Epitaxy techniques

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 Muenster 06/01/2020 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 06/01/2020 3

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. 06/01/2020 4 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) 06/01/2020 5

6. H omoepitaxy 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., 06/01/2020 6 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., 06/01/2020 7 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. 06/01/2020 8 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 06/01/2020 9

10. Epitaxy Techniques Liquid-Phase Epitaxy (LPE) Vapor-Phase Epitaxy (VPE) Molecular Beam Epitaxy (MBE) 06/01/2020 10

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 µ m/min ~10-100 times faster than in MOVPE or MBE e.g.: thick layers of GaAlAs with uniform composition. 06/01/2020 11          

12. LPE Techniques: 06/01/2020 12 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. 06/01/2020 13

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 06/01/2020 14

15. PVD Types Cathodic Arc Deposition Electron beam PVD Close-space sublimation Pulsed laser deposition Sputter deposition Pulsed electron deposition Sublimation sandwich method 06/01/2020 15

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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 µ m/min. 06/01/2020 17

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 06/01/2020 18

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 06/01/2020 19

20. CVD Equipment 06/01/2020 20 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 ((CH 3 ) 3 In) and phosphine (PH 3 ). 06/01/2020 21

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/ 06/01/2020 22

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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: 0.0 1 µ m/ 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 06/01/2020 24

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 06/01/2020 25

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 06/01/2020 26

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 06/01/2020 27

28. Applications Membranes and Fibres – Membranes, Optical fibers for telecommunications . 06/01/2020 28 https://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. 06/01/2020 29 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 06/01/2020 30

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 06/01/2020 31

32. THANKYOU FOR LISENING ANY QUESTIONS? 06/01/2020 32

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