VLSI Layout using Microwind Kishore C Acharya

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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 the Colors submenu click on Color

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

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

Creating SPICE Netlist From File menu select menu item Convert Info Select SPICE netlist

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)

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

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

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

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