Connecting to Bond Pads in 0.35um

[ja2bo2t]

We are working in a 0.35um TSMC technology and I have been using the Tanner Hi-ESD Pad library as a guide for designing our pads (digital I and O, analog references, analog out, and power). In this library, and the others that I can find online, the pad is normally only connected to using M1, and it is normally only about a ~20um trace opening to ~40um through 45 degree angles at the pad. On chip we are using a 80um width power bus on M2 and M3; is there any reason why the pad cannot be connected to on M2 and M3? Is it for the ESD protection circuitry?

 

[erikl]

... is there any reason why the pad cannot be connected to on M2 and M3? Is it for the ESD protection circuitry?

No, I don't think so. Anyway, you always have to go to top metal latest at the pad itself. For power bus connection, M1 routing to the pad doesn't matter because of the larger capacity to GND (which is even welcome), but for signal routing better the higher metal levels should be used to keep parasitic capacitance low.