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Poly Oriantation in analog layout (vlsi)

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vidiyala

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Hi Friends

In Layout we are using orientation of metals and poly etc
i know that metal orientation is used to make the connectivity easier

BUT WHAT IS THE USE OF POLY ORIENTATION IN LAYOUT.

Thanks in advanced.
 

Some advanced nodes go as far as requiring only one
orientation of poly (E-W, or N-S) to make lithography
work ("stick" style, Lam Research). Certainly you want
-uniform- orientation between any devices that are to
match, and this may even include the S-D direction as
things like extensions and halo are not strictly self aligned
and can make variations in source resistance etc. if you
"butterfly" a matched pair.
 
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    SEULI

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Hi Friends

In Layout we are using orientation of metals and poly etc
i know that metal orientation is used to make the connectivity easier

BUT WHAT IS THE USE OF POLY ORIENTATION IN LAYOUT.

Thanks in advanced.

it's something you cannot pick in most cases, as the foundry will only support one orientation. In older technologies you could pick the poly orientation such that you could change the aspect ratio of a certain block. It was a common trick for SRAM blocks so you could rotate them to better fit your floorplan.
 

Thank you for ur reply

with the orientation how source resistance is going to change
or any other parameters
 

Hi Friends

In Layout we are using orientation of metals and poly etc
i know that metal orientation is used to make the connectivity easier

BUT WHAT IS THE USE OF POLY ORIENTATION IN LAYOUT.

Thanks in advanced.

Because during lithography step in fabrication process it prevents from mismatches due to pattern shifts between the transistors which may effect the performance
 

Orientation doesn't prevent mismatches. There is still reasonable variation from transistor to transistor. The process is optimised for a given orientation, however. If you understand how the fin layer is drawn, you will quickly realise why.
 

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