FreePDK45:LithoSim Kit Installation

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As the minimum feature size shrinks, optical effects in lithography play a larger part in yield. In order to model these effects and identify places in a layout where optical effects may affect functionality, we have inplemented a Calibre Litho-Friendly Design (LFD) rule deck. Using the LFD tool, the mask image of a layer is generated, then applied to an optical model which generates Process Variability bands. These PV bands represent the largest and smallest shape that is likely to print from the mask image. The LFD tool will flag errors where it is likely that the printed image will be problematic.

This kit is not included in the FreePDK base-kit distribution, because it would more than double the file-size. If lithography simulation catches on, then we may eventually include this kit as part of the base-kit distribution.


You must first install the FreePDK (at least version 1.2) in order to use the LithoSim Kit. Once that kit is installed, follow these quick steps:

  • Download the file NCSU-LithoSim-FreePDK45-1.2.tar from the NCSU CDK Download Page.
  • Unpack the tarfile: "tar xvf NCSU-LithoSim-FreePDK45-1.2.tar". The tar file contains a file called NCSU-LithoSim-FreePDK45-1.2.tar.gz. (You can verify the validity of this file using the instructions in the README file if you want to.)
  • Move the file NCSU-LithoSim-FreePDK45-1.2.tar.gz file to the directory above where you installed the FreePDK and cd to that directory. You should see the "FreePDK45" directory in the current directoy's listing.
  • Execute the command "tar xzf NCSU-LithoSim-FreePDK45-1.2.tar.gz" from that directory. All files should be unpacked into the correct directories.

See the file README.LithoSim.txt in the root directory for a detailed list of the files included in this distribution.

Running Calibre LFD

Calibre LFD can be executed just like Calibre DRC in interactive mode. The interactive mode is easy to use and is explained in the Layout Tutorial #4 - Lithography Simulation . This tutorial assumes that you have already worked through Layout Tutorial #1 - Introduction to Layout and DRC.

Please note that this kit has been designed to work with Calibre2007 and later.