[SOLVED] Endcap and Decap Usage in P&R

[ranaya]

Hi All,
I want to perform place and route based on UMC 65nm node. However in the design kit, I cannot find above "physical only" cells and instead there are only filler cells (with/without n/p capacitors) and well tap cells. I was wondering whether the Endcaps and Decaps can be replaced by those filler cells with capacitors. Is this possible ?

 

[ThisIsNotSam]

Hi All,
I want to perform place and route based on UMC 65nm node. However in the design kit, I cannot find above "physical only" cells and instead there are only filler cells (with/without n/p capacitors) and well tap cells. I was wondering whether the Endcaps and Decaps can be replaced by those filler cells with capacitors. Is this possible ?

there is no difference between a filler cell that serves as a decap or a specific cell that serves as decap. just terminology, same effect.

as to endcap, they have two reasons to exist: make row termination drc clean, and make timing of the cells near the end the same as the ones in the middle. if your process does not require these, you don't need endcaps.

 

[ranaya]

Thanks for your quick response.

there is no difference between a filler cell that serves as a decap or a specific cell that serves as decap. just terminology, same effect.

So at the finishing stage, where the filler cells are added, can all those be filler cells which do have capacitors ? I prefer to use N+P cap fillers as they are smaller, however P cap (only) filler provides very low leakage.

Anuradha

 

[ThisIsNotSam]

So at the finishing stage, where the filler cells are added, can all those be filler cells which do have capacitors ?

It is legal, but there are consequences. You may pay the price in leakage.

 

[kumar_eee]

there is no difference between a filler cell that serves as a decap or a specific cell that serves as decap. just terminology, same effect.

as to endcap, they have two reasons to exist: make row termination drc clean, and make timing of the cells near the end the same as the ones in the middle. if your process does not require these, you don't need endcaps.

Perfect answer!!!. My comments are below.

Process team/Fab comes with certain requirements of well alignments/well rings on layout boundary, if the designer knows the alignment DRC , he can draw well rings/sometimes metal around the boundary to meet process requirements.

When these cells are placed on boundaries of a partition/sub design,we are ensuring that the integration at higher level will not see any abutment problems.

 

[gstekboy]

Not needed unless you are not running any calibre DRC checks.

 

[ThisIsNotSam]

Not needed unless you are not running any calibre DRC checks.

I don't see how this is related

 

[gstekboy]

Hi ,
For place and route tool tool won’t care physical only cells. The run will go through pnr without any fail.

 

[ThisIsNotSam]

Hi ,
For place and route tool tool won’t care physical only cells. The run will go through pnr without any fail.

That's not good advice. You need the endcaps/tiecells in there as early as possible to make sure you are not messing your floorplan or underestimating the block area.