VLSI Layout using Microwind

1
VLSI Layout using Microwind

• Kishore C Acharya

2
Getting Microwind

• Go to the website
• http//www.microwind.org
• Download the freeware version of the microwind in
  a Folder called microwind_source
• Unzip the files in a Folder called
  microwind_layout

3
Setting Up Technology File

• Launch the program microwind2.exe from the folder
  microwind2-7 within microwind_layout folder
• From File Menu-gt Select Foundry
• Browse to Folder Micrrowind2-7 and open the
  file cmos06.rul On the Layout window at the Top
  left there is a ruler. The ruler should say 5
  lambda and 1.5 micron

4
Creating your own rule file

• If the appropriate rule file is not available,
  you can create your own rule file
• Using notepad open the file default.rul in
  microwind2-7 folder
• Edit appropriate parameters
• Save as a new file
• Note Oxide thickness is defined in l3tox within
  spice parameters

5
Suggested Directory Tree
Main Directory C or D
Microwind_source
Microwind_layout
Contains microwind2,zip
Microwind2-7
ee393_layout
Contains all layout files And special .rul files
Contains all microwind files Automatically built
during Unzip
6
Opening and Saving Layout Files

• Open From File menu Select Open and Browse to
  the folder ee393_layout and open the appropriate
  .msk file
• Save From File Menu select Menu item Save as and
  save layout file in ee393_layout directory

You must setup Technology Right after Launch
before any work
7
Working with Layout Notes

• To draw a transistor click on the transistor
  symbol in the Palette window.
• Select transistor type (PMOS or NMOS)
• Select the units in lambda and specify width in
  terms of lambda
• Delete select the Gun icon and either click on
  each color section or draw a border around the
  device

8
To Do Layout

• Select the appropriate trace e.g. poly, metal1,
  contact etc.
• Draw a rectangle by dragging the mouse and the
  appropriate trace will be drawn as you release
  the mouse button

9
Design rule checker

• During layout process check if the component
  placements such as NMOS, PMOS transistors are
  correct.
• From the Analysis menu select the menu item
  Design Rule Checker
• If the placements are correct Checker will report
  No error
• If there are errors, checker will display them on
  the components in the placement window
• Clicking the mouse in the placement window will
  remove the error display

10
Well Contacts

• From Palette menu select contact (three bars next
  to transistor symbol)
• Select N to Metal contact
• Place the contact on a Metal line over the N well
  (if needed extend the N well over the Vdd bus
• Run design rule checker

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Substrate Contacts

• From Palette menu select contact (three bars next
  to transistor symbol)
• Select P to Metal contact
• Place the contact on a Metal line (ground bus)
  next to the NMOS transistor
• Run design rule checker

12
Metal to Metal Contacts

• From Palette menu select contact (three bars next
  to transistor symbol)
• Set Poly to Diff Contact selection to none
• Check (?) appropriate metal to metal contact
  (e.g. Metal 1 to Metal 2)
• Place the contact on the intersection of the two
  Metal lines
• Run design rule checker

13
Working with Layout Notes Continued

• Rotate Flip From Edit Menu select menu item
  Flip or Rotate -gt Flip or Rotation angle
• Draw a box around the object
• Move From Edit Menu select menu item Move or
  Stretch
• Draw a box around the object and move the object
  by dragging the mouse
• click on an edge of the object and stretch it by
  dragging the mouse

14
Working with Layout Notes Continued

• Pan From the tool bar use left, right top and
  bottom arrows for panning alternatively use the
  arrow keys from the keyboard
• Move stepwise From Edit Menu select menu item
  Move Step By Step
• Draw a box around the object and move the object
  by clicking on the arrows that appears on the
  screen

15
Working with Layout Notes Continued

• Delete From the menu bar select the gun symbol
  (Delete Some Layout)
• Method 1Draw a box around the object to be
  deleted using the mouse and let go the mouse
  button
• Method 2Place the mouse pointer on the object
  to be deleted and click the right button

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Working with Layout Notes Continued

• Zoom in From the tool bar use Zoom in icon and
  then click on the Layout Window
• Zoom out From the tool bar use Zoom out icon and
  then click on the Layout Window
• On the tool bar click on the draw box icon to
  stop Zoom operation
• To Print From the File Menu select Menu item
  Print Layout

17
Obtaining parasitic values

• Put the mouse on a section of the Layout (e.g.
  Metal lines, Gate connections etc) and click the
  right button of the mouse.
• From the displayed menu at the mouse point select
  the menu item Node Properties
• A new window called Navigator will be displayed
• Read the parasitic values displayed in the
  navigator Window
• If the parasitic values are not displayed click
  on Props Tab of the Navigator window

18
Some drawing design rule help

• Make width of all metal lines 4l
• Make spacing between two adjacent metal lines 6l
• When making contact between metal and
  polysilicon, build a 4l by 4l pad with
  polysilicon for connection
• For layouts needing many connections use Metal 1
  for Horizontal lines and Metal 2 for vertical
  lines

19
Changing Layout display

• To BW Layout
• From File Menu Select menu item Colors
• From Colors submenu click on Monochrome
• From Colors Submenu White or Black back ground
  can be selected by clicking on White background
• To Color Layout
• From File Menu Select menu item Colors
• From the Colors submenu click on Color

20
Naming Nodes and Assigning Parameters

• Select a node by double clicking on it
• Right click and select Text Properties
• Type name of the (e.g. In, Vdd, Out etc.) node in
  the Label name box
• Select node type by clicking on the button
• Enter appropriate parameters
• For observation in simulation click not in
  simulation
• Observable variable are shown in italics
• Click on Assign button
• Click on Move icon and move name into the node by
  clicking on it

21
Assigning Virtual Components

• From the Edit menu select menu item Virtual RLC
• Click on the R or L or C

22
Creating SPICE Netlist

• From File menu select menu item Convert Info
• Select SPICE netlist

23
About SPICE in Microwind

• SPICE Model files are located in rule file
• Supported Simulation Type
• Frequency Sweep Analysis (Frequency vs. time)
• DC Analysis (Static Voltage vs. Voltage
• Transient Analysis (Voltage vs. time
  Voltage,Current vs. time)
• Model Selection (Level 1, Level 3 BSIM)

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Running Simulation

• If default Vdd is not correct Set default voltage
  to desired voltage in rule file
• To find the variable in rule file search for
  vdd
• Set Vdd 5.0 for I/O Vddh 5.0 or 3.3 for
  core logic
• Select Run Simulation from Simulate menu
• Select Simulation type from sub menu
• Setup simulation parameter in simulation dialog
  box that appears

25
Model Parameter Selection

• Default model is level 3
• To use different model from simulate menu select
  using model then model type (Level 1 or BSIM)
  from submenu
• Simulation parameters (Model, voltage range,
  temperature etc.)can be setup by Selecting
  Simulation parameter menu item from Simulation
  Menu

26
Simulation Parameter Setup

• For Transient Analysis (Voltage vs. time or
  Voltage, Current vs. time)
• Set to desired duration by clicking into the
  Time Scale dialog item (center right)
• For DC Analysis (Static Voltage vs. Voltage
• Set to desired voltage range by clicking into the
  X Scale dialog item (center right)
• Simulation could be repeated by clicking into
  Reset or more button

27
Getting Microwind2

• Go to the website
• http//www.microwind.org
• Click on the Hyperlink (Location Top right)
• New A book on CMOS design by J. Uyemura based
  on Microwind
• Click on the hyperlink (Location Below the
  description of the book)
• Microwind 2.7 (lite version)
• Download the file in a Folder called
  microwind_source
• Unzip the files in a Folder called
  microwind_layout