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![REFERENCES
[1] G. H. Bernstein, D. A. Hill, and W. Liu, “New high-contrast developers for poly(methyl
methacrylate) resist,” J. Appl. Phys., vol. 71, no. 8, pp.4066–4075, 1992.
[2] S. D. Berger and J. M. Gibson, “New approach to projection electron lithography with
demonstrated 0.1 micron linewidth,” Appl. Phys. Lett., vol. 57, pp. 153–155, 1990.
[3] I. Brodie and J. J. Muray, The Physics of Micro/Nano-Fabrication. New York: Plenum, 1992.
[4] C. D. Chen, W. Kuo, D. S. Chung, J. H. Shyu, and C. S. Wu, “Evidence for suppression of
superconductivity by spin imbalance in Co-Al-Co single electron transistors,” Phys. Rev. Lett., vol. 88,
no. 4,pp. 47 001–47 004, 2002.
[5] Z. Cui, A. Gerardino, M. Gentili, E. Di Fabrizio, and P. Prewett, “Comparative study of AZPN114 and
SAL601 chemically amplified resists for electron beam nanolithography,” J. Vac. Sci. Technol. B, vol.
16, no.6, pp. 3284–3288, 1998.](https://image.slidesharecdn.com/98f16e42-3ef0-42d3-8199-8b5b5a7715ae-160718051145/75/556-2nd-presentation-by-teja-21-2048.jpg)
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556 2nd presentation by teja
- 1. Electron Beam Lithography inNanoscale Fabrication Recent Development BY: TEJASRI SALADI
- 2. Agenda Nanoscale Fabrication Conventional Photolithography techniques Electron Beam Lithography Projection Printing Direct Writing E-beam Resists Recent techniques in electron beam lithography Challenges in e beam lithography and ways to overcome Future scope Conclusion
- 3. Nanoscale Fabrication Nanofabricationis the design and manufacture of devices with dimensions measured in nanometers. One nanometer is 10 -9 meter, or a millionth of a millimeter.
- 4. Techniques used earlierin Nanoscale Fabrication There are several ways that nanofabrication might be done. One method involves scaling down integrated-circuit fabrication that has been standard since the 1970s, removing one atom at a time until the desired structure emerges. A more sophisticated hypothetical scheme involves the assembly of a chip atom-by-atom. One such conventional technique used in nanoscale fabrication is “Photolithography”
- 5. Photolithography Photolithography, alsotermed optical lithography or UV lithography, is a process used in microfabrication to pattern parts of a thin film or the bulk of a substrate. Because of its diffraction limit, conventional optical or ultraviolet photolithography is becoming increasingly inadequate.
- 6. Electron Beam Lithography Electron-beam lithography (often abbreviated as e-beam lithography) is the practice of scanning a focused beam of electrons to draw custom shapes on a surface covered with an electron-sensitive film called a resist ("exposing"). The main advantages of e-beam lithography over the conventional photolithograph techniques include very high resolution and versatile pattern formation. It is the most powerful technique for fabricating the features as small as 3 to 5 nm. Electron beam lithography process
- 7. EBL System Electron source: Electronsmay be emitted from a conducting material either by heating or by applying an electric field. Stigmators: A stigmator is a special type of lens used for the alignment of e-beam. Stigmators may be either electrostatic or magnetic and consist of four or more poles. Electron Lenses: Electron lenses can be made only to converge, not diverge. Electrons can be focused either by electrostatic forces or magnetic forces. Apertures: Apertures are small holes through which the beam passes on its way down the column. Blanking Plates: Blanking plates are use to modify the e-beam, these are simple electrostatic deflector. Electron-beam lithography system
- 8. Schemes used ine-beam Lithography Two distinct schemes used in electron beam lithography are 1. Projection Printing 2. Direct writing In projection printing, a relatively large sized electron-beam pattern is projected in parallel through the mask onto a resist-coated substrate by using a high-precision lens system; In direct writing, a small spot of the electron beam is written directly onto a resist- coated substrate, eliminating the expensive and time-consuming production of masks.
- 9. Direct Writing andProjection Printing
- 10. Projection Printing Projection EBLdevelopment further proceeds with the techniques Scattering with angular limitation in projection electron-beam lithography (SCALPEL) system projection reduction exposure with variable axis immersion lenses (PREVAIL)technology
- 11. Direct Writing Itis the most common EBL approach which uses finely focused Guassian round beam. The another technique which is carried out in direct writing EBL is Lift-off process. It is an additive process that adds material to the substrate.
- 12. E-beam Resists Electron beamresists are the resists which are normally coated on the substrate to record the image of the pattern to be transferred. Electron beam resists are of two types. They are 1) Positive Resists 2) Negative Resists
- 13. Types of E-beamresists
- 14. Electron beam lithographybenefits Print complex patterns directly on wafers Eliminates the diffraction problem High resolution up to 20 nm(photolithography ~50nm) Flexible technique
- 15. Defects in e-beamlithography and challenges faced Despite the high resolution of electron-beam lithography, the generation of defects during electron-beam lithography is often not considered by users. Defects may be classified into two categories: 1. Data-related defects 2. Physical defects. This is Expensive and complicated technoloogy Proximity effect
- 16. Recent techniques andtheir comparison with e-beam lithography Nano imprint lithography X-ray lithography Dip-Pen (DPN) nanolithography
- 17. Nano-imprint lithography(recent technique) Nano-imprintlithography (NIL) is a lithography technique that combines the speed of optical lithography with the resolution of EBL, we use NIL to make nanostructured substrates. When compared to e-beam lithography, it is a simple nanolithography process with low cost, high throughput and high resolution
- 18. Comparison of variouslithography techniques
- 19. Applications 1. Fabrication ofvery high density molds for nano-imprint lithography (NIL) and for the 2. Fabrication of Multiple Tunnel Junction devices that can be used for single electron device applications or for the connection of small molecules. 3. In X-ray lithography techniques and DPN techniques.
- 20. Conclusion The currentdevelopment of electron beam lithography in nanofabrication has been reviewed. Both the technologies of direct writing and projection printing are examined and compared. Challenges faced in e-beam technology were overcome by various other recent techniques and these were compared to the e-beam lithography. Thus lithography techniques helps in fabrication processes of nanoscale devices their scope continues in future.
- 21. REFERENCES [1] G. H.Bernstein, D. A. Hill, and W. Liu, “New high-contrast developers for poly(methyl methacrylate) resist,” J. Appl. Phys., vol. 71, no. 8, pp.4066–4075, 1992. [2] S. D. Berger and J. M. Gibson, “New approach to projection electron lithography with demonstrated 0.1 micron linewidth,” Appl. Phys. Lett., vol. 57, pp. 153–155, 1990. [3] I. Brodie and J. J. Muray, The Physics of Micro/Nano-Fabrication. New York: Plenum, 1992. [4] C. D. Chen, W. Kuo, D. S. Chung, J. H. Shyu, and C. S. Wu, “Evidence for suppression of superconductivity by spin imbalance in Co-Al-Co single electron transistors,” Phys. Rev. Lett., vol. 88, no. 4,pp. 47 001–47 004, 2002. [5] Z. Cui, A. Gerardino, M. Gentili, E. Di Fabrizio, and P. Prewett, “Comparative study of AZPN114 and SAL601 chemically amplified resists for electron beam nanolithography,” J. Vac. Sci. Technol. B, vol. 16, no.6, pp. 3284–3288, 1998.
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