[SOLVED] What is the difference between contact and Via?

[skamthey]

contact & Via

Hi,
What is the difference between contact and Via.

Can we place M1-poly, M2-M1, M3-M2 contacts one over each other so that they overlap in the layout?

 

[kapilsn]

A contact is used to create a commection between M1 and the poly or M1 and OD.
Vias are used for connections between metal layer.
Ex VIA12 for connection between M1 and M2
VIA23 for connection between M2 and M3

yes we can place contact and vias over each other in the layout .If we see the crosssection of the IC they are placed on a diffrent plane.

Regards,
Kapil

 

[keith1200rs]

yes we can place contact and vias over each other in the layout .If we see the crosssection of the IC they are placed on a diffrent plane.

That may be true for some processes and layers, but not all. VIA1 and CONT is likely to be against the design rules because they both connect to MET1. You need to check the process design rules to be sure.

Keith.

 

[erikl]

VIA1 and CONT is likely to be against the design rules because they both connect to MET1. You need to check the process design rules to be sure.
Keith.

Since planarisation (CMP) is standard (for process sizes ≈ ≤ 0.35µm), this doesn't seem to be a pb. any more.

BTW: Just for the bonding pads, stacking VIA(n+1) over VIA is usually not allowed.

 

[keith1200rs]

VIA1 and CONT is likely to be against the design rules because they both connect to MET1. You need to check the process design rules to be sure.
Keith.

Since planarisation (CMP) is standard (for process sizes ≈ ≤ 0.35µm), this doesn't seem to be a pb. any more.

Thanks, that makes sense. I had looked at a 0.8um process and VIA over CONT was certainly forbidden except on pads. On 0.35 it wasn't mentioned so I assume it is allowed.

Keith.