Heidelberg µPG 501

The Heidelberg μPG 501 is a tabletop maskless (i.e. direct-write) ultra-violet photolithography system. It utilizes a 10 W LED diode operating at 390 nm, a 600 × 800 pixel digital micromirror device, and motorized stage, to expose patterns on a resist-coated substrate. The system has a writing speed of 50 mm²/min for the resist AZ 1505 on silicon with a resolution limit of 1 µm, and is therefore well suited for rapid prototyping, and writing larger structures that would be too time consuming for EBL. The Heidelberg is compatible with DXF, GDS, and CIF CAD files. The main instrument PC is offline, but it's connected on an online design PC. In order to copy your design files to the instrument PC, you must first copy them to the design PC, and then from the instrument PC, copy the design file to the... FIXME.

Operating instructions

Measure the diode intensity

1. Make sure the stage is empty.
2. From the 'µPG 501 menu', select 'Tools', and then 'Intens. diode'.
3. Follow the on-screen instructions. The intensity of the diode will be measured at 40°C. Enter the measured value into the logbook on the design PC.

Load your chip

1. Press 'Load substrate' in the software menu. The stage will be moved into the loading position, and a software dialog box will open.
2. Open the dust cover.
3. Place your chip or substrate on the center of the stage, over the four small vacuum holes. Please note the orientation of the coordinate system; the x direction points outwards from the front of the instrument.
4. Enable the vacuum, by toggling the vacuum switch. Make sure your sample is firmly fixed in place. For larger substrates (e.g. 2 inch wafers or larger), you may need to enable suction on additional vacuum regions. Talk to a cleanroom staff member if that is the case.
5. Close the dust cover.
6. Press OK in the software dialog box. The stage will be moved to it's home position, and another dialog box will open.
7. Make sure that the substrate is below the writehead (metallic disc with red light emanating from the center). Not doing so may cause the writehead to be driven into the sample during the next step, potentially severely damaging the system.
8. Press 'yes' in the dialog box for pneumatic focusing (recommended, but requires a distance of approx. 3 mm to the edge of the sample), or 'no' for optical focusing (use for small samples, or when writing close the sample edges).

Design conversion

1. Copy your design file to the Design PC.
2. On the instrument PC, copy to the design file to the correct FIXME, depending on the file type.
3. Select 'Start Conversion Interface' in the 'µPG 501 menu'
4. Create a new job file, by selecting 'File' and 'New' in the conversion interface. Use job file name along the lines of NAME_DATE.
5. Work through the conversion interface. If you plan on performing an alignment exposure, remember to uncheck 'Automatic Centering', and press the 'Reset' button.
6. Finish converting your design by clicking 'Complete Tasks' and then 'Complete Expose Jobs'.

Chip Exposure

1. Click 'Select Design' in the 'µPG 501 menu', and select your converted file (with the FIXME extension).
2. In the right panel of the 'µPG 501 menu', under 'Exposure mode', select the type of exposure you want.
   1. 'Standard Exposure': For blank chips
   2. 'Alignment': For aligning exposures to e.g. chip edges, crosses, etc.
   3. 'Target Mode': Allows users to draw squares to be exposed.
3. Press 'Next'
4. Set your exposure time and defocus (e.g. obtained from a dose test). For an alignment exposure, locate the features (e.g. crosses) that you wish to align to, and enter their corresponding design coordinates.
5. Start the exposure. A progress bar will be shown along with the time remaining.

Exposure

• Dose test
• Standard exposure (blank chip, no alignment to edge, etc)
• Alignment:
  • Edge alignment on a blank rectangular chip
  • Cross alignment: Works like a dream
  • Manual alignment: If you don't have well defined alignment crosses