Pattern Area

The cost of electron beam lithography is proportional to the pattern area, dose and beam current. The dose depends on the photoresist, the beam current depends on the desired pattern quality/resolution and the pattern area depends on the user. It is extremely useful to determine the total print time using the write time calculator to accurately plan the session or make adjustments to the pattern to reduce cost.

A write session that takes more than several hours should be carefully considered. For example, we briefly estimated that a single print for a prospective project will take 80 hours to print. At a rate of $200/hr, this will cost $16,000 to print a single sample. This may be acceptable if the sample is guaranteed to work, but we took a more prudent approach by asking the following questions:

After careful consideration, we decided to perform a 1 hour test print to determine the lowest possible dose and highest possible current that will yield an acceptable pattern. From this exercise, we determined a condition that allowed us to print the patterns at least 4.5x faster which effectively reduced the cost from $16,000 to $3,556 per print!

KLayout - Compute Layer Area Macro

KLayout can be used to quickly and accurately determine the pattern area by using a macro. Download the macro named calc_area_hier.lym and follow the instructions at the beginning of the webpage to install it. This will add a new menu item called Tools -> Compute Layer Area. To macro will compute the total area of all selected layers for the top cell. To use the macro:

  1. Right click on a cell and select "Show As New Top" from the drop down menu
  2. Highlight the layers of interest
  3. Run the macro by selecting Tools -> Compute Layer Area
  4. A dialog box will appear displaying the total area for each selected layer
  5. Convert the area units from μm2 to mm2