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iDFM Flow: An ECO Implementation of

Metal, Via Filling

Giriraj Kakol, Dibyendu Goswami, Rajesh Karturi, Suryanarayana

Prekke, Intel Corporation, Bangalore, India

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Motivation

As the complexity of designs and process design rules are growing

with every generation, getting a correct by construction DFM fill isbecoming increasingly difficult

PDEs (Physical Design Engineers) end up spending huge

manual effort in cleaning-up DRC and density violations

All the manual effort is lost when there is a design ECO that makes

previous fill polygons obsolete as it could potentially create DRCs,

shorts on the ECO-implemented database.

Running DFM flows from scratch is not viable as this would

require spending the same amount of manual effort as before

to clean up the DRCs

Need automation to improve on ECO Layout productivity

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Prior Art

Manual Effort of cleaning the DRCs, Shorts

Spends nearly two days on a typical ECO per partition

Tedious and Error Prone


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iDFM Filling

Incremental Fill Flow relies on re-using the old fill data as much as

possible

No re-filling


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Fill

Legalization Detection and removal of shorts/DRCs

DRCs are detected through foundry runset


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Cleanup of Shorts Short is detected if a metX fill polygon overlaps or touches a metX

design (route) polygon The portion of the fill polygon that overlaps the design polygon is

removed

In case of metX fill touching the route polygon, it is shrunk along

the preferred routing direction by 1 manufacturing grid so that

touch can be avoided.

Any additional DRCs created at this stage are handled in later

stages of DRC correction


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iDFM Flow Steps


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Identify density failing windows (Metals/Vias)

on trimmed database

incrementally re-fill without creating

additional shorts.

Fill flow doesnt produce clean fill db as it

cant comprehend all complicated DRCs at

UDSM process nodes.

Fill trimming cleans shorts, DRCs but refilling

introduces more DRCs which are addressed

incrementally

Certain cases need addition of small stubs to

fill/cell data depending on the design rule.

TAT (Turn Around time) of iDFM is 6X faster

than rerunning fill from scratch

Trim Done

Density

Error?

Incremental

Filling

DRC analysis

and Fixing

Clean Fill DB

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iDFM Advantages

Short clean fill: Removes the Original FILL polygons overlapping on

ECO polygons for avoiding shorts.

Shorter runtime: Incrementally FILLs Metals and Vias based on

density and DRC requirements.

DRC clean Filling: Set of algorithms to handle individual DRCs.

Addresses Via density issues: Incrementally generates FILL Vias by

connecting only the floating metal fills; without causing any shorts.

Parallelize filling: Option to independently FILL set of Metal and

Vias.

Region Filling: BBOX option to correct only in the specified window.

Easily portable: Easy portability to next process nodes.iDFM Flow: An ECO Implementation of Metal, Via FillingISPD 2013

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Results

Proved solution for ECO implementation on all in-house projects

99% of the DRCs introduced by the fill are being removed

Shorts clean ECO DB with metal fill

Very few density errors

6X improvement in TAT (Turn Around time) for ECOimplementation.

8 person weeks of manual effort reduction on one of the internal

CPU projects.


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DRC Results

Addressing DRC requirements through iDFM:


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50

100

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Metal1 Metal2 Metal3 Metal4 Metal5 Metal6 Metal7 Metal8

Pre iDFM DRCs

Post iDFM DRCs

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Density Results

Addressing density requirements through iDFM:


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Metal1 Metal2 Metal3 Metal4 Metal5 Metal6 Metal7 Metal8

Pre iDFM Density failing windows

Post iDFM density failing windows

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Conclusion

Automated flow that replaces the tedious and error-prone manual

approach of correcting the DRCs, shorts on ECO Database.

Generic approach : Independent of process node.

Judicious re-use of Foundry runsets (rules deck)

Applied special treatment to the errors that are reported by the

runsets to enable Metal/Via DRC and density errors.

Bounding box and layer specific iDFM to improve throughput

Incremental Refill on density failing windows


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Back up slides for poster

presentation


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Original FILL and CELL:

FINAL FILL and CELL after incrementally refilling to correct

DRC/density:

Incremental Refill:

Fill Polygon

Signal

Polygon


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Addressing complex DRVs Addition of stubs to Signal/FILL nets for cleaning DRCs.

Patterning Signal/FILL nets for clean DRCs.


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16iDFM Flow: An ECO Implementation of Metal, Via FillingISPD 2013

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