Autostep 200 Mask Making Guidance

Photomask Ordering Info

• Plate Material: Soda-Lime or Quartz / Chrome
• Dimensions: 5" x 5" x 0.090"
• Magnification: 5x (assuming CAD file shows on-wafer patterns)
• Right Reading if Chrome is Down (assuming CAD file shows on-wafer patterns)
• Barcode is optional, but recommended. Max number of characters for GCA barcodes is 10
• Instruct vendor that design is for a "GCA AutoStep200 with 5x reduction".
• You can insert your design into the photomask template yourself (below) with no barcode, or ask the vendor to insert your 1x (wafer-scale) design into the appropriate GCA template and they can add a barcode.

CAD Files

• Photomask Template: Dark-field (polygons/objects are clear) at 5x Magnification (GDS)
  • This template is designed to be submitted to the photomask vendor to print as-is, no scaling applied - it is already at 5x magnification.
  • Insert your wafer-scale designs into the template as Instances scaled UP by 5x.
  • Template is written for "objects/polygons are CLEAR" - choose your design polarity accordingly.
  • Your device cell should have center of die at (0,0), and instance it into the template with coords (0,0).
• GCA Alignment Marks CAD File can be downloaded here.
  • You can optionally include these in your die, allowing the system to perform Local alignment in addition to std. Global alignment.
• Registration/Overlay/Alignment Measurement: 100nm Vernier CAD file

Mask Layout

• Maximum exposable single-image size: 14.8 x 14.8 mm at 1x wafer-scale (74mm square at 5x reticle-scale). Photomask vendor can accept up to max. 78mm X 78mm @ 5x reticle-scale.
• For multiple Images (patterns) per photomask mask: ≥1mm (wafer-scale) / ≥5mm @ 5x mask-scale of chrome in between adjacent Images/patterns.
• For multiple Images per photomask, you'll need to calculate the distance, in mm, for the shutter blade positions to block off the unwanted regions of the mask.
  • There are 4 shutter blades, XL(left)/XR(right)/YF(front)/YR(rear), that start at Position=0mm (not blocking any part of the mask), and can extend up to Position=97mm, blocking the entire mask. For the first 13mm (Position = 0→13mm), nothing is blocked on the 14.8mm exposure field.
  • Remember that the photomask is rotated 180° from how it's loaded into the reticle box.

Alignment Marks (Global, Local/DFAS)

To learn more about how these alignment marks work with the system, see the reticle handbook

To Do: "Reticle handbook" is missing!

.  In our system we mainly use manual global alignment to get +/- 0.25 or better alignment tolerance. Local alignment can be used but needs some characterization for each process.

• Global alignment marks:  These marks and how to place them on the mask are described on page 5-44 to 5-47 of the reticle handbook and are included as an attachment to this document. The difference of our system from the manual is that the objectives are 63.5 mm apart, not 76.2 mm as indicated in the manual.  The distance of this mark (or marks) to the center of the cell in X and Y should be noted, this is the key offset and will be required when exposing a job.  (Positive offset values are left for X and up for Y).
• Local alignment marks:  Uses Digital Fine-Alignment System (DFAS). These marks and how to place them on the mask are described on page 5-33 to 5-34 of the reticle handbook and are included as an attachment to this document.  If possible use one of each type if you desire to try to use local alignment. These can be light or dark field in nature.  The distance of the center point of this mark (or marks) to the center of the cell in X and Y should be noted, this is the key offset and will be required when exposing a job.
• Alignment Marks CAD File can be downloaded here.

Test Structures

• Vernier Scales: These can be included to quantify the alignment offset after an exposure is done.  The reticle handbook has an example of vernier scales on pages 5-49 to 5-53.  You should include them for any layers that require critical alignment.
• Resolution:  If you have room in the mask layout, it is good to have features that can give the resolution of a given exposure.  The resolution should show both “pillars” and “trenches” in the resist so that you can see whether the focus or exposure needs some tweaking for your particular process.