Diamond like carbon
Muresan Mihai
Carbon
• Carbon is the fourth most abundant chemical
element in the universe by mass
• The structures of eight allotropes of carbon:
a) Diamond
b) Graphite
c) Lonsdaleite
d) C60 Fullerene
e) C540 Fullerene
f) C70 Fullerene
g) Amorphous carbon
h) SWCNT
Carbon
• Diamond – the hardest naturally occurring
substance
• Graphite – the cheapest fuel (coal), electrical
conductor, heat resistant material and lubricant
• Fullerenes – potential medical use
• CNT – strongest and stiffest material, possible
high electric conductivity, composite polymers,
ultracapacitors
• Graphene – ballistic electrical conductivity, gas
detectors, IC, biodevices
• a-C – a material that is not diamond or graphite
a-C
• a-C:H can be split in four types:
1.
2.
3.
4.
polymer-like a-C:H (PLCH) with
the highest H content (40–60%),
but soft
harder diamond-like a-C:H (DLCH)
with intermediate H content (20–
40 at. %),
hydrogenated tetrahedral
amorphous carbon films (ta-C:H)
with fixed H content 25–30 at. % H
graphite-like a-C:H with less than
20 at. % of H
a-C:H properties
High thermal conductivity
High hardness
Good abrasion coefficient
Low friction coefficient
Gas barrier
Inertness
Wide band gaps
a-C problems
• Bad adhesion (especially on metals)
• High stressed films
• Thermal stability under 300OC (a-C:H)
• Solving the problems:
Fabrication of intermediate metallic layer
Intermediate compound layer (WC, TiC)
Doping with different elements
DLC uses
a-C and hard films production
PECVD
2015
2010
2009
782
mil $
905
mil $
1.7
bn $
Arc
discharge
Magnetron sputtering
Why PECVD?
•
•
•
•
•
•
Relatively easy to produce plasma
Pure deposition due to low pressure
Large size depositions
Precision of the coating
Low melting point substrates
Good dielectric properties
PECVD System
PECVD system
•
•
•
•
•
PECVD deposition
CCP RF 13.56 MHz
Vacuum system (~10-4 Pa)
Gas flow meters
420 mm electrode
PECVD chemistry
Types of DLC films
• DLC from CH4, H2
• DLC:N with N2
• DLC:SiOx with HMDSO/HMDSZ
Deposition at room temperature
Low cost
Relative big substrates
Why DLC:N films?
Preparation of DLC films
CH4
H2
N2
Power
Self-bias
Pressure
Time
d
[sccm]
[sccm]
[sccm]
[W]
[V]
[Pa]
[min]
[nm]
CH16
8.5
2.5
2.5
100
-130
12
60
114
CH17
8.5
2.5
2.5
50
-50
12
60
216
CH30
8.5
5
0
100
-75
12
30
101
Sample
Characterization of DLC films
• ellipsometry - Jobin Yvon UVISEL 190-1000
nm
• reflectometry - Perkin Elmer Lambda45 1901000 nm
• FTIR transmittance - Bruker Vertex 80v 3707000 cm-1 correct transmittance accessory
• depth sensing indentation - Fischerscope H100
with Vickers indenter
• ion beam spectroscopies - Rutherford
Backscattering Spectroscopy (RBS) and Elastic
Recoil Detection Analysis (ERDA)
Optical characterization
Egσ
Egπ
[eV]
[eV]
CH16
5.012
CH17
CH30
Sample
pσ
pπ
a
0.509
0.854
1.438
0.996
5.086
0.440
0.851
1.070
0.978
4.737
0.752
0.930
1.158
0.989
Optical characterization
Optical characterization
Mechanical characterization
Sample
CH16
CH17
CH30
CH30 a
Y [GPa]
130
68
155
124
H [GPa]
18,5
6,7
21,7
13,1
Chemical composition
1%
0%
C
H
N
O
34%
CH30
Ar content below 0.3%
65%
10%
CH17
38%
13% 1%
6%
46%
29%
CH16
57%
a-C:H:SiOx films
Hpl [GPa]
25
20
1.0
cHMDSO=21%
friction coefficient
15
10
Y [GPa]
160
140
120
100
80
1.0
Dcr
speed
load
0.6
15 cm/s
10 N
0.4
0.2
0.0
0
1000
2000
3000
4000
5000
number of cycles
0.5
0.0
Pin-on disc testing conditions:
Al2O3 ball with diameter of 6mm
0.8
0
5
10
SiOx [%]
15
6000
7000
Conclusions
Hard DLC films can be produced on low melting
point substrates
DLC:N films can be used on metallic substrates
DLC:SiOx films present higher thermal stability
o The method is relatively cheap, can cover large
substrates and can be employed for low melting
point substrates (plastics)
Thank you for your attention