Specific Process Knowledge/Lithography/Strip

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Strip Comparison Table

Equipment		Plasma Asher 3: Descum	Plasma Asher 4	Plasma Asher 5	Resist strip	Lift-off
Purpose		Resist descum	Clean wafers only, no metal	All purposes	Resist strip, no metal lift off	Lift-off
Method		Plasma ashing	Plasma ashing	Plasma ashing	Solvent and ultra sound	Solvent and ultra sound
Process parameters	Process gasses	O2 (flow unknown)	O2 (0-500 sccm) N2 (0-500 sccm)	O2 (0-500 sccm) N2 (0-500 sccm) CF4 (0-200 sccm)	NA	NA
	Max. process power	100 W (100%)	1000 W	1000 W	NA	NA
	Solvent	NA	NA	NA	NMP (Remover 1165) Rinse in IPA	NMP (Remover 1165) Rinse in IPA
Substrates	Batch size	1 small sample 1 50 mm wafer 1 100 mm wafer	1 small sample 1 50 mm wafer 1-25 100 mm wafers 1-25 150 mm wafers 1-25 200 mm wafers	1 small sample 1 50 mm wafer 1-25 100 mm wafers 1-25 150 mm wafers 1-25 200 mm wafers	1 - 25 100 mm wafers 1 - 25 150 mm wafers	1 - 25 100 mm wafers 1 - 25 150 mm wafers
	Allowed materials	Silicon, glass, and polymer substrates Film or pattern of all but Type IV	No metals allowed - including metal oxides No III-V materials Silicon, glass, and polymer substrates Film or pattern of photoresist/polymer	Silicon, III-V, and glass substrates Film or pattern of all but Type IV	No metals allowed - including metal oxides Silicon, glass, and polymer substrates Film or pattern of photoresist/polymer	Silicon and glass substrates Film or pattern of all but Type IV

Plasma Ashing

	Photoresist stripping	Descum after lithography	Surface treatment of plastic, ceramic and metal	Ashing of organic material
Process pressure	0.5-1.5 mbar	0.5-1.5 mbar	0.5-1.5 mbar	0.5-1.5 mbar
Process gases	O2 (140 sccm) N2 (60 sccm)	O2 (70-210 sccm) N2 (0-70 sccm)	O2, CF4, N2 or their mixtures	O2
Process power	1000 W	150-1000 W	150-1000 W	1000 W or less for heat- sensitive materials
Process time	5-90 minutes	1-10 minutes	seconds to minutes	Between 0.5 and 20 hours, depending on the material
Batch size	1-25	1-25	1 wafer at a time	1 wafer at a time, use a container, e.g Petri dish

Process gas ratio for plasma asher 4 & 5

Ashing rate as function of gas mix ratio.

The ashing rate is related to the gas mix, usually expressed as percentage of nitrogen of the total amount of gas.

Test using a single 100 mm wafer in the center of the process chamber shows that 30-80% nitrogen gives the highest ashing rate.

Test parameters:
Total gas flow rate: 500 sccm
Gas mix ratio: tested parameter
DSC: not used for this test
Chamber pressure: 1.2 mbar
Power: 1000 W
Processing time: 2 minutes
Temperature (average): 43°C

Process chamber pressure for plasma asher 4 & 5

Ashing rate as function of chamber pressure.

The ashing rate is related to the chamber pressure during processing.

Test using a single 100 mm wafer in the center of the process chamber shows that a chamber pressure of 1.3 mbar gives the highest ashing rate.

Test parameters:
Total gas flow rate: 150 sccm
Gas mix ratio: 30% nitrogen
DSC: tested parameter
Chamber pressure: tested parameter
Power: 1000 W
Processing time: 2 minutes
Temperature (average): 43°C

Process gas flow rate for plasma asher 4 & 5

Ashing rate as function of total gas flow rate.

The ashing rate is related to the total gas flow rate during processing.

Test using a single 100 mm wafer in the center of the process chamber shows that a total flow rate of 200 sccm gives the highest ashing rate.

Test parameters:
Total gas flow rate: tested parameter
Gas mix ratio: 30% nitrogen
DSC: 1.3 mbar
Chamber pressure: 1.3 mbar
Power: 1000 W
Processing time: 2 minutes
Temperature (average): 43°C

Process power for plasma asher 4 & 5

Ashing rate as function of microwave power.

The ashing rate is related to the power used during processing. Higher power gives higher ashing rate. There is an unexpected peak at 800 W which we will investigate further.

Test using a single 100 mm wafer in the center of the process chamber shows that a power of 1000 W gives the highest ashing rate.

Test parameters:
Total gas flow rate: 200 sccm
Gas mix ratio: 30% nitrogen
DSC: 1.3 mbar
Chamber pressure: 1.3 mbar
Power: tested parameter
Processing time: 2 minutes
Temperature (average): 43°C

Process temperature for plasma asher 4 & 5

Ashing rate as function of temperature.

The ashing rate is related to the temperature during processing. Higher temperature gives higher ashing rate.

Test using a single 100 mm wafer in the center of the process chamber shows that increasing processing temperature gives increasing ashing rate.

Test parameters:
Total gas flow rate: 200 sccm
Gas mix ratio: 30% nitrogen
DSC: 1.3 mbar
Chamber pressure: 1.3 mbar
Power: 1000 W
Processing time: 2 minutes
Temperature (average): tested parameter

Plasma Asher 1

Plasma asher 1 was decommissioned 2024-12-02.

Information about decommissioned tool can be found here.

Plasma Asher 2

Plasma asher 2 was decommissioned 2024-12-02.

Information about decommissioned tool can be found here.

Plasma Asher 3: Descum

Plasma Asher 3: Descum is placed A-5

The Plasma Asher 3: Descum dedicated for resist descum i.e. removal of remains resist traces after development. It has a small chamber, so you can only load a single 100 mm substrate or a few smaller pieces.

In this machine, only O2 and N2 gases are used for processes.

Typical process parameters when operating the equipment:
Process: Photoresist descum
Pressure: 0.2-0.8 mbar
Gas: O₂
Power: 50-100%
Time:1 -10 minutes (depending on photoresist type and thickness)

The other materials have not been tested yet.

The user manual, user APV, and contact information can be found in LabManager - requires login

Process Information

Detailed information about descum processing on Plasma asher 3: Descum can be found here.

Plasma Asher 4

Plasma asher 4 in cleanroom E-5.

Coming soon

Plasma Asher 5

Plasma asher 5 in cleanroom E-5.

The Plasma Asher 5 can be used for the following processes:

• Photoresist stripping
• Descumming
• Surface cleaning
• Removal of organic passivation layers and masks

Furthermore plasma processing using CF₄ in plasma asher 5 can be used for:

• Etching of glass and ceramic
• Etching of SiO₂, Si₃N₄, Si
• Removal of polyimide layers

Plasma asher 5 can be used for almost every material, but if you have any doubt if your materials are compatible/allowed in plasma asher 5, feel free to ask the lithography group at Nanolab.

The user manual, risk assessment, and contact information can be found in LabManager - requires login

Process Information

• SiO₂ etch using Plasma Asher 5
• Descum using plasma asher 5

Resist Strip

Resist strip bench in D-3

This resist strip is only for wafers without metal and SU-8.

There are one Remover 1165 bath for stripping and one IPA bath for rinsing.

Here are the main rules for resist strip use:

• Place the wafers in a wafer holder and put them in the first bath for 10 min, this time is depending how much resist you have on the surface.
• After the strip rinse your wafers in the IPA bath for 2-3 min.
• Rinse your wafers for 4-5 min. in running water after stripping.

The user manual and contact information can be found in LabManager: Resist Strip - requires login

Overview of wet bench 06 and 07

	Resist Strip	Lift-off
General description	Wet stripping of resist	Lift-off process
Chemical solution	NMP Remover 1165	NMP Remover 1165
Process temperature	Up to 65°C	Up to 65°C
Batch size	1 - 25 wafers	1 - 25 wafers
Size of substrate	100 mm wafers 150 mm wafers	100 mm wafers 150 mm wafers
Allowed materials	Silicon Silicon Oxide Silicon Nitride Silicon Oxynitride	All metals except Type IV (Pb, Te)