What is the difference between PODE and CPODE?

When we talk about CPODE (Continuous Poly on Diffusion Edge) and PODE (Poly on Diffusion Edge), we’re looking at how the poly gate interacts with the diffusion edge in standard cell layouts. If you're working on layouts in advanced nodes like 7nm or 5nm, you'll likely deal with these concepts regularly.

PODE (Poly on Diffusion Edge)

When you use PODE, the poly gate ends at the active (diffusion) edge of the standard cell. That means it doesn’t continue into the neighboring cell. This makes it easier for you to handle isolation between cells. There’s less risk of shorting, and you don’t have to worry much about complex edge processing. We usually see this approach in older or less dense technologies, where the gate pitch isn’t as tight.

CPODE (Continuous Poly on Diffusion Edge)

In CPODE, the poly runs continuously across the diffusion edge into the next cell. When we want to achieve aggressive scaling, especially in FinFET or GAA designs, we go with CPODE. It helps us pack transistors more tightly by reducing the contacted poly pitch (CPP). But when you use this, you have to be more careful. We need special cut patterns and dielectric fill to properly isolate the source and drain regions, or you could run into shorting issues between contacts.

If you use PODE, you get a simpler layout with better isolation, but it's not as compact. When we choose CPODE, we get better density and smaller CPP, but we also take on more complexity during layout and fabrication. So, if you're working in advanced nodes, we often have to use CPODE despite the added challenges—because scaling matters.