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

I've really enjoyed the whole process, I've learned a lot. For a long time it’s been something I've wanted to do but the idea of just going at it on your own is a bit daunting. You're not really going to know what you're going to get out of it. And you're not going to know if what you've actually done is correct, so having an option to take a course with some other people has been a really great way of learning it.

Jamie Iles (digital course)