resist-free and busbar compatible plating route on tcos ... · resist-free and busbar compatible...

©Fraunhofer ISE/Foto: Guido Kirsch

© Fraunhofer ISE

Resist-free and Busbar Compatible Plating Route on TCOs Developed on SHJ Solar Cells

Thibaud Hatt, Jonas Bartsch, Sven Kluska and Markus Glatthaar

Fraunhofer Institute for Solar Energy Systems ISE, Freiburg – Germany

9th Metallization & Interconnection Workshop 2020

R 23 G 156 B 125

R 242 G 148 B 0

R 31 G 130 B 192

R 226 G 0 B 26

R 177 G 200 B 0

R 254 G 239 B 214

R 225 G 227 B 227

© Fraunhofer ISE

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High-efficiency potential of SHJ solar cells

Kaneka in 2015 h = 25.1% (Cu on front-side, busbars) [1]

Hanergy in 2020 h = 25.1% (Ag both-sides, busbar-less) [2]

Motivation Silicon Heterojunction Solar Cells

T. Hatt et al., 9th Metallization and Interconnection Workshop, 2020

[1] D. Adachi et al., Appl. Phys. Lett., vol. 107, no. 23, 2015. [2] X. Ru et al., Sol. Mat., vol. 215, p. 110643, 2020.

R 23 G 156 B 125

R 242 G 148 B 0

R 31 G 130 B 192

R 226 G 0 B 26

R 177 G 200 B 0

R 254 G 239 B 214

R 225 G 227 B 227

© Fraunhofer ISE

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High-efficiency potential of SHJ solar cells

Kaneka in 2015 h = 25.1% (Cu on front-side, busbars) [1]

Hanergy in 2020 h = 25.1% (Ag both-sides, busbar-less) [2]

Motivation Silicon Heterojunction Solar Cells

Why Cu-plating as low-T° metallization? Performance Conductiv ity , adhesion, contact res istiv ity…

Cost raw material Cu (dividing Ag price by factor > 100) [3]

Module-interconnection Versatile (BB-soldering / ECA / SWCT / Shingling…)

PV future (TW-scale) By 2030 might exceed Ag worldwide production [4-5]

Cuplated @ Fh-ISE

10 µm


[1] D. Adachi et al., Appl. Phys. Lett., vol. 107, no. 23, 2015. [2] X. Ru et al., Sol. Mat., vol. 215, p. 110643, 2020. [3] S. Kluska et al., PV Inter. vol. 44, 2020.

[4] N.M. Haegel, Science, 364, 836–838, 2019. [5] P.J. Verlinden, 2.0 TW Workshop, Denver, USA 2018.

R 23 G 156 B 125

R 242 G 148 B 0

R 31 G 130 B 192

R 226 G 0 B 26

R 177 G 200 B 0

R 254 G 239 B 214

R 225 G 227 B 227

© Fraunhofer ISE

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Cu-plated metallization on TCOs

Several plating approach (different mask, seed-layer on TCO, mono/bifacial plating…) [5-6]

Resist masking on PVD metal-seed high h of 24.7% with busbars [6]

Challenge by copper plating TCOs masking

[5] T. Hatt et al., Sol. RRL, vol. 26, p. 1900006, 2019. [6] A. Lachowicz et al., 8th MIW, 2019. T. Hatt et al., 9th Metallization and

Interconnection Workshop, 2020

R 23 G 156 B 125

R 242 G 148 B 0

R 31 G 130 B 192

R 226 G 0 B 26

R 177 G 200 B 0

R 254 G 239 B 214

R 225 G 227 B 227

© Fraunhofer ISE

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Cu-plated metallization on TCOs

Several plating approach (different mask, seed-layer on TCO, mono/bifacial plating…) [5-6]

Resist masking on PVD metal-seed high h of 24.7% with busbars [6]

„NOBLE“ approach @ Fh-ISE [5]

Resist-free (patterning 5% cell area)

Simultaneous bifacial plating

Low contact resistivity

High adhesion

Challenge by copper plating TCOs masking

[5] T. Hatt et al., Sol. RRL, vol. 26, p. 1900006, 2019. [6] A. Lachowicz et al., 8th MIW, 2019. T. Hatt et al., 9th Metallization and


*NOBLE Native Oxide Barrier Layer for selective Electroplating

R 23 G 156 B 125

R 242 G 148 B 0

R 31 G 130 B 192

R 226 G 0 B 26

R 177 G 200 B 0

R 254 G 239 B 214

R 225 G 227 B 227

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Multi-task PVD metal stack on TCO

Plating mask Al + native AlOx

Homogeneous current distribution simultaneous bifacial plating

PVD TCO/Metals (Al on top) Characteristics


R 23 G 156 B 125

R 242 G 148 B 0

R 31 G 130 B 192

R 226 G 0 B 26

R 177 G 200 B 0

R 254 G 239 B 214

R 225 G 227 B 227

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Performance of PVD TiW or Ti as contacting layer on ITO [7]

Low contact resistivity ρc ≤ 1 mΩcm²

Ti TiW

0.1

0.5

1.0

2.0

3.0

4.05.0

10.0

Conta

ct

resis

itiv

ity ρ

c [

mΩ

cm

²]

Contacting metal-layer on ITO


[7] T. Hatt al., 47th IEEE-PVSC, 2020. T. Hatt et al., 9th Metallization and


R 23 G 156 B 125

R 242 G 148 B 0

R 31 G 130 B 192

R 226 G 0 B 26

R 177 G 200 B 0

R 254 G 239 B 214

R 225 G 227 B 227

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Performance of PVD TiW or Ti as contacting layer on ITO [7]

Low contact resistivity ρc ≤ 1 mΩcm²

High adhesion > 2 N/mm (busbar peel test 90°)

PVD metal stack selectively etch-back [5]


[5] T. Hatt et al., Sol. RRL, vol. 26, p. 1900006, 2019. [7] T. Hatt al., 47th IEEE-PVSC, 2020.

Ti TiW

0.1

0.5

1.0

2.0

3.0

4.05.0

10.0

Conta

ct

resis

itiv

ity ρ

c [

mΩ

cm

²]

Contacting metal-layer on ITO


R 23 G 156 B 125

R 242 G 148 B 0

R 31 G 130 B 192

R 226 G 0 B 26

R 177 G 200 B 0

R 254 G 239 B 214

R 225 G 227 B 227

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Patterning by inkjet-printing of etchantaq

Wetting on Al/AlOx

Grid patterning Al/AlOx local removal by inkjet-printing


Al/AlOx

R 23 G 156 B 125

R 242 G 148 B 0

R 31 G 130 B 192

R 226 G 0 B 26

R 177 G 200 B 0

R 254 G 239 B 214

R 225 G 227 B 227

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Wetting on Al/AlOx atmosphere / time dependent [8]

Adsorption alkyl molecules


[8] T. Hatt et al., 9th SiliconPV, 2019.

5 days


Al/AlOx

R 23 G 156 B 125

R 242 G 148 B 0

R 31 G 130 B 192

R 226 G 0 B 26

R 177 G 200 B 0

R 254 G 239 B 214

R 225 G 227 B 227

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Chemical functionalization of Al/AlOx with self-assembled monolayer (ODPA) [9]

Adsorption by condensation reaction or ionic attraction on Al2O3

[10]


[8] T. Hatt et al., 9th SiliconPV, 2019. [9] T. Hatt et al., submitted, 2020. [10] P. Thissen et al., ACS Langmuir, vol. 26, no. 1, pp. 156–164, 2010.


ODPA: octadecyl-phosphonic acid

PO

OHOH

(ODPA)

Al/AlOx

R 23 G 156 B 125

R 242 G 148 B 0

R 31 G 130 B 192

R 226 G 0 B 26

R 177 G 200 B 0

R 254 G 239 B 214

R 225 G 227 B 227

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ODPA functionalization of Al/AlOx (ODPA) [9]

FTIR-ATR measurements on native AlOx

Vibration of CH2 / CH3 ≈ 2900 cm-1

Vibration of P=O ≈ 1100 cm-1


[8] T. Hatt et al., 9th SiliconPV, 2019. [9] T. Hatt et al., submitted, 2020.



R 23 G 156 B 125

R 242 G 148 B 0

R 31 G 130 B 192

R 226 G 0 B 26

R 177 G 200 B 0

R 254 G 239 B 214

R 225 G 227 B 227

© Fraunhofer ISE

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Vibration of CH2 / CH3 ≈ 2900 cm-1

Vibration of P=O ≈ 1100 cm-1

XPS measurements on native AlOx

C1s increase / O1s decrease

P2p difficult to observe due to Al2s





PO

OHOH

(ODPA)

R 23 G 156 B 125

R 242 G 148 B 0

R 31 G 130 B 192

R 226 G 0 B 26

R 177 G 200 B 0

R 254 G 239 B 214

R 225 G 227 B 227

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XPS measurements on native AlOx

Contact angle (CA) measurements on textured SHJ cells

CA after 30s ≥ 115°

CA stabilized ≈ 135° (after ≈ 1-2 hours)





PO

OHOH

(ODPA)

No ODPA

R 23 G 156 B 125

R 242 G 148 B 0

R 31 G 130 B 192

R 226 G 0 B 26

R 177 G 200 B 0

R 254 G 239 B 214

R 225 G 227 B 227

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Patterning of full area SHJ solar cells [9]


[8] T. Hatt et al., 9th SiliconPV, 2019. [9] T. Hatt et al., submitted, 2020. T. Hatt et al., 9th Metallization and


*Cu / Al layers sputtered @

157 m

m Al/AlOx

Opened

Patterned solar cell ITO / Cu / Al50nm

Al/AlOx

R 23 G 156 B 125

R 242 G 148 B 0

R 31 G 130 B 192

R 226 G 0 B 26

R 177 G 200 B 0

R 254 G 239 B 214

R 225 G 227 B 227

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Patterning of full area SHJ solar cells [9] microscopy (72 different spots)




157 m

m

20 mm

Al/AlOx

10 f

ing

ers

Opened

Patterned solar cell ITO / Cu / Al50nm

25 µm

w l

Al/AlOx

Cu

25 µm

25 µm

w l

w l


25 µm

Al/AlOx (not opened)

x50

R 23 G 156 B 125

R 242 G 148 B 0

R 31 G 130 B 192

R 226 G 0 B 26

R 177 G 200 B 0

R 254 G 239 B 214

R 225 G 227 B 227

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Narrow to wide patterning on same wafer

Inhomogeneous even on same wafer





wl 72.7 ± 29.7 µm wl 44.0 ± 23.8 µm

No ODPA

R 23 G 156 B 125

R 242 G 148 B 0

R 31 G 130 B 192

R 226 G 0 B 26

R 177 G 200 B 0

R 254 G 239 B 214

R 225 G 227 B 227

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Narrow patterning

Homogeneous on full wafer





wl 72.7 ± 29.7 µm wl 44.0 ± 23.8 µm

No ODPA

wl 26.9 ± 3.1 µm

With ODPA

R 23 G 156 B 125

R 242 G 148 B 0

R 31 G 130 B 192

R 226 G 0 B 26

R 177 G 200 B 0

R 254 G 239 B 214

R 225 G 227 B 227

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Selective Cu plating on metal-seed [8]

Homogeneous narrow fingers plated ≤ 30 µm [9]

Cu plating Selective deposition


20 µm 20 µm

Al/AlOx

Metal-seed

Al/AlOx

Cu-plated

SEM picture


R 23 G 156 B 125

R 242 G 148 B 0

R 31 G 130 B 192

R 226 G 0 B 26

R 177 G 200 B 0

R 254 G 239 B 214

R 225 G 227 B 227

© Fraunhofer ISE

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Selective Cu plating on metal-seed [8]

Homogeneous narrow fingers plated ≤ 30 µm [9]

Selective wet etch-back of PVD metal layers [5]

Cu plating and etch-back Selective

[5] T. Hatt et al., Sol. RRL, vol. 26, p. 1900006, 2019. [8] T. Hatt et al., 9th SiliconPV, 2019. [9] T. Hatt et al., submitted, 2020.

20 µm 20 µm

Al/AlOx

Metal-seed

Al/AlOx

Cu-plated

26 µm

SEM picture


R 23 G 156 B 125

R 242 G 148 B 0

R 31 G 130 B 192

R 226 G 0 B 26

R 177 G 200 B 0

R 254 G 239 B 214

R 225 G 227 B 227

© Fraunhofer ISE

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Development of this novel metallization

Al patterning modification proof of concept

Upscaling on full area solar cells (M2)

Optimization of contacting layer and ρc

SHJ solar cells efficiency „NOBLE“ metallization



[3] S. Kluska et al., PV Inter. vol. 44, 2020. [5] T. Hatt et al., Sol. RRL, vol. 26, p. 1900006, 2019 [7] T. Hatt al., 47th IEEE-PVSC, 2020. [8] T. Hatt et al., 9th SiliconPV, 2019.

R 23 G 156 B 125

R 242 G 148 B 0

R 31 G 130 B 192

R 226 G 0 B 26

R 177 G 200 B 0

R 254 G 239 B 214

R 225 G 227 B 227

© Fraunhofer ISE

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Development of this novel metallization

Al patterning modification proof of concept

Upscaling on full area solar cells (M2)

Optimization of contacting layer and ρc

Optimization of inkjet-printing patterning with SAM

SHJ solar cells efficiency „NOBLE“ metallization

Both SHJ cells no light soaking


[3] S. Kluska et al., PV Inter. vol. 44, 2020. [5] T. Hatt et al., Sol. RRL, vol. 26, p. 1900006, 2019 [7] T. Hatt al., 47th IEEE-PVSC, 2020. [8] T. Hatt et al., 9th SiliconPV, 2019.

Area [cm²]

Voc [mV]

pFF [%]

FF [%]

Jsc [mV]

Rs [Ωcm²]

η [%]

222* 736 84.8 81.3 37.9 0.5 22.7

RefSP 735 84.6 81.5 38.3 0.7 22.9


R 23 G 156 B 125

R 242 G 148 B 0

R 31 G 130 B 192

R 226 G 0 B 26

R 177 G 200 B 0

R 254 G 239 B 214

R 225 G 227 B 227

© Fraunhofer ISE

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Summary Novel Cu-metallization

NOBLE metallization on TCOs for SHJ solar cells

Simultaneous bifacial Cu-plating

Low-cost – no resist, only grid-area to be patterned

TCO + Metal stack PVD tool

Al-patterning Inkjet-printer

Cu-plating + etch-back Wet chemical baths


R 23 G 156 B 125

R 242 G 148 B 0

R 31 G 130 B 192

R 226 G 0 B 26

R 177 G 200 B 0

R 254 G 239 B 214

R 225 G 227 B 227

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Summary Novel Cu-metallization

NOBLE metallization on TCOs for SHJ solar cells

Simultaneous bifacial Cu-plating

Low-cost – no resist, only grid-area to be patterned

Inkjet-printing patterning optimized

Chemical functionalization of Al/AlOx surface with SAM

Characterization of the fast ODPA adsorption

Homogeneous fine patterning ≤ 30µm wide

Successful transfer to large area SHJ solar cells (M2)

η 22.7% on large area with FF > 81% and Rs < 0.5 Ω∙cm²

TCO + Metal stack PVD tool

Al-patterning Inkjet-printer

Cu-plating + etch-back Wet chemical baths


R 23 G 156 B 125

R 242 G 148 B 0

R 31 G 130 B 192

R 226 G 0 B 26

R 177 G 200 B 0

R 254 G 239 B 214

R 225 G 227 B 227

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Acknowledgment The authors would like to thank …

…the Fraunhofer society for funding within the project “LEO” (contract no. 840 190)

…all co-workers at Fraunhofer ISE and VON ARDENNE for metal sputtering

…you for your attention!

[email protected]

Fraunhofer Institute for Solar Energy Systems ISE

Thibaud Hatt | Advanced Development for High Efficiency Silicon Solar Cells


resist-free and busbar compatible plating route on tcos ... · resist-free and busbar compatible...

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