Calculating Resistance and Metal width for Power MOS

Status
Not open for further replies.
R

raju.hirematt

Newbie level 1
Joined
Sep 25, 2009
Messages
1
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Location
Bangalore
Visit site
Activity points
1,288
Hi,
I want to calculate resistance of the power mos and also width of the metal layer used for power routing. Let say, my mos transistor has L=0.3u, W=50u and M=150 and I fingered it and made width of 10u. In this case how can I calculate the total resistance of the MOS and also power routing metal layer (so that I should not get any EM and IR drop).

Thanks in advance,
Raj
 

Well, of course you will get -some- I*R drop.

I have found interconnect to be as much as half the
total, in doing 100mOhm IC pass-FETs - with thick
metal, even.

You have to do it bottoms-up, I've just used Excel and
serial squares, parallel stipes, etc. to get the totals.
Lots of measuring and manual entry. Don't forget the
vias (tungsten plugs are very resistive and also a
bad electromigration-ratings hit).
 
The more detailed you make the simulation (you should simulate this) the more accurate your resistance calculation. Metal 1 resistance usually overwhelms all the other metal resistances because it is in narrow stripes on the drains and sources. One half of the MOSFET has all the metal 1 strapped with vias to metal 2, the other half is a long metal 1 strip. I usually simulate each strip as a metal 1 resistor, 50% of the length of the unstrapped side.

Don't forget bond wire resistance.
 
Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…