1. PROPERTIES OF THIN FILMS
MADE BY
ION BEAM DEPOSITION
Resistive Coating for Gaseous Detectors
May Bari – Italy
Diamond-Like Carbon
and related resistive coatings
for Micro-Pattern Gaseous Detectors
Antonio Valentini

2. Ion – Solid Interactions
SPUTTERING PROCESS
Ion
Target
RCGD - Bari, May A. Valentini

3. Simulated Trajectories
Computer simulation: Displacement of Cu atoms due to the impact of 1.5 keV Argon ions
(a) Trajectories within the entire volume of collision cascade for 10 incident particles
(b,c) Transport of target atoms out of and into the designated layer (20 incident particles)
(d) Trajectories of sputtered atoms (50 incident particles)
0 1 7
1.5 KeV Ar+
RCGD - Bari, May A. Valentini

4. Ion incidence angle effects emitted particles from the target
Less efficiency More efficiency
Cone angle exit particles Uniform direction exit particles
RCGD - Bari, May A. Valentini

5. DUAL ION BEAM SPUTTERING SCHEME
DUAL ION BEAM SPUTTERING SCHEME Ar
PUMPING GROUP
ION BEAM SOURCE 1
(Ar/H2/O2)
ASSISTANCE ION
SOURCE
TARGET 1
SUBSTRATE
QCM
TARGET 2
ION BEAM SOURCE 2
RCGD - Bari, May A. Valentini

6. High Energy High Current
DUAL GRIDS ION SOURCE GRIDLESS ION SOURCE
High Energy High Current e-
ION
BEAM
RCGD - Bari, May A. Valentini

7. DIAMOND-LIKE CARBON (DLC)
Metastable form of amorphous carbon, containing a significant fraction of sp3 bonds, which gives the structure properties similar to those of diamond.
Variable features with % of sp2 bonds
RCGD - Bari, May A. Valentini

8. DLC IBS PREVIOUS ACTIVITY 2007-2008 IB SPUTTERING ASSISTANCEIB
SPUTTERING
ASSISTANCE
Temp
I beam (mA)
V beam (V)
Ar (sccm)
CH4 (sccm)
I beam (mA)
H2 (sccm)
T (°C)
0745 60
1200
2,5 /
18,8
100 1 4
905
0752
800 20
700
0753
19,1
900
0801
off
300
0803 2
0804
600
0805
Amb
0806
0807 90
0808
0809 25 3
0810
0853
0854
150
RCGD - Bari, May A. Valentini

9. CHEMICAL ANALYSIS RESULTS
XPS
DLC CVD DIAMOND
Campioni
sp2
sp3 F4 - 82 F5 81 F6 86
SAMPLES
sp2
sp3
0803 17 48
0805 14 51
0807 28 40
0808 22 54
0810 20 49
0853 23 Ib Vb Ar / Ia Va
CH4
Tsub
0808 60
800
2,5 / 20 90 2
900
RCGD - Bari, May A. Valentini

10. APPLICATIONS
In order to stabilize the photoemissive properties of the CsI
1,5 nm of IBS DLC on
20 nm of Thermal Evaporated CsI
Conductive Silicon substrate
RCGD - Bari, May A. Valentini

11. Conductive Layer for CsI – Head-On
APPLICATIONS
Conductive Layer for CsI – Head-On
2016
Ion Beam Sputtering
Sample
Material
Thickness (nm)
1532
ITO 10
1533 5
1533ox
ITOox
1534 Ni C
1535 3
1536
NiC+ Ni
3+0.5
1537
C+Ni
1538 1
RCGD - Bari, May A. Valentini

12. Conductive layer UV Transmittance
RESULTS
Conductive layer UV Transmittance
Selected Layer
(C 2.5 nm + Ni 0.5 nm)
RCGD - Bari, May A. Valentini

13. Good adhesion of DLC on Kapton Sheet Resistance of about 100 M
APPLICATIONS
ION BEAM SPUTTERING APPLIED FOR DLC FORMATION ON KAPTON
The goals!
Good adhesion of DLC on Kapton
Sheet Resistance of about 100 M
RCGD - Bari, May A. Valentini

14. Good adhesion of DLC on Kapton
To improve adhesion:
Chemical surface cleaning
Surface pretreatment with Ion Beam: Vb=150V - Ib=1A - (5 sccm Ar + 4 sccm H2)
Scotch tape test results:
Copper on Kapton
DLC on Kapton
No Pretreatment
Pretreatment
Pretreatment
Scotch tape
Scotch tape
RCGD - Bari, May A. Valentini

15. ION BEAM SPUTTERING DEPOSITION PARAMETERS
Vbeam = V Ibeam = mA
Sputtering gas: Ar (2.5 sccm)
Vass = 50 – 150 V Iass = 0.05 – 1.2 A
Assistance gas : Ar – Ar+N2 – Ar+H2
Film thickness = 50 – 100 nm Dep. rate =  nm/sec
Sample size 6x6 cm2
At now 22 samples
and
Parameter values have been setted for each one
Starting from
The Sheet Resistance values obtained on previous samples
RCGD - Bari, May A. Valentini

16. SHEET RESISTANCE MEASUREMENTS
Two Probe
Cu-bars: 6 x 0.5 x 0.5 cm3
D = 6 cm; L = 5 cm
Sample on soft tissue (mouse pad) to increase contact under pressure.
Orientations: Horizontal & Vertical.
Insulation Tester: Megger MIT 410
Multimeter: Agilent 34401°
Four Point Probe
S=2 mm
Circular Tool
Radii r1=1 cm & r2= 2 cm
RCGD - Bari, May A. Valentini

17. Sheet Resistance _ Results
RCGD - Bari, May A. Valentini

18. Chemical Analysis _ Results
XPS
1928
280
282
284
286
288
290
292
294
296
298
Binding Energy (eV)
1929
280
282
284
286
288
290
292
294
296
298
Binding Energy (eV)
Sputt V 50 mA
Assist V 70 mA
Gas assist. (sccm) 2.1 Ar 1 H2
1928
1929
BE /eV ± 0.1
Abb%
C–C (sp3)
284.7 79
C– O
285.9 13
286.0 12
C=O
287.2 5
287.3
COOH
288.6 3
288.5 4
RCGD - Bari, May A. Valentini

19. Chemical Analysis _ Results
XPS %C %O %N
%Si
%Ar
%Cu
1928
78.8
14.5
2.5
3.1
1.1 --
1929
75.1
16.4
3.4
1.0
Surface contaminations
Any (or very low) contribution of Csp2 at the surface
RCGD - Bari, May A. Valentini

20. IB contribution in DLC formation Csp3-Csp3 or Csp3-H1s
The carbon atoms Ion Sputtered from Graphite target are more likely to form sp2-hybridezed carbon bonding
The Nitrogen in Assistance Beam
encreases sp2- hybridized carbon bonding
encreases the localized states at the Fermi level that favor
the cunduction by hopping mechanisms
Higher content of sp2-hybridized carbon bonding and hopping
will reduce the film resistivity !!
The Hydrogen in Assiatance Beam facilitates the formation of sp3 carbon strucuture as sum of bonds
Csp3-Csp3 or Csp3-H1s
As the energy of Ar ions used for sputtering encreases the
graphite sputtering rate encreases
RCGD - Bari, May A. Valentini

21. Sheet Resistance Values and Film Properties
Preliminary results from Raman Analysis
Rs = 0.5 M/Square  > 50 G/Square
Higher Sputtering Energy Increases sp3/sp Higher Rs
N2 assistance Does not change significantly sp3/sp The Lowest Rs
H2 assistance Control sp3/sp Control Rs *
Rs values nearest the 100 M/Square
RCGD - Bari, May A. Valentini

22. 400mm in diameter substrates 16cm RF deposition source
Large Area Ion Beam Deposition System
400mm in diameter substrates
16cm RF deposition source
and
RF neutralizers
12cm RF assist ion source.
6 x 22/30 cm RF Ion Beam Source
RCGD - Bari, May A. Valentini

23. Summary DLC films with controlled properties Next Step
Assisted Ion Beam Sputtering has many indipendent parameters to be set
and
More tests are necessary
but
The technique is promising to grow
DLC films with controlled properties
Next Step
Tests on the reproducibility
Chemical Analysis on DLC deposited on Kapton (Raman)
XPS in depth analysis
Tests on the effects of CH4 in the Assistance Beam
RCGD - Bari, May A. Valentini

24. Thanks for the attention
RCGD - Bari, May A. Valentini