Continue to Site

Welcome to

Welcome to our site! is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

metal density calculation

Not open for further replies.


Junior Member level 2
Jul 2, 2015
Reaction score
Trophy points
Activity points
How can i calculate the metal density in a particular layout? Is there any formula to measure it?

thanks in advance

The formula is {metal area}/{total area} but this is not
much help. You have to tabulate all of the in-layer
features to get the {metal area}. This is usually done
using DRC scripts since those tools are right for this kind
of thing.

Use foundry provided Density rules - as freebird stated above.. these are kind of DRC rules..
Calibre, PVS, Assura can do a density check.

Back to Basics:
Metal Density - is a point function, and therefore various functional representations are possible, {there is nothing like absolute value of density}. That means - different functional representations & context, can result in different density numbers, in the same design, at some specific X,Y location on a specific layer.
Let us see what the above means...
For a design - for a particular metal layer , say metal-2, {sum-total metal-2 area} / {total design area} = overall density of metal-2 in the design.
However, that is too gross representation, that does not ascertain how uniformly metal2 {route & fills or floating metals} is distributed across the whole area - some part of the chip might still has too much of metal-2, and some other places too sparse, although achieving overall density.. In most cases, density is measured by sub-dividing design into multiple smaller tiles/windows and density is measured on a tile-by-tile basis. Most popular method of density measurement mechanisms are 'walking-window' and 'centre-weighted-average-window'.

"Walking window" also known as "Stepping Windows" : in which a window of specified dimension (say 100um by 100um) is used for measuring density - then the window is moved along X-axis by half window dimension (that is 50um) - and again density is measured in that window, and such thing goes on - till it reaches X-max of the design, then the window moves half of its Y-size along Y-axis, again started moving in X-axis - in a very similar way a scanner scans a document. So, any point in a design - is most likely fall in the overlap zone of 4 windows. 1/4th {a quadrant} of a window stores the average density of 4 overlapping windows.
"Center weighted average windows" : in this method, multiple different concentric windows(rectangles /or/ squares) [from smaller to bigger dimensions] are put around a point in the design and density is measured in each of the window, and then all the density numbers are added together with a weight-factor to each of them (normalized) - to represent the effective density number.

Which method to choose - and why?
For a given foundry & process-node, Foundry will dictate {in the DRM} - on what exact density measurement technique they want, with tile/window(s) dimensions and step dimensions and in case of weighted average - the weight factors and so on..

Not open for further replies.

Part and Inventory Search

Welcome to