GDSII/GDS2 is a binary file format that represents the layers needed to produce an ASIC.

In the OpenLane flow, Magic is used to ‘stream’ the final GDSII files.

All shapes are assigned to a given GDSII layer, and each layer ends up being used to create a mask, although often this may involve the combination of one or more GDSII layers to form one mask, and the shapes are often grown, or shrunk, or merged and thus what ends up on the mask may not be the same as what was drawn by the designer. Each mask is then used in a photolithographic step to produce the chip.

We can use other programs or even software libraries to generate valid GDSII files. Here I’ve used gdspy to convert the Hackaday logo into GDSII.

You can check the very simple program out here

The Skywater PDK defines all the layers that we can use in the GDSII files.

Course feedback

The Zero to ASIC course was great! Through this course I became more proficient with Verilog and started to not just appreciate, but actually enjoy the design verification! It offers the glimpse at the superpower too - seeing the traces of the original design in what used to be just squiggly lines of the masks before. Plus, I am getting my own piece of a silicon 🙂

Renaldas Zioma (digital course)