Photoresist bilayer S18xx + LOL 1000 for < µm UV lithography

Photoresist bilayer S18xx + LOL 1000 for < µm UV lithographyEdit

Recipe:

• Dehydratation: hotplate 155°C x 2 min + cooling

• Adhesion promotion (optional): Primer Shipley 30 s static + 3000 rpm x 60 s

• Dispense of ballast resist: LOL 1000 (filtered) all over the wafer + spin 6000* rpm x 60 s.

* high resolution allowed but deposition thickness must be below 150 nm)

• Softbake of ballast resist: hotplate 155 °C x 5 min + cooling

• Dispense of optically active resist: Shipley S1805 (filtered) all over the wafer + spin 6000 rpm x 60 s (accelerate in 2 s)

• Softbake of optically active resist: Hotplate 115°C x 60 s + cooling

• UV Exposure: 3” square mask in vacuum contact. 15 s x 5.7 mW/cm2 on MJB3 or 1.2 s x 30.5  mW/cm2 with i-line (365 nm) filter on MJB4.

• Development: Pure MF319 developer : shake @ room temperature and rinse in water

* The developing time is a critical parameter if your goal is a submicron resolution. It has to be measured each time, using a test wafer for instance. It can depend strongly on the storing time at air of the MF319 and on the amount of resist already dissolved during previous developments.
It can be determined by observing the red cloud formed by the resist dissolved close to the edges of big pattern elements, while moving the wafer back and forth in the developer. The correct time corresponds to the disappearance of the cloud + 5-10 seconds depending on the targeted undercut. Typical time is between 30+5 and 60+10 s.

• Drying (optional): Hotplate  60°C x 2 min

• Evaporation: Deposition below 150 nm.

• Lift-off: Ultrasonic bath / Remover  1165 @ 50 °C x (9 min in a first bath + 1 min in a new clean bath). Rinse with water. Dry.

Good Luck ;-)