Protek Protective Stop Layer

General information

The ProTEK B3 primer and protective coating combination may be used for the following applications:

  • to cover and protect frontside structures during backside processes (eg. KOH etch).
  • to minimize wet etch damage caused by punch-through.
Example process: front side circuitry coated with Protek, for through-wafer KOH etching to allow access to SiN membranes

Processing steps

Sawatec manual coater + two hotplates in Zone 13 are required. Before starting, set one hotplate temperature to 205°C, and the second one to 120°C.

ProTEK B3 Primer:

  • Spin coat: 1500 RPM for 60 s, acceleration: 1000 RPM/s. Dispense with a pipette into the central 2-3 centimeter area of the wafer before the start of spinning.
  • Softbake: 205°C for 60 s. Use a metal surface to cool the wafer down after the bake has finished.

ProTEK B3 Protective coating:

  • Spin coat: 1000-4000 RPM for 60 s, acceleration: 1000 RPM/s. Dispense directly from the beaker into the central 2-3 centimeter area of the wafer before the start of spinning.
    1500 RPM approximately results in 6.5um, and 3000 RPM creates a 4.5um thick film.
  • First bake: 120°C for 120 s.
  • Second bake: 205°C for 60 s.

Note: an excess amount of dispensed coating material may form some spiderweb-like foamy structure around the coater. Remove with a paper wipe if necessary. Acetone may need to be used after multiple coatings to clean up properly. To avoid, make sure to dispense the minimal amount required.

The backside of the wafers may need to be cleaned with a Q-tip and acetone. If not possible, inform staff before proceeding. When finished, check the hotplate and spinner chuck surfaces, and clean as necessary.

Removal of the protective layer

To remove the ProTEK after the process has finished, use the High_Strip_10 min recipe of the Tepla in Zone 02. The oxygen plasma will remove the protective layer, but some particles or a thin layer of polymer residues may remain on the substrate surface.

Next, immerse the samples into the piranha bath in Zone 02 for 10 minutes to remove any leftover residues. If applicable, follow with a QDR (Quick dump rinse), then the SRD (Spin rinse dry) or manual dry.

Alternatively, if the sample may not be compatible with piranha, the Remover 1165 can be used in Zone 02. Placing the sample into the bath for 10 minutes removes all remaining residues. If applicable, follow similarly with a QDR (Quick dump rinse), then the SRD (Spin rinse dry) or manual dry.

Storage recommendations

  • ProTEK B3 Primer: room temperature shelf life is 180 days.
  • ProTEK B3 Coating: room temperature, shelf life is 365 days.

Availability

Get in touch with litho staff members for details and training.