picosecond timing project - resistance reproducibility & thermal coefficient of … ·...
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Resistance Reproducibility & Thermal
Coefficient of ALD coatings at Argonne
(LAPD project collaboration meeting 06-10-2010)
Anil Mane, Qing Peng, Jeffrey Elam(Group leader)
ALD Research Program, Process Technology Research Group
Energy Systems Division.
Outline
LAPD Project: Importance of atomic layer deposition (ALD)
Development of novel resistive coatings by ALD at Argonne
Electrical measurements and thermal coefficient study of resistive coatings
Next plan and Summary
LAPD collaboration Meeting
26/10/2010
LAPD project background
Apply the basic concept of “micro-channel plate” (MCP) detectors to the development of large-area photo-detectors (LAPDs) *8”x8” MCP + with quantum efficiencies and gains similar to those of photo-tubes.
To design and fabricate “economical” robust LAPDs that can be tailored for a wide variety of applications that now use photomultipliers.
LAPD fabrication divided into sub-projects:
1. Development of higher quantum efficiency photo-cathodes
2. Use of Atomic Layer Deposition (ALD) to control the chemistry and surface characteristics of resistive and secondary emission surfaces on MCPs
3. Electronics
4. Assembly
5. Testing
LAPD collaboration Meeting
36/10/2010
“Microchannel plate” detectors
44
Channels
6/10/2010
LAPD collaboration Meeting
“Microchannel plate” detectors
55
Channels
6/10/2010
LAPD collaboration Meeting
• Continuous-dynode electron multiplier in presence ofa strong electric field (~ 1kVA/MCP)
• Electron amplifier (x104-107)
6
Conventional MCP Fabrication
Draw lead-glass fiber bundle
Slice, polish, chemical etch
Heat in hydrogen
Top/Bottom electrode coating (NiCr)
Drawbacks
Expensive
Resistance and secondary emission properties are linked
Limited optimize MCP performance for applications where lifetime, gain, substrate size, composition and thermal runaway are important
MCP fabrication
6/10/2010
LAPD collaboration Meeting
7
Conventional MCP Fabrication
Draw lead glass fiber bundle
Slice, polish, chemical etch
Heat in hydrogen
Top/Bottom electrode coating (NiCr)
Drawbacks
Expensive
Resistance and secondary emission properties are linked
Limited optimize MCP performance for applications where lifetime, gain, substrate size, composition and thermal runaway are important
LAPD Approach
Start with porous, non-lead glass
ALD (resistive + SEE layer) coating
Thermal treatment
Top/Bottom Electrode coating (NiCr)
Advantages
Independent control over composition of Resistive and SEE coating
Low thermal coefficient of resistance
Applicable: Ceramics, SiO2, plastics, polymers MCPs
Low cost (No major issue for scale-up with ALD)
MCP fabrication
MCP Structure
1) resistive coating (ALD)2) emissive coating (ALD)3) conductive coating (thermal
evaporation or sputtering)
pore
Bare MCP ALD (R+SEE) Electrode (NiCr)
33 mm
6/10/2010
LAPD collaboration Meeting
8
Ultimate goal
6/10/2010
LAPD collaboration Meeting
Received from Incom Inc.
Create workable 8”x8”MCP with ALD
8”
8”
Materials selection for functionalisation of MCPs
• Secondary electron emission coating:
o Al2O3, MgO, Diamond, MgF2, …………
• Resistive coating: Composites of Metal and insulatoro Variety of material
o Reliability
o Scaling and Cost
• Why ALD process?
o Atomic level control over composition, thickness,
o Excellent uniformity and conformal coating on very high aspect ratio (>98%)
o Large area deposition, batch processing (low cost)
• Developed workable few novel resistive coatings by ALD process:
o Submitted patent application
o Here after named as Chemistry-1, 2, ….
o Tested with different ALD grown SEE layers
LAPD collaboration Meeting
96/10/2010
ALD coating on MCP: Chemistry #1 Resistivity
10
• Good control over resistivity • Several MCP pairs shows good “Gain data”
-Matt Wetstein will present status later
6/10/2010
LAPD collaboration Meeting
% of metal ALD cycles doping in oxide
1.E+06
1.E+08
1.E+10
1.E+12
1.E+14
5 10 15 20 25 30 35
Re
sist
ivit
y (
oh
m-c
m)
W % in Al2O3
Resistivity vs. % W in Al2O3 on MCP
•Linear I-V on MCP
Workable resistivity range for 33mm MCP
y = 1E-08x - 2E-09
-2.E-07
-1.E-07
-1.E-21
1.E-07
2.E-07
-10 -5 0 5 10
I(A
)
V(V)
30% W in Al2O3
MCP
ALD coating on MCP: Chemistry #1
11
• Uniform and smooth ALD coating on Si(100) surface
6/10/2010
LAPD collaboration Meeting
% of metal ALD cycles doping in oxide
1.E+06
1.E+08
1.E+10
1.E+12
1.E+14
5 10 15 20 25 30 35
Re
sist
ivit
y (
oh
m-c
m)
W % in Al2O3
Resistivity vs. % W in Al2O3 on MCP
Roughness
•Maximum RMS roughness < 3%
AFM on planer substrate (Courtesy: Hau Wang)
10% 20% 30%
0.506nm 0.889nm 1.41nm
ALD coating on MCP: Chemistry #1
12
• Uniform and smooth ALD coating pores of MCP
6/10/2010
LAPD collaboration Meeting
% of metal ALD cycles doping in oxide
1.E+06
1.E+08
1.E+10
1.E+12
1.E+14
5 10 15 20 25 30 35
Re
sist
ivit
y (
oh
m-c
m)
W % in Al2O3
Resistivity vs. % W in Al2O3 on MCP
Roughness
•Maximum RMS roughness < 3%
AFM on planer substrate (Courtesy: Hau Wang)
10% 20% 30%
0.506nm 0.889nm 1.41nm
Reproducibility: ALD Chemistry #1
6/10/2010
LAPD collaboration Meeting
13
620
630
640
650
660
0 5 10 15 20
Thic
kne
ss [A
]
# of MCP
Thickness
Thickness on Si(100) Resistance
1.E+06
1.E+08
1.E+10
1.E+12
1.E+14
0 5 10 15 20
Re
sist
ance
(oh
m)
# of MCP
On GlassOn MCP
Composition AComposition B
Composition A Composition B
• Excellent reproducible thickness and resistance on Glass• Resistance variation on MCP cause by electrode “end spoiling”
- Electrode coating plays very crucial role and need reliable source
LAPD collaboration Meeting
14
1.E+00
1.E+03
1.E+06
1.E+09
1.E+12
1.E+15
0 5 10 15
Re
sist
ivit
y (
oh
m-c
m)
Mo % in Al2O3
Data on Glass
6/10/2010
Resistivity of ALD coating on Glass: Chemistry #2
• Better control process than chemistry 1: uniform and smooth ALD coating• Similar resistivity range (like chemisty-1) with low % of metal doping• Process tested on large substrates capable ALD reactor
% of metal ALD cycles doping in oxide
•Linear I-V on Glass
Workable resistivity range for 33mm MCP
Process scale-up test: ALD chemistry #2
LAPD collaboration Meeting
15
12”x12” Glass
300mm Si wafer
Resistive coating process tested on custom made large substrate processing ALD reactor
6/10/2010
Large substrate testing: ALD Chemistry #2
LAPD collaboration Meeting
16
Item Thickness [A] Index of refraction (n)
Minimum 775 1.72
Maximum 794 1.77
Average 785 1.73
% STDV (1σ) 0.57 0.84
Thickness Index of refraction
Loca
tio
n a
cro
ss s
ub
stra
te
Location across substrate
6/10/2010
-150 -100 -50 0 50 100 150
-150
-100
-50
0
50
100
150
Y(m
m)
X (mm)
775.0
777.4
779.8
782.1
784.5
786.9
789.3
791.6
794.0
-150 -100 -50 0 50 100 150
-150
-100
-50
0
50
100
150
Y(m
m)
X (mm)
1.715
1.722
1.730
1.737
1.744
1.751
1.759
1.766
1.773
17
-100 -50 0 50 100
-1.0x10-5
-5.0x10-6
0.0
5.0x10-6
1.0x10-5
I(A
)
V(V)
30C
40C
50C
60C
70C
80C
90C
100C
20 30 40 50 60 70 80 90 100 110
106
107
108
109
Re
sis
tan
ce
(M
)
Temperature (oC)
Thermal characteristics: ALD of Chemistry #2 on MCP
I-V data at different temperature
6/10/2010
LAPD collaboration Meeting
10 20 30 40 50 60 70 80 90 100 110
16
17
18
19
Ln
(R)
Temperature(C)
Equation y = a + b*x
Weight No Weighting
Residual Sum of Squares
0.00897
Adj. R-Square 0.99779
Value Standard Error
C1 Intercept 19.41289 0.04112
C1 Slope -0.03352 5.96598E-4100M @RT
T for 100M =-0.033
Thermal coefficient
MCP Resistance (air) T
Commercial (~0.7 cm2) 6.5G -0.0451
With ALD Chemistry-1 500M -0.0337
With ALD Chemistry-2 100M -0.0335
• Linear I-V characteristic for all temperature • ALD coated MCPs shows lower T Reduced thermal runaway
Thermal coefficient of resistance = Rmcp=R0exp(-βT(Tmcp-T0))
18
1) Developed several novel ALD of resistive coating processes
-Excellent control over thickness, uniformity, resistance & thermal coefficient
2) Demonstrated the scalability of the resistive ALD process
3) Contact electrode plays crucial role in resistance tuning
-Need attention especially for 8”x8” MCP
4) Achieved all Year 1 and some Year 2 LAPD project goals for ALD group
6/10/2010
LAPD collaboration Meeting
Summary
Next plan
Gain test for several ALD functionalized MCP
MCPs are extremely sensitive to moisture Resistance optimization in vacuum
Testing of alternative ALD grown SEE layer
Process qualification on commercial ALD system
-(Beneq TFS 500, Tool installation is in progress)
Functionalization of 8”x8” MCPs on Beneq ALD system
After patent, write few publications
Thank you for your attention.
LAPD collaboration Meeting
196/10/2010