Distance of layers involved in a parasitic capacitor

Hi all Cadence experts,

I am wondering if there is a way to get the distance between the two
layers involved in a parasitic capacitor extracted by QRC? Each
parasitic capacitor requires two involving plates, I need to find out
the distance between the two.

The distance should be calculated at the point where the capacitance
was sensed by Cadence (I assume that point is also the closest the two
plates come together).

Is there a way to do this? I think Cadence extraction tool knows this
info because it calculates the capacitor value but it does not spit
out the info. Even a switch to force Cadence extraction tool to spit
this info out will do the job for me.

Many thanks in advance for any help/clue in this regard.

Regards,

Hrh

 

Hi there,

I really think that Cadence Qrc DOESN'T know about the distance
between layers.
It only calculates the Caps based on the intersection area (eventually
can
involve perimeter too).

For ditance between layers the best answer, I think, should come from
the people which are developing the technology you are working with.

Best Regards,
Marcel

 

With all due respect, I disagree. How can QRC report a capacitance
value without knowing the distance between the two conducting plates
involved? The distance between plates is designer dependent not
necessarily technology related. The designer can draw two metal
polygons far or close from/to each other.

At least the QRCFS (QRC field solver) should know this distance.

Regards,

Hrh

 

Hi there,

Probable I've misunderstood something.
I was assuming that you are looking for vertical distance between
shapes of different layers which are overlapping and create a
capacitor.
Is this not what you want ?

Maybe you want just the distance between 2 polygons (in 2D)?!?!

Best Regards,
Marcel

 

Hi Marcel,

My terminology was not quiet right, I should have used "conducting
plates" instead of "layers".

So, when you have a layout, there are many polygons, they may run in
parallel at the same layer, or may overlap at different layers, and
all different combinations which overall lead to many parasitic
capacitors. A capacitor's value is determined by the distance between
the conducting plates, the dielectric material between the plates
(e.g. SiO2) and its permittivity, and the shared area between the
conducting plates.

Now what I want is to find the distance between a parasitic
capacitor's "conducting plates". If the conducting plates are not
parallel to each other, then I want the distance at the point
conducting plates come _closest_ to each other. This is really a 3D
problem not 2D.

My gut feeling is QRC or its Field Solver has access to and uses this
information. I just don't know how to get it out.

Regards,

Hrh