Laser induced forward transfer with high resolution for microelectronics applications

Pulsed lasers can be used to eject materials from transparent donors through an ablation-based expulsion mechanism. Laser Induced Forward Transfer (LIFT) is an approach based on expelling material from a donor towards a receiver. The method can be potentially exploited to develop multi-material deposition systems for producing freestanding products as well as hybrid manufacturing combined with other processes for microelectronics applications. The size of the ejected material depends on temporal and spatial interaction of the laser beam as well as the size of the donor material. The combined use of femtosecond pulses, UV wavelength, and nm-sized solid donors can allow to reduce the droplet size towards nm scale. Hence, this work shows the development of the system architecture and the process for the laser induced forward transfer of PVD produced pure titanium. The relationship between the laser related parameters, the formation of the droplets and different regimes were defined. Single droplets with sub-micrometer diameters and heights in nanometer range were successfully produced. The results are then used for developing a platform for 3D material deposition from nano to microscale dimensions to be used in microelectronic applications

Laser induced forward and reverse transfer for additive manufacturing of multimaterial micro components

Pulsed laser can be used to eject materials from transparent donors through an ablation based expulsion mechanism. The material ejection can be controlled through the correct design of the donor materials and the laser optical setup. The ejected material in the form of sub-micrometric droplets can be stacked in order to achieve freestanding 3D components in the micrometric scale. This work depicts the use of a femtosecond pulsed UV laser to deposit material from solid donors in forward and reverse transfer modes in a flexible manner. The system architecture and the process development were carried out as a collaboration between Technoprobe and Politecnico di Milano. In the laser induced forward transfer (LIFT) mode, PVD produced pure titanium layers deposited on transparent glass is deposited in a drop-by-drop fashion to produce free- standing 3D micro metal objects. In the laser induced reverse transfer (LIRT) mode solid metals are transferred to transparent media to produce 2D layers with in-situ material mixing capabilities