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Lift-off Comparison Table

Equipment		Lift-off	Fume hood 03: Solvents
Purpose		Lift-off of e.g. metal using UV resists e-beam resists	General solvent work, including lift-off. DO NOT use other fume hoods for lift-off: Fume hood 04: Solvents Fume hood 09: UV development or Fume hood 10: e-beam development
Bath chemical		NMP (Remover 1165) / Rinse in IPA	User defined
Process parameters	Process temperature	Heating of the bath is possible. The heating has been limited to 60°C	Heating is possible using portable hotplate or portable ultrasonic bath
Process parameters	Ultrasonic agitation	Continuous or pulsed The power may be varied	Ultrasonic agitation is possible using portable ultrasonic bath
Substrates	Substrate size	100 mm wafers 150 mm wafers	In principle any, typically chips
	Allowed materials	Silicon or glass wafers Film or patterning of all but Type IV (Pb, Te)	Any cleanroom material
	Batch	1 - 25	1

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 at Nanolab

Lift-off wet bench 07

The user manual, and contact information can be found in LabManager

Equipment		Lift-off
Purpose		AZ 5214E lift-off AZ nLOF lift-off
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
Process parameters	Ultrasonic agitation	Continuous or pulsed The power may be varied
Substrates	Substrate size	100 mm wafers 150 mm wafers
	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