Specific Process Knowledge/Lithography/Coaters

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Coater Comparison Table

Equipment		Spin Coater: Gamma UV	Spin Coater: Süss Stepper	Spin Coater: Gamma E-beam and UV	Spin Coater: RCD8	Spin Coater: LabSpin 02	Spin Coater: LabSpin 03	Spray Coater
Purpose		In-line substrate HMDS priming Coating and baking of AZ MiR 701 (29cps) AZ nLOF 2020 AZ 5214E	Coating and baking of BARC (DUV42S-6) KRF M230Y KRF M35G UVN2300-0.8	In-line substrate HMDS priming Coating and baking of AR-P 6200 (CSAR) AZ 5214E AZ MiR 701 (29cps) AZ 4562 Edge bead removal on novolac-based resist and SU-8	Coating of SU-8 AZ 5214E AZ 4562 AZ MiR AZ nLOF Edge bead removal	Coating of E-beam resists CSAR, ZEP, PMMA/MMA, HSQ(FOx) Coating of UV resists AZ5214E, AZ4562, AZMiR701, AZnLOF, SU-8 Coating of imprint resists		Spraying imprint resist Spraying photoresist Spraying of other solutions
Performance	Substrate handling	Cassette-to-cassette Vacuum handling and detection Vacuum spin chuck	Cassette-to-cassette Vacuum handling and detection Vacuum spin chuck	Cassette-to-cassette Vacuum handling and detection Vacuum spin chuck	Single substrate Vacuum chuck for 4" and 6" 4" non-vacuum chuck for fragile substrates	Single substrate Vacuum chucks for chips, 2", 4", and 6" 4" edge handling chuck		Can handle almost any sample size and shape
	Permanent media	AZ MiR 701 (29cps) resist AZ nLOF 2020 resist AZ 5214E resist PGMEA solvent for backside rinse and spinner bowl cleaning	DUV42S-6 (BARC) KRF M230Y resist KRF M35G resist	AR-P 6200.09 (CSAR) for 2", 4", and 6" AZ5214E for 2", 4", and 6" AZ MiR 701 (29cps) for 4", and 6" AZ4562 for 4", and 6" PGMEA solvent for edge bead removal, backside rinse, and spinner bowl cleaning	No permanent media	Only manual dispense		No permanent media
	Manual dispense option	no manual dispense syringe dispense (60cc) of PGMEA-based resist	no manual dispense syringe dispense (60cc) of PGMEA and anisole-based resist	no manual dispense syringe dispense (30cc) of PGMEA and anisole-based resist (2" only)	yes pneumatic dispense for SU-8 resist and EBR solvent	Only manual dispense		Two syringe pumps
Process parameter range	Spindle speed	10 - 6000 rpm	10 - 6000 rpm	10 - 6000 rpm	10 - 5000 rpm (3000 rpm with non-vacuum chuck)	100 - 5000 rpm (3000 rpm with edge handling chuck)
	Gyrset	no	no	no	optional (max. speed 3000 rpm)	no
Substrates	Substrate size	50 mm wafers (tool change required) 100 mm wafers 150 mm wafers 200 mm wafers (tool change required)	100 mm wafers 150 mm wafers 200 mm wafers (may require tool change)	2" or 50 mm wafers 100 mm wafers 150 mm wafers	100 mm wafer 150 mm wafer	50 mm wafers 100 mm wafers 150 mm wafer small pieces down to 10x10 mm2		Any sample(s) that fit inside machine
	Batch size	1 - 25	1 - 25	1 - 25	1	1		1
	Allowed materials	Silicon Glass No resist or crystalbond allowed in the HMDS module	Silicon Glass	Silicon III-V materials Glass No resist or crystalbond allowed in the HMDS module	All cleanroom materials except III-V materials	Silicon III-V materials Glass		All chemicals to be spray coated must be approved specifically for spray coating Any non-toxic, non-particulate and non-crosslinking material is likely to be approved

Spin coating

The typical spin coating process consists of the following steps:

1. Priming (typically HMDS)
2. Resist dispense (static or dynamic)
   • Optional: Acceleration to a low spin speed if dynamic dispense is used
   • Optional: Resist spreading at low spin speed
3. Spin-off
4. Backside rinse (typically during spin-off)
5. Optional: Edge-bead removal
6. Softbake (contact or proximity)

After priming, the wafer is is transferred to the spin coater. If static dispense is used, the wafer remains static during the resist dispense. In the case of dynamic dispense, the wafer rotates at low spin speed during the dispense. Using too high spin speed during dispense can cause surface wetting issues, while a too low spin speed causes the resist to flow onto the backside of the wafer. After dispense, a short spin at low spin speed may be used in order to spread the resist over the wafer surface before spin-off.

Spin-off

The spin-off cycle determines the thickness of the resist coating. For a given resist, the thickness is primarily a function of the spin-off speed and the spin-off time, both following an inverse power-law:

$y=k\cdot x^{-a}$

The acceleration to the spin-off speed also influences the thickness, but the effect is dependent on previous steps. The spin-off is usually a simple spin at one speed, but it may be comprised of several steps at different spin speeds. After spin-off, the wafer is decelerated.

The coated thickness, $t$, as a function of the spin-off speed, $w$, follows an inverse power-law:

$t=k\cdot w^{-a}$

The constant, $k$, is a function of the resist viscosity and solid content, as well as the spin-off time. The exponent, $a$, is dependent on solvent evaporation, and is typically ~½ for UV resists. This means that from the thickness $t_{1}$ achieved at spin speed $w_{1}$, one can estimate the spin speed $w_{2}$ needed to achieve thickness $t_{2}$ using the relation:

$t_{1}\cdot w_{1}^{1/2}=t_{2}\cdot w_{2}^{1/2}\Rightarrow w_{2}=w_{1}\cdot {\frac {t_{1}^{2}}{t_{2}^{2}}}$

For thick SU-8, however, $a$ is observed to be ~1 (probably due to the low solvent content and/or the formation of skin). In this case, the relation simply becomes:

$t_{1}\cdot w_{1}=t_{2}\cdot w_{2}\Rightarrow w_{2}=w_{1}\cdot {\frac {t_{1}}{t_{2}}}$

Backside rinse

If the spin speed is too low during resist dispense, resist may creep over the edge of the wafer and onto the backside. Some resist tend to leave fine strings of resist protruding from the edge of the wafer, or folded onto the backside, an effect sometimes referred to as "cotton candy".

Any resist on the edge and backside of the wafer will contaminate the end effector, softbake hotplate, and subsequent wafers.

In a backside rinse step, solvent administered through a nozzle to the backside of the wafer, while spinning at low or medium spin speed, dissolves the resist and washes it away. After the rinse, a short spin at medium spin speed dries the wafer before the softbake.

During the backside rinse solvent inevitably creeps onto the front side of the wafer. This effect may be used to dissolve and subsequently remove an edge-bead, but it may also leave the rim of the wafer exposed. As an alternative to backside rinse, a wafer, which is contaminated on the backside, may be softbaked in proximity, in order to protect the hotplate from contamination. This leaves front side coating intact, but also leaves the backside dirty.

Edge bead

During spin coating, resist builds up at the edge of the wafer due to the change in surface tension at the edge, as well as extra drying from turbulence created by the wafer edge.

This phenomenon is called edge-bead. Dependent on spin coating parameters, the coating may be several times thicker at the edge than in the central area. In a subsequent hard contact exposure step (mask aligner), this edge-bead introduces an undesired proximity gap, which reduces the lateral resolution, and may even cause the wafer to stick to the mask.

In an edge-bead removal step, solvent administered through a nozzle positioned at the edge of the wafer, while spinning at low or medium spin speed, dissolves the resist and washes it away. After the removal, a short spin at medium spin speed dries the wafer before the softbake. Dependent on the viscosity (solvent content) of the resist after the edge-bead removal, this drying spin may cause the resist to re-flow and create a secondary edge-bead. In some cases, it may be necessary to (partially) softbake the resist before edge-bead removal.

Softbake

After spin coating, the solvent in the resist must be evaporated in a baking step, in order to solidify the resist. This softbake can be carried out as a contact bake or a proximity bake. In a contact bake, the wafer is held in close contact to the hotplate surface while resting on shallow bumps only 150 µm above the hotplate. In a proximity bake, the wafer is first moved into proximity, e.g. 1mm, of the hotplate surface, then held there (on the lift pins) for the duration of the bake.

Spin coaters at DTU Nanolab

Spin Coater: Gamma UV

Spin Coater: Gamma UV in E-5

Spin Coater: Gamma UV was installed at DTU Nanolab in March 2015. It is a Gamma 2M cluster from Süss MicroTec with spin coating, HMDS vapour priming, and baking modules.

The system handles 4" and 6" wafers without size conversion, and can be set up to handle 2" or 8".

The coater is equipped with 3 different resist lines, as well as 1 syringe line:

• AZ MiR 701
• AZ nLOF 2020
• AZ 5214E
• Syringe, which can be used for various resists

The processes that are available on the system are developed by Nanolab. Upon request, it is possible to establish new processes. Use of the syringe requires special training, and would as a starting point require batches in excess of 20 wafers.

Training video

The user manual, quality control procedures and results, user APVs, and contact information can be found in LabManager - requires login

Process information

• General Process Information
• Quality Control (QC)
• Standard Processes
• Syringe processes

Equipment performance and process related parameters

Purpose		HMDS priming Spin coating of PGMEA based UV resists Spin coating of E-beam resists 1) Soft baking
Resist		AZ MiR 701 (29cps) AZ nLOF 2020 AZ 5214E 60cc syringe dispense
Performance	HMDS contact angle	60 - 80°
	Coating thickness	AZ MiR 701: 1.5-4 µm AZ nLOF 2020: 1.5-5 µm AZ 5214E: 1.5-5 µm AZ 4562: 5-15 µm
Process parameters	Priming temperature	120 °C
	Spin speed	10 - 6000 rpm
	Spin acceleration	10 - 10000 rpm/s
	Hotplate temperature	25 - 200 °C
	Cool plate temperature	21 °C
Substrates	Substrate size	50 mm wafers 1) 100 mm wafers 150 mm wafers 200 mm wafers 1)
	Allowed materials	Silicon and glass Resists and crystalbond are not allowed in the HMDS module
	Batch	1 - 25

¹⁾ Requires tool change.

Spin coater: Süss stepper

The SÜSS Spinner-Stepper is placed in F-3

This spinner is dedicated for spinning DUV resists. The spinner is fully automatic and can run up to 25 substrates in a batch 4", 6", and 8" size (8" requires tool change). The machine is equipped with the 3 resist lines (DUV42S-6, KRF M230Y, and KRF M35G), as well as a syringe dispense system.

The user manual, quality control procedures and results, user APVs, and contact information can be found in LabManager:

Equipment info in LabManager - requires login

DUV resist overview

The spinning process will be performed by the customer together with the Photolith group of Nanolab. In case you would like to do DUV lithography please contact Lithography team, who will consult you and run your wafers together with you.

Bottom Anti Reflection Coating (BARC):

• Manufacturers website: DUV 42S-6
• Datasheet: DUV42S-6 - requires login

Positive DUV resist for spin coating in 600-300nm thickness range:

• Manufacturers website: KrF M230Y
• Datasheet: KrF M230Y - requires login

Positive DUV resist for spin coating in 1600-800nm thickness range:

• Manufacturers website: KrF M35G
• Datasheet: KrF M35G - requires login

Negative DUV resist for spin coating in 1400-800nm or diluted with EC Solvent in 1:1 in 400-200nm thickness range:

• Manufacturers website: UVN2300-0.8
• Datasheet: UVN2300-0.8 - requires login

Process information

• General Process Information
• Quality Control (QC)
• Standard Processes

Equipment performance and process related parameters

Purpose		Spin coating and soft baking of BARC Spin coating and soft baking of DUV resists Post exposure baking
Resist		BARC DUV42S-6 Positive tone resist KRF M230Y Positive tone resist KRF M35G Negative tone resist UVN2300-0.8
Performance	Coating thickness	BARC DUV42S-6 60-90nm Positive tone resist KRF M230Y 300-600nm Positive tone resist KRF M35G 800-1600nm Negative tone resist UVN2300-0.8 200-1400nm
Process parameters	Spin speed	10 - 5000 rpm
	Spin acceleration	100 - 10000 rpm/s
	Hotplate temperature	175°C for BARC baking 130°C for positive tone resist soft baking and post exposure baking 100°C for negative tone resist soft baking and post exposure baking
Substrates	Substrate size	100 mm wafers 150 mm wafers 200 mm wafers (requires tool change)
	Allowed materials	Any standard cleanroom material
	Batch	1 - 25

Spin Coater: Gamma E-beam and UV

Spin Coater: Gamma E-beam & UV in E-5

Spin Coater: Gamma E-beam and UV was installed at DTU Nanolab in June 2017. It is a Gamma 4M cluster from Süss MicroTec with spin coating, HMDS vapour priming, and baking modules. The system handles 2", 4", and 6" wafers without size conversion, using two separate coater stations.

The 2" coater station is equipped with 1 resist line, as well as 1 syringe line:

• AR-P 6200.09 (CSAR)
• Syringe, which can be used for various resists (anisole-based or PGMEA-based). We currently recommend against using the syringe, as the process setup is quite demanding. Use a manual spin coater instead.

The 4"/6" coater station is equipped with 4 different resists lines:

• AZ 5214E
• AZ MiR 701
• AR-P 6200.09 (CSAR)
• AZ 4562

The processes that are available on the system are developed by Nanolab. Upon request, it is possible to establish new processes. Use of the syringe requires special training, and requires batch processing - it is not for processing a few wafers now and then.

Training video

The user manual, quality control procedures and results, user APVs, and contact information can be found in LabManager - requires login

Process information

• General Process information
• Quality Control (QC)
• Standard Processes:
• Syringe Processes

Equipment performance and process related parameters

Purpose		HMDS priming Spin coating of anisole based E-beam resists Spin coating of PGMEA based UV resists Soft baking Edge bead removal (CSAR and novolac-based UV resists)
Resist		AR-P 6200.09 (CSAR) AZ 5214E AZ MiR 701 (29cps) AZ 4562 30cc syringe dispense
Performance	HMDS contact angle	60 - 80° (on Silicon)
	Coating thickness	AR-P 6200.09 (CSAR): 170-500 nm AZ 5214E: 1.5-5 µm AZ MiR 701: 1.5-4 µm AZ 4562: 5-25 µm
Process parameters	Priming temperature	120 °C
	Spin speed	10 - 6000 rpm
	Spin acceleration	10 - 10000 rpm/s
	Hotplate temperature	25 - 200 °C
	Cool plate temperature	21 °C
Substrates	Substrate size	50 mm wafers 100 mm wafers 150 mm wafers
	Allowed materials	Silicon, III-V, and glass   Resists and crystalbond are not allowed in the HMDS module
	Batch	1 - 25

Spin Coater: RCD8

Spin coater: RCD8 is located in C-1

Spin Coater: RCD8 is a model RCD8 T spin coater from Süss MicroTec with a motorized media arm and Gyrset functionality. It's primary purpose is spin coating of SU-8 resist.

However, due to the possibility of using a non-vacuum chuck, the spin coater is also suitable for coating of substrates with e.g. textured backsides or membranes.

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

Process information

• Spin coating
• Automatic dispense
• Recipes and templates
• Processing results

Equipment performance and process related parameters

Purpose		Spin coating of SU-8 resists Spin coating of PGMEA based AZ resists Spin coating of wafers with structured backside Edge bead removal
Resist		manual dispense automatic dispense from syringe
Performance	Coating thickness	SU-8 resits: 0.1-200+ µm AZ 5214E: 1.5-3 µm AZ 4562: 8-15 µm AZ MiR 701: 1.5-3 µm AZ nLOF 2020: 2-3.5 µm
Process parameters	Spin speed	Vacuum chuck: 10 - 5000 rpm Non-vacuum chuck: Max. 3000 rpm
	Spin acceleration	10 - 3000 rpm/s Max. 1500 rpm/s with Gyrset
Substrates	Substrate size	100 mm wafers 150 mm wafers (vacuum chuck only)
	Allowed materials	All cleanroom materials ?
	Batch	1

Spin coater: Labspin

Spin Coater: Labspin 02	Spin Coater: Labspin 03 + fumehood 11
Loacted in wetbench 08 in E-5	Located in wetbench 09 in E-5
LabSpin 6, Süss MicroTec	LabSpin 6, Süss MicroTec

Training video: LabSpin02 + 03

Process information

Spin curves (LabSpin 6):

• AZ 5214E‎
• AZ nLOF 2020
• ZEP 520A‎
• FOX-15
• AZ 4562‎
• CSAR 6200
• AZ MiR 701.

More information on resists (incl. spin curves) is available in the resist overview.

Available bowlsets:

Bowlset name	Component solvent	Cleaning solvent	List of resists	Comments
AZ resist	PGMEA/Ethyl Lactate	Acetone	AZ 5214E AZ 4562 AZ MiR 701 AZ nLOF 2000 series mr-I8100R	Two bowlsets available
CSAR/ZEP/mrEBL/PMMA	Anisole	Remover 1165	AR-P 6200 series (CSAR 62) ZEP520A mr EBL 6000 PMMA (in anisole) UV5 mr-T85L XNIL26 mri8000 mr-I 7010E mr-XNIL26_SF mrNIL210
HSQ/AR-N 8200	MIBK/PGMEA	Acetone	HSQ (FOx series) AR-N 8200
OrmoComp/OrmoStamp	Propyl Acetate	Acetone	OrmoComp OrmoStamp OrmoPrime OrmoClad Inkron mr-I-7030R mr-I 8020E mr-I-7010E mrNIL210 mr-I 8500E mr-T85 MRT HI01XP Protek B3 mrUVCur21 mr-I 8100E_XP mrNIL210 MRT HI01XP mr-NIL 6000.3E mr-I 8100R_XP
BCB/CYCLOTENE	Mesitylene	T1100	3022-X 4022-X
Epoxy/Acrylate	Cyclopentanone/PGMEA	Acetone	SU-8 2000 series mr-DWL LOR (1A, 3A, 5A) mr-i 8030e mr-NIL200 DELO-PRE/OM4310 OrmoStamp Inkron mr-I 8020E OM4310
AR-P 617/AR-N 7520	PGME/PGMEA	Acetone	AR-N 7500 series
Polymer Ps-b-PDMS/block copolymer	Heptane	Ethyl Acetate
DIRTY bowlset	Anything Organic	Use the appropriate cleaning reagent for your resist

Equipment performance and process related parameters

Purpose	Labspin	Spin coating of resist ONLY in dedicated bowlsets Please do NOT use substances which is not for the dedicated bowlsets
	All purpose	Spin coating of dirty substances in All purpose
Process parameters	Spin speed	Vacuum chuck: 100 - 8000 rpm Edge handling chuck: Max. 3000 rpm
	Spin acceleration	200 - 4000 rpm/s
Substrates	Substrate size	Chips 5x5 mm and up 50 mm wafers 100 mm wafers 150 mm wafers
	Allowed materials	All cleanroom materials Please ONLY use substances which is for the dedicated bowlsets in labspins
	Batch	1

Spray Coater

Spray Coater in Cleanroom C-1

The spray coater at DTU Nanolab is located in Cleanroom C-1. The machine is an ExactaCoat from Sono-tek which can be fitted with one of three different nozzles depending on the nature of the spray coating tasks at hand. The three different nozzles (Impact, AccuMist and Vortex) are optimized for different applications such as spray coating of large areas (e.g. entire wafers), smaller areas (e.g. wafer pieces or other small samples) or already structured samples that cannot be coated uniformly by spin coating. All nozzles use an ultrasonic tranducer for atomizing the solution to be spray coated. It is therefore a prerequisite that all components are compatible with this process. This is the case with most substances, although process parameters may need optimization to give satisfactory results.

Practically any sample that will fit inside the spray coater can be processed. Spray patterns are easily programmed either using predefined spray patterns (1D line, 2D rectangles/circles/meanders/spirals) or custom 3D spray patterns.

The spray coating process as well as major features of the three nozzles are described into more detail in the manual which can be found via the Equipment Info page in LabManager under the Documents sections. The manual can also be found in Labmanager - requires login

Further information about the spray coater (manual, process log, technical information etc.) can be found in LabManger:

Spray coater in LabManager - requires login

Process development

Spray coating using TI spray:
The TI spray resist is the standard spray coater resist used at DTU Nanolab. It requires no dilution and performs well.

Spray coating using other resists:
Other resists are allowed, but most require dilution, as the spray coater will not work with any resist viscosity higher than 20 cP.

Equipment performance and process related parameters

Equipment		Spray Coater
Purpose		Spraying imprint resists (primarily mr-NIL 6000E and mr-I 8000E) Spraying photoresist (primarily AZ-4562) Spraying of other solutions
Performance	Substrate handling	Can handle almost any sample size and shape (although no automatic handling)
	Permanent media	No permanent media
	Manual dispense option	Two syringe pumps
Process parameter range	Solution viscosity	Should not exceed 20 cP
	Chemical properties	Must be non-toxic Must be compatible with titanium Resistant to ultrasonic sonication
Substrates	Batch size	Any sample(s) size and number that fit inside machine
	Allowed materials	All chemicals to be spray coated must be approved specifically for spray coating Most non-toxic, non-particulate and non-crosslinking material likely to be approved Suspensions challenging due to very low diameter tubing