| Title |
Effect of Temporal and Spatial Process Parameters on Microchip Transfer Characteristics and Yield in Laser-Induced Forward Transfer (LIFT) |
| Authors |
류성(Seong Ryu) ; 김도영(DoYoung Kim) ; 김준영(Junyeong Kim) ; 박지원(Jiwon Park) ; 김양도(Yangdo Kim) ; 이승기(Seoung-Ki Lee) |
| DOI |
https://doi.org/10.3365/KJMM.2026.64.7.618 |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
Laser frequency; Laser-induced forward transfer; Microchip transfer; Process optimization; Transfer yield |
| Abstract |
This study investigates the effects of temporal and spatial process parameters on microchip transfer using laser-induced forward transfer (LIFT), with the aim of establishing a reliable and scalable transfer strategy for microelectronic applications. The transfer behavior was systematically analyzed as a function of laser frequency, chip size, and the ratio between the laser spot size and chip size, which govern the temporal energy delivery and spatial energy distribution during the transfer process. From a temporal perspective, the laser frequency determines the number of effective pulse interactions and the degree of pulse overlap, both of which influence the energy accumulation within the dynamic release layer. The results show that excessively low frequencies lead to insufficient energy delivery, while excessively high frequencies induce excessive temporal overlap and thermal accumulation, resulting in unstable transfer. An intermediate frequency condition was found to provide the most stable transfer behavior under the present experimental conditions. From a spatial perspective, the spot-to-chip size ratio plays a critical role in controlling the uniformity of energy distribution across the microchip. A mismatch between the laser spot size and chip size leads to localized energy concentration, which can cause thermal damage or incomplete transfer. In contrast, an optimized ratio enables uniform energy delivery, resulting in stable transfer with minimal defects. Under the optimized conditions identified in this study, a large-area microchip array consisting of 300 devices was successfully transferred with high spatial uniformity. The transfer yield exceeded 99%, and reproducibility tests conducted over five repeated trials confirmed consistent transfer performance with minimal variation. These results demonstrate that the coupled control of temporal and spatial energy conditions is essential for achieving reliable and scalable microchip transfer. |