[SOLVED] routing with metal layers over MOS

Status
Not open for further replies.
S

shriraj19

Newbie level 5
Joined
Jun 11, 2005
Messages
10
Helped
1
Reputation
2
Reaction score
1
Trophy points
1,283
Visit site
Activity points
1,332
i am lay-outing an OTA which is a critical block for and 16-bit ADC.
can i route with metals over MOS, to save area?
 

Hi,

Actually I cant understand your question..

but, i can tell some tips regarding metal routing..

You can route metals over MOS but you should not touch or short the MOS terminals with the SAME mETAL.. fOR EXAMPLE, IF you use metal1 means u cant draw over mos becuase the drain and source of the mos covered with metal1 so u can use metal 2 and others,, no problem to route over MOS..

HOpe u understand this.. and Any doubt ask me..
 

but i heard that for critical analog and rf circuits the metal over poly should be avoided????


 

Routing with metal 1 or 2 will affect dopings in gate or drain/source and obviously add parasitic capacitances.
From Metal3 and above, it affect only parasitic capacitance. So, we avoid such routing.
In some case, those effects are not critical if your amplifier is not critical ...
 

yeah u can do it but make sure that u don't route metal1.
From metal2 and above will be fine and also while routing keep in mind that u should'nt use vias (any vias) above the active(PO+OD) area. If u place a via above active it effects the Vt of the mos, which is critical.
 

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…