what is metal filling ?why it is using after complting routi

what is metal filling ?why it is using after complting routiing ?

Because to maitain particular density..For example if ur building a house then the bricks are to be in a sequential manner am i right? If one of the brick is missing then it may not be uniform and u may not get the proper building block.....Its a density issue..

Hope it is clear for u..If u still have any doubt then u cme back to me...

Re: what is metal filling ?why it is using after complting r

Hi,

I have doubt regarding this metal fill.Is there any other purpose of metal fill other than metal density,like cross talk or timing.Suppose my design having sufficient metal density,I didn't do metal fill, this will effect on any other way on design

Re: what is metal filling ?why it is using after complting r

metal fill is done to avoid electromigration effect.

Re: what is metal filling ?why it is using after complting r

designer_ec said:

Hi,

I have doubt regarding this metal fill.Is there any other purpose of metal fill other than metal density,like cross talk or timing.Suppose my design having sufficient metal density,I didn't do metal fill, this will effect on any other way on design

Click to expand...

Although the global density may be ok, a local density requirement also has to be made (typically 200um x 200um squares that stagger across the die in 100um steps). For the most part, metal fill is for manufacturability. It is only needed in planar processes and if is not satisfied, dishing or the rubbing off of metal traces can occur.

Metal fill is also typically done in small squares (100um^2) as something greater than that will give floating metal violations.

This is not to say that life is great once the metal fill is inserted as it can cause problems for RF circuits if not accounted for. If you autofill a chip and you have coplanar transmission lines, the fill can be placed between the ground and the signal trace, thereby affecting your impedance of the line. For digital circuits, it's less critical.

Re: what is metal filling ?why it is using after complting r

Korgull is correct. Also, metal fill has nothing to do with electromigration.

As Korgull said, fill is added purely for manufacturability purposes. It is not something the designers want. That is why it is added right at the end, after routing, after the design is done.

Unfortunately, the fill can impact the timing on the wires because it changes the wire-to-wire capacitance.

Re: what is metal filling ?why it is using after complting r

p_shinde said:

metal fill is done to avoid electromigration effect.

Click to expand...

This is completely wrong. It has nothing to do with EM. It is used to gain a better uniformity during CMP process.

You are right complexplasma but respect other members. They might have wrong understanding of concepts. Purpose of this forum is knowledge sharing. We are here is to correct and help them, not to scold them.