Specific Process Knowledge/Lithography/LiftOff
Feedback to this page: click here
Lift-off process
The lift-off process is used to pattern a material that can be deposited as a film on a substrate. The material is patterned by depositing the film on top of a patterned masking material, which is then dissolved, thus leaving only parts of the substrate covered in the material. Although this may in theory be done using any combination of mask and material, the most common is using photoresist as a lift-off mask for metal.
The image to the left shows a schematic of the lift off process.
- 1. The substrate is coated with the masking material.
- 2. The masking material is patterned. The mask must be a negative image of the desired material pattern.
- 3. The material is deposited on top of both mask and substrate. The mask sidewall slope should be negative in order to prevent the material covering the sidewalls during deposition.
- 4. The masking material is dissolved, thus lifting part of the deposited material.
- 5. The remaining material forms the desired pattern on the substrate.
Lift-off wet bench 07
The user manual, and contact information can be found in LabManager
| Equipment | Lift-off | |
|---|---|---|
| Purpose |
| |
| Bath chemical |
NMP (Remover 1165) / Rinse in IPA | |
| Process parameters | Process temperature |
Heating of the bath is possible. The heating has been limited to 60°C |
| Ultrasonic agitation |
Continuous or pulsed The power may be varied | |
| Substrates | Substrate size |
|
| Allowed materials |
Silicon or glass wafers Film or patterning of all but Type IV (Pb, Te) | |
| Batch |
1 - 25 | |
Process information
Lift-off is used for lift-off using resists that are soluble in NMP (N-Methyl-Pyrrolidone), supplied in the cleanroom as "Remover 1165". Both AZ 5214E and AZ nLOF are soluble in NMP.
For information on processing of AZ nLOF, see here: Process_Flow_AZ_nLOF_2020.docx For information on image reversal of AZ 5214E, see here: Process_Flow_AZ5214_rev.docx