From pico to femto: Laser technology for large area thin ... · Laser Welding/brazing Marking. ......

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From pico to femto:

Laser technology for large area thin film and micromachining

Precisiebeurs 2012

Laser technology for large area thin film and micromachining

• ECN and laser technology

Laser Welding

Marking

Cutting 

Thin film processing

Micro machining

Laser technology for large area thin film and micromachining

• ECN and laser technology

Laser Welding/brazingMarking

Cutting 

Thin film processing

Micro machining

Laser technology for large area thin film and micromachining

• ECN and laser technology

Laser Welding/soldering

Marking

Cutting 

Thin film processingMicro machining

Thin film Solar

Source: Thin Film Solar CellsEd. J. Poortmans, V. ArkhipovFrank Lenzmann

2 μm

Thin film: structure

• Example: NIP Cell on nontransparent foil. 

‐

Thin film: structure

• Example: NIP Cell on nontransparent foil. 

‐

Thin film, Serialisation basic technologies

• Back end –

R2R 

–

Sheet to sheet 

• Laser –

Depth selective (wavelength, pulse energy, pulse width)

–

Alignment

• Inkjet –

Conductive (Ag,Cu, Al)

–

Insulator 

Serialisation: a generic process for thin film

• In process interconnection 

• P1,P2,P3 –

Alignment on large substrates

–

Transparent substrates

–

No R2R possible

–

8 steps

–

Deposition and structuring combined

• Back end interconnection

• 7 process steps (4 deposition, 1 laser, 2 inkjet)–

Deposition of all layers

–

Selective ablation

–

One setup / one machine

–

Transport and alignment reduction

–

R2R compatible

Serialisation: a generic process for thin film

Σ

4 steps

Example P2 scribe

Example P1 scribe

Processing thin film Si

ITO removal 

Amorf NIP Si on steel

λ

1030 nm

tp

1ps

Spotsize 30 μm

Processing thin film Si

Amorf Si, nip stack,10 x 10 cm samples, ECN Baseline

9 ps vs. 0.25 ps. 

same optics, power, wavelength, sample, machine, software

2 different processes: layer fragmenting , layer ablation

Optimum. 

below 1 ps

Processing thin film Si, pulse width

aSi, nip stack,10 x 10 cm samples, ECN Baseline 

P = 1.9 W, Q = 100 kHz, fΘ

160 mm, z = 0 mm, v = 2000 mm/s, ep

19 μJ0.25 ps, scribe width 40 μm 9 ps

100 μm 100 μm

Processing thin film Si

aSi, nip stack,10 x 10 cm samples, ECN Baseline 

P = 0.5 W, Q = 100 kHz, fΘ

160 mm, z= 0 mm, v=1000 mm/s, ep

5 μJ0.25 ps

9 ps

100 μm50 μm

Processing thin film Si

aSi, nip stack,10 x 10 cm samples, ECN Baseline 

P = 0.2 W, Q = 100 kHz, fΘ

160 mm, z = 0 mm, v = 100 

mm/s, ep

2 μJ0.25 ps

9 ps

Processing thin film Si

100 μm 100 μm

Si solar cell structure

Processing Si

http://www.solliance.eu/

Si cell structure

Inkjet in laser pattern

200 μm. 

Processing Si

http://www.solliance.eu/

Micro machiningPulse width 250 fs - 10 ps

Ripple structures, laser-induced periodical surface structure (LIPSS)

first discovery by Birnbaum 1965.

Ripples on steel I/IV

Ripples on steel II/IV

Ripples on steel III/IV

λ

1030 nm

tp 250 fs

Spotsize 30 μm

Ripples on steel IV/IV

Period 0.9 μmAmplitude ~ 200 nm

Laser technology for large area thin film and micromachining

• ECN and laser technology

Laser Welding/soldering

Marking

Cutting 

Thin film processing

Micro machining

Al foil cutting I/IV

λ

1030 nm

tp 250 fs

Spotsize 30 μm

Samples not cleaned

Al foil cutting II/IV

Al foil cutting III/IV

Top view

Bottom view

Al foil cutting IV/IV

Side view

Cu foil cutting I/II

250 fs

10 ns

Cu foil cutting II/II250 fs

Micro machining SiN I/III

Volume subtraction on curved sample to create flat surface

mathematica

Dxf files

Micro machining SiN II/III

Micro machining SiN III/III

Micro machining, next step

Confocal measured feedback and calibration of shapes

Dxf files Product

30 x 30 cm area structuring

Tec 7 glass

See ECN standHardened glass

Engineering of an experimental system

All samples made by Adem femto – pico laser facility

ECN, Eindhoven HTC 29

http://www.adem-innovationlab.nl/home/

University of Twente, University of Delft University of Eindhoven+ ECN.

Phd students and capital investments.

Femto,pico or nano ?

High intensity, low average femto second very effective (all materials absorp),

Shorter pulse lengths give higher conversion efficiency (green and UV).

Each pulse result in a higher temperature, also femto.

Processing strategy remains necessary.

Wavelength vs. intensity absorption.

High thermal conductivity materials , accept longer pulses, higher pulse freq.

Low thermal conductivity materials, short pulses, longer time between pulses

Engineering of an experimental system

• System setup–

Open platform for laser experiments

• Mechanics–

2.5 m/s on one axis

–

Integration of laser scanners with xy movement

–

R2R capability

• Optics–

Short pulse and high intensities

• Software–

Automation of experiments

• Process capabilities–

Tunable Pulse width 

–

Three wavelengths available

Project AdemPlatform with focus on 

Pulse width range , three wavelength solution.Pico second /  femto secondRoll to roll  and sheet to sheet. TCP/IP communication (camera, power, scanners, users)

One beam path approach compactallignment optics 

Experimental system

Specs. adem system

Wavelength  1030 nm & 515 nm & 343 nm,

pulse width 250 fs – 10 ps

10 W @ 1030 nm, 5 W @ 515 nm, 2 W @ 343 nm (Light conversion)

XYZ (1300 mm x 600 mm x 200 mm) accuracy. X 5μm , Y 5μm,  Z 3μm high speed Y axis, 2.5 m/sR2R handling (300 mm, ~ 0.5 m/s)

Downflow (prevent optical damage)(NXP)

Laser safety cabinet, optics interfaces(ECN)

Laser (Lightwave)

Optical table(Philips)

Optics(Sill/molenaar)

Translation system(Q’sys)

Experimental system

Software and communication

Rocks (master)

Excelsheet

Samlight(scanners)

Rocks (slave)

XY2-100TCP/IP RS232 trigger

Aerotech

Fire wire

Software and communication

Step and scan

Software and communication

Smart vision in combination with Rocks

Rocks have the ability to interact on position 

information from a machine vision camera. 

Rocks support smart vision cameras:

•

Philips Inca and Dica series 

• National Instruments 177x series

• Cognex Insight Micro series

Software and communication

Camera integration

R2R

Simple foil handling

Integrated in movement system

Non indexed, relative position

R2R , non indexed

R2R, non indexed