The presentation mainly describes different types of techniques that are available for making thin-layer depositions. This includes CVD, PVD, and MBE.

1. Preparation Techniques : Epitaxial
Technology
Rohith Cherukuri
Materials Science and Engineering
University of Applied Sciences Muenster06/01/2020 1

2. Preparation Techniques : Epitaxial
Technology
Rohith Cherukuri
Materials Science and Engineering
University of Applied Sciences Muenster
06/01/2020 2

3. Outline
• Introduction
• Epitaxy Types
• Epitaxy Techniques
• Applications
• Conclusion
• References
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4. What is Epitaxy?
Epi implies ABOVE
Taxis implies an ordered manner
Epitaxy refers to a type of crystal growth or
material deposition in which new crystalline
layers are formed with respect to the
crystalline substrate.
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https://www.mlz-garching.de/mbe

5. Epitaxy Types
Depending on substrate and Epitaxial layer
• Homoepitaxy
• Heteroepitaxy
Depending on growth direction
• Homo/Heterotopotaxy
• Pendeo-epitaxy or Epitaxial lateral overgrowth (ELO or ELOG)
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6. Homoepitaxy
• The substrate and thin film are the same, often
silicon on silicon.
• This is often used to grow films that are purer
than the substrate, and which can be doped
independently of it.
e.g. Si on Si etc.,
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https://www.universitywafer.com/silicon-
carbide-inventory.html

7. Heteroepitaxy
This is performed with different materials and
often used to grow films of materials for
which crystals can’t otherwise be obtained
e.g. silicon on sapphire,
GaAs on Silicon etc.,
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Epitaxial growth of InGaAs/GaAs
quantum-dot
degruyter.com/view/j/nanoph.2015.4.issue-2/nanoph-
2014-0024/nanoph-2014-0024.xml

8. Homo/Heterotopotaxy
• This method is similar to
homo/heteroepitaxy except growth is
not limited to two-dimensional growth;
• The substrate is similar only in structure
to the thin-film material.
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https://www.slideshare.net/kritickasharma/ic-technology-chemical-
vapour-deposition-and-epitaxial-layer-growth

9. Pendeo-epitaxy or Epitaxial lateral overgrowth
(ELO or ELOG)
• A heteroepitaxial film grows vertically and laterally
simultaneously.
• It is particularly important for compound such as GaAs
and GaN
e.g. GaN on sapphire wafer .,
Schematic of Pendeo-epitaxy(PE)
http://blog.naver.com/PostView.nhn?blogId=namgoocha&
logNo=220561768213
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10. Epitaxy Techniques
• Liquid-Phase Epitaxy (LPE)
• Vapor-Phase Epitaxy (VPE)
• Molecular Beam Epitaxy (MBE)
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11. Liquid-Phase Epitaxy (LPE)
• Growing the crystal from the contact between the substrate and a
liquid source of the material to grow.
• Hard to make thin films
• Growth Rate: 0.1-1 µm/min ~10-100 times faster than in MOVPE
or MBE
e.g.: thick layers of GaAlAs with uniform composition.
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12. LPE Techniques:
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Basic structure of graphite horizontal
sliding boat LPE
Schematic diagram of a dipping
LPE
Tipping LPE furnace
per2017_Chapter_EpitaxialCrystalGrowthMethodsA

13. Vapor-Phase Epitaxy (VPE)
• Physical Vapor Deposition - PVD, the compound to be grown or its constituents are
evaporated and subsequently transported through the relevant reactor toward the
substrate.
• Chemical Vapor Deposition - CVD, volatile species containing the constituent
elements of the layer to be grown are produced first in- or outside the reactor and
transported as streams of vapor towards the reaction zone near the substrate.
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14. Physical Vapor Deposition(PVD)
• Deposition of a material in the vapor phase onto a
solid in a vacuum.
• The coating method involves purely physical
processes such as high-temperature vacuum
evaporation with subsequent condensation, or plasma
sputter bombardment
• Usually no chemical reactions take place Carried out
in a vacuum atmosphere
• Used for thin and uniform coating or films
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15. PVD Types
• Cathodic Arc Deposition
• Electron beam PVD
• Close-space sublimation
• Pulsed laser deposition
• Sputter deposition
• Pulsed electron deposition
• Sublimation sandwich method
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16. 06/01/2020 16

17. Chemical Vapor Deposition (CVD)
• It is a chemical process used to produce high-purity, high-performance solid
materials.
• The wafer (substrate) is exposed to one or more volatile precursors, which react
and/or decompose on the substrate surface to produce the desired deposit.
• Frequently, volatile by-products are also produced, which are removed by gas
flow through the reaction chamber.
• Growth rate: ~0.1 µm/min.
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18. CVD Family
CVD => Chemical Vapor Deposition
PE-CVD => Plasma Enhanced CVD
MO-CVD => Metal Organic CVD
AP-CVD=> Atmospheric pressure CVD
LP-CVD =>Low-pressure CVD
UHV-CVD=>Ultrahigh vacuum CVD
AA-CVD=>Aerosol assisted CVD
DLI-CVD=>Direct liquid injection CVD
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19. CVD System
• Gas delivery system –
• Reaction chamber –
• Substrate loading mechanism-
• Energy source –
• Vacuum system –
• Exhaust system –
• Process control equipment-
Low pressure chemical vapor deposition
http://lnf-wiki.eecs.umich.edu/wiki/Low_pressure_chemical_vapor_deposition
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20. CVD Equipment
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http://fr.worldtempus.com/article/montres/innovation-et-technique/tag-heuer-conversation-avec-les-atomes--le-
nouveau-balancier-en-composite-de-carbone-27183.html
Carbon + 150 system by CVD Equipment Corporation, USA; configured per TAG Heuer
specifications and operated in La Chaux-de-Fonds

21. Metal Organic-CVD
• The surface reaction of organic compounds or
metalorganics and metal hydrides containing
the required chemical elements.
• For example, indium phosphide could be
grown in a reactor on a substrate by
introducing Trimethylindium ((CH3)3In) and
phosphine (PH3).
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22. Plasma-Enhanced CVD
• PECVD uses electrical energy to transform the
gas mixture into reactive radicals, ions, neutral
atoms and molecules, and other highly excited
species.
• Depending on the nature of these interactions ,
either etching or deposition takes place at
substrate.
Plasma-Enhanced CVD Process
https://rvcethinfilms.wordpress.com/2016/08/09/unit-2/
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23. 06/01/2020 23

24. Molecular Beam Epitaxy (MBE)
• Due to the interaction of molecular or
atomic beams on a surface of a heated
crystalline substrate
• Relies on the sublimation of ultrapure
elements, then condensation of them on
wafer
• In a vaccum chamber (Pressure ~10-11
Torr )
• Growth rate: 0.01µm/min
Schematic drawing of the MBE system
https://www.researchgate.net/figure/Schematic-drawing-of-the-MBE-
system-black-lines-with-surface-diffractometer-gray_fig2_202364044
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25. MBE Equipment
Ultra high purity molecular beam epitaxy (MBE) machine for GaAs-based hetero- and nanostructures
L: https://www.fkf.mpg.de/273938/30_Oxide_MBE_Lab
R: nano.tum.de/index.php?id=90
L R
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26. MBE: Working Principle
• The Solid source materials sublimate
• They provide an angular distribution of atoms
or molecules in a beam
• The substrate is heated to the necessary
temperature.
• The gaseous elements then condense on the
wafer where they may react with each other.
Schematic view of the MBE Growth Chamber
https://www.fkf.mpg.de/273938/30_Oxide_MBE_Lab
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27. Applications
• Coatings – Coatings for a variety of applications
such as wear resistance, corrosion resistance, high
temperature protection, erosion protection and
combinations.
• Semiconductors (III-V group, II-VI group and
related devices) – Integrated circuits, sensors and
optoelectronic devices
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28. Applications
Membranes and Fibres – Membranes, Optical fibers for telecommunications.
06/01/2020 28https://pubs.rsc.org/en/content/articlehtml/2018/ra/c7ra09822g

29. Applications
Composites – Preforms can be infiltrated using CVD techniques to produce ceramic
matrix composites such as carbon-carbon, carbon-silicon carbide and silicon
carbide-silicon carbide composites.
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Carbon composite Hairspring in iron atoms on Silicon wafer @ TAG Heuer
http://fr.worldtempus.com/article/montres/innovation-et-technique/tag-heuer-conversation-avec-les-atomes--le-
nouveau-balancier-en-composite-de-carbone-27183.html

30. Conclusion
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31. References
• http://users.wfu.edu/ucerkb/Nan242/L12-Epitaxy.pdf
• https://www.researchgate.net/profile/James_Harris9/publication/33706394
• https://www.researchgate.net/publication/237305868
• https://s3.amazonaws.com/ppt-download/pvdandcvdprocess-140508080132-phpapp02.pdf
• https://www.sciencedirect.com/topics/chemistry/liquid-phase-epitaxy
• https://doi.org/10.1016/B978-0-08-102183-5.00001-7
• H.J. Scheel:The Technology of Crystal Growth and Epitaxy, ed. by H.J. Scheel, T. Fukuda
• M.G. Astles: Liquid Phase Epitaxial Growth of IIIV Compound Semiconductor Materials and Their Device Applications
• Walter S. Knodle and Robert Chow: Molecular beam epitaxy: Equipment and practice
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32. THANKYOU
FOR
LISENING
ANY QUESTIONS?
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