Probing timescales during back side ablation of Molybdenum thin films with optical and electrical measurement techniques

Bartl, Dominik; Ametowobla, M.; Schmid, Florian; Letsch, Andreas; Häfner, Matthias; Nolte, Stefan; Tünnermann, Andreas

doi:10.1364/oe.21.016431

Cited by 10 publications

(4 citation statements)

References 36 publications

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“…The ejection time scale is estimated to be only τ ∼ V=L ∼ 100 ns, assuming a velocity V ≈ 100 m=s and a length scale L ≈ 10 μm [18], resulting in challenging visualization conditions. So far, time-resolved visualization has been achieved for relatively thick liquid-film [19][20][21][22][23] and solid-phase [24][25][26] or pastetransfer [27,28] processes. Observations of LIFT processing of Au [29], Ni [30], Al [31], and Cr [32] do not provide sufficient spatial resolutions to track the process in detail.…”

Section: Introductionmentioning

confidence: 99%

Ejection Regimes in Picosecond Laser-Induced Forward Transfer of Metals

et al. 2015

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Laser-induced forward transfer (LIFT) is a 3D direct-write method suitable for precision printing of various materials, including pure metals. To understand the ejection mechanism and thereby improve deposition, here we present visualizations of ejection events at high-spatial (submicrometer) and hightemporal resolutions, for picosecond LIFT of copper and gold films with a thickness 50 nm ≤ d ≤ 400 nm. For increasing fluences, these visualizations reveals the fluence threshold below which no ejection is observed, followed by the release of a metal cap (i.e., a hemisphere-shaped droplet), the formation of an elongated jet, and the release of a metal spray. For each ejection regime, the driving mechanisms are analyzed, aided by a two-temperature model. Cap ejection is driven by relaxation of thermal stresses induced by laser-induced heating, whereas jet and spray ejections are vapor driven (as the metal film is partly vaporized). We introduce energy balances that provide the ejection velocity in qualitative agreement with our velocity measurements. The threshold fluences separating the ejection regimes are determined. In addition, the fluence threshold below which no ejection is observed is quantitatively described using a balance between the surface energy and the inertia of the (locally melted) film. In conclusion, the ejection type can now be controlled, which allows for improved deposition of pure metal droplets and sprays.

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Section: Introductionmentioning

confidence: 99%

Ejection Regimes in Picosecond Laser-Induced Forward Transfer of Metals

et al. 2015

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“…The experimental results show that the diameters of ablated spots are well consistent with the values by the equation. The equation [14][15][16] :…”

Section: Results and Analysismentioning

confidence: 99%

Experimental Study on Formation of the Microstructure on Copper Film Using Ultraviolet Nanosecond Laser

Zhao

et al. 2017

AMM

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In this paper, the ablated microstructures on copper film affected by ultraviolet nanosecond pulse laser are presented. The experimental system was consisted of two lasers, optics and controlling electronics. A 3000mW, 355nm Q-switched ultraviolet lasers was used to the micro-polishing experiments in the work. The repetition rate of the ultraviolet pulse laser is from single-shot to 100kHz, and the pulse width is less than 40ns. The sample used in experiment is copper film (200 nm) sputtered on glass. A series of experiments at different laser parameters and speed of work platform are done. The ablating experiments are also carried out on focusing and defocusing application in the laser direct writer. The results were analyzed.

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“…When tensile strengths within back contact and absorber exceed certain levels the material within the laser spot region is expelled in an explosive eruption (comparable to induced ablation on Mo back contacts). [31][32][33] The resulting edges of the groove formed by this induced ablation process are therefore sharp and exhibit no features associated with molten material. Especially shunts, frequently introduced at the active (i.e., faced to the cell side) edges of P1 or P3, if CIS was molten there, are completely absent.…”

Section: Post-absorber Patterning Processmentioning

confidence: 99%

Innovative front end processing for next generation CIS module production

Probst¹,

Jasenek²,

Sandfort³

et al. 2015

Jpn. J. Appl. Phys.

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The successful implementation of two new process steps into an existing Cu(In,Ga)(Se,S) 2 (CIS) production line was achieved. One, a newly developed back contact, aims for a better process control, as far as the transition of the metallic back contact to a selenide/metal bi-layer during CIS-formation is concerned. This was done by the introduction of a corrosion resistant barrier layer, which reliably stops chalcogenide diffusion from the top. By doing so, a back contact layer is obtained, with well defined properties in which the functionalities of the back electrode now is divided between two separated layers. The other development presented in this paper, tackles the complexity of CIS-module production and the interferences between the different processes required. By shifting the P1-scribing process after i-ZnO deposition, the process sequence for CIS is simplified and it will be shown that this new P1i exhibits superior properties as far as CIS morphology and groove quality is concerned.

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Probing timescales during back side ablation of Molybdenum thin films with optical and electrical measurement techniques

Cited by 10 publications

References 36 publications

Ejection Regimes in Picosecond Laser-Induced Forward Transfer of Metals

Ejection Regimes in Picosecond Laser-Induced Forward Transfer of Metals

Experimental Study on Formation of the Microstructure on Copper Film Using Ultraviolet Nanosecond Laser

Innovative front end processing for next generation CIS module production

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