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

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Setting Up Technology File

• Launch the program microwind2.exe from the folder microwind2-7 within microwind_layout folder

• From File Menu-> 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

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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

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Suggested Directory Tree

Main Directory C or D

Microwind_source Microwind_layout

Microwind2-7 ee393_layout

Contains all microwind filesAutomatically built during Unzip

Contains all layout filesAnd special .rul files

Contains microwind2,zip

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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

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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

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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

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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

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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

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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

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Working with Layout Notes Continued

• Rotate & Flip: From Edit Menu select menu item Flip or Rotate -> 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

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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

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Working with Layout Notes Continued

• Delete: From the menu bar select the gun symbol (Delete Some Layout)– Method 1:Draw a box around the object to be

deleted using the mouse and let go the mouse button

– Method 2:Place 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

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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

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Some drawing & design rule help

• Make width of all metal lines 4• Make spacing between two adjacent metal lines 6• When making contact between metal and

polysilicon, build a 4 by 4 pad with polysilicon for connection

• For layouts needing many connections use Metal 1 for Horizontal lines and Metal 2 for vertical lines

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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

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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

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Assigning Virtual Components

• From the Edit menu select menu item Virtual RLC

• Click on the R or L or C

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Creating SPICE Netlist

• From File menu select menu item Convert Info

• Select SPICE netlist

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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

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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

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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

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Getting Microwind2

• Go to the websitehttp://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