Specific Process Knowledge/Lithography/Coaters

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	Spin Coater: Manual All Purpose	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	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		Coating of ESPACER Experimental resists Coating on Experimental substrates	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		Single substrate Vacuum 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		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				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)		100 - 7000 rpm
	Gyrset	no	no	no	optional (max. speed 3000 rpm)	no		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		50 mm wafers 100 mm wafers 150 mm wafer small pieces down to 3x3 mm2	Any sample(s) that fit inside machine
	Batch size	1 - 25	1 - 25	1 - 25	1	1		1	1
	Allowed materials	Silicon Glass	Silicon Glass	Silicon III-V materials Glass	All cleanroom materials except III-V materials	Silicon III-V materials Glass		All cleanroom materials	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 process of spin coating consists of a selection of the following steps:

• Priming (typically HMDS)
• Acceleration to a low spin speed if dynamic dispense is used
• Resist dispense (static or dynamic)
• Resist spreading at low spin speed
• Spin-off
• Backside rinse (typically during spin-off)
• Edge-bead removal
• Softbake (contact or proximity)

After priming, the wafer is centered on the coater chuck and held in place by vacuum, or in some cases pins. If static dispense is used, the wafer remains static during the ensuing 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*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 * w^-a. The constant, k, is a function of the resist viscosity and solid content, and 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 t₁ achieved at spin speed w₁, one can estimate the spin speed w₂ needed to achieve thickness t₂ using the relation:
t₁*w₁^½ = t₂*w₂^½ => w₂ = w₁ * t₁²/t₂².
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:
t₁*w₁ = t₂*w₂ => w₂ = w₁ * t₁/t₂.

Backside rinse

Dependent on the spin speeds used in the various steps of the spin coating, resist may creep over the edge of the wafer and onto the backside. Also, some resists 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". This resist will contaminate the softbake hotplate, and thus subsequent wafers with resist. 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 left dirty on the backside by the spin coat process 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. This phenomenon is called an 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, this edge-bead induces 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 at the point of 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 formulation 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 150µm 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

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Coater comparison table

Spin Coater: Gamma UV was installed at DTU Nanolab in March 2015. It is a Gamma 2M cluster from Süss MicroTec with spin coating, 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 resists lines:

• AZ MiR 701
• AZ nLOF 2020
• AZ 5214E

and

• 1 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

Process information

General Process Information

Standard Processes:

• Quality Control (QC)
• HMDS
• AZ MiR 701
• AZ nLOF 2020
• AZ 5214E

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 No resist or crystalbond allowed in the HMDS module
	Batch	1 - 25

¹⁾ Requires tool change.

Spin Coater: Gamma E-beam and UV

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Coater comparison table

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

Spin Coater: Gamma E-beam and UV will be installed at DTU Nanolab in June 2017. It is a Gamma 4M cluster from Süss MicroTec with spin coating, 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 2 different resists lines:

• AZ 5214E
• AR-P 6200.09 (CSAR)

and

• 1 syringe, which can be used for various resists (anisole or PGMEA-based).

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 would as a starting point require batches in excess of 20 wafers.

Training video (for Spin Coater: Gamma UV)

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

Process information

General Process information

Standard Processes:

• Quality Control (QC)
• HMDS
• AZ 5214E on Coater1 and Coater2
• AZ MiR 701 on Coater2
• CSAR on Coater1 and Coater2
• AZ 4562 on Coater2
• Edge bead removal on Coater1 and Coater2

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) 4"/6" only AZ 4562 4"/6" only 30cc syringe dispense 2" only
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 No resist or crystalbond allowed in the HMDS module
	Batch	1 - 25

Spin Coater: RCD8

Spin coater: RCD8 is located in C-1

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Coater comparison table

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

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

Manual Spin Coaters

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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 - 5000 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

Spin Coater: Labspin 02	Spin Coater: Labspin 03 + fumehood 11	Spin Coater: Manual All Purpose
Loacted in wetbench 08 in E-5	Located in wetbench 09 in E-5	Located in fumehood in C-1
LabSpin 6, Süss MicroTec	LabSpin 6, Süss MicroTec	WS-650, Laurell
LabManager	LabManager	LabManager

Training video: LabSpin02 + 03

Process information

Spin curves (LabSpin 6): AZ 5214E‎, AZ nLOF 2020, ZEP 520A‎, FOX-15, AZ 4562‎, CSAR 6200