Ultrafast parallel laser processing of materials for high throughput manufacturing

Laser patterning is a key industrial process in the manufacturing of organic light emitting diode (OLED) displays, solid-state lighting foils and solar cells. Ultrafast lasers are of particular interest for this application as they may enable selective ablative removal of OLED layers with minimal energy density requirements on the target. Since sufficient laser output from commercial laser sources is currently exceeding single beam process requirements, parallel processing with multiple beams could provide a novel route for up-scaling processing speed and reduce manufacturing costs. In this paper, we propose the use of a reflective liquid crystal on silicon spatial light modulator, driven by fast computer-generated holograms, for splitting a parent laser beam into a number of beamlets and to digitally manipulate their position and laser intensity on the target. With successful blocking of the non-diffracted zero order beam and subsequent delivery of the SLM diffracted beams using a galvanometer scanner and flat-field f-theta lens, we demonstrate high throughput precision patterning of silicon and thin film electrodes (ITO anode and metal cathode) on flexible and glass substrates. It is additionally shown that, by carefully adjusting the number of beams per line, one can selectively remove different amount of materials simultaneously in adjacent locations all within a single scanning step. Microscopic examination with optical microscopy and white light interferomety revealed the extent of resolution, process quality and assisted quantification of the process speed gain. The benefits and current limitations of this technique are discussed in detail.