Femtosecond Laser Processes in Nanometric Multi-layer Thin Film Structures

Most micro/nano-electronic and optical systems consist of multilayered structures made of semiconductors, metals and insulators. One of the key issues in packaged systems and in displays is the capability to repair defects at advanced stages of manufacturing. Currently in many micro/nano-electronics packaging and in most flat panel displays (FPDs), the systems size is increasing while device resolution is improving. Our presentation focuses on FPDs to demonstrate our novel laser repair methodology, which could be applied also to advanced-packaging of nano-scale electronic systems. The need for inspection and repair becomes critical due to the unavoidable defect density which affects the yield. Therefore, a tool for defect identification and repair adds significant value to FPD production. In fabrication, the patterned layers are typically built up sequentially, and defects can be removed after each layer patterning. Typical thickness of such thin layer is tens to hundreds of nanometers, requiring a very accurate laser repair process, which also becomes more challenging as the complexity of the layers increases and the range of materials used in display manufacturing expands.

Thin film transistors are built up from layers of transparent conductors such as ITO and ZnO, metals such as aluminum, molybdenum or copper and dielectrics such as silicon nitride and silicon dioxide. Femtosecond laser tends to be the best candidate for selective removal of thin layers in complex structures. In this work we demonstrate laser repair process of transistor structures such as its source gate or drain, while keeping the underlying layer(s) unaffected. Also, no debris on the regions surrounding the repair site, thermal effect or any degradation in quality is allowed in the repair site. This process can be applied to wide range of micro fabricated systems involving nanometric scale layers, including FPD and high-resolution packages of advanced nanoelectronics systems.