5 Replies Latest reply on Jun 16, 2010 1:58 PM by chris_balcom

    check alignment


      Hi All,
      This discussion is regarding to check the "alignment structure"  is properly placed in GDS or not.
      We are placing "alignment structure" in our layout(GDSII) at two location,those are
      *Lower left of the cell and rotation is R0
      and other one at
      *Upper right of the cell and rotation is R90

      These structures will be kept at specific distance from the BBOX of cell,but BBOX will be different for different cells.
      What is the best option check these  "alignment structure" placement in GDS using calibre DRC/Compare GDS?


      Govind Kulkarni

        • 1. Re: check alignment

          Hi Govind,


          I hope we see ideas from other people too, and I'm happy to offer a few to get the ball rolling.


          At first glance, this sounds like something that may be appropriate for "pattern matching". If the relationship between the alignment structure and the BBOX is always supposed to be exactly the same, maybe pattern matching would be a good way to check those two locations. I haven't used pattern matching so I'm not familiar with other details yet.


          EXTENT CELL BBOX is another possibility but I don't know if it will accomodate the rotational checking you want. Aside from the open question about the rotation, it might be easy to get the extent of the alignment structure and then size it the exact amount of the desired spacing, then check the edge of the oversided extent to make sure it is exactly coincident with the edge of the BBOX. I suppose each alignment structure should be coincident with two edges of the BBOX, and that furthermore, all 4 edges of the BBOX would then eventually be coincident with edges from the oversided alignment structures.


          What do you think of those ideas?

          • 2. Re: check alignment

            Hi Chris,

            Thanks for the reply.

            I am not finding any details on the "pattern matching" can you please help me on this.

            Also this is My idea to check the structures:

            Some how we have to create a two "alignment structure" placed GDS, one is at 0,0 with RO rotation and the other one is at upper right(X-Y are not fixed values) with R90.

            Placing a first structure at 0,0 can be achieved by LAYOUT SYSTEM {GDS | GDS2 | GDSII} (By default the instance/cell will merge/place at 0,0 -R0)

            But placing the other structure at specified X-Y location or at specified offset is the thing unknown to me,we no need to worry about the rotation because I can create a one more cell with a rotated structure of R-90 to merge.


            Please somebody give some suggetion to place a structure at specified X-Y location or at specified offset.


            Govind Kulkarni   

            • 3. Re: check alignment



              What about using EXTENT CELL command combined with the SHIFT command to move the polygons in one direction with the intent of measuring the area of the shifted polygon outside the original. Unless the extents are square, you can determine which is rotated 0 and 90 degrees based on area.



              • 4. Re: check alignment


                Thanks for your reply.

                Other polygon I am able to generate using

                SHIFT and ROTATE commands.

                • 5. Re: check alignment

                  Hi Govind,


                  I went to SupportNet and searched for:   pattern matching

                  (First I clicked the button to "search all my products")


                  Here are a few hits that seemed interesting:


                  Pattern Matching Flow...


                  Calibre Pattern Matching in Verification Runs...


                  Pattern Matching Invocation


                  If you're not using pattern matching already, then it may be fairly involved to adopt it just for this one check, I'm not sure about that.