Micro: Surface Functionalization 1
10:00am - 10:15am
Fabrication of complex periodic patterns on a metallic drum for high throughput roll-to-roll processing
1Dresden University of Technology, Germany; 2Fraunhofer Institute for Material and Beam Technology, Germany
In this study, the development of complex periodic structures on massive metal drums by means of direct laser interference patterning (DLIP) is demonstrated. The DLIP technology allows the formation of high-resolution periodical structures (even with sub-micrometer resolution) at high fabrication speeds on large surface areas. These advantages drastically reduce the patterning costs of the drums that are broadly used in roll-to-roll processing. We demonstrate the ability to control individually each laser spot (e.g. period) to form complex periodical patterns to be used as decorative elements exhibiting structural colors. These patterns are then replicated on a polymer foil by an industrial hot-embossing roll-to-roll process at speeds up to 50 m/min. This process brings the industrial fabrication of such patterns to the next level in terms of throughput and is thus suitable for mass production.
10:15am - 10:30am
Improving the bond strength of metal-FRP-hybrids with thermal sprayed copper using pulsed laser-based processing approaches
1Fraunhofer IWS, Germany; 2Chemnitz University of Technology, Germany; 3Technische Universität Dresden, Germany
Ablation processes during laser treatment of carbon fiber-reinforced plastics with pulsed lasers of various wavelengths and pulse durations are investigated. Three general surface pretreatment strategies are used, including laser-roughening, selective matrix removal and laser micro-structuring. Various ablation mechanisms, including evaporation and matrix delamination are observed, depending on the employed laser source. Selected laser structured substrates were coated with copper by a wire arc spraying process. Bonding strengths up to 18.1 ± 2.6 MPa and 18.7 ± 2.0 MPa were achieved in pull-off tests and shear tensile tests, respectively, by the combination of the roughening process and the micro-structuring approach. Consequently, the bonding strength could be increased up to ~ 200 % compared to the common pre-treatment by grit-blasting.
10:30am - 10:45am
Low temperature and high concentration laser doping system for fabrication of 4H-SiC power devices
1Grad. Sch. ISEE. Kyushu Univ.,; 2Dept. of Gigaphoton Next GLP, Kyushu Univ.
We propose a high-concentration and low crystal damage doping method by irradiating KrF excimer laser to the deposited films contains of dopant atoms on the 4H-SiC surfaces. This laser doping method is a low-temperature process that reduces the thermal stress to the substrate, and can achieve doping concentration of ~1020 cm-3 or more, which exceeds the limit of the ion implantation method.
In this study, we investigated the peak energy dependence of the crystal damage and surface roughness by controlling the pulse width of the laser for doping. As a result, it is found that the crystal damage and surface roughness were reduced by suppressing the peak energy. In addition to this, we report on the construction of a laser doping system to improve compatibility with the manufacturing process of 4H-SiC power devices.
10:45am - 11:00am
Excimer laser annealing method with the controlled grain size of poly-Si films for large display panels
1Department of Gigaphoton Next GLP, Kyushu University; 2Graduate School of Information Science and Electrical Engineering, Kyushu University; 3New Industry Creation Hatchery Center, Tohoku University; 4Malaysia-Japan International Institute of Technology, Universiti Teknologi Malaysia
Low-temperature polycrystalline Si thin film transistors (TFTs) crystallized using the Excimer Laser Annealing (ELA) method have been used as backplanes for active matrix organic displays due to their high electron mobility. However, the current ELA method requires a long axis of the line beam which is equivalent to the short axis of the substrate's size, and there is a limitation in application to a large glass substrate. One of the methods to overcome this problem is to anneal the entire surface by folding back the beam. However, in the overlapping region of the laser, the crystal grain size becomes large, and the device characteristics become ununiform. In this study, we report on the results of evaluating the TFT characteristics by controlling the crystal grain position and size by laser annealing with a periodic intensity distribution induced by a dot array mask to form the same crystal grain size in the overlap regions.