The future perspective of nano-material synthesis will be dependent on a dry chemistry process called CVD. This slide tells about how they work and about process parameters.

1. Natinael Kokeb
270064
1
Chemical vapor deposition polymerization
CVD
June 13, 2022
Modern Polymers

2. C H E M I C A L
V A P O R
D E P O S I T I O N
P O L Y M E R I Z A T I
O N S ?
D E S C R I P T I O N
O F M E T H O D S
CVDP method is used to produce the thin film deposit using
one or more vapor phase monomers (volatile) in order to
undergo polymerization.
No need to dissolve macromolecules, this enables insoluble
polymers to be coated and prevents solvent damage to the
substrate.
Ayse et.al. Designing polymer surfaces via vapor deposition. Materials Today. V.13, 5. 2010. 26-33, ISSN 1369-
Introduction

3. C H E M I C A L
V A P O R
D E P O S I T I O N
P O L Y M E R I Z A T I
O N S ?
D E S C R I P T I O N
O F M E T H O D S
Fig. 1 | Schematic of general elementary steps of a typical CVD process.
Sun, L., Yuan, G., et al. Chemical vapour deposition. Nat Rev Methods Primers 1, 5 (2021). 10.1038/s43586-
Introduction

4. C V D Introduction
Interferometer/Ellipsometry measures the coating
(1) Transport of reacting gaseous species
to the surface of a substrate,
(2) Adsorption of the species on that
surface,
(3) Heterogeneous surface reaction
catalyzed by the surface of the
substrate,
(4) Surface diffusion of the species to
growth sites,
(5) Nucleation and growth of the film on
the substrate, and
(6) Desorption of gaseous reaction
products and transport of reaction
products away from the surface.
Sun, L., Yuan, G., et al. Chemical vapour deposition. Nat Rev Methods Primers 1, 5 (2021). 10.1038/s43586-

5. • Temperature,
• Pressure,
• Reactant gas concentration, and
• Total gas flow
Require accurate control and
monitoring.
• Pyrolysis,
• Oxidation,
• Reduction,
• Hydrolysis,
• Combination and
May be catalyzed by the
substrate.
Main CVD process parameters Chemical reactions
Sun, L., Yuan, G., et al. Chemical vapour deposition. Nat Rev Methods Primers 1, 5 (2021). 10.1038/s43586-

6. M E T H O D S A N D T H E I R
C L A S S I F I C AT I O N
C
V
D Source
• Atomic layer deposition (Inorganic materials)
• Molecular layer deposition (Organic materials)
Position of reactor
setup
 Horizontal CVD
 Vertical CVD
Pressure inside
reactor
 Atmospheric pressure CVD
 Low-pressure CVD (Ex. Ti)
 Ultra high CVD
They vary by amount of pressure
used
For high heat resistant materials
Stimulus used in
reactor
 Oxidative CVD
 Plasma enhanced
CVD
 Laser assisted CVD
 Photo-initiated CVD
 Initiated CVD
For polymers and biological
material samples b/c they degrade
by heat
N.B CVD processes are
categorized by the conditions used.
Sun, L., Yuan, G., et al. Chemical vapour deposition. Nat Rev Methods Primers 1, 5 (2021). 10.1038/s43586-

7. P L A S M A E N H A N C E D C V D ( P E C V D )
 Where plasma + thermal energy, for the reactions b/n
excited species and the substrate.
 Precursors are decomposed in reactive plasma by the
collisions b/n energetic electrons and gas molecules.
Zheng Bo et.al. Plasma-enhanced CVD. Nanoscale, 2013,5, 5180-5204. https://doi.org/10.1039/C3NR33449J
Methods
 Plasma excitation creates the active species that initiate
polymerization.
 Both organic and inorganic materials can be used as
precursors.
 However, PECVD involves a complex mechanism

8. O X I D AT I V E C V D
( O C V D )
 Needs volatile precursors to be delivered into the vacuum
chamber without decomposition.
 Enables the step growth of electrically conducting
polymers such as poly(ethylenedioxythiophene)
(PEDOT).
M
E
C
H
A
N
I
S
M
 The oxidant and monomer are delivered to
the substrate through the vapor phase.
 Adsorption and spontaneous reaction proceed
directly on the substrate. No additional
excitation of reactants is required.
 Conducting polymer layers synthesized using
preapplied oxidant in combination with vapor
phase monomers.
FeCl3
Fig. 3 (a) Schematic of a typical oCVD reactor. (b) Chemical structures of conducting polymer deposited by oCVD. PEDOT (poly(ethylenedioxythiophene))
Ayse et.al. Designing polymer surfaces via vapor deposition. Materials Today. V.13, 5. 2010. 26-33, ISSN 1369-

9. L A S E R - A S S I S T E D C V D
Sun, L., Yuan, G., et al. Chemical vapour deposition. Nat Rev Methods Primers 1, 5 (2021). 10.1038/s43586-
 Laser beam is used to locally heat the
semiconductor substrate, causing the
vapor deposition chemical reaction to
proceed faster at that site.
 Gas phase precursors are thermally
decomposed, and the resulting chemical
species 1) deposit on a surface, or 2)
react, form the desired compound

10. I N I T I AT E D C V D ( I C V D )
Ayse et.al. Designing polymer surfaces via vapor deposition. Materials
Today. V.13, 5. 2010. 26-33, ISSN 1369-7021.
Front. Bioeng. Biotechnol., 16 April 2021
| https://doi.org/10.3389/fbioe.2021.670541
 It is low-energy, one step, solvent-free process
needs monomer(Ex. acrylates) and an initiator
species(ex. tert-butyl peroxide).
 The certain temperature (~250°C) filaments
results in formation of free radicals from the
initiator without cracking of the monomer.
 Adsorption and polymerization on a cooled
substrate. In the absence of an initiator species,
film growth is negligible.
 For chain growth polymers including PTFE14,
acrylates.

11. P R O C E S S E S O F G R O W I N G G R A P H E N E O N M E T A L
S U B S T R A T E S A N D D I E L E C T R I C S U B S T R A T E S
Fig. 3 | Schematic of experimental processes for growing graphene
using CVD.
Sun, L., Yuan, G., et al. Chemical vapour deposition. Nat Rev Methods Primers 1, 5 (2021). 10.1038/s43586-
O2 to reduce nucleation density
H2 activate weekly oxidized copper surface
@1200 oc

12. S U M M A R Y
 There are plenty of methods of chemical vapour deposition.
However, using of appropriate method depends on the properties
of the substrate and precursors

13. THANK YOU
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