gdsfill

gdsfill is an open-source tool for inserting dummy metal fill into semiconductor layouts. It helps designers meet density requirements and prepare GDSII layouts for manufacturing by analyzing, erasing, and generating dummy fill patterns across multiple layers. The tool is designed to integrate easily into existing design flows and ensures reproducible, automated preparation of layouts before tape-out.

This project is still under development. Please report any issues you encounter and always verify your layout before tape-out deadlines to prevent submission failures.

Installation

gdsfill can be installed as a Python package. We recommend using a virtual environment to keep dependencies isolated.

$ python3 -m venv venv
$ source venv/bin/activate
(venv) $ pip install --updage pip
(venv) $ pip install gdsfill

Density

This command calculates the utilization per layer and prints the values. It is useful to check layer density before and after running the fill process:

gdsfill density <my-layout.gds>

Erase

If a layout already contains dummy fill, or if previous fills should be removed, this command erases all dummy metal fill from a layout:

gdsfill erase <my-layout.gds>

Fill

To insert dummy metal fill into all supported layers of a layout, run:

gdsfill fill <my-layout.gds>

By default, gdsfill creates a temporary directory for intermediate data. Use --keep-data to retain all generated files in a directory called gdsfill-tmp:

gdsfill fill <my-layout.gds> --keep-data

If you only want to simulate the process without modifying the layout file, use --dry-run:

gdsfill fill <my-layout.gds> --dry-run

Custom Configuration

By default, gdsfill inserts dummy metal fill into each layer using predefined parameters. To apply different parameters or restrict fill to specific layers, you can create a custom configuration file.

The following example config inserts fill only into TopMetal1 and TopMetal2:

PDK: ihp-sg13g2
layers:
  TopMetal1:
    algorithm: Square
    density: 60
    deviation: 1
  TopMetal2:
    algorithm: Square
    density: 60
    deviation: 1

Note

Example config files are available in gdsfill/configs.

To use a custom config file, pass it with --config-file:

gdsfill fill <my-layout.gds> --config-file <my-config-file.yaml>