CylindricalPost-Magnetron Sputtering
for High Rate Niobium deposition
Cristian Pira
Cristian Pira 4 October 2010
CERN standard configuration
Is it perfect?
2 Important limitations for the target:
1) Not punctual source2) Technological limits
Cristian Pira 4 October 2010
Punctual Source
> 28 °
R. Losito, CERN SL-Note-98-008, February 1998 R. Losito, CERN SL-Note-2000-047 CT, July 2000
Cristian Pira 4 October 2010
Technological limits
• Longitudinal Electron Beam Welding
• Low Target Consumption
• Bad Target Cooling
• Difficulty to empty the Nb/Steel air
space
Cristian Pira 4 October 2010
Project Goal
• Eliminate the technological limitsof CERN cathode
• Realize a punctual source
Low Target Area
Cristian Pira 4 October 2010
Why High Rate Sputtering?
Decreases impurities in film growth
RN
Nf
ii
iii
fi = fraction of impurities of i species
Ni = Numbers of i speciesi = Stiking factor of i speciesR = Deposition Rate
L. I. Maissel, R. Glang,Handbook of thin film technology, Mc Graw-Hill, 1970
Cristian Pira 4 October 2010
coil
B B
Cylindrical VS Post Magnetron
Cristian Pira 4 October 2010
Abnormal Glow
DischargeThermionic Emission
Thermionic Emission
Cristian Pira 4 October 2010
Cathode Section
BNInsulator
Grounded Tube
Shield
Water tube
PotentialTube
Vacuum Ceramic
Feedthrough
CF100FlangeBN
Insulator
Allumina Pipe
Post Magnetron
Nb tube
Cristian Pira 4 October 2010
Cathode
Cristian Pira 4 October 2010
High Rate Sputtering System
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High Rate Sputtering System
Cristian Pira 4 October 2010
Samples holder
1
2
34 5
6
7
8
Cristian Pira 4 October 2010
Sputtering Conditions
Base Pressure 210-9 mbarPAr = 710-3 mbar
I = 15 – 20 AV 250 Vt =15 minT cavity = 200-300 °CDeposition Rate = 2,5 nm/s
Cristian Pira 4 October 2010
I-V Characteristics
0 2 4 6 8 10 12 14 16 18 20250
300
350
400
450
500
550
600
650
P = 7*10-3 mbar
V
(V
olt
)
I (Ampere)
Cristian Pira 4 October 2010
1 2 3 4 5 6 7 8
0.0
0.5
1.0
1.5
2.0
2.5
3.00
.5
0.5
1.6
1.4
0.4
0.7
0.7
0
0.9
2
1.5
9
1.7
0
1.4
4
0.6
5
0.8
7
0.5
6
0.7
1
0.9
6
1.2
6
1.3
6
0.9
2
1.0
4
1.1
6 1.5
6
2.4
7
2.0
9
2.1
0 2.5
7
1.8
6
1.5
1
1.2
9
1.0
6
1.7
7
2.4
2
2.0
1 2.3
1
1.1
8
1.2
81.6
4 2.1
7 2.5
5
2.5
6
1.8
9
1.6
2
1.6
6
Film Thickness
Cav1
Cav2
Cav3
Cav4
Cav5
Cav6
Cavity Position
mm
Thickness
Cristian Pira 4 October 2010
Open Wing Post Magnetron
Cristian Pira 4 October 2010
Grain Size15
,70
15,3
0 22,6
0
15,4
5
19,1
5
17,7
0
18,6
1
18,6
6
22,3
5
23,6
3
23,0
1
28,4
4
26,7
3
24,6
3
27,1
1
26,6
5
25,7
0
26,1
1
25,9
6
31,4
9
0,00
5,00
10,00
15,00
20,00
25,00
30,00
35,00
1 2 3 4
nm
Cavity Position
Grain Size
CERN1
Cav3
Cav4
Cav5
Cav6
32
41
Cilyndrical
Magnetron
~ 15 nm
Post Magnetron
> 25 nm
Cristian Pira 4 October 2010
RRR
5,0
7,5
4,6
4,2
5,7 6,0 6,3
9,0
5,0
6,5
6,2
7,7
4,2 5,
4 5,9 6,5
0,0
2,0
4,0
6,0
8,0
10,0
1 2 3 4
RRR
Cavity Position
RRR
Cav3
Cav4
Cav5
Cav6 32
41
4<RRR<9
Cristian Pira 4 October 2010
Tc
9,1
2
9,1
8
9,1
6
9,2
0
9,2
0
9,2
2 9,3
0
9,3
4
9,1
6
9,1
4
9,1
5 9,2
6
9,0
9
9,0
9
9,0
7
9,1
2
8,70
8,80
8,90
9,00
9,10
9,20
9,30
9,40
1 2 3 4
Tc (K)
Posizione nella cavità
Tc
Cav3
Cav4
Cav5
Cav6 32
41
Tc < 9,26 K
Cristian Pira 4 October 2010
Why?
• Cavity degassing?
• Bombardment of cavity wall by
electrons?
• Diffusion of Silicon or Oxigenfrom the quartz to the film?
• Target poisoning?
• Cavity degassing?
• Bombardment of cavity wall by
electrons?
• Diffusion of Silicon or Oxigenfrom the quartz to the film?
• Target poisoning?
Cristian Pira 4 October 2010
RRR VS Sputtering Angle
Tonini et al., LNL Annual Report 2004
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