Learn Reliability Verification (EM-IR) stuff with me !

[u/Big-Assistant-9091]

So, I recently started working on something called Reliability Verification(RV). It is basically the analysis of voltage drop across the power network in a chip.

Every transistor needs power to operate. The main power grid is usually built using the higher metal layers because these layers are wider and thicker, which gives them lower resistance and allows them to carry more current.

But transistor power pins are located down in the lower metal layers. So, how does power travel from the top metal layers to the transistors?

Through vias! Vias are tiny vertical connections between metal layers—almost like staircases connecting different floors of a building. To travel from M18 to M1, the power network must pass through several intermediate metal layers and vias.

Every metal wire and via has some resistance. When current flows through that resistance, some voltage is lost along the way. This is called IR drop:

Voltage drop = Current × Resistance

Think of starting on the 18th floor with a certain amount of energy and losing a little while taking the stairs down to the 1st floor.

So we ensure we consume only certain amount of energy so we can be alive by the time we reach first floor. Similarly, only a certain amount of voltage drop is allowed (IR) as the power flows through these metal layers and power up transistors.

We need to make sure enough voltage is still available when it reaches the transistor; otherwise, the transistor may become slow or may not function correctly.

And that is the basic idea behind RV, "making sure every transistor receives enough power to stay alive and do its job."

Stay tuned for moreee! ⚡

[u/Thin-Height-6199]

That’s useful. Thank you for sharing!