Why we put a Boron implant / Salicide blockage layer on ESD structures?

[omsi]

Hello,

Can anyone give me the reason why we put an Boron implant / Salicide blockage layer on ESD structures.
Also why do we maintain more spacing between diffusion contacts and Active poly?

Please Reply ASAP.

Thanks in Anticipation,
OMSI

 

[k_90]

Re: ESD Layout

Hello,

Salicide is used to DECREASE the amount of resistance over contacts and poly ect. By adding salicide block you increase the amount of resistance which improves the esd as the current cannot flow as easy down the wrong path.

When a chip fails esd it is normally a short between the drain & source and the easiest way for the current to flow is through the contact which then shorts. Have at least 4x the minimum distance from contact 2 contact and contact 2 poly.

 

[layoutmaster]

ESD Layout

Actually, it's Silicide and not Salicide. The silicidation is used to reduce sheet resistance for instance in POLY and also in Source and Drain difusions, in order to reduce the parasitic resistance.

IN the ESD case, and that's correct from K-90 post, by blocking the silidication you increase the parasitic difusion resistance and then improve your esd performance by making the current flow in a more controlled way.