Low Resolution Mask Making Procedure

UPDATE: We have also made masks with a minimum feature 9 microns on a, .635 micron grid 8"x10" for $40 (or on a .8 micron grid for $25). Need to convert files. Photoplot store is now closed. New source including 1/50 mil resloution: www.fineline-imaging.com.

Prepare file in LEDIT

• It helps to reduce the size of dark features slightly; our present vendor (PreTech) overexposes the film. Dark features in an interdigitate electrode array come out about10 microns larger than designed. For example, a grating with 25 micron lines and spaces should be drawn with 15 micron lines and 35 micron spaces.
• No circles ("flashes"); polygon "circles" from CircCIF are OK
• All features in positive quadrant
• Polygon size is limited by number of characters; seems to be about 75 verticies for coordinates specified by large numbers (10,000).
• A template is available: MASKtemplate.tdb (for use with L-Edit) or MASKtemplate.cif (may also be used in MAGIC)
  The mask plate is 4" square, the exposure is 3" diameter, but best not to use the outer 1/4" of a wafer if possible. There are two circles on the template which do not print; one at 3" diameter, and one at 2.5".
• IMPORTANT: It is best to use the template. If you do not, and you do use polyons, it seems that you must include at least one rectangle in the file before any polygons, or it may print a black page. There is apparently some initilization problem, presumable with psmask which is solved by including at least one rectangle. You can delete the resllution marks in the template file.
• Only one cell--create single cell as follows:
  • copy data (mycell) to a new cell (myflat) and flatten
  • copy that to a new file (temp:myflat), and delete cell0 in that file.
• Rename CIF layers for which mask files are desired to one or more of the following: CPG CCP CAA CCA CMF CMS CVA CSP CSN CWP CWN COG. However, more than one mask level can be combined into a single printout (of CPG for example) as follows:
  • Rename cell myflat to myflat1
  • Under SETUP, choose CIF..., and change the name of the first desired layer to CPG.
  • Save as a CIF file (temp1.cif).
  • Repeat for other layers (myflat2...).
  • Read layers back into LEDIT, and place in a single cell.
  • The final file must again contain a single flat cell, with a single layer of CIF name CPG.
• Use SSH protocol (e.g. NiftyTelnet or SFTP normal FTP login will probably not be accepted because it allows a clear send of password) to transfer to sunray.dartmouth.edu [previously sunset.dartmouth.edu] (use TEXT mode). You need a northstar login (northstar is Dartmouth's unix network; it is similar to but independent from Thayer's unix network.
• Login to sunray.dartmouth.edu, and type:

  tr "\015" "\012" < filename.cif | psmask
  
  [or if the file came text mode from a mac type: psmask < filename.cif]
  

• Edit file CPG from ps to eps, save as myfile.eps. For a bounding box starting at the LL corner of the file and extending 8" (576 point) to the right and 10.5" (756 point) up, the first two lines should read as follows.

  %!PS-Adobe-3.0 EPSF-3.0
  %%BoundingBox: 0 0 576 756
  

• If you have text (there is text in the mask template above): To change the text font size from the default 6 point, edit the 6 the line shown below in the file (the division by 2.8e-5 is because the entire file is scaled from points to centi-microns). Note, if you have text, without the EPS box above it may not print. You also need to tell PreTech to be sure to run the file through the RamPage system. There are 72 points to the inch; a point size of 0.7 is just readable by some with the naked eye, easily readable with a magnifying glass.

  /Helvetica findfont 6 2.83e-05 div scalefont setfont 
  

• FETCH or FTP the myfile.eps from sunray (use TEXT mode).
• Verify that it will import into WORD as an eps file, and that it prints well on a 600dpi laswerwriter (just drag the eps file onto the printer icon).
• Rename the file namedate.eps (e.g. cgl080195.eps). The .eps is important.
• Use disk doubler (or stuffit) to create a self expanding archive (SEA).
• If you're not using Blitzmail, binhex the SEA file so it can be sent over e mail (Blitzmail does this automatically when sending off campus).
• Email to info@pretech.com, attention Jim, Tell them you want
  • 8.5X11 inch film output
  • Maximum resolution: 4040 dpi (6.5micron laser spot)
  • POSITIVE (or NEGATIVE) film.
  • If text is needed: run it through the RamPage system; note, there are two places where 4040 dpi resolution needs to be set.
  • Do NOT convert to pdf (that will limit the resolution).
  • Follow up with a phone call: 802-296-7737