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What is a manufaturing grid ?

NAADHAN

Hi All,

                 Can anyone explain me what is a manufaturing GRID  & its significance in our design?

 

Thanks & regards,

NAADHAN

  •  Hi Naadhan,

    The manufacturing grid is the smallest resolution of your technology process. The value can be found in the tech lef file, for example:

    MANUFACTURINGGRID 0.005 ;

     but I always double-check with the sign-off DRC deck to make sure this is correct. Any shapes created in your design must align to this grid, otherwise you will get DRC errors. 

    - Kari

  • Hi Kari,

        Thanks .....but can you elaborate more on

    1)How our cells get aligned with the manufacturing grid ?

    2) what are the circumstances that may lead to mis-alignment with manufacturing grid and the precautions to avoid it?

    3) Can cells as well as nets get mis-aligned ??

    Thanks & Regards,

    NAADHAN

  •  Hi Naadhan,

    Cells actually are aligned with the "placement" grid, which is a multiple of the manufacturing grid. The placement grid is really made up of the rows in your floorplan. The rows are composed of SITEs. For example, in the LEF you will see that each std cell references a SITE that is defined either in the std cell LEF or the tech LEF. The std cell SITE will have the same height as your std cells, but the width will be as small as your smallest filler cell. When you create ROWs in your floorplan, you are really laying out a bunch of these SITEs side by side. The std cells then get placed on these rows.

    So, as long as you have everything defined correctly - manufacturing grid, SITE definitions, and ROWs in your floorplan, you should always be aligned with the manufacturing grid. Encounter knows what the grid is, and will only place things (cells and wires) on grid. Occasionally, you will find something offgrid - maybe a hand-placed cell, or a hand-routed wire, where you either turned off DRC checks or maybe entered bad coordinates directly into a fp or DEF file. But these days, you really have to work pretty hard to get something offgrid. :-)

    Nonetheless, you can always check for any offgrid shapes with Verify Geometry, and of course, your final signoff DRC deck.

    I hope this has answered your questions!

    - kari

  • Hi Cary,

    I am getting in trouble with a lef file not having specified the manufacturing grid. If I add the line as you said:

    MANUFACTURINGGRID 0.005 ;

    the lef file is not accepted. My guess the syntax is missing something but I don'.t know what. Can you tell me the what is wrong?

    The value is correct because the tool takes the same valeu by default (it's for cmosp18).

    All the best for you,

    Andries

  • Hi Andries,

                  There is no problem with the syntax.

    MANUFACTURINGGRID 0.005 ;  -----> is correct in syntax. Problem is because of something else .

    NAADHAN

  • Hi Andries ,

     May be you need to check the place were you added this .....
    Have look at this :
                       

    Order of LEF Statements

    LEF files can contain the following statements. You can specify statements in any order;

    however, data must be defined before it is used. For example, the     UNITS statement must be

    defined before any statements that use values that are dependent on UNITS values, LAYER

    statements must be defined before statements that use the layer names, and VIA statements

    must be defined before referencing them in other statements. If you specify statements in the

    following order, all data is defined before being used.

    [VERSION statement][BUSBITCHARS

    statement]

    [DIVIDERCHAR statement][UNITS

    statement]

    [MANUFACTURINGGRID statement][USEMINSPACING

    statement]

    [CLEARANCEMEASURE statement ;]

    [PROPERTYDEFINITIONS statement]

    Hope this might help you...

    Regards,

    NAADHAN

  • Hi NAADHAN,

    Thank you very much for your prompt answer. I really appreciate it. I put the statement MANUFACTURINGGRID right after the UNITS in the tech file.

    The syntax thing came up when I see the units are declared like this

    UNITS
        DATABASE MICRONS 1000  ;
    END UNITS


     so I thought that it might need for MANUFACTURINGGRID something different. My problem is that writing

    MANUFACTURINGGRID 0.005 ;

    the import process stops. Removing the line, the import goes fine.

    Now the place is right, the syntax OK, I don`t see what else to look for?

     

    Thank you very much,

    Andries

  •  Here is the top of my current LEF file:

    VERSION 5.6 ;
    NAMESCASESENSITIVE ON ;
    BUSBITCHARS "[" ;
    DIVIDERCHAR "/"  ;

    UNITS
        DATABASE MICRONS 1000  ;
    END UNITS

    MANUFACTURINGGRID 0.005 ;
    USEMINSPACING PIN OFF ;
    USEMINSPACING OBS OFF ;

    PROPERTYDEFINITIONS
        PIN ASSIGNTYPE STRING ;
    END PROPERTYDEFINITIONS

    Do you see any major differences between this and your lef? Can you cut and paste the part of your log file where it complains about reading in the LEF?

     

  • Hi,
    There are quite few: version 5.1, BUSBITCHARS "[" ;DIVIDERCHAR "/"  ;  &  PROPERTYDEFINITIONS
    were missing.
    In my file I  did BUSBITCHARS "[ ]" to make it run correctly.
    Now it is quite fine.
    If my documentation is written that

    Before you verify geometry, the design must meet the following conditions:

    The following LEF statements must be specified:

    ❑ CLEARANCEMEASURE

    ❑ USEMINSPACING statements for obstructions and pins

    For more information, see the LEF/DEF Language Reference.

    The design must be routed.

     
    and I see that you don't have CLEARANCEMEASURE like CLEARANCEMEASURE MAXXY ;
    but as I said your LEF file is working fine.
     
    Thanks a lot.
     
    PS. The log file:
     
    Loading Lef file Inputs/vs18tech.lef...
    ***ERROR*** <parse error> at line 44
    Last token was <um>
    **ERROR: (SOCLF-3): Error found when processing LEF file 'Inputs/vs18tech.lef'
    **ERROR: (SOCLF-26): Seems no technology information defined in fisrt lef file.
    Please rearrange the lef file order and make sure the technology lef file is the
    first one, exit and restart First Encounter.
    although the statement was at the right place.
     
    To start from begining I would say that somehow it was better when the statement was missing completly (see the log):
     
    **ERROR: (SOCLF-81): No MANUFACTURINGGRID value was given, it is set to minimum LEF unit of 0.005 um.
     
     
    but, it was always .... a but....
     
    at the routing moment the tools was complaining that the MANUFACTURINGGRID  was missing and comes up with errors.

  • Hi Kari:

    i have the error: No MANUFACTURINGGRID value was given. It is set to minimum LEF unit of 0.005 um

    i have two.lef file, one is .lef, another is _antenna.lef

    the top of my .LEF file is:

    VERSION 5.3 ;

    NAMESCASESENSITIVE ON ;

    UNITS
        DATABASE MICRONS 2000  ;
    END UNITS

     

    the top of my _antenna.lef file is :

    VERSION 5.4 ;

    MANUFACTURINGGRID 0.005 ;

     i don't know what is wrong with my LEF file? Thank you very much!

     

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