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SHOCKWAVE INDUCED THIN FILM DELAMINATION (SWIFD):
A NON-THERMAL STRUCTURING METHOD OF FUNCTIONAL
LAYER
Pierre Lorenz, Martin Ehrhardt, Lukas Bayer, Klaus Zimmer
Leibniz-Institut für Oberflächenmodifizierung e. V., Permoserstr. 15, 04318 Leipzig, Germany
www.solarion.net
LANE 2016 9th Int. Conf. on Photonic Technologies
SP 1: Short pulse processes
September 19. – 22. 2016, Fürth, Germany
2
Motivation
Set-up
Experimental results
Shockwave delamination of CIGS (SWIFD)
CIGS on PI substrate
CIGS on stainless steel
SWIFD of CIGS further dependency
Additional tension force
Confinement and laser spot size
Temperature
Conclusion and Outlook
Outline
3 1. Motivation
Selective structuring of multi-layer functional thin films using a laser-induced shockwave delamination process
• The microstructuring of thin films especially for electronic applications without damaging the layers or the substrate is a challenge for conventional methods. • Laser methods like laser ablation are on special interest.
4 1. Motivation
Selective structuring of multi-layer functional thin films using a laser-induced shockwave delamination process
Monolithic integrated interconnection
P1 P2 P3 P1 P2 P3
active area dead zone
• The Patterning of thin films especially for electronic applications without damaging the layers or the substrate is a challenge for conventional methods.
5 1. Motivation
Selective structuring of multi-layer functional thin films using a laser-induced shockwave delamination process
• The microstructuring of thin films especially for electronic applications without damaging the layers or the substrate is a challenge for conventional methods. • Laser methods like laser ablation are on special interest.
ADVANTAGE: fast, flexible, easy, and large area structuring DISADVANTAGE: laser-induced material modifications mostly due to the released heat; can be observed already at ultra short laser pulses • Alternative:
mechanically scribing SWIFD: shock-wave-induced thin-film delamination
7
10 µm
3. laser ablation
nanosecond picosecond femtosecond
5 µm
l = 248 nm, Dtp = 25 ns
SEM
• high ablation rate • strong molten modification
• moderate ablation rate • molten edge modification
• small ablation rate • molten edge mod.
l =1064 nm, Dtp = 10 ps l =775 nm, Dtp = 150 fs
5 µm
Summary of laser structuring at different pulse duration inclusive exemplary SEM images based on the CIGS sample produced at Solarion AG
(B) Martin Ehrhardt, Phys. Proc. 83 (2016)74-82
l =1550 nm, Dtp = 5 ns
(B)
• Stress-assisted laser lift-off delaminationB)
8 2. Experimental Set-Up
• available Laser
Excimer Laser Nd:YVO4
l [nm] 193, 248, 351 355, 532, 1064 780
25 ns 10 ps 150 fs
top hat profile
1064, 1550
Dtp
Fiber laser
nanosecond
1-600 ns
Gaussian profile Gaussian profile
picosecond
Ti:Al2O3
femtosecond
laser-induced shockwave delamination
laser ablation
Gaussian profile
9
N = 0 N = 1
laser Schematic illustration of the SWIFD process
4. SWIFD – CIGS on PI
sho
ckw
ave
pla
sma
plu
me
7.015.03.05104)( lbp
(1)
(A)
Polyimide
damping of the shockwave
pressure of the shockwave
10
N = 3 N = 4
laser
Schematic illustration of the SWIFD process
4. SWIFD – CIGS on PI
Summary SWIFD - CIGS solar cells on PI: grey: no effect on the front side; turquoise: instable region: unspecific delamination; green: delamination of CIGS including the ITO; yellow: delamination of the CIGS with damage of Mo; red: full penetration of the PI
11 4. SWIFD – CIGS on PI
(1) P. Lorenz et al., Appl. Surf. Sci. 336 (2015) 43
SEM and EDX images after the laser treatment ( ~ 2.8 J/cm², N = 1, A ~ 0.8 mm²)
SEM
ED
X
12 4. SWIFD – CIGS on PI
(2) P. Lorenz et al., Physics Procedia 56 (2014) 1015
Optical microscopic image
N = 4
N = 6
N = 8
top hat beam profile area A = 100 x 100 µm²
p = 57 MPa 82 MPa
(left) Summary of the irradiation results of the CIGS solar cells on PI (grey: no effect on the front side; turquoise: instable region: unspecific delamination; green: delamination of CIGS including the ITO front contact; yellow: delamination of the CIGS with damage of molybdenum back contact; red: full penetration of the PI). (middle) Optical microscopic image of the laser-treated CIGS solar cell at ~2.65 J/cm², N=4-8, (dark region: non-modified CIGS solar cell, bright region: uncovered Mo back contact) (right) Necessary remaining PI thickness d dependent on the laser fluence
~
2.6
5 J
/cm
²
13 4. SWIFD – CIGS on PI
(1) P. Lorenz et al., Appl. Surf. Sci. 336 (2015) 43
Shadowgraph images (~2.8 J/cm²) at different time delays Δ
Schematic illustration of the pump probe experiment used
Schematic summary of the different laser-induced effects
14 4. SWIFD – CIGS on PI
removal of material from the rear side of PI substrate
bending of the substrate delamination and “fly away” of the CIGS material
rear side shock wave formation process
(1) P. Lorenz et al., Appl. Surf. Sci. 336 (2015) 43
15 4. SWIFD – CIGS on stainless steel
Pulse number
4
9
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
Flu
en
ce [
J/cm
²] 270
257
222
173
129
84
57
(left) EDX images of the front side of a sample after the SWIFD process. (middle) magnified view of the delaminated area shown in the left images. (right) High resolution SEM image of the broken CIGS edge.
16 5. SWIFD – CIGS further dependency
5.1 additional tension force
5.2 Confinement
and laser spot size
5.3 temperature
17 5.2 Conefinement and laser spot size
103
104
105
0.1
1
10
without
H2O
fluence thre
shold
th [J/c
m²]
irradiated area A0 [µm²]
N = 1
with H2O
Schematic illustration of the set up used
CIGS delamination threshold th dependence on irradiated area A0 with and without confinement
flexible substrate
layer
SEM images of the front side of a rear side irradiated CIGS solar cell at different laser fluences and irradiated area A0 = d².
N = 1
18 5. SWIFD – CIGS further dependency
0.0 0.1 0.2 0.3 0.4
1.5
2.0
2.5
3.0
CIG
S d
ela
min
ati
on
th
resh
old
th
[J/c
m2]
normalized tension force Fn [N/mm]
N = 7
0 50 100 1500
1
2
3
4
5
6
7
8
= 3 J/cm²
= 2.8 J/cm²
= 2.5 J/cm²
Nth
temperature T [°C]
tension force Confinement temperature
103
104
105
0.1
1
10
without
H2O
fluence thre
shold
th [J/c
m²]
irradiated area A0 [µm²]
N = 1
with H2O
19 7. SWIFD – Theory
Ft
u
2
2
D
D
D
D
p
pcmJ
n
p
p
A
ttt
ttMPat
tb
tp
,00
095)(
²/8.2
l
12
0
0
)(
2
11)(
kk
Lc
tvkpvp
Schematic illustration of the used model
(a) Calculated deformation of the CIGS solar cells (b) Calculated bending-induced displacement Dz at (0,0) (c) Displacement of the “fly away” CIGS
(a) (b)
(c)
20 8. Conclusion and outlook
The shockwave delamination process allows the selective removal of the CIGS material from the Mo back contact at different substrates.
shockwave delamination laser ablation
+
-
thermal edge modification no thermal edge modification
fast structuring method + fast structuring method + low lateral precision
-
+ + fabrication of high efficient solar modules
fabrication of high efficient solar modules
The SWIFD process is especially suitable for thermal sensitive materials like OLED and
organic solar cells.