Mask Submission Procedure

Britton Plourde 1/98 (Updated by Sergey Frolov  6/04)

(1) Design pattern using LASI

• Draw a 100mm square as the upper leftmost feature in the drawing. Put this square in a layer by itself (I’ve been putting it in layer 50). CPRX will assign the upper left corner of this square as the reference point for mexing (see below).
• Keep cell names to 6 or fewer letters or numbers (i.e. no dashes, underscores, etc.)

 (2) Create .TLC file in LASI

• If you designed your drawing in AutoCAD, you may find software called LinkCAD useful. It can convert from .DXF (the output of AutoCAD) to .TLC or .GDS. Check the converted files. Make sure the units are right, and that dark and light regions of your AutoCAD drawing correspond to the same in the converted drawing. LASI can also convert .DXF to .TLC via dxf2tlc.exe, but this feature doesn't work correctly sometimes.
• If you need to use angles, the preferred angles are 45 degree, and 1:2 or 2:1. Use "Octagonal cursor" function of LASI to create angles. Angles close to  but not quite the preferred angles are the worst. The reason is that the conversion program generates millions of rectangular shapes to implement such angles for beam writing.

(3) Create .GDS file

• Run "tlc2gds.exe" located in the lasi7\ root directory (or use the 'System' menu in LASI7).
• If pattern contains text, make sure the ‘convert text’ option is selected.

 (4) Transfer .GDS files to  isis.micro.uiuc.edu  (or 'ISIS', the Alpha machine at Microelectronics)

• Our account is VANHAR (ask for password, or ask John Hughes to reset it)
• Try to keep all .GDS files for each mask in a separate subdirectory. (‘md [.<dir-name>]’)
• Changing directories in VMS, ex.: ‘cd [vanhar.array]’
• Use ftp program in binary mode. ***

 (5) Convert .GDS files using CPRX on ‘ISIS’

• CPRX is a combination of several beam-writing routines with the interface written by J. Hughes.
• Check with John Hughes for the latest version.
• Type CPRX to run, while in directory contain the relevant .GDS files.
• CPRX will ask for .GDS file to convert (can only convert one at a time) and the name of the corresponding cell (in most cases the two will be the same).
• CPRX will ask for the origin ref. layer described above in (1).
• Use default value for field size.
• Only perform a coarse/fine split if pattern contains features larger than 20mm (this threshold used to be 10 mm). If pattern is split, it will be written in two stages: one beam current value will be used to write the fine features, then another current will be used to fill in the coarse regions.
• Proximity correction is useful for obtaining sharp features and good corners on small patterns, so in general, it should be used. However, if pattern is complex (e.g. Penrose array), proximity correction can take a long time (days).

• darkfield = mask mostly chrome, features are clear glass

  lightfield = mask mostly clear, features are in chrome

• CPRX will generate several files (all in binary, I think) which start with the cell name followed by ‘L#.’, where ‘#’ will be the particular layer (i.e. each layer of pattern will have its own set of files). The ‘.’ will be followed by a combination of files with six possible extensions:
• {B} - no prox., no split
  {BF ; BC} - no prox, split
  {BPF ; BC, DOS} - prox, splt
  {BP ; DOS} - prox, no split.
  These are the files that must be referenced in .JOB file.

(6) Check conversion results

• You can use CAPROX program to view GDS and B, BF, BC etc. files, to check if the conversion went well. CAPROX displays elementary shapes into which your patterns are split for beam-writing by CPRX. Things to look for are discontinuities or other geometric conversion errors. Pay special attention to the angles. Angles other than 45 or arctan(1:2) degrees could cause CPRX to create thousands of shapes to better fit these angles. Remember that if coarse/fine split is performed, CPRX may split your pattern so that part of it appears in *.BF files, and the rest - in *.BC files.
• To run CAPROX, use X-Windows in the REXEC mode, the X-WIN command line should read '@dvhpc10.com'. If running CAPROX not on DVHPC10, be sure to create a file yourcomputer.com in [.vanhar]  directory on ISIS, which should be identical to dvhpc10.com, but with yourcomputer.mrl.uiuc.edu as a display node address. This ensures that the graphic output of CAPROX is relayed to your computer.
• CAPROX only runs in the Pseudo Color mode, make sure that the pseudo color mode is selected in X-WIN configuration.
• You can run @dvhpc10.com file from the telnet terminal as an alternative way to start CAPROX, if CAPROX cannot be started by X-WIN.

 (7) Layout mask

• This determines where patterns will be placed on the 2x2in² mask area.
• Coordinates are in mm: |x| < 25.4, |y| < 25.4, upper left corner is (-25.4,-25.4).
• Make sure patterns don’t overlap. Since you are placing the patterns relative to their upper leftmost feature (actually the orig. ref. layer, square, but basically the same thing), it’s quite possible to make a mistake and misjudge the width of something. - BE CAREFUL!
• Features placed outside  2x2in² area will be difficult to copy in the present mask aligner.

 (8) Write job file

• Use a text editor such as ‘notepad’, ‘wordpad’, etc.
• Follow an old job file as an example - several recent JOB files are on the DVH group website, the most recent being TB.JOB.
• some important terms in .JOB file:

 (9) Submit a job request form to John Hughes

• Copy all binary files from ISIS to the PDP computer (the machine that actually runs the beamwriting). Type the following line:
  COPY *.B* HATHOR"200 232"::[200,232]
  and be careful there is no space before the open quote or after the close quote. Use a similar command to copy the .DOS files if proximity correction was used.
• Fill in the electronic job submission form: Form for Mask Submissions

 (10) Problems or questions, ask:

• John Hughes, 324 Microelectronics
  office: 3-4674
  lab: 4-5845
  email: hughes @uiuc.e d u
• Sergey Frolov, B9 MRL
  office: 5-0213
  lab: 3-0099
  email: frolov @uiuc.e d u