nikogian
New Member
Offline
Posts: 2
|
Hi all, I need some help with calculating the metal widths in my design in order to avoid electromigration. My IC process provides me with the maximum allowed DC current density for each metal layer, VIA etc at 110 degrees Celsius. I have the following questions concerning the width calculation:
1) What about AC currents? the process gives me a rule about the allowed peak AC current density but what about steady sinusoidal currents? Should I calculate the width according to the effective current Iac/(2*pi) ? (Iac is the amplitude of the sinusoidal current)
2) When a wire transfers both AC and DC current, Should I just add the DC current and the effective AC current and then calculate the width?
3) What about the temperature. I don't think my circuit will ever reach 110 degrees while working. Is there a chance the the given DC current values are too pessimistic? If so, is there a way to calculate the maximum current density at a lower temperature?
4) I have read that electromigration is not a very big problem at high frequencies. If I calculate the width for sinusoidal currents using the effective current Iac/(2*pi), it seems like frequency is ignored. How can I account for the AC current frequency while calculating the metal width?
Thanks in advance, John
|