Microdroplet deposition of copper film by femtosecond laser-induced forward transfer

Abstract

Phase change mechanisms during femtosecond laser pulse train ablation of nickel thin filmsCopper microdroplets were deposited onto a quartz substrate by the laser-induced forward transfer ͑LIFT͒ using laser pulses of 148 fs at a center wavelength of 775 nm. The droplets with 2 -3 m diameters were transferred at a laser pulse energy slightly above the threshold at which the copper film could be removed completely. The droplet formation was a result of the blow-off of a molten film from the quartz substrate by a compressive stress of plasma when the free surface was melted and was different from the microdroplet formation by the LIFT technique using nanosecond laser pulse.

Laser printing of silicon nanoparticles with resonant optical electric and magnetic responses

“…This method is based on laser-induced transfer of molten nanodroplets initiated by tightly focused laser pulses. A similar approach has already been applied to the controlled fabrication of metal nanoparticles [27][28][29][30][31][32] . A more sophisticated method using a ring-shaped femtosecond laser intensity distribution has been recently applied for the generation of single Si nanoparticles from bulk Si targets 17 .…”

Solid-phase laser-induced forward transfer of variable shapes using a liquid-crystal spatial light modulator

“…with the donor layer thickness d = 100 nm, the specific heat capacity C p ¼ 2:5 Á 10 6 J=ðm 3 KÞ, density q ¼ 19;300 kg=m 3 , latent heat of fusion L m ¼ 0:6 Á 10 5 J=kg, and reflectivity R ¼ 0:6 for the given wavelength of 515 nm wavelength [26,27]. It is found that the perimeter fluence level of F ¼ 0:24 J=cm 2 is sufficient to melt the donor layer, which is in accordance with the experimental results.…”

“…Laser-induced forward transfer (commonly abbreviated to LIFT) is a direct-write technique that allows the selective transfer of many materials on a micrometer scale [1][2][3][4][5], including liquids [6] and living cells [7,8]. In the LIFT process, a thin film serves as a donor material that is to be transferred, which is referred to as the donor layer, see Fig.…”

Laser-induced forward transfer of pure metals

“…Therefore, controlled deposition is often achieved in liquid phase. In this regime, for LIFT just above the ejection threshold fluence, a single spherical deposit is observed [18,42,49]. At intermediate ejection fluence levels, deposition of a torus-like shape is observed [18], which indicates that the droplet solidified in a spread-out state.…”

“…So far, application of pure-metal LIFT for 3D direct-write has been limited to the deposition of single metal droplets [18,42,49], conductive lines or tracks [10,19], and the deposition of nanoparticles [50]. This is because two challenging requirements have to be simultaneously fulfilled for consistent deposition: the impact location of a single droplet has to be limited to the previously deposited droplet's impact area, and good adhesion between the deposited droplets is required.…”