Jeonbuk National University (JBNU) master's student Hyunseong Ryu (Department of Flexible Printed Electronics; Los Alamos National Laboratory-Jeonbuk National University Engineering Institute-Korea; supervising professor Kang Rae-hyung) received the Outstanding Presentation Paper Award at the recent Spring Conference of the Aerospace Systems Engineering Society for his research on a new terahertz (THz) signal-processing algorithm that enables more precise measurement of the thickness of ultra-thin film structures.

As the semiconductor, display, and advanced materials industries become more sophisticated, the need for technologies that can accurately measure the thickness of thin film structures at the micro- and nano-scale is increasing. Terahertz (THz) waves, often called the 'dream electromagnetic waves,' are harmless to the human body and highly penetrating, making them a promising next-generation non-destructive inspection technology. However, when measuring extremely thin films, the incident peak signal and the rear-surface reflection peak signal overlap, making accurate signal separation difficult.

To address this issue, Hyunseong Ryu developed an algorithm that calculates thickness using second- and third-order reflection peak signals, which are not affected by overlap, instead of the first rear-surface reflection peak that directly abuts the incident peak.

This approach derives a new effective refractive index and improves model accuracy, enabling effective thickness calculation even for ultra-thin structures that were difficult to measure precisely using conventional methods.

The technique is noteworthy because it can extract a pure THz signal without interference even in extremely thin films, thereby dramatically improving measurement precision. In particular, since thin film thickness and defect measurement can be achieved solely by improving the signal-processing algorithm without expensive additional equipment, its commercialization potential is considered high.

Professor Kang Rae-hyung, the supervising professor, said, 'This research is a meaningful achievement that overcomes the physical limitations of existing terahertz non-destructive inspection technology through refined signal analysis techniques,' and added, 'It will be used as a core technology for real-time quality monitoring in precision manufacturing processes such as semiconductor packaging, flexible printed electronics, and multilayer thin-film coatings.'

Meanwhile, the award is seen as further validation of the Los Alamos National Laboratory-Jeonbuk National University Engineering Institute-Korea research team's accumulated expertise in non-destructive inspection and structural health monitoring.