As of February, 2008, SNF no longer offers in-house maskmaking. We now rely on commercial services which have in recent years become quite competitive.

Vendor Services: There are a number of vendors which SNF labmembers have used to provide maskmaking services. Academic labmembers have access to special pricing; more information is available on this website (SUNet ID required.) Industrial labmembers are eligible for SNF Industrial rates; contact SNF Staff members or the providers listed for more information. Non-Stanford academics are also eligible for academic pricing and may contact Staff for information.

When ordering masks, be aware of the following special requirements for masks to be used on the ASML system at SNF:

• Only mask suppliers approved by the ASML engineering staff at SNF may be used for fabricating masks to be used on the ASML system here. Currently, only Compugraphics and Benchmark are approved as suppliers.
  
• Modified masks (including adhered films or materials, cut-down plates) may not be used on the ASML system at SNF without prior approval from the ASML engineering staff.
  

Transparency Films : For an inexpensive alternative, a mylar transparency print from a high-resolution photo-quality copier (also called "film plotting") can be used as a contact mask in place of a standard photolithography mask. Transparency films don't wear well and have limited feature size resolution (depending on the print quality), but they are cost-effective for limited patterning of larger structures. A caveat: conventional laser printers do not print densely enough for to sufficiently block UV illumination; only film plotters with print density of at least 3800 dpi will work. Go <here> for a list of film plotter providers.

Getting Started: First, you'll need to layout your design. Some good references are listed below.

Contact Mask Design Principles, by Alissa Fitzgerald, AFM Associates, (Process considerations for layouts -- applicable to steppers as well)

Photomask Basics, by Bill Martin (or "all that mask terminology explained" -essential for filling out any Mask Order Form)

The E341 Guide to Tanner LEdit, by Sung-Jin Park (cool tricks with LEdit)

"Tips and Tricks for using LEdit" , contributed by several labmembers.

Layout your device: The recommended file format for quality mask layouts is GDSII. Layouts can be done in AutoCAD or other programs which output to DXF, but be aware that there are common problems and extra costs often associated when submitting files to maskmaking services using DXF formats (see Photomask Basics). SNF recommends using Tanner LEdit (though other GDSII layout programs are often used too) because it is flexible, yet robust. The CAD room, across from the Gowning Room, houses two dedicated desktop CAD PC's which are loaded with Tanner LEdit. The left-side PC also contains several nifty utilities which allow file conversion between DXF (for die-hard AutoCAD users), GDSII, and PostScript (for printer later or for creating Transparency Masks). These are available for anyone to use; instructions and guidelines for their use are posted above each system. SNF also has several Tanner LEdit portable license keys, which Stanford researchers can check out. Contact Staff for more info.

When using LEdit, make sure to review the "Tips and Tricks for using LEdit" section. This page lists the optimal program settings and ways to get the most from your layout with minimal cost and confusion. If you have comments and suggestions to add to this or any other page, contact staff.

And if you have other general questions about maskmaking, please feel free contact Process Staff.