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Questions on Grid and DBU in Virtuoso layout editor

winever

Hi everybody,

Could anyone tell me the exact definition of Grid and DBU(database unit) in Virtuoso layout editor? What do they refer to respectively? What should be taken into consideration when setting these two parameters or can I set them arbitrarily? Some references on the internet say that the DBU is the minimum resolution unit of a layout and for a standard GDSII stream file, it should be set to 0.001um. And the Grid size is proportional to the minimum electron-beam-spot size used to create the masks. It seems that these two terms are critical when doing layout design, for they are related to masks fabrication. But what do they exactly refer to? I am still confused now. Could anyone explain these two terms to me in detail and offer me some advice on how to set the value of these two terms? I really appreciate it for you help.

 

Regards,

Winever.   

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  • Marc Heise

     Hi Winever,

     

    DBU  are Database Units , thats the resolution your layout data is stored with in the Database. The value you are actually set is called DBUperUU ( Database Units per User Unit ) . A user unit is usually 1um , a DBUperUU of 2000 which is common these days would lead to 1um/2000 = 0.5nm database resolution.

    This is not necessarily your drawing grid, which you allready described correctly as the resolution your mask creator can handle.

     

    Regards,

    Marc

Reply
  • Marc Heise

     Hi Winever,

     

    DBU  are Database Units , thats the resolution your layout data is stored with in the Database. The value you are actually set is called DBUperUU ( Database Units per User Unit ) . A user unit is usually 1um , a DBUperUU of 2000 which is common these days would lead to 1um/2000 = 0.5nm database resolution.

    This is not necessarily your drawing grid, which you allready described correctly as the resolution your mask creator can handle.

     

    Regards,

    Marc

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