Images from left to right:

1
MPW Design IntroductionComputer Assisted Design
Tools

• Images from left to right
• Microwave circulator made with gmsh/getdp
• 3D structure made from layout with Coventor
  Architect
• Tip field emitter isosurface plot of voltage
  contours from ANSYS simulation

2
Engineering/Design Kits for SensoNor Foundry
Processes

• Why do we need design tools for MEMS ?
• SensoNor Engineering Kit
• MPW Design Handbook
• Electronic Design Aids (based mainly on Tanner
  L-Edit)
• Possible software solutions
• Non-dedicated software.
• Dedicated software.
• Collaborations / Commercial Design Kits
• Coventorware design kit
• MemsCap Design Kit (TALENT project)

Image Fluid dynamics simulation using gmsh/gstdp
3
CAD Tools for MEMS

• Why do we need integrated design tools for MEMS
  (1) ?
• MEMS design Today
• Its almost like doing digital design 25 years
  ago, where you crawl over layouts on the
  floorN.R. Swart, Analog Devices
• Future wish
• . doing systems designs without a Ph.D. in
  MEMS.... design functional MEMS systems right
  out of the boxKris Pister, UCB

Images Models from www.coventor.com
4
CAD Tools for MEMS, cont..

• Why do we need integrated design tools for MEMS
  (2) ?
• Design process of MEMS is not automated
• Design iterations often require manufacturing
  cycle
• Foundry specific design kits
• allow external designers easy access to
  manufacturing
• incorporate design intelligence
• design with confidence in established processes
• virtual prototyping / reduce time to market

Image Field lines of an electrostatic actuator
found using gmsh/getdp
5
Design tool development
6
Software tools(1)

• Desired
• One tool to fully define 3D structures through
  mask-design.
• Using the same tool to define physical
  properties.
• System simulation from structures and properties
  defined above.

Image LEdit from Tanner used for MEMS layout.
7
Software tools (2)

• A MEMS-project may require
• Design of a mechanical sensor/actuator device.
• Includes simulation of thermal, electronic and
  mechanical behaviour for 3D structure defined by
  mask layout.
• Design and simulation of an ASIC.
• Requires tools for circuit design, simulation and
  layout (if analogue).
• Design and simulation (thermal- and
  stress-simulations) of packaging.

Image Screenshot from Tanner LEdit
8
Software tools (3)Non-dedicated software

• Many single domain CAD tools exists
• Circuit simulators SPICE (several flavours),
  Cadence INCISIVE, PSCAN, JSim, Eldo many more.
• Layout tools LEdit, CleWin, Cadence Virtuoso,
  Electric many more.
• General numeric solvers
• Finite element solvers Felt, FEMLab, ANSYS,
  ABAQUS, SESAM, gmsh/getDp many more
• Images
• Top Screenshot from LEdit
• of Tanner Research Inc.
• Bottom Screenshot from
• FEM-solver gmsh/getdp.

9
Software tools (4)Non-dedicated software

• Non-dedicated software-pros
• Very flexible.
• A full set of software can be obtained for free
  through the GNU licences.
• Well established user groups

• Non-dedicated software-cons
• Non-compatible representations of the system.
  Requires transformation by hand(2D-gt3D).
• Expensive to buy industry-standard packages.
• Requires the user to know a lot of software
  packages.
• Some packages offers to many possibilities which
  may be confusing.
• Image interior view of an electrostatic
  octo-pole benchmark used to validate ANSYS
  solution accuracy at the nano-scale level
  (courtesy Andreas Heike).
• Gnu is Not Unix. Open source free software
  liscense

10
Software tools (5)Dedicated software.

• Two main packages exist
• Coventor (www.coventor.com)
• MEMS Xplorer and MEMS Pro form MEMScap
  (www.memscap.com)

Above Layout from MEMS Pro (based on LEdit
) Left Varactor layout (Screenshot) from
Coventor
11
Coventorwww.coventor.com

• Offers lumped modelling of micromechanics based
  on behavioural model building blocks. Library
  includes beams, electrostatic force-fields and
  membranes. Enables easy system simulation through
  circuit simulators.
• Layout to 3D structure conversion from process
  description.
• Detailed analysis through integrated FEM modules.
• Extraction of macro models for quicker design
  iteration.
• Can be interfaced with the advanced FEM solvers
  as ABACUS or ANSYS.
• Offers modules for process and package design and
  modelling as well.

Over Varactor 3D model from layout
shown on prev. slide. Below Vizualisation of
micro-mirror array made with
Coventor.
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MEMS Xplorer/Pro

• MEMS Xplorer/MEMSPro(www.memscap.com)
• Offers design tools through integrated
  Tanner(LEdit) modules.
• Converts layout(2D) to 3D models. Based on
  process description.
• Exports structures to .sat and ANSYS-specific 3D
  formats.
• Software compatible with ANSYS, an advanced
  FEM-solver.
• ANSYS
• General finite element software.
• Offers full system simulation.
• Offers macro model/reduced-order model for system
  simulation in circuit simulation software.
• .sat Common 3D file format Industry standard.

Image Screenshot from MEMS Xplorer
13
Coventor vs. MEMS Xplorer/Pro
Comments Coventor offers tools for process
simulations and packaging as well. Both software
packages are available from Europaractice. For
more detailed descriptions see www.coventor.com
or www.memscap.com
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SensoNor Engineering Kit

• MPW Design Handbook Electronic Design Aids
• Technology files (incl. design rules)
• Etch simulator (parameter file)
• Library elements
• low / high level
• layout / behaviour model
• Bulk etch calculator

15
Technology File

• File containing
• Setup of (allowed) mask layers
• Design rules (DRC for Tanner, later for Coventor,
  Cadence, Mentor and MemsCap)
• Process parameter (sheet resistance, etc.)

Image Screenshot from Tanner L-Edit.
16
Etch Simulator

• Necessary for
• more complex or non conventional structures
• convex-corner-undercutting compensation
  structures
• (as used in full-thickness masses e.g.)
• Parameter file available for SIMODE

Image SIMODE etch simulator screenshot.
Available from www.infotech.tu-chemnitz.de
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Library Elements

• From low-level to high-level layout cells
• Available as fixed size (min. size) or as
  scalable/parametric elements
• Both electrical and mechanical structures
• Design rule compatible
• Macro-file in L-Edit and/or GDSII-file

1bar pressure sensor library element
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Library Elements layout generators
19
Library Elements list of examples

• Thin and thick membranes
• Membranes with resistors
• Chip templates for MPW
• Wafer templates
• Pressure sensor series (measurement ranges 1,
  2, 5, 10, 30, 60 bar)

• Substrate contacts
• Epi contacts
• Contacts to p-conductor
• Conductor crossings
• Buried and surface piezoresistors
• Bond pads
• Bond pad areas
• Etched through-holes

20
PresLib (Pressure Sensor Library)
1bar, 2bar, 5bar, 10bar, 30bar 60bar
21
Chip Templates
4 different sizes 3x3 mm2 3x6 mm2 6x3 mm2 6x6 mm2
Bond pad area - fixed size
Maximum size of top cavity
22
Bulk Etch Calculator (EXCEL sheet)
Calculates membrane dimensions with tolerances
Useful for placing sensing resistors
23
Bulk Etch Calculator (layout generator)
BETCH mask
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Microsystem SensoNor Design Kit

• Template file (Layout Drawing and Editing)
• Material Properties Database
• Process-flow file for 3D Solid Model Construction
• Advanced visualization (clip etc.)
• Low and high-level library cells
• Quick-start tutorial

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MEMSCAP SensoNor-Design Kit (Not yet available)

• Layout Tool Extension (Non Manhattan Shapes)
• Layout to 3D Solid Model Generation
• Parameterized Cell Libraries
• Layout device generators
• Behavioral models for pressure sensors (VHDL-AMS)

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Ch 6 Design Tools
End of this Chapter Comments or questions?