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  1. #1
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    Poly Oriantation in analog layout (vlsi)

    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.

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  2. #2
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    Re: Poly Oriantation in analog layout (vlsi)

    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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  3. #3
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    Re: Poly Oriantation in analog layout (vlsi)

    Quote Originally Posted by vidiyala View Post
    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.
    Really, I am not Sam.



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  4. #4
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    Re: Poly Oriantation in analog layout (vlsi)

    Thank you for ur reply

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



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    Re: Poly Oriantation in analog layout (vlsi)

    Quote Originally Posted by vidiyala View Post
    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



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  6. #6
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    Re: Poly Oriantation in analog layout (vlsi)

    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.
    Really, I am not Sam.



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