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Recently, many researchers have tried to develop stretchable semiconducting thin films that can maintain their electrical performance under stretching. However, the fabrication processes have not been sufficiently practical and feasible to be used for soft electronics. Here, a stretchable high‐performance organic semiconducting thin film is fabricated by exploiting simultaneous patterning and pinning of a polymer semiconductor solution on an elastomeric substrate in which creasing‐instability has occurred. As a result, a mesh‐like polymer semiconducting thin film having vacant regions in the crease centers and surrounding crystalline regions near them can be fabricated. Due to the mesh‐like morphology and the percolated crystalline regions, the polymer semiconducting thin film shows superior stretchability and charge‐transport performance compared to the reference flat polymer thin film. When incorporated into organic thin‐film transistors, the DPP‐DTT polymer semiconducting thin film maintains its high field‐effect carrier mobility (0.53 ± 0.03 cm2 (V s)−1) under a strain ε of 80% and is highly stable under repeated stretching cycles at an ε of 50%. [ABSTRACT FROM AUTHOR]

UV-absorbing silicon suboxide (SiOx, x≈1) films can be patterned by excimer laser ablation and subsequently oxidized to fused silica by thermal annealing. This two-step process allows for the fabrication of microstructured components made entirely of fused silica. For example, diffractive optical elements with two phase-quantized levels (binary DOEs) can be produced via structured rear-side ablation of a thin film of silicon suboxide on a fused silica substrate followed by oxidation. Such phase elements can be used as projection masks for precise laser microfabrication, e.g. for parallel nano hole drilling. In addition to these binary patterns, multilevel phase structures are produced by repeating the ablation step after recoating the structured surface with additional layers of silicon suboxide. A diffractive phase element in form of a three-level line grating exhibits a diffraction efficiency of more than 60% in the +1st order. This efficiency can be enhanced by increasing the number of recoating and ablation steps and, thus, the number of phase levels. Within the levels, a surface roughness of Ra ≈ 3 nm is obtained. [ABSTRACT FROM AUTHOR]

High speed patterning of a 30 nm thick Aluminium thin film on a flexible Polyethylene Terephthalate substrate was demonstrated with the aid of Computer Generated Holograms (CGH׳s) applied to a phase only Spatial Light Modulator. Low fluence picosecond laser pulses minimise thermal damage to the sensitive substrate and thus clean, single and multi-beam, front side thin film removal is achieved with good edge quality. Interestingly, rear side ablation shows significant Al film delamination. Measured front and rear side ablation thresholds were F th =0.20±0.01 J cm −2 and F th =0.15±0.01 J cm −2 respectively. With laser repetition rate of 200 kHz and 8 diffractive spots, a film removal rate of R >0.5 cm 2 s −1 was demonstrated during patterning with a fixed CGH and 5 W average laser power. The effective laser repetition rate was f eff ~1.3 MHz. The application of 30 stored CGH׳s switching up to 10 Hz was also synchronised with motion control, allowing dynamic large area multi-beam patterning which however, slows micro-fabrication. [ABSTRACT FROM AUTHOR]

Abstract: A key factor in engineering integrated devices such as electro-optic switches or waveguides is the patterning of high quality crystalline thin films into specific geometries. In this contribution high vacuum chemical vapor deposition (HV-CVD) was employed to grow titanium dioxide (TiO2) patterns onto silicon. The directed nature of precursor transport – which originates from the high vacuum environment during the process – allows shading certain regions on the substrate by shadow masks and thus depositing patterned thin films. While the use of such masks is an emerging field in stencil or shadow mask lithography, their use for structuring thin films within HV-CVD has not been reported so far. The advantage of the employed technique is the precise control of lateral spacing and of the distance between shading mask and substrate surface which is achieved by manufacturing them directly on the substrate. As precursor transport takes place in the molecular flow regime, the precursor impinging rates (and therefore the film growth rates) on the surface can be simulated as function of the reactor and shading mask geometry using a comparatively simple mathematical model. In the current contribution such a mathematical model, which predicts impinging rates on plain or shadow mask structured substrates, is presented. Its validity is confirmed by TiO2-deposition on plain silicon substrates (450°C) using titanium tetra isopropoxide as precursor. Limitations of the patterning process are investigated by the deposition of TiO2 on structured substrates and subsequent shadow mask lift-off. The geometry of the deposits is according to the mathematical model. Shading effects due to the growing film enables to fabricate deposits with predetermined variations in topography and non-flat top deposits which are complicated to obtain by classical clean room processes. As a result of the enhanced residual pressure of decomposition products and titanium precursors and the corresponding surface coverage of them, growth conditions differ in proximity of the shadowed areas compared to the case of plain substrates and the obtained film thickness differs significantly from predictions. [Copyright &y& Elsevier]

Abstract: Interference of several identical laser beams allows fabrication of periodical structures over large areas. Scanned interference pattern method for increased patterning flexibility of thin metal films is proposed. Periodical arrays of circular holes were fabricated by 6 interfering beams. By displacing the sample in small steps between laser shots, holes can be overlapped and structures independent on interference intensity distribution can be obtained. Slit and cross-shaped structures were fabricated in various metal films using direct structuring with nanosecond pulses. Cross-shaped periodical structures in thin films can be applied as band bass filters for terahertz and infrared radiation. Peak frequency and band width of fabricated pattern was calculated and influence of rounded corners of the crosses evaluated. [Copyright &y& Elsevier]

The optimization of laser-induced forward transfer (LIFT) process using laser ablation of thin film and the evaluation of the dependence in laser spot size on the resolution of deposited material are reported. Ni thin film of several hundred of nanometer thickness, which is deposited on fused silica substrate, was irradiated by single pulse of KrF excimer laser (wavelength: 248 nm, pulse width: 30 ns), and transferred to a Si acceptor substrate. Images of the plume, which were photographed using image intensified CCD camera, indicated the cause of transfer of particles. The deposited material with clear contour was obtained under the condition that thin film was in contact with an acceptor substrate to inhibit the transfer of particles which were generated by laser irradiation. The resolution of a deposited material tended to be improved as the size of laser spot became smaller. [Copyright &y& Elsevier]

Dependence of size accuracy of deposited structure on the film–acceptor substrate distance and fluence, and the factors which influence the dependences were investigated. Au and Ni thin films of several tens to hundreds of nanometer thickness deposited on quartz substrates using ion sputtering deposition were irradiated by single pulse of KrF excimer laser (wavelength: 248 nm, pulse width 30 ns). Changes in the intensity of reflected He–Ne laser from the front and rear sides of the thin films show that film removal finishes during the excimer laser pulse. Plume images and shadowgraphs of transferring materials show that the velocity of both the leading edge of the plume and the transferring materials become faster with increasing fluence, and that the transferring material precedes the plume. At lower fluences, the deposited structure shows bad appearance due to incomplete removal from the support substrate. At higher fluences, the big shock causes the wide range of spread of deposited structure when the transferring particles have a collision with the acceptor substrate. At optimum fluences, high size accuracy of the deposited structure is achieved when the film–substrate distance is made as short as possible. [Copyright &y& Elsevier]