Specific Process Knowledge/Lithography

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Lithography

Lithography is a method used for transferring a pattern from a physical or digital mask onto the substrate. At DTU Nanolab we have four different types of lithography available:

• UV Lithography: UV lithography is used for making features as small as about 1 micrometer
• DUV Stepper Lithography: DUV lithography is used for features as small as 200 nm
• E-beam Lithography: The smallest features can be made in our e-beam writers - about 10 nm
• Nano Imprint Lithography: for stamping without irradiation

Comparing lithography methods at DTU Nanolab

	UV Lithography	DUV Stepper Lithography	E-beam Lithography	Nano Imprint Lithography
Generel description	Pattern transfer via ultraviolet (UV) light	Pattern transfer via deep ultraviolet (DUV) light	Patterning by electron beam	Pattern transfer via hot embossing (HE)
Pattern size range	~1 µm and up (resist type, thickness, and pattern dependent)	~200 nm and up (pattern type, shape and pitch dependent)	~10-1000 nm (and larger at high currents)	~20 nm and up
Resist type	UV sensitive: AZ 5214E, AZ 4562, AZ MiR 701 (positive) AZ 5214E, AZ nLOF 2020, SU-8 (negative)	DUV sensitive: JSR KRF M230Y, JSR KRF M35G (positive) UVN2300-0.8 (negative)	E-beam sensitive: AR-P6200 CSAR, ZEP502A , PMMA (positive) HSQ, mr-EBL, AR-N 7520 (negative)	Imprint polymers: Topas PMMA mr-I 7030R
Resist thickness range	~0.5 µm to 200 µm	~50 nm to 2 µm	~30 nm to 1 µm	~100 nm to 2 µm
Typical exposure time	Mask aligner: 10-180 s per wafer Maskless aligner: 5-60 minutes per wafer	Process dependent: Pattern Pattern area Dose Throughput is up to 60 wafers/hour	Process dependent: Dose [µC/cm2]: $Q$ Beam current [A]: $I$ Pattern area [cm2]: $a$ Process time [s]: $t={\frac {Q\cdot a}{I}}$	Process dependent, including heating/cooling rates
Substrate size	chips down to 3 mm x 3 mm 50 mm wafers 100 mm wafers 150 mm wafers 200 mm wafers	100 mm wafers 150 mm wafers 200 mm wafers	We have cassettes fitting: 4 small samples (slit openings: 20mm, 12mm, 8mm, 4mm) 6 wafers of 50 mm in size 3 wafers of 100 mm in size 1 wafer of 150 mm in size 1 wafer of 200 mm in size Only one cassette can be loaded at a time	small samples 50 mm wafers 100 mm wafers 150 mm wafers
Allowed materials	Any standard cleanroom material	Any standard cleanroom material	Any standard cleanroom material, except: Materials that will degas Graphene requires special treatment	Any standard cleanroom material

Equipment and Process Pages

Pre-lithography Resist User bottles in the cleanroom UV Resist DUV Resist E-beam Resist Imprint Resist Substrate Pre-treatment HMDS BHF Oven 250C

Coating Automatic spin coating Spin Coater: Gamma UV Spin Coater: Süss Stepper Spin Coater: Gamma e-beam & UV Manual spin coating Spin Coater: RCD8 Spin Coater: Labspin 02/03 Spray coating Spray Coater Soft & hard baking Hotplates Ovens

Exposure/design transfer UV Exposure Tools Aligner: MA6-1 Aligner: MA6-2 Aligner: Maskless 01 Aligner: Maskless 02 Aligner: Maskless 03 Aligner: Maskless 04 Deep-UV Exposure DUV Stepper (Canon FPA-3000EX4) Electron Beam Exposure JEOL 9500 Raith Eline Nano Imprint Lithography Molecular Vapour Deposition Imprinter 01

Development Manual development Manual beaker development SU-8 development Developer: SU8 (Wetbench) Semi-automatic puddle development Developer: E-beam 02 Developer: TMAH Manual 02 Automatic puddle development Developer: TMAH UV-lithography Developer: TMAH Stepper

Post-lithography Descum Plasma Asher 3: Descum Plasma Asher 4 Plasma Asher 5 BHF Lift-off Lift-off Strip Plasma Asher 3: Descum Plasma Asher 4 Plasma Asher 5 Resist Strip

Lithography Tool Package Training

DTU Nanolab offers a Tool Package Training for Lithography (TPT Lithography). You are required to pass this course, in order to get access to the lithography equipment inside the DTU Nanolabs cleanroom facility. The course includes theory on lithographic processes and training videos for equipment operation. The theory part consists of lecture videos followed by quizzes for each section. Once completed successfully, you can do the online training that explains the operation for the specific lithography equipment you want to use in more detail. After completing the online training, you can request hands-on training for the equipment inside the cleanroom via training@nanolab.dtu.dk.

The course is available via DTU Learn. You sign up for the course by enrolling yourself in the course here.

Course Layout

1. Online lecture videos (theory)
2. Quizzes for each section
3. Online training videos (equipment operation)
4. Individual hands-on training

Individual hands-on training can be requested via training@nanolab.dtu.dk.

Learning objectives

• Coating
• Exposure
• Development
• Resist, substrates and pre-treatment
• Post-lithography steps

Qualifying Prerequisites

• Cleanroom safety course at DTU Nanolab
• Admission to the cleanroom must be obtained before the group training session

Course Responsible

• Jens Hindborg Hemmingsen
• Thomas Aarøe Anhøj

If you have questions you can contact us via lithography@nanolab.dtu.dk.

Knowledge and Information about Lithography

Literature Franssila, 2010, Chapter 9: Optical Lithography Franssila, 2010, Chapter 10: Advanced Lithography Handbook of Microlithography, Micromachining, and Microfabrication, Chapter 2: E-beam Lithography Stefan Landis,Lithography, Chapter 3: E-beam Lithography Application notes from MicroChemicals GmbH, e.g. Lithography Trouble-Shooter Lecture videos Lithography TPT lecture videos: Current version (6 videos, 1:28 hours:minutes in total) on YouTube Old version (7 videos, 2:41 hours in total) on YouTube A full lecture series from a UT Austin course on microfabrication by "litho guru" Chris Mack. Half of the lectures are on (projection) lithography :-)	Training videos Training Video: Automatic Spin Coater Training Video: Manual Spin Coater Labspin Training Video: UV Mask Aligner Part I (Operation) Training Video: UV Mask Aligner Part II (Alignment) Training Video: Maskless aligner Training Video Training Video: Maskless aligner Conversion Training Video: Maskless aligner Series and Navigation Training Video: Maskless aligner Alignment Training Video: Automatic Puddle Developer Training Video: Manual Puddle Developer Playlists on YouTube: Maskless aligner (MLA) training videos Lithography equipment training videos (old)	Manuals NB: Access to manuals require DTU login Automatic Spin Coater: Spin Coater: Gamma UV Manual Spin Coater: Spin Coater: Labspin 02 or Spin Coater: Labspin 03 Maskless Aligners: MLA 01 or MLA 02 or MLA 02 UV Mask Aligner: MA6-2 Automatic Puddle Developer: Developer: TMAH UV-lithography Manual Puddle Developer: Developer: TMAH Manual Manual E-beam Developer: Developer: E-beam Manual Process Flows UV resist process flows E-beam resist process flows