeling tools are helping MEMS designers streamline their design process and leverage the availability of finite element analysis (FEA) soft-ware. Associative mask definition gives the MEMS designer even more power, letting the designer concentrate on refining micron-scale structures in 3D and letting the mask follow the design. Your choice of solid modeling tools is critical to achieving results in the MEMS world. Solid-Works® is easily mastered, even by part-time designers. SolidWorks allows the designer to design the MEMS structure, analyze it, generate the photomasks, and design all the related product packaging and assembly equipment. This guide identifies key issues and explains advantages of SolidWorks 3D modeling soft-ware for MEMS designers.

• 3D visualization provides MEMS designers a first check of design intent, proper operation, collision avoidance, and package stack-up.

• MEMS designers have created impressive structures, frequently using layout software that is inherently two-dimensional. These accomplishments are impressive, but true 3D tools offer MEMS de-signers better design visualization. This gives designers a clear and accurate review of parts and assemblies early in the design cycle.

• SolidWorks provides true solid modeling capability, avoiding the need to acquire extremely expensive high-end specialty design software marketed strictly for MEMS design and analysis.

• 3D visualization facilitates communication within the organization and beyond. Not only is the MEMS designer more able to explain design intent to colleagues, but scholarly presentations, articles and requests for funding benefit from showing 3D features.

• To shorten time-to-market for your MEMS designs, you need to identify potential problems early in the design cycle, before com-mitting to a mask or processing wafers. SolidWorks Office Profes-sional includes PhotoWorks™, SolidWorks Animator, and 3D Instant Website software, that enable excellent visualization capabilities by providing photorealistic rendering, full-motion animation, and web-based presentation of the finished design.

• Clearance design rules can be particularly important for surface micromachining to ensure proper etching and separation of parts during lift-off processes. SolidWorks enables checks for interferences or specific clearances between components using Dynamic Assembly Motion and Collision Detection. Any interference will stop motion between parts that contact and the point of interference will be highlighted by changing color. Physical Simula-tion takes motion checking to the next level by presenting meshing parts, such as meshing gears, and showing their operation in the assembly.

Solid Modeling and Analysis of MEMS Structures

• 3D visualization

• Sub-micron feature definition

• Patterns and creation of patterns of patterns

• The power of configura-tion management

• Complex assembly de-sign support

• Associative photomask definition

• Finite element analysis (FEA) of MEMS struc-tures for thermo-mechanical, electro-static, and fluid flow behavior

• Design Re-Use

• Ease of use

• Collaboration tools

• Tightly integrated com-plementary applications

• One standard CAD tool to design everything

This guide addresses the following topics:

3D Visualization

The Standard in 3D

This micro-transformer was de-signed in 3D with SolidWorks and fabri-cated with MEMGen Corporation’s EFAB™ technology.

As microfabrication tech-niques extend our grasp into the realm of microns, as with this fiber positioner, Solid-Works guides the way with sub-micron solid modeling and analysis.

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• SolidWorks solid modeling software provides MEMS designers with

sub-micron feature generation capability. In fact, the user can choose to work in microns, nanometers, or even angstroms as ap-propriate.

• Features in most MEMS devices are several microns or tens of mi-

crons. SolidWorks allows designers to work on this scale and still define sub-micron features in structures (such as die-mounted, packaged assemblies) with dimensions of tens of millimeters.

• This sub-micron definition capability means that certain types of

optical gratings may be described fully as a solid model, with all the power that SolidWorks can bring to such entity creations.

• SolidWorks saves designers time and simplifies model construction by allowing patterns of model features. Bosses and cuts are just two of the features that may be patterned within a part. Patterns may be linear, rectangular, or defined by a curve.

• Patterns may also be employed within an assembly. Several com-

ponent parts may be dragged into an assembly, or the designer can simply define a pattern of components.

• Patterns of patterns may also be defined. Using the gear patterns

at left as an example, the pattern of six gears may be defined as an element, then patterning the pattern creates a photomask to produce a large number of such gears.

• Circular patterns of linear patterns are supported, as are linear

patterns of circular patterns. In fact, the pattern definition and pattern-of-a-pattern definition are independent. Each may be con-structed from: linear, circular, or curve geometries.

• Configuration Management is the ability to control design variations from within a single file or document. This applies to parts and as-semblies, with the effects propagating to drawings, including pho-tomask drawings.

• Configuration Management enables the generation of multiple ver-

sions of parts, assemblies, and drawings in a single document with a minimal amount of time and effort. Configurations make use of design tables, derived design data, component properties, relation-ships, viewing states, and other attributes, storing part and assem-bly information in one area for greater efficiency. SolidWorks offers multilevel configurations, called nested configurations, to optimize the power, organization, and efficiencies of configurations.

• SolidWorks Configuration Management gives you maximum

flexibility in creating multiple design variations covering a wide range of needs. New configurations are easily developed from

Configuration Management

Sub-Micron Feature Definition

Patterns and Patterns of Patterns

This gear, designed in Solid-Works, is 10 microns thick and 120 microns in diameter. The detail shows a fiducial which is 0.4 microns wide and 10 microns long, etched to a depth of 0.5 micron.

Each gear above contains a pattern of holes and extruded cuts. A radial pattern of such gears may be defined as at left, then a rectangular pat-tern of such patterns may be defined, as shown at right. Defining patterns in this fash-ion eases photomask creation.

Design tables are Microsoft® Excel spreadsheets embedded within the drawing.

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previously created designs to further speed development and meet market needs for data reuse.

• A simple application of this capability would be to create various

versions of MEMS structures that automatically scale both surface feature size and etch depth as dimensions increase. The various versions of this MEMS design can be created within a single SolidWorks model file for simplicity and easy design control. “What if” scenarios for different design requirements such as film thick-ness and modulus can be quickly explored by turning on and off various configurations of a part or assembly. Etched well dimensions and sizing of cutouts can be tied to design data for each chip size. As the chip requirements change, the necessary wafer level dimensions automatically update to reflect the new design.

• Components involving multistage processing, such as surface mi-

cromachining or LIGA, can easily be documented by using multiple configurations of a single part. Configuration Management techniques can generate a discrete version of a part or assembly as necessary to reflect a separate version or in-process state. These versions help you compare designs, track expected perform-ance, and develop process plans.

• Because change and flexibility are keys to effective design, the

importance of configurations to the designer cannot be overstated and SolidWorks is the only product among powerful, easy-to-use 3D CAD products that offers configurations for both parts and assemblies.

• The ability to handle assemblies with thousands of parts without

compromising performance is a requirement of 3D CAD solutions for designing wafers full of MEMS devices such as accelerometers, orifices, mirrors for Micro-Opto-Electro-Mechanical Systems (MOEMS), or arrays of Micro-Structure Technology (MST) devices, such as miniature gears.

• The ability to manage large assemblies easily allows product designers to take on a broader range of projects and gain greater

flexibility in solving design problems. • The challenges associated with large-assembly MEMS device design

are often unpredictable and complex. SolidWorks 3D modeling software, with its Large Assembly Mode, offers unparalleled

performance for applications involving a large number of parts, allowing product designers to design and assemble tens of thou-

sands of components and evaluate complete assemblies. • SolidWorks provides built-in tools for evaluating assembly designs,

including motion simulation and visualization (Physical Simulation), interference checking, collision detection, clearance information, and creation of envelopes for defining the full range of motion for an assembly. Clearance design rules can be set for micromachining operations. These tools help MEMS designers identify necessary changes in assembly development, which can be easily made using simple drag-and-drop assembly structure reorder operations.

Complex Assembly Design Support

Two design variations for an etched silicon well structure. A design table offers agile fea-ture re-definition during pre-liminary design studies. De-sign tables together with the Configuration Manager tree provide defined configurations that can be called up as needed.

Assembly level configurations can pull together etch depth and film thickness.

A large MEMS array could con-tain tens of thousands of ele-ments. The solid model pic-tured here contains a 10 x 10 array of tiny diving board structures. Analysis of mod-els such as this, and signifi-cantly larger, can be readily achieved on common desktop computers or workstations.

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• Many organizations accelerate development through concurrent design approaches where several designers or teams work at the same time on separate components or subassemblies of a large assembly. SolidWorks 3D modeling software supports concurrent design, providing powerful capabilities that enable Configuration Management, top-down design techniques, and design

collaboration.

• For MEMS device design, fully associative assemblies are critical for effectively using bottom-up and top-down assembly design techniques. Associativity guarantees that all elements of a model are electronically associated or connected, including assembly models, components, and drawings. This means that when a change is made to any SolidWorks file, that change is automatically made in all associated files.

• After surveying numerous MEMS designers actively working in the

field, we have received feedback that mask definition should be associative to model changes. SolidWorks developers have put in place powerful tools that will streamline mask generation in GDS II file formats from associative DXF files, which link directly to model definition changes.

• Bottom-up associative design encompasses the creation of new

components and integration of these with existing components into assemblies. This is important when components must be designed based on strict limitations imposed on component properties, then checked for integration in the context of the overall assembly. Each of these parts can be edited within the assembly as needed.

• Top-down associative design involves working with an existing

assembly to develop new components for use with that assembly. Because new components reference existing parts in the assembly, any changes made to any of the parts are reflected throughout the design. In the MEMS arena, this means that a component can be created or modified within the context of the overall device model, allowing real-time modification for fit and function. Modifications automatically propagate throughout the assembly and drawings, maintaining design intent.

• Examples of top-down design include developing a package for a

MEMS device that realizes a certain stack height and footprint, generating a maximum envelope (length, width, and height) for a chip within a required finished package size. Configuration Man-agement enables the new parts to be linked through the assembly and to the photomask definition drawing file.

• Designers can now run initial stress analysis checks on MEMS de-signs up-front using COSMOSXpress™ FEA software that is in-cluded with every license of SolidWorks. Furthermore, COSMOS products in the COSMOSWorks™ analysis software product line en-able thermal, stress, deflection, buckling, non-linear, and electro-magnetic analysis. Partners such as MSC.Software (MSC.visualNastran FEA for SolidWorks) also provide Certified Gold

Associative Photomask Definition

Integrated Finite Element Analysis (FEA): Ther-mal, Mechanical, Electrostatic, and Fluid Flow

Because the drawing dimen-sions are associative, they automatically propagate throughout the model, draw-ings, and configuration tables.

This positive photomask was generated associatively from a solid model. Below is the corresponding negative pho-tomask.

COSMOSWorks brings high-end performance to desktop computer users. This mesh, which features over 130,000 nodes, was automatically generated by the standard COSMOS mesher, utilizing controls that increased reso-lution where needed.

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Product Solution analysis products for use with SolidWorks. COS-MOSFloWorks™ from COSMOS provides CFD (computational flow dynamics) analysis for flow and heat transfer applications.

• Reliability is a key factor that differentiates various MEMS device

technologies and designs. Companies that are able to build in reli-ability from the initial design stage will have an advantage in gain-ing market acceptance. COSMOSWorks facilitates early-on reliable design by allowing MEMS designers to perform a range of FEA on initial designs. From thermal analysis to static analysis, COSMOS ensures device behavior will be within design limits, avoiding ther-mal or stress-induced failure.

• Thermal analysis is critically important for MEMS package design.

It also plays a pivotal role in predicting device operation for certain technologies, such as thermo-optic planar waveguides and resistor arrays. Using the SolidWorks solid model as a starting point, COS-MOS can perform steady-state or transient thermal analysis on parts or assemblies. After meshing the design, the designer sets any relevant constraints (for example, the underside of a substrate may be considered clamped to a certain temperature because it is intimately bonded to a thermoelectric cooler), then the designer sets power or heat flux conditions associated with a geometrical feature of the model. Because component material properties in-clude thermal conductivity, coefficient of thermal expansion, and heat capacity, the designer gets a realistic prediction of tempera-ture distributions under prescribed conditions.

• By coupling the power of FEA studies with Configuration Manage-

ment, the designer can quickly converge on the best-form design solution over many degrees of freedom. For example, a range of epoxy bond layer thicknesses may be studied in coordination with evaluating a broad range of epoxy thermal conductivities.

• COSMOS Static analysis capability is a tool that empowers the

MEMS designer to avoid catastrophic immediate or long-term fail-ure modes. The diving board analysis at left, for example, showed that although desirable deflection distances could be achieved with a shallow (5 micron) etch and a thin (1 micron) diving board, the resultant stress in the moving element would result in early failure. After several permutations were analyzed, a balance between risk and performance was achieved. In some cases, designers will learn that changing preset variables is insufficient to resolve the trade-off, then re-design of one or more core elements will be necessary. COSMOS then guides the way in conjunction with Configuration Management.

• For most MEMS devices, and particularly those whose performance

depends on electrostatic performance (such as piezoelectrics or deformable mirrors), electrostatic analysis capability is necessary to fully predict device performance. The simple cantilever beam model shown here was solved to model beam deflection under dif-ferent potentials between the stationary and moving elements. The results can then be compared to the effects of shock and vibration to optimize performance under real world conditions.

• Fluid flow analysis is important across a range of MEMS applica-

tions. Whether you’re trying to get heat out of a package, and therefore need to determine which heat exchanger has the best properties; or you’re designing a MEMS orifice or pump whose op-

Thermal analysis of a MEMS subassembly.

Deflection and stress profiles are easily computed with COS-MOSWorks.

COSMOSEMS was used to ana-lyze performance of this canti-lever beam under various volt-ages. (The aqua-colored vol-ume represents air.)

COSMOSEMS computed the potential distribution shown at top. The predicted deflec-tion is shown in the lower plot.

COSMOS-FloWorks was used to model the air flow through this circuit board environment, allowing the designer to optimize pack-age characteristics such as chassis cut-outs or heat ex-changer configuration.

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erability is directly tied to fluid handling, COSMOSFloWorks™ offers high-powered computational flow dynamics analysis in a straight-forward interface.

• MEMS designers frequently have a large amount of legacy data (data created from previous projects or fab runs).

• Legacy data may form a starting point for new designs or can con-

tribute key elements to the development process, including projects based on collaborator-supplied CAD data. Unfortunately it is often available in various 2D and 3D formats. The ability to use these varying formats helps designers leverage legacy data, work side-by-side with designers who use other CAD systems, speed develop-ment, respond to market needs, and increase financial

returns. • SolidWorks 3D CAD software offers the widest number of data

translation formats of any CAD solution. A list of the supported formats is provided on the SolidWorks datasheet. Designers mi-grating to SolidWorks from 2D CAD will greatly benefit from new functionality including view folding, which enables legacy DWG or DXF™ drawing views to be used more efficiently to create new 3D models. A new import wizard with an AutoCAD-oriented help sys-tem also streamlines the migration process.

• After 3D legacy data is imported into SolidWorks, the

FeatureWorks® feature recognition product (a component of SolidWorks Office Professional) further speeds design work by searching the incoming file data for features, such as bosses, holes, ribs, sheetmetal features, and fillets. These features are then con-verted into native SolidWorks features and inserted in the Solid-Works FeatureManager® design tree for easy modification, reorder-ing, and other standard SolidWorks operations.

• Feature Palette is a powerful tool for designers who have already

accumulated a large arsenal of SolidWorks parts or assemblies. The Feature Palette, shown at left, operates as an “always on top” window holding frequently used SolidWorks file. The designer can save time by simply dragging required components for a new as-sembly directly from the Feature Palette and dropping them into the new design.

• MEMS designers need and want powerful functionality from their 3D CAD software, but it must be easy to learn and use since they are not using it all the time. If the software is powerful yet easy to use then the designer can be productive even with only occasional use.

• SolidWorks is gaining favor with MEMS designers worldwide as they

come to appreciate the fit between SolidWorks capabilities and their requirements.

Design Re-Use

Feature Palette speeds up de-sign by keeping a handy set of prior design elements at the user’s disposal. The elements can be fresh designs, or con-verted from legacy data.

This model was imported from an IGES file to SolidWorks. With FeatureWorks feature recognition software, im-ported geometry can easily be turned into an editable, pa-rameterized feature-based solid model.

Ease of Use DXF files and DWG files can be easily imported and in-corporated into sketches and drawings.

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• Design collaboration has become an increasingly important part of the development process, enabling designers to share designs eas-ily with anyone, anywhere.

• Collaboration tools offer new ways for product designers to work

more effectively with other members of the development team. The ability to share design resources over the Internet can benefits MEMS designers, from independent consultants to engineers in large multinational corporations.

• SolidWorks collaboration tools enable the MEMS designer to convey

2D and 3D product design information to colleagues, customers, funding agencies, and suppliers easily and efficiently. eDrawings Professional is the first email-enabled communication tool that dramatically eases the review of 2D and 3D design infor-mation across your extended product development teams. With eDrawings Professional you can generate accurate representations of 2D and 3D models that anyone can view, mark up, and measure without having to purchase their own markup tools. eDrawings files provide an effective means of communicating 2D and 3D de-sign information to customers, vendors, collaborators, production personnel, and everyone else involved in the product development process. www.solidworks.com/edrawings/

3D Instant Website provides the capability to publish product design data to a live web site of interactive 3D design content. A few simple mouse clicks from within SolidWorks allow a designer to publish a SolidWorks model to a web site and communicate the design to the entire work team, including other designers, manu-facturing staff, marketing management, purchasing agents, suppli-ers, and customers. Visitors to the site can easily view, rotate, zoom, and evaluate the design as well as offer comments. www.solidworks.com/3dinstantwebsite/

• Available best-in-class partner solutions are fully integrated into the core SolidWorks 3D modeling software to offer a complete, single-window approach to medical product design.

• SolidWorks software development focuses solely on 3D design tools

to ensure continuous innovation. CAD companies that build strong ties to Solution Partners for best-in-class, extended solutions — such as finite element analysis (FEA), computer-aided manufacturing (CAM), product data management (PDM), and kinematics — make sure that development is done by the companies best suited for the job. The results are more complete product design and development solutions.

• SolidWorks provides an unmatched selection of Solution Partner

products plus the highest level of add-on product integration in the industry. Certified Gold Products offer the look-and-feel of

SolidWorks software, simplifying learning and use and extending best-in-class functionality. All Certified Gold Products offer single-window integration with SolidWorks, are fully associative, and un-dergo a rigorous testing and certification process by SolidWorks to ensure compatibility with every release of SolidWorks.

Collaboration Tools

Integrated Solution Partner Products

3D Instant Website enables design communication world-wide. You can publish to a hosted web site instantly.

SEM photo of the RF filter, also featured above in the 3D In-stant Website.

A scanning micro-mirror. A broad range of fabrication techniques benefit from solid modeling with SolidWorks.

A scanning micro-mirror. A broad range of fabrication techniques benefit from solid modeling with SolidWorks.

eDrawings allow the MEMS designer to communicate de-signs, such as this variable capacitor, readily to col-leagues, customers, or ven-dors. A micrograph of the capacitor appears below.

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• Several SolidWorks partners have demonstrated efficient use of

SolidWorks in conjunction with COSMOSWorks for the design, analysis, and fabrication of MEMS structures and MEMS-related ma-terials.

• Elsyca NV markets software for modeling electrochemical reactions.

Elsyca has supplied the electronics industry with custom electro-chemical deposition analysis tools that model reaction cell behavior during deposition processes on silicon wafers. One of their electro-chemical cell design evaluations, with deposition current spatial characteristics appears at left.

• Another SolidWorks partner, MEMGen Corporation, uses SolidWorks

to design MEMS devices, which they fabricate for customers in a captive fab facility using their exclusive license to EFAB™ technol-ogy. The photos at left illustrate the accurate predictive nature of the SolidWorks model for this technology.

Electronic-oriented tools: CircuitWorks from Zeal Solutions offers a SolidWorks Certified Gold Product solution that enables the merging of 2D IDF format PCB data and component 3D data to build com-plete 3D models of PCB assemblies. These exact models result in optimized packaging designs with minimum envelope sizes. Kinematics tools: Kinematics analysis is helpful for developing products requiring complex motion including many MEMS devices. COSMOS (COSMOSMotion™) and Certified Gold Product Solution Partner Solid Dynamics (MotionWorks) offer these type of analysis tools. For a complete listing of SolidWorks Solution Partner products, please refer to the “Partner” section of the SolidWorks web site at www.solidworks.com.

• SolidWorks offers a unique degree of integration with add-on solu-

tions, supplying valuable functionality beyond that found in the core CAD product. These solutions operate from within SolidWorks and can be added at any time to meet new or existing needs.

• SolidWorks Office Professional combines the full functionality of SolidWorks CAD software with the following design communication, CAD productivity tools, and data management tools:

SolidWorks Office Professional Design Communication Tools Demonstrate more effectively how products look and perform with SolidWorks design communication tools:

SolidWorks Animator— animation software for creating com-pelling AVI files from SolidWorks parts and assemblies. PhotoWorks— rendering software for creating photorealistic images. 3D Instant Website— an easy-to-use tool for publishing live web sites with 3D interactive content. eDrawings Professional— tools necessary to visualize, inter-pret, measure, mark up, and expedite the review of 2D and 3D product designs across your extended design team.

CircuitWorks allows realistic PC board layout visualization, as in this packaged MEMS de-vice mounted onto a board populated with other ICs, SMT capacitors, and resistors.

Elsyca models electrochemical wafer deposition and etching processes.

MEMGen Corporation uses EFAB™ technology to produce MEMS devices defined with SolidWorks.

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• As organizations increasingly struggle to run leaner and increase

productivity, solutions that optimize their existing capital and hu-man resource investments become more imperative. This para-digm applies to research organizations and for-profit corporations alike. Fortunately, SolidWorks is an investment that has broad ap-plication for MEMS design.

• SolidWorks handles design at the sub-micron level, assembles

thousands of components in assemblies, provides native FEA that can be easily enhanced with tightly integrated analysis products, and designs structures measuring many tens of meters, including packaging automation equipment.

• When weighing information to decide between high-end, special-

ized design software specifically targeting MEMS design vs. Solid-Works, which is an effective single tool for myriad applications, a number of features should be considered. Features that recom-mend SolidWorks include: → Ease of use, so even part-time users can maintain productivity → Ease of learning, allowing new users to quickly contribute to

collaborative design efforts → Associativity, from assembly through component parts to mask

definition → Efficient Power, FEA of complex assemblies running easily on

standard desktop computers → Agility, SolidWorks can be used both to design sub-micron

MEMS features and packaging line equipment measuring tens of meters

For additional information about SolidWorks and its products, checkout the online SolidWorks Express newsletter at: http://www.solidworks.com/swexpress/index.html. SolidWorks Corporation 300 Baker Avenue Concord, MA 01742 USA Toll Free: +1-800-693-9000 Outside the U.S.: +1-978-371-5011 www.solidworks.com info@solidworks.com

Making the Decision

One Tool for all Design Needs

This automated packaging cell was designed with Solid-Works. Design the MEMS device with SolidWorks, then output the mask, design the packaging, and even the automation to put it all to-gether. Solid modeling across several dimensional decades ensures everything fits, everything works.

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SolidWorks is a registered trademark, FeatureManager is a jointly owned registered trademark, and PhotoWorks and PDMWorks are trademarks of SolidWorks Corporation. FeatureWorks is a registered trademark of Geometric Software Solutions Co. All other company and product names are trademarks or registered trademarks of their respective owners.

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