Laser technologies have always been and will continue to be a pivotal innovation driver in various high-tech verticals. Mobile displays for the looming 5G world as well as the booming e-mobility market are to a large part enabled by the laser power and precision needed to process thinnest layers and finest structures otherwise not attainable. Recently, magnetic confinement fusion has entered the zero-carbon energy roadmap due to the commercial availability of high temperature superconducting (HTS) thin film material. This new material is now available in large quantities and enables considerably higher magnetic field strengths and thus the construction of many times smaller fusion reactors able to contribute to the zero-carbon climate goal. Laser technology is at the heart of processing the game changing HTStapes for the new generation of fusion magnets.
Pulsed laser deposition has evolved into a production technology for growing thin film materials with properties which are challenging to obtain by classical deposition methods such as sputtering or sol-gel deposition. Novel wafer based PLD system technology based on powerful excimer lasers allows universities, institutes and foundries to add 30+ new materials and material systems to their deposition portfolio enabling fabrication e.g. of electro-optical materials, transparent conductive oxides and perovskites. Dielectric, ferroelectric and piezoelectric material depositions can also be performed in any desirable sequence and can run with a single wafer load-lock, cassette handler or integrated with pre-clean station as part of the Solmates cluster platform. Deposition results obtained with the latest 300 mm wafer platform will be discussed.
MicroLED displays are among the most promising technologies for very small and large displays soon. The market adoption strongly depends on costs of the display. Shrinking MicroLED sizes with additional throughput and yield improvements are the key to a wider spread usage of the technology. Laser Lift-Off, a release of III-V based MicroLED´s from the growth wafer, and laser-based mass transfer are two mandatory process steps within the MicroLED display process chain. A UV laser masked based high precision imaging system will be presented which is capable to process GaN based MicroLED´s down to a few microns. The flexible maskbased system can process single die´s, large fields, and selective patterns of LED dies. Process results are depending on the precision and alignment of the dedicated laser beam. The influence of beam-to-die alignment, energy densities, material combination, and contact versus non-contact transfer will be shown and discussed. Both LLO and transfer can be scaled to large field sizes to enable a high throughput processing that pushes the technology into reasonable production time scales. Beam shapes, process speed assumptions, and capable substrate sizes will be discussed. Finally, a flexible system concept will be presented that can cover both LLO and selective mass transfer with corresponding different energy densities. This system concept has a capability to process MicroLED displays for AR/VR but also larger formats e.g. tiles which can be combined to large MicroLED TV´s or commercial signage applications.
In industrial laser micro processing, throughput is as important as process quality. Treating large areas in minimum time is pivotal in achieving reduced unit costs in high-volume production. Excimer lasers meet the requirements for clean and precise structuring and enable the smallest structures in an efficient way. The latest technical developments in high power excimer lasers is bound to take cost-efficient UV-laser micro processing to the next level and bridges the gap between achievable precision and achievable throughput. New excimer laser developments and beam concepts together with latest performance data for upscaling both UV power and UV pulse energy will be the topic of this paper against the background of upcoming market trends and high volume applications.
We report on fast and flexible laser processing technology for crystalline solar cells by using ultra-short laser pulses and
a combination of Diffractive Optical Elements (DOE´s) for beam splitting with conventional scanner technology. The
focus is laid on damage reduction, decreasing processing times, and efficient processing strategies. We demonstrate the
process conversion from single-spot to multi-spot ablation of thin-films and bulk material, e.g. nitride ablation and edge
isolation. We will point out an increase in ablation efficiency by a factor of 3 and an additional increase in processing
speed by a factor of > 50 for surface ablation processes. The DOE in combination with scanner technology provides a
fast and flexible system where only an industrial proven DOE has to be implemented in front of the scanner. Due to this
modification the technology can be easily adapted. Using multi-spot technology for processing of crystalline solar cells,
heat accumulation has to be analyzed. Limitations in spot distance and geometrical arrangements are discussed and
described mathematically. Results and process windows will be shown for a thin-film ablation (surface) and a laser edge
isolation (bulk) process on crystalline solar cells. An estimation of cycle times and area throughput will show the
potential for using DOE´s especially combined with ultra-short pulse lasers.
The cleaving process has the potential to replace the dicing of thin wafers. Its inherent advantages are no mechanical
forces to the substrate, no material losses, and high edge quality. In order to determine the fundamental mechanisms
leading to a reliable cleaving process the complex interaction of wavelength and temperature dependent absorption, heat
transfer, material elongation and finally crack formation is theoretically described and experimentally verified. A
successful process observed if sufficient thermal stress can be generated to induce a crack and if no surface deformation
occurs due to overheating. Most relevant parameters determining the process window are irradiated power, cutting speed,
and focus spot size. The results of these parameter variations are presented. Accuracy and reproducibility is
demonstrated by cleaving stripes of different widths fulfilling the requirements of the electronic packaging industry. In
the third section the influence of the crystalline orientation is investigated. As a result mono-crystalline silicon exhibits
an anisotropic behaviour when changing the cutting direction whereas for polycrystalline substrates a permanent change
of the crystal structure is found at the grain boundary. Finally, the obtainable edge quality is presented briefly, which
leads to higher sample strengths compared to conventional laser and mechanical processes.
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