AllenD
Member level 5
Hi Team,
I am using TSMC 65nm for analog circuit tapeout and I have a small question about connecting the core to the I/Os.
I am using TSMC designed ESD devices, which is under the bondpad. As is known, "analog signal ESDs" is just a wire with some clamps to power supply and ground. (in other words, "analog signal ESDs", for LVS purpose, have the bondpad terminal and core terminal shorted together). But for layout view of "analog signal ESDs", the bong pad terminal is on the top layer (of course, that's how it connect to bondpad) and core terminal is on the bottom layer (M2, which is closer to the active devices)
My questions is how should I connect the core signal trace to the bondpad? I can:
A. Connect the core signal trace from top metal directly to the bandpad. Then the signal trace is clean and neat. But does this mean the signal trace is "further away" from the ESD device and the ESD protection may degrade?
B. Via down my signal trace from top metal to M2 and connect to the ESD terminal. Does this mean the signal trace has to endure the via down and up plus the more resistive M2 trace? But the M2 portion of the signal trace is really close to the active ESD devices, hence a better ESD protection?
The two options have the exact same LVS result. But from the layout point of view, which is better practice and why?
Thanks!
Allen
I am using TSMC 65nm for analog circuit tapeout and I have a small question about connecting the core to the I/Os.
I am using TSMC designed ESD devices, which is under the bondpad. As is known, "analog signal ESDs" is just a wire with some clamps to power supply and ground. (in other words, "analog signal ESDs", for LVS purpose, have the bondpad terminal and core terminal shorted together). But for layout view of "analog signal ESDs", the bong pad terminal is on the top layer (of course, that's how it connect to bondpad) and core terminal is on the bottom layer (M2, which is closer to the active devices)
My questions is how should I connect the core signal trace to the bondpad? I can:
A. Connect the core signal trace from top metal directly to the bandpad. Then the signal trace is clean and neat. But does this mean the signal trace is "further away" from the ESD device and the ESD protection may degrade?
B. Via down my signal trace from top metal to M2 and connect to the ESD terminal. Does this mean the signal trace has to endure the via down and up plus the more resistive M2 trace? But the M2 portion of the signal trace is really close to the active ESD devices, hence a better ESD protection?
The two options have the exact same LVS result. But from the layout point of view, which is better practice and why?
Thanks!
Allen