Photolithgraphy#

Note

This page is still under active development

Equipments#

  • Maskaligner

  • Spin-corter

  • Clean room

Materials & Reagents#

  • SU-8 2100

  • SU-8 RG remover

  • SU-8 developer

  • IPA

  • Silicon wafer

Protocols#

  1. Clean the wafer with acetone and IPA, and spin it fast to dry.

  2. Dispense about 4 ml of SU-8 2100 onto a cleaned and dehydrated 6-inch silicon wafer.

  3. Coat the dispensed SU-8 uniformly on the wafer using a spin coater at 500 rpm for 10 seconds with an acceleration of 100 rpm/sec and then sequentially spin at 1500 rpm for 30 sec with an acceleration of 300 rpm/second.

  4. Soft bake the wafer for 10 min at 65 °C and for 40 min at 95 °C on a hot plate.

Important

Keep the coated wafers level. Although different combinations of photoresist, spin parameters and baking time can be used to generate a layer with a given thickness, we recommend the specific SU-8 photoresist formulations and spin rates that we report here, which have been optimized. I The procedure for spin-coating photoresist, photolithography, and wafer development is dependent on the specific equipment used and the process parameters (e.g., humidity, temperature, gas pressure, and UV intensity).

  1. Use a transparency photomask printed over 20,000 dpi positioned over the wafer to produce the master by exposing the wafer to an appropriate dose of UV light as per Microchem’s protocol (350-370 J/cm2).

  2. After exposure, bake the wafer for 5 min at 65 °C and for 15 min at 95 °C on the hot plate.

  3. Develop 20 min in SU-8 photoresist developer. Rinse the substrate briefly with SU-8 Remover RG and IPA and gently dry it with pressurized nitrogen gas.

  4. The wafer was baked for 3 min at 150℃ in the oven.