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Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
A. Zöller, H. Hagedorn, W. Lehnert, J. Pistner, M. Scherer,
Alzenau
2Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
Outline
� Plasma Assisted Reactive Magnetron Sputtering (PARMS)
� System layout
� Material properties
� Typical interference filter application
� UV coatings
� Defect investigation
� LIDT on HR mirrors
� Conclusion
3Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
Plasma Assisted Reactive Magnetron Sputtering
Load lock valve
Dual magnetronProcess module
Turn table
Substrate heater
Plasma source
Substrate
4Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
Plasma Assisted Reactive Magnetron Sputtering
Ar+e-
Magnetron 1
MF Power supply ~
Magnetron 2
Cathode
AnodeAnode
Cathode
Magnetron 2 Magnetron 1
Vt
Plasma stabilization by MF Dual Magnetron Sputtering
5Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
System layout
� HELIOS 400 / 800
• 100mm
- 16 substrate carrier
- useful area 12 x 78cm²
= 0,12m²
• 200mm- 12 substrate carrier
- useful area 12 x 314cm²
= 0,38m²
6Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
Substrate handling
HELIOS single substrate load lock
7Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
Substrate handling
HELIOS substrate transfer
8Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
Substrate handling
HELIOS substrate transfer
9Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
Direct optical monitoring
■ Intermittent direct on-substrate monitoring
Load Lock Valve
10Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
Coating materials
���� Low intrinsic compressive coating stress
0,33- 1001,48SiO2
0,5-1802,075HfO2
0,5-702,13ZrO2
0,6- 902,166Ta2O5
0,55- 1502,365Nb2O5
0,4- 1151,67Al2O3
0,45- 3001,48SiO2
Deposition rate[nm/s]
Film stress [MPa]
Ref. index n@ 550nm
Material
11Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
Plasma Assisted Reactive Magnetron Sputtering
Helios magnetron sputtering system with direct monitoring
Coating materials: Nb2O5 / SiO2
Short wave pass filter
OD > 7 @ 750nm-1100nm
12Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
Plasma Assisted Reactive Magnetron Sputtering
0
10
20
30
40
50
60
70
80
90
100
200 300 400 500 600 700 800 900 1000 1100 1200
Wavelength (nm)
Tra
ns
mit
tan
ce
(%
)
Theory_Front+Back
090609-2-4-F+B_P2
090609-2-4-F+B_P3
090609-2-4-F+B_P4
090615-B+F_P9
090615-B+F_P11
� Band pass filter with broad blocking range OD6
Design
Front and backside
coating
H = Nb2O5
L = SiO2
Total layer number
94 / 104
Total thickness
9,4µm / 10.4µm
13Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
Plasma Assisted Reactive Magnetron Sputtering
11-Cavity Bandpass Filter Ta (50% BW=30nm)
Helios magnetron sputtering system with direct monitoring
Optical Performance of the monitor glass (first run)
(w/o backside AR coating)Coating materials: Ta2O5 / SiO2
0
10
20
30
40
50
60
70
80
90
100
410 430 450 470 490 510
Wavelength (nm)
Tra
nsm
itta
nce
(%
)
Theory
OMS in chamber
14Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
Plasma Assisted Reactive Magnetron Sputtering
13-Cavity Bandpass Filter for life science applications
Helios magnetron sputtering system with direct monitoring
0,5 dB (89%) BW– 47,7 nm
3dB (50%) BW – 48,0 nm
10dB (10%) BW – 49,2 nm
30dB (0,1%) BW – 53 nm
steepness – >50dB/nm
Highest peak - 0,3dB (95%)w/o backside AR
-40
-35
-30
-25
-20
-15
-10
-5
0
400 420 440 460 480 500 520 540
Wavelength (nm)
Tra
ns
mit
an
ce
(d
B)
1st run
2nd run
Coating materials: Nb2O5 / SiO2
Optical Performance of the monitor glass (w/o backside AR coating)
15Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
Plasma Assisted Reactive Magnetron Sputtering
1-Cavity NBP Filter with Ta2O5/SiO2
Magnetron sputtering with direct monitoring
Optical Performance of the monitor glass (w/o backside AR-coating)
Highest peak – 0,2 dB
3dB (50%) BW – 2,1 nm
Substrates 16
Useful area @ Uniformity <+-0,2%
Diameter 60- 80mm
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
1050 1052 1054 1056 1058 1060 1062 1064 1066 1068 1070 1072 1074 1076 1078 1080
Wavelength / nm
Tra
nsm
itta
nce
/ d
B
Absorption:
Single Layer 4 λλλλ /4@1064nm
Ta2O5 < 4ppmSiO2 < 3ppm
16Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
Plasma Assisted Reactive Magnetron Sputtering
Single side coating
H = Nb2O5
L = SiO2
Total layer number
198
Total thickness
20µm
Batch time
app. 13h
4-fold-notch filter, AOI=10°
0
10
20
30
40
50
60
70
80
90
100
420 460 500 540 580 620 660 700 740
Wavelength [nm]
Tra
nsm
itta
nce [
%]
Theory
Pos 3
Pos 4
Pos 5
Pos 7
Pos 9
Pos 10
Pos 11
Spec. Tavg
� Multi notch filter
17Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
UV- and VIS Filter Coatings by PARMS
Dispersion n & k of optimized HfO2, ZrO2, and Ta2O5
2
2.05
2.1
2.15
2.2
2.25
2.3
2.35
2.4
2.45
2.5
200 250 300 350 400 450 500 550 600
Wavelength (nm)
Refr
acti
ve I
nd
ex n
0.0E+00
1.0E-04
2.0E-04
3.0E-04
4.0E-04
5.0E-04
6.0E-04
7.0E-04
8.0E-04
9.0E-04
1.0E-03
Exti
ncti
on
k
n Ta2O5 n ZrO2 n HfO2
k Ta2O5 k ZrO2 k HfO2
18Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
UV- and VIS Filter Coatings by PARMS
0,5-170λ λ λ λ ≥ 2502,075HfO2
0,5-70λ λ λ λ ≥ 2802,130ZrO2
0,6-90λ λ λ λ ≥ 3252,166Ta2O5
Rate (nm/s)Streß (MPa)k < 1 E- 3n (550nm)Material
Properties of optimized HfO2, ZrO2, and Ta2O5 films
19Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
UV- Filter Coatings by PARMS
Al2O3 and SiO2 for UV applications
� Dispersion n & k of optimized Al2O3 and SiO2
1,50
1,55
1,60
1,65
1,70
1,75
1,80
1,85
1,90
200 210 220 230 240 250 260 270 280
Wavelength [nm]
Refr
acti
ve I
nd
ex
n
0,0E+00
5,0E-04
1,0E-03
1,5E-03
2,0E-03
2,5E-03
3,0E-03
3,5E-03
4,0E-03
Exti
ncti
on
k
n SiO2 n Al2O3 k SiO2 k Al2O3
20Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
UV Filter Coatings by PARMS
Direct optical monitoring @212nm
- BP Filter 212nm, 6 cavity, 90 layer Al2O3 and SiO2
0
10
20
30
40
50
60
70
80
90
100
200 205 210 215 220 225
Wavelength (nm)
Tra
ns
mit
tan
ce
(%
)
measured in chamber
CWL=212.025
FWHM=7.55nm
21Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
UV- Filter Coatings by PARMS
Al2O3 for UV applications
� Mirror for 193nm, Result
Mirror for 193nm based on Al2O3 and SiO2 with HELIOS PARMS
0
2
4
6
8
10
12
14
16
18
20
185 190 195 200 205
Wavelength [nm]
Tra
nsm
itta
nce
[%
]
80
82
84
86
88
90
92
94
96
98
100
Refl
ec
tan
ce [
%]
T Helios R Helios R APS
22Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
■ Refractive index n at 550nm vs. power ratio Nb/Si+Nb
Co-sputtering: Intermediate refractive indices
Refractive index vs. power ratio of reactive co-sputtered NbxSiyOz layers
1,4
1,5
1,6
1,7
1,8
1,9
2
2,1
2,2
2,3
2,4
0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1
Power ratio [Nb/Si+Nb]
Re
frac
tiv
e i
nd
ex
n
n at 550nm
SiO2 Nb2O5
23Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
Rugate type Filter with co-sputtering
■ Rugate/notch filter design: λλλλ/4 design
Refractive index profile
1,4
1,5
1,6
1,7
1,8
1,9
2,0
2,1
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41
Number of QWOT
Re
fra
cti
ve
in
de
x a
t 6
00
nm
24Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
■ Rugate filter with λλλλ/4 layer design
- Comparison with theory and reproducibility
Rugate type Filter with co-sputtering
HELIOS rugate/notch Filter, comparison of theory with 4 repro runs
0
10
20
30
40
50
60
70
80
90
100
350 400 450 500 550 600 650 700 750 800 850
Wavelength [nm]
Tra
ns
mit
tan
ce [
%] 050607-02 Pos. 2
050607-05 Pos. 2
050608-02 Pos. 2
050608-05 Pos. 2
Rugate Disign-41L
Process time 3h
25Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
Defect formation Helios prototype, SiO2
� Defect density of < 5 cm-2 for a longer period achievable
� No onset of defect generation until the end of the target lifetime
� Advanced configuration: Circular SiO2 target, RF-powered
26Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
LIDT S-on-1 @ 1064nm SiO2 (RF)
� Single layer 4 L
� Substrate Suprasil
27Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
LIDT S-on-1 @ 1064nm SiO2 (RF); Ta2O5(MF)
� HR Mirror (HL)^11 L
� Substrate Suprasil
28Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
LIDT S-on-1 @ 1064nm SiO2 (RF); Ta2O5(MF)
� HR Mirror (HL)^11 L
� Substrate Silicon Wafer
29Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
LIDT S-on-1 @ 1064nm SiO2 (RF); Ta2O5(MF)
� HR Mirror (HL)^18 L
� Substrate Silicon Wafer
30Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
PARMS Coatings @ 1064nm SiO2/Ta2O5
99.991%
90ppm
0.47nm
Reflection
Total loss
(CRD)
Surface roughness
RMS
158 J/cm2
0%- LIDT
@ 1064nm
H 1 on 1
SiO2/Ta2O5
Si-Wafer
/super polished
Coating material
Substrate
HR Mirror
HL^18L
@1064nm
Design
31Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
Conclusion
� PARMS has shown within the last 10 years to be
capable to produce the most complex interference filter
with high productivity
� PARMS can produce coatings with high laser damage
threshold and very low total losses
� Using RF sputtering for SiO2 can lower the defect
density significant
32Photonex 2012; Plasma Assisted Reactive Magnetron Sputtering of High Performance Interference Filters
Thank you for your attention !