This study investigated the effect of temperature on the aspect-ratio etching of SiO₂ in CF₄/H₂/Ar plasma using patterned samples of a 200 nm trench in a low-temperature reactive-ion etching system. Lower temperatures resulted in higher etch rates and aspect ratios for SiO₂. However, the plasma property was constant with the chuck temperature, indicated by the line intensity ratio from optical emission spectroscopy monitoring of the plasma. The variables obtained from the characterization of the etched profile for the 200 nm trench after etching were analyzed as a function of temperature. A reduction in the necking ratio affected the etch rate and aspect ratio of SiO₂. The etching mechanism of the aspect ratio etching of SiO₂ was discussed based on the results of the surface composition at necking via energy-dispersive X-ray spectroscopy with temperature. The results suggested that the neutral species reaching the etch front of SiO₂ had a low sticking coefficient. The bowing ratio decreased with lowering temperature, indicating the presence of directional ions during etching. Therefore, a lower temperature for the aspect ratio etching of SiO₂ could achieve a faster etch rate and a higher aspect ratio of SiO₂ via the reduction of necking than higher temperatures.

This study investigated the effect of temperature on the aspect-ratio etching of SiO₂ in CF₄/H₂/Ar plasma using patterned samples of a 200 nm trench in a low-temperature reactive-ion etching system. Lower temperatures resulted in higher etch rates and aspect ratios for SiO₂. However, the plasma property was constant with the chuck temperature, indicated by the line intensity ratio from optical emission spectroscopy monitoring of the plasma. The variables obtained from the characterization of the etched profile for the 200 nm trench after etching were analyzed as a function of temperature. A reduction in the necking ratio affected the etch rate and aspect ratio of SiO₂. The etching mechanism of the aspect ratio etching of SiO₂ was discussed based on the results of the surface composition at necking via energy-dispersive X-ray spectroscopy with temperature. The results suggested that the neutral species reaching the etch front of SiO₂ had a low sticking coefficient. The bowing ratio decreased with lowering temperature, indicating the presence of directional ions during etching. Therefore, a lower temperature for the aspect ratio etching of SiO₂ could achieve a faster etch rate and a higher aspect ratio of SiO₂ via the reduction of necking than higher temperatures.

Abstract Among the characteristics of the low-temperature plasma often used in semiconductor processes, electron density plays an important role for understanding the plasma physics. Therefore, various studies involving invasive and non-invasive methods have been conducted to measure the electron density. This study aims to verify the possibility of measuring the electron density by simultaneously utilizing the characteristics of both invasive and non-invasive methods using a reflectometer attached to a commercial Wi-Fi antenna on a wafer in the vacuum chamber. The electron density was additionally measured using an interferometer and a single Langmuir probe under the same experimental conditions to assess the reliability of the reflectometer results, and the results were compared. The experiments were performed by increasing the 13.56 MHz radio frequency power applied to generate the plasma discharge in the 300 mm inductively coupled plasma bevel etcher equipment from 200 W to 400 W and 600 W, respectively. The electron densities measured using the three measurement methods (reflectometer/interferometer/single Langmuir probe) were confirmed to be in excellent agreement. Hence, the in-situ reflectometer on the wafer was verified to produce reliable results.

The efficiency of simultaneous treatment of the cold atmospheric pressure plasma jet (CAP) and hydrogen peroxide (H2O2) was investigated. A CAP with a thin and long plume was generated with Ar gas and applied to a common oral bacterium, Enterococcus faecalis (E. faecalis). The bactericidal efficiency was evaluated with the electron microscopy and the colony forming unit (CFU) assay. The underlying mechanisms were studied by measuring extracellular chemical changes in the water solution and by measuring biological responses such as the trans-membrane potential, the intracellular oxidative stress, and the membrane permeability. The combination of CAP with H2O2 could provide dramatic synergistic effects in bacterial disinfection through the enhanced membrane transportation of reactive species and the oxidation of intracellular molecules. Since the byproducts of both H2O2 and CAP are not significantly toxic, the synergistic bactericidal effects of their combination could be a good candidate to clinical applications.

A laboratory-scale experiment was conducted to reproduce plasma with properties similar to re-entry plasma and measure the plasma density using a microwave reflectometer system. To reproduce a similar re-entry plasma, a high-temperature refractory anode vacuum arc plasma method was used among arc plasma discharge methods, and arc plasma having high temperature, high speed, and high-density plasma characteristics was discharged inside a vacuum chamber. A hot refractory anode made of tungsten was used to show high-temperature plasma characteristics, and high-density plasma characteristics were demonstrated using re-evaporation around the anode. In addition, high-speed plasma characteristics were exhibited using a brass cathode. This kind of arc plasma discharge has a high temperature and is characterized by high fluctuation. It was determined that a microwave reflectometer system with good spatial resolution and non-invasiveness would be suitable to measure plasma with these characteristics. The reflection coefficient was measured using a reflector system by comparing the voltage between the traveling wave applied to the plasma and the reflected wave reflected by the plasma, and the technique of analyzing the plasma density using the difference between these reflection coefficients was used. In this study, the plasma density according to the pressure change was typically measured as 10¹²-10¹³ cm^-3, which showed a similar tendency to the result of measuring the actual re-entry plasma density.

The use of NF₃ is significantly increasing every year. However, NF₃ is a greenhouse gas with a very high global warming potential. Therefore, the development of a material to replace NF₃ is required. F₃NO is considered a potential replacement to NF₃. In this study, the characteristics and cleaning performance of the F₃NO plasma to replace the greenhouse gas NF₃ were examined. Etching of SiO₂ thin films was performed, the DC offset of the plasma of both gases (i.e., NF₃ and F₃NO) was analyzed, and a residual gas analysis was performed. Based on the analysis results, the characteristics of the F₃NO plasma were studied, and the SiO₂ etch rates of the NF₃ and F₃NO plasmas were compared. The results show that the etch rates of the two gases have a difference of 95% on average, and therefore, the cleaning performance of the F₃NO plasma was demonstrated, and the potential benefit of replacing NF₃ with F₃NO was confirmed.

The atmospheric-pressure plasma (APP) process is used in various fields nowadays. One important characteristic of the APP process is the temperature of the wafer heated by the atmospheric-pressure plasma. In this study, the effects of the input power and the discharge distance on the heat generated during the atmospheric plasma process were analyzed, and the mechanism was predicted. We used a fluoroptic thermometer and infrared camera to measure the wafer temperature and a VI probe and a current probe to measure the electrical properties. The results showed that, as the input power was increased, the wafer temperature increased, and as the discharge distance was increased, the wafer temperature decreased. Thus, we can confirm that resistance heating was the mechanism that caused the wafer temperature to rise; it is related to the current intensity and the resistance of the current flowing through the wafer.