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Lithography Techniques Piotr Matyba Department of Physics Umeå University

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Page 1: Lithography Techniques

Lithography Techniques

Piotr Matyba

Department of Physics

Umeå University

Page 2: Lithography Techniques


Motivation for micro and nanotechnology

Techniques for micro and nano patterning

Soft lithography


E-beam lithography

Ion-beam lithography

Future and possible development

Page 3: Lithography Techniques

Moore’s low

The complexity for minimum component costs has increased at a rate of roughly a factor of two per year ... Certainly over the short term this rate can be expected to continue, if not to increase. Over the longer term, the rate of increase is a bitmore uncertain, although there is no reason to believe it will not remain nearly constant for at least 10 years. That means by 1975, the number of components per integrated circuit for minimum cost will be 65,000. I believe that such a large circuit can be built on a single wafer. (Electronics Magazine, 19th April 1965)

Page 4: Lithography Techniques

Techniques for micro patterning

Page 5: Lithography Techniques

Add one more slide explain how it is done in practice

Page 6: Lithography Techniques

Typical flowchart for fabrication

substrate resist spinning


metal deposition

etchinglift off


electrolytic growth

Page 7: Lithography Techniques


Reproduction of a pattern ↔ expose a resist to open windows in a controlled way

Page 8: Lithography Techniques

First planar technology (1957)

Page 9: Lithography Techniques



not soluble

Page 10: Lithography Techniques

Ideal photoresist

In contrary to photography one does not want any grayscale, the highest contrast is desired

Negative resist

Positive resist

Page 11: Lithography Techniques

Optical lithography by contact

Page 12: Lithography Techniques

Projection lithography

Page 13: Lithography Techniques

Evolution of projection lithography

Page 14: Lithography Techniques

Phase shifting masks (PSM)

The use of PSM techniques allows to go down to the Rayleight criterion, k=0.61 to k=0.4

85 nm gate with PSM

transmision phase shift

Page 15: Lithography Techniques

Resolution Enhanced Techniques

Nature, T. Ito & S. Okazaki

Film Thickness 60um, 10um posts6:1 aspect ratio structures

10µ line/space features 6:1 aspect ratio structures

Page 16: Lithography Techniques

193nm lithography

Page 17: Lithography Techniques

Extreme UV (EUV) lithography

EUV is absorbed by all materials, and gasses

vacuum required !Physikalisch-Technische Bundesanstalt, Annual Report 2002

Page 18: Lithography Techniques

Photons are not for ever !




- High surface figure

- Aspherization

Flare (contrast loss)

- Spatial frequency roughness

Reflectivity loss

- Graded multilayer thickness

Competition between immersion 157nm technology and EUV technology. The industry however seems to develop lens/immersion approach.

Page 19: Lithography Techniques

X-ray lithography

Page 20: Lithography Techniques

X-ray mask

Page 21: Lithography Techniques

Examples of X-ray lithography

+ Good resolution

- Complex and expensive

- Time demanding

Page 22: Lithography Techniques

3D X-ray lithography

Produces 3D structures, with potential application to photonic crystals

Page 23: Lithography Techniques

Electron beam lithography

Electron beam spot less than 10nm

Very small wavelength no diffraction limitation

Direct writing no mask needed

Resolution depends upon the photoresist, limitation ~1nm

Sequential writing, small throughput

Page 24: Lithography Techniques

Electron-resist interaction

Page 25: Lithography Techniques

Multilayer technique

Page 26: Lithography Techniques

E-beam writing

Schottky Emitter tip

Tungsten heating filament

Reservoir (ZrN)

Crystal W

Page 27: Lithography Techniques

Hard density track patterning on a real magnetic hard disk

Pitch ~60nm

50 nm gold dots on a silicon wafer

Page 28: Lithography Techniques

Ion beam litography

Holes in a silicone membrane

Trenching in GaAs

30kV Gallium ionsIon beam spot size <10nm

rapidly absorbed

Page 29: Lithography Techniques

Near field lithography (soft)

The pattern is reproduced by a mold or a stamp

Fast and efficient method

No scaling, 1:1 ratio

Page 30: Lithography Techniques


Development of light based techniques for industrial applications (EUV range)

Further development of soft lithography techniques

Techniques based upon self assembling abilities of certain materials. Resolution below 1nm.

A huge effort put on a production of photo resistive materials with good properties for EUV lithography