Nanometer Pattern Generation System (NPGS)

Make: 
J.C. Nabity, Lithography Systems
Model: 
NPGS
category: 
Lithography
contact: 
John Li <jun.li@mcgill.ca>
location: 
Wong Microscopy center
Coral Name: 
n/a

Associated Documents and References

  • User's manual for NPGS v9.1.

 

Equipment Used

  • NPGS software, DesignCAD Express 16

 

Basic directions

The basic directions are presented in this page. For any question, please refer to the NPGS manual. Or use the "What's this" icon in the lower right corner of the NPGS and Run File Editor windows.

 

Starting with the program

Running the program 

  • Double-click the NPGS icon on the desktop.
  • If you use the NPGS computer connected to the microscope, a calibration of the DAC can take place. Let this calibration complete without interruption.

Creating a new project directory

  • Select "Project - Create New Project" In NPGS menu. Enter the name of your project and click the Create button.

NPGS window

Designing a pattern

  • Start DesignCAD Express from NPGS window.

DesignCAD Express 16 window

  • Press Crt+G or select "Options - Grid settings...". Check the Display grid and Snap grid boxes. Adjust the grid step if necessary.
  • Use the functions under NPGS tab to draw filled polygons and/or lines and/or circles.
  • When your drawing is completed, use the command "NPGS - CheckAll" to check for common errors and ignored entities.
  • Use the command "NPGS - MaxMag" to check the size of the field. Press o key to center the writing field and to optimize the magnification value.
Warning: Make sure that the correct MAG scale value is used. For the Mira3 system, the MAG scale is 222220.
  • Save the file by using the "NPGS - Save" command. The pattern will be saved to the current NPGS project in a *.dc2 file.

Note: The normal command "File - Save" should not be used.


Creating a run file

  • Select Run File Editor from the "Commands" menu.

NPGS Run File Editor

  • Choose the type of the first entity between "Alignment", "Pattern", "Array", "Fracture", "MoveOnly", "Command" or "Comment". The default one is "Pattern".
  • For one of  the 4 first entities, double click on the "Pattern Name" prompt to bring up a list of the available *.dc2 files in the current project. Select a pattern in the list and double click on it or click "Open".
  • Set the parameters of the entity in the right hand hand side of the window labeled "Highlighted Entity Data". For the "Pattern" entity, the important parameters are the "Magnification", "Center-To-Center Distance", "Line Spacing", "Measured Beam Current, "Dose" (Area, Line or Point).
  • Add entities by increasing the "Number of entities to process".
  • When the run file is completed, click the "Save" button and enter a name. The run file will be saved to the current NPGS project in a *.rf6 file.
  • Click the "Simulate Writing" button to simulate the real time writing and to perform an error-check. For complex run files with several patterns, the button "Estimate Total Time" will give a faster summary of the pattern writing.

Tips

Exposure tests

To determine the optimal parameters to expose a pattern, a variety of exposure times and point spacings must be tested. In DesignCAD, a pattern may be duplicated using the "MakeArray" command and each copy may be set to a unique color. Then a different dose (i.e. exposure time) can be attributed to each color in the run file by using the "Set Doses" button which allows a serie of doses to be easily generated. The copies of each line of the array can be set to a different layer also, so that point spacing can be tested.

A test pattern can be repeated also by using the "Array" entity in the run file with "Exposure Steps for Array" enabled. The serie of doses is set by selecting "View". During exposure, the stage moves according to the column and row spacings of the array ("Array Spacing").

Alignment marks, windows and patterns to align

In general, the alignment marks/windows and patterns are designed separately in 2 DC2 files. An offset can occur due to diverse mistakes (writing field not centered in both files, error in the position of the patterns, ...). To avoid this problem, the alignment marks, the windows and the patterns should be drawn in the same file.

Each window/overlay set is drawn in a seperate layer, as well as the pattern to align. For example, with 4 alignment marks, the window/overlays are drawn in layers 1 to 4, and the pattern can be drawn from layer 5 to 19.

In the Run File Editor, the layers used for patterns are skipped in "Highlighted Entity Data" of the "Alignment" entity, whereas the layers for windows/overlays are skipped for the "Pattern" entity.