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Extending the NPLUS layer between two PMOS transistors

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Junus2012

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Hello,

I saw this layout where the designers extend the NPLUS layer between two PMOS transistors in NWELL technology,
the two transistors are not sharing the drain or the source, so how he can merge the NPLUS layer in between ?

Thanks


nplus.png

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Sorry, the NPLUS are for the NMOS,
However it is the same issue if we talk about PMOS where it is PPLUS, can we extend it between two transistors when they dont share a contact

- - - Updated - - -

here is another image of extended PPlus layer between four PMOS transistors

2nd.png

I am confused because between a two PMOS the NTUB should be in between, but now between them is the PPLUS
 

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Last edited:

NPLUS and PPLUS are hard-masked by ACTIVE so simply
putting (say) PPLUS somewhere doesn't mean PPLUS is
present on the silicon.

Spacing rules for the "soft mask" of NPLUS. PPLUS may be
too coarse for best packing (litho for ACTIVE will be well
optimized in process development; NPLUS and PPLUS
being masked by ACTIVE, those masks are usually
considered "non-critical" and likely have min width and
min space which are larger than ACTIVE min and space.
Sometimes you will see NPLUS and PPLUS allowed to
be butted, or at a large gap but not a tight one.
 
Thank you freebird for your answer

it is useful to me to know that PPLUS for the PMOS or the NPLUS for the NMOS has no effct on the silicon, in this way I can avoid the minimum space DRC between these layers by merging them, hence optimizing layout area.

I have a further quesion,
In the technology I am using there is no NDIFF or PDIFF, there is only one layer of Diffusion, and I think the diffusion is then defined by the PPLUS or NPLUS, that is what I am thinking, then in my opinion this layer should cover the diffusion area only, why it is extended in the out region of the diffsion ?

Best Regards
 

Some technologies make PPLUS = !NPLUS (or vice
versa) saving them one mask level's reticle cost and
eliminating the creation of a field implant mask as
another step / cost-point.
 
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