About the inductor layout

[gaom9]

Hi,
I met a strange question about the inductor layout when doing the LVS.
I am designing a LNA circuit which contains 3 inductors, and I used the PDK which is 1P4M process to generate Layouts of them. The Layout of the inductor is make up by Metal4. And the three inductors are connected out from their ports by different metals, two by Metal3 and one by Metal4.
But there is a strange question come out when doing the LVS.
The three inductors are reported different errors.
The two inductors which connected out from their ports by Metal3 can not be recognized, the one inductor which connected out from its ports by Metal4 can be recognized but its parameters do not match the parameters of SCH (but its parameters are the same in SCH and Layout).

Why?...........................................
Please help me.........................

Thank you.
Best regards!


Inductor connected by Metal3

Inductor connected by Metal4

 

[jecyhale]

You should check it will the foundry.

 

[shhaha]

I also meet the same problem in lvs: all parameters on schematic and layout are same but after lvs the inductor parameter of inner radius became zero in layout (dismatch information)while the actual parameter was still no changed.Anyone can help us?Thanks!!

 

[sat]

If you look at the extraction rules - think from the point - What is the difference between - a routed metal4 drawing [which might take any amount of turns ]- versus an inductor? - how the spiraling metal forms an inductor.
You will discover - it is a dummy layer - inside which, metal4 shapes are not treated as conductor, rather part of device recognition shape.

Now, what does that mean? - it means you should be extremely careful - to not to drop a tiniest piece of unwanted metal shape inside some dead-zone [I didn't say dummy layer, because at times this drawn-dummy is internally sized-up or sized-down]
And, how does it recognize turns - maybe by counting edges, or, number of bends, angled-intersection of edges - and some numerical calculations inside the dummy/dead-zone/device-zone.
While connecting an Ind device - if you inadvertently introduce metal pieces - inside the zone - your device might not form well - or might lead to parameter-mismatch.

 

[nsccad]

Your extraction rule desk coding could be difference depend which tool you are using. You should use some CAD layers to help out with the terminals define.