Overview

Birck supplies a selection of photoresists for both optical and electron beam lithography.

Optical Lithography:

• AZ 1518AZ1518: Positive photoresist, thicknesses from 1-4
• AZ 9260AZ9260: Positive photoresist
• SU8SU-8: Positive resist

Electron Beam Lithography:

• 950 PMMA A4: Positive resist
• XR1541 (HSQ): Negative resist

Section

Subsection

Sub-subsection

References

Main Wiki Page

Optical Photoresists

AZ1518

Composition

Electron Beam Photoresists

950 PMMA A4

Properties

• Composition: 4% polymethylmethacrylate of average molecular weight 950,000 dissolved in anisole.
• Refractive Index: 1.49-1.52 at 632.8nm.
• Good adhesion to most substrates

Manufacturer recommended process: (summarized from Microchem PMMA Data Sheet)

1. Solvent clean of substrate.
2. Dispense 5 - 8 mL for a 150 mm wafer.
3. Ramp to 500 RPM for 5 s OR let sit without rotation for 10 s.
4. Quick ramp to spin speed, holding for 45 s.
5. Prebake on hot plate at 180 C for 60-90 s.
6. Expose with dose between 50-500 μC/cm² depending on equipment and polymer.
7. Development: For high resolution, 1:3 MIBK to IPA. Rinse in IPA or DI water immediately following develop to prevent scumming. Blow dry.
8. (Optional) Postbake: 100 C hot plate for 60-90 s. Note that PMMA will reflow above 125 C.
9. Removal: Will generally be removed by common positive PR strippers, including acetone. Thorough removal can be accomplished with Remover PG at 50-60 C.

Image Added

Image Added

References

AZ1518

PMMA:

Microchem product page

Microchem PMMA FAQ

Microchem PMMA Data Sheet