Stepper Mask-Making Guidelines (Generic): Difference between revisions

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'''Tutorial:''' If you are not familiar with the difference between designing Contact Litho Masks and Stepper Litho Masks/Reticles, please review this short tutorial:
'''Tutorial:''' If you are not familiar with the difference between designing Contact Litho Masks and Stepper Litho Masks/Reticles, please review this short tutorial:


*[https://wiki.nanofab.ucsb.edu/w/images/c/cb/Demis_D_John_-_Stepper_Reticle_Layout_vs_Wafer_Layout.pdf Demis D. John - Stepper Reticle Layout vs. Wafer Layout.pdf][[File:Stepper Reticle Tutorial - Reticle Masking Schematic.png|alt=Schematic of stepper blocking off adjacent Images on reticle and exposure onto different wafer locations.|thumb|268.6x268.6px|Reticle Patterns (“images”) are independent of wafer-layout.  The reticle could contain 20 variations while the wafer could have only a few of the Images actually exposed, in any desired location on the wafer, determined buy the Job Programming.]]
*[https://wiki.nanofab.ucsb.edu/w/images/c/cb/Demis_D_John_-_Stepper_Reticle_Layout_vs_Wafer_Layout.pdf Demis D. John - Stepper Reticle Layout vs. Wafer Layout.pdf][[File:Stepper Reticle Tutorial - Reticle Masking Schematic.png|alt=Schematic of stepper blocking off adjacent Images on reticle and exposure onto different wafer locations.|thumb|268.6x268.6px|Reticle Patterns (“images”) are independent of wafer-layout.  The reticle could contain 20 variations while the wafer could have only a few of the Images actually exposed, in any desired location on the wafer, determined buy the Job Programming.|link=https://wiki.nanofab.ucsb.edu/w/images/c/cb/Demis_D_John_-_Stepper_Reticle_Layout_vs_Wafer_Layout.pdf]]


For the stepper you are designing for, make sure you know:
For the stepper you are designing for, make sure you know:

Revision as of 19:22, 19 July 2024

Generic Stepper Mask Parameters

Tutorial: If you are not familiar with the difference between designing Contact Litho Masks and Stepper Litho Masks/Reticles, please review this short tutorial:

  • Demis D. John - Stepper Reticle Layout vs. Wafer Layout.pdf
    Schematic of stepper blocking off adjacent Images on reticle and exposure onto different wafer locations.
    Reticle Patterns (“images”) are independent of wafer-layout.  The reticle could contain 20 variations while the wafer could have only a few of the Images actually exposed, in any desired location on the wafer, determined buy the Job Programming.

For the stepper you are designing for, make sure you know:

  1. The maximum exposure field size, and
  2. The minimum gap between adjacent patterns/images that must be dark chrome (for the system's reticle shutters to block adjacent images)
  3. Either the quoted product number from our photomask vendor quotes, or reticle size/thickness/material (eg. 5" x 5" x 0.090", Soda-Lime glass)

These values will vary depending on the stepper you're designing for. Contact the Stepper's Process Expert or Tool Supervisor to find out these values.

Generic Stepper design/programming CAD files & spreadsheets

  • Example Toppan Order Form via Digidat
    • Academic users may request the UCSB Nanofab's quotes from various photomask vendors.
  • Fill out this Spreadsheet before programming your job on the machine, using your CAD file:
  • On-wafer alignment marks:
    • This pattern is usually available on a system reticle - you are not required to include the alignment mark pattern in your own designs.
    • Please check for the specific Stepper you are using.

Example CAD File and Programming

Using an Example CAD file, here is the corresponding Mask Order Form & Spreadsheet:

CAD Tips

  • By default, Wafer flat is Down (–Y) with respect to your CAD file.
  • Utilize the "Cell" and "Cell Instancing" functionality in your CAD layout program! (aka. a "Block" in AutoCAD). Highly recommended to use KLayout, not AutoCAD. See Calculators + Utilities > CAD Design Tips for tutorials.
  • Center your entire design around the coordinates (0,0). (0,0) should always be the center of your device, wafer and/or photomask/reticle. Photomask vendors should then NOT "auto center" your designs on the plate.
  • Inside each sub-Cell, also design around the cell's (0,0) origin.
  • Create a Cell called "reticle_layout" or similar, that is an exact representation of what the printed reticle patterns should look like (typically at 1x wafer-scale, if not including the outer templates for the stepper system). Instance the Device's Cells into reticle_layout, and reference this Cell on your mask order form. (You can also Instance the same cells into "device_layout" and "wafer_layout" cells during design/verification.)

If you follow the above rules, your printed "reticle_layout" Cell will have Instances of each of your design's Images/patterns, and the coordinates/sizes of these Cells are exactly what you use to write your Stepper program.

See the example CAD Files here: