Tae-Min Choi

This paper describes the radio-frequency (RF) characteristics of stacked metal–insulator–metal (MIM) capacitors used in RF CMOS technology. To ensure accurate analysis, various de-embedding methods for stacked MIM capacitors were verified, and an improved RF model was constructed accordingly. To develop an equivalent circuit for the improved RF model by analyzing the RF characteristics of stacked MIM capacitors, we compared de-embedding methods for measured stacked MIM capacitors: one-step (open-pattern or short-pattern) de-embedding and two-step (combined open-pattern and short-pattern) de-embedding. For the analysis of stacked MIM capacitors, at least two-step de-embedding was used, while for precise de-embedding, three-step de-embedding using a thru pattern was employed. Based on the measured values obtained using these two-step de-embedding methods, a modified equivalent circuit was constructed. This circuit was analyzed based on various parameters, including MIM capacitance, quality factor, S-parameter, and Y-parameter, and the results were comparatively examined. The findings highlight outstanding accuracy of the modified model, which is maintained even in high frequency bands.

This research focuses on the real-time monitoring of SiCOH thin films grown by chemical vapor deposition (CVD) using Raman spectroscopy. To ensure the reliability of CVD-deposited materials in semiconductor processes, the study analyzes the growth and properties of thin films in situ. With the increasing demand for low-dielectric constant (low-k) materials due to the miniaturization of semiconductor components, real-time monitoring becomes essential for controlling film thickness, quality, and composition during deposition. Dual laser wavelengths (405 nm and 532 nm) were used to capture Raman spectra and observe changes in film thickness, crystallinity, and the bonding structures of Si-C, Si-OH, and C-C. The results demonstrate that Raman spectroscopy effectively detects real-time molecular changes in thin films, showing a clear correlation between deposition time and film properties such as crystallinity and bond formation. This approach provides valuable insights for optimizing semiconductor thin film processes in real-time.

Many viruses, bacteria, and pollen that cause diseases such as COVID-19 are inhaled by humans as aerosols. Therefore, wearing a mask to block pathogen-containing aerosols is crucial for disease prevention. However, current masks have a drawback—residual bacteria on the mask surface can become aerosolized again, spreading infections. To address this, a reusable mask incorporating the antibacterial properties of silver particles should be developed to suppress the immune response to pathogens and pollen that contact the mask surface. This study analyzed protein surface changes in pollen shells following electroless silver plating on polypropylene (PP) filters of KF94 masks using microcurrent. Pore density increased from 7.94% before microcurrent application to 14.8% and 16.9%, depending on the duration of exposure. These results suggest that microcurrents alter pollen surfaces and affect the proteins in pollen shells that trigger hay fever, confirming the potential for preventing pollen allergies.

In this study, we analyzed the electrical characteristics of metal–insulator–metal (MIM) capacitors fabricated with reference to insulator (Si_xN_y) thickness and deposition condition. Si_xN_y thicknesses of 650 Å, 500 Å, and 400 Å were used with four different conditions designated as MIM (N content 1.49), NEWMIM (N content 28.1), DAMANIT (N content 1.43), and NIT (N content 0.30), deposited by controlling gas flow and RF power as a function of N content. Capacitor characteristics were evaluated mainly in terms of the relationship between leakage current and breakdown voltage (BV). Current–voltage (I–V) characterizations revealed that a higher N–H/Si–H ratio effectively suppressed trap-assisted leakage conduction and enhanced dielectric robustness under high-field stress. Among the tested conditions, the NEWMIM process demonstrated the most favorable electrical performance with highest N contents. The MIM and NEWMIM conditions proved most effective among the evaluated processes, achieving sufficient BV values (>20 V) for reliable MIM capacitor operation and proposing a process optimization framework for integrating medium-density Si_xN_y–based MIM capacitors (2 fF/µm²) with sufficiently high BV values in the future.

This study explores the effects of different passivation gases on the properties of polymers formed on aluminum (Al) sidewalls during the etching process in Al-based interconnect structures. The research compares the use of nitrogen (N₂) and ethylene diluted with helium (C₂H₄/He) as passivation gases, focusing on the resulting polymer’s composition, thickness, and strength, as well as the levels of residual chlorine post-etch. The findings reveal that using C₂H₄ leads to the formation of a thinner, weaker polymer with lower chlorine residue compared to the thicker, stronger polymer formed with N₂. Elemental analysis further highlights significant differences in carbon and oxygen content, with C₂H₄-based polymers exhibiting lower carbon and higher oxygen levels. These results underscore the critical impact of passivation gas choice on the etching process and the integrity of Al-based interconnects, offering valuable insights for optimizing metal etching processes in semiconductor manufacturing.

We examined how controlling variables in a pre-metallization Ar sputter-etching process for in situ contact-hole cleaning affects the contact-hole profile, etching rate, and substrate damage. By adjusting process parameters, we confirmed that increasing plasma power lowered the DC bias but enhanced the etching rate of SiO₂, while increasing RF power raised both, with RF power having a more pronounced effect. Higher Ar flow rate reduced etching uniformity and slightly lowered the DC bias. There was no significant difference in the amount of etching between the oxide film types, but the nitride/oxide selectivity ratio was about 1:2. Physical damage during Ar sputter-etching was closely linked to DC bias. finally, Finally, etching of the Si and CoSi₂ sublayers was performed on the device contact hole model. At this time, Si losses of up to about 31.7 Å/s occurred, and the etch speed was strongly affected by the DC bias. By optimizing the RF power and plasma power, we achieved a Si/CoSi₂ etch selectivity ratio of about 1:2.

The development of metal–insulator–semiconductor (MIS) capacitors requires device miniaturization and excellent electrical properties. Traditional SiO₂ gate dielectrics have reached their physical limits. In this context, high-k materials such as TiO₂ are emerging as promising alternatives to SiO₂. However, the deposition of dielectric layers in MIS capacitors typically requires high-vacuum equipment and challenging processing conditions. Therefore, in this study, we present a new method to effectively fabricate a poly(vinylidene fluoride) (PVDF)-based TiO₂ dielectric layer via electrospinning. Nano-microscale layers were formed via electrospinning by applying a high voltage to a polymer solution, and electrical properties were analyzed as a function of the TiO₂ crystalline phase and residual amount of PVDF at different annealing temperatures. Improved electrical properties were observed with increasing TiO₂ anatase content, and the residual amount of PVDF decreased with increasing annealing temperature. The sample annealed at 600 °C showed a lower leakage current than those annealed at 300 and 450 °C, with a leakage current density of 7.5 × 10⁻¹³ A/cm² when Vg = 0 V. Thus, electrospinning-based coating is a cost-effective method to fabricate dielectric thin films. Further studies will show that it is flexible and dielectric tunable, thus contributing to improve the performance of next-generation electronic devices.