MLA150 - Design Guidelines

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Notes and specifications to help you design your CAD drawings for use on the Maskless Aligner, Heidelberg MLA150.

The term Convert refers to the Unix conversion software used to import your CAD files into the MLA150Menu software.

General CAD Guidelines

  • GDS / GDSii is the preferred file format (fewest errors).  DXF, CIF, BMP and Gerber are also available.
  • Note the Cell that you want to print.  Only one Cell may be printed, so use Cell Instancing to create combinations of Cells.
  • Note the Layer(s) to print.  The system can select either a single Layer, or can combine multiple layers via Boolean OR.
  • The Origin (0,0) in your file is the reference for all coordinates during exposure, including alignment mark exposure/measurement.
  • Your file name cannot contain any spaces or special characters except for underscores.
  • Make sure the file extension is all lower case (e.g. .gds not .GDS) as some design programs (e.g. Klayout) will create a file with an upper case file extension.

CAD Design File Specifications

GDS aka. GDSii

  • This is the preferred file format for import into the machine.
  • Make note of the "Cell" that you want to print, often called the "top cell" as it can contain a hierarchy of other child/instanced cells.
    • This is called "GDS Structure" in the Convert software.


Common export format for users of AutoCAD.

  • DXF files can often lose the "units" when exported, meaning the Convert software may not know if a length of "10" means "10 mm" or "10 µm".
  • It is easy for these files to have "open polygons", meaning the ends of the polygon don't attach, preventing the software from calculating the filled-in area to write. You can use L-Edit or KLayout's Design Rule Checker automation to try and locate these kinds of errors.
  • Make sure to use Convert's [Viewer] and the [Measure] tool to make sure the scaling factors are correct.


The BMP Pixelsizes are shown in the BMP options when importing a file into Convert. The BMP pixel size can be adjusted to change the scaling of the bmp file (from 40 to 4000nm). The base pixel size is 40nm.


To Be Added


To Be Added

High-Resolution Writing

It has been suggested to use the "CD Bias" (Critical dimension) to reduce your feature sizes during the Convert process, and then compensate by going to higher exposure doses (widening the features back to original size). If you choose a "-200 nm" CD Bias, then run a Focus-Exposure Array ("Series" in MLAMenu), you will look for the higher/lower doses (depending on photoresist and design polarity) that bring the features back to the original designed sizes.

Overexposing alleviates the stitching boundaries.