Laser-material interaction-based electronic device transfer technology and van der Waals materials patterning technology

Abstract

Laser-material interaction involves a wide range of physical and chemical processes. Gaining a comprehensive understanding of this interaction is of paramount importance for applications ranging from industrial processes to medical treatments. Using this knowledge, we can effectively utilize lasers in a variety of fields. This thesis describes the development of laser-based techniques, including laser-assisted μLED mass transfer process and laser patterning of 2D van der Waals materials. In Chapter 2, a laser-assisted transfer technology was introduced to demonstrate a skin-attachable μLED mask for skin regeneration effects. We carefully optimized process parameters including laser power and shot time that affect transfer yield. In just a few minutes, about 3,000 μLEDs were transferred and densely arranged on a face-shaped FPCB. In addition, light distribution was induced by applying a light diffusion layer (LDL) to irradiate uniform light on the facial skin. The μLED mask generated little heat and the skin temperature reached 37.4℃ after 30 minutes of use, confirming that it was safe from low-temperature burns. Implemented with laser-assisted transfer technology, the μLED mask is expected to help people take care of their facial skin. In Chapter 3, we presented a novel laser patterning technique for 2D van der Waals materials that does not require photoresist, enabling high-resolution and high-throughput processes. This breakthrough was achieved using a XeCl excimer laser operating at a wavelength of 308 nm, with a pulse duration of just a few nanoseconds and emitting intense light. Our laser patterning technology has broad applicability extending to a variety of 2D van der Waals materials and substrates. It enables direct patterning of van der Waals materials including mono- and bi-layer MoS$_2$, graphene, monolayer WSe$_2$ and 2D metal-organic framework (MOF) on a wide range of substrates such as glass and polymers. By comparing the morphology of materials patterned using conventional photolithography and our laser patterning process, we demonstrated that our laser patterning technology can rapidly pattern large-area 2D van der Waals materials without sacrificing material properties.