Summary form only given. Evolution of metastable argon atom density (1s 5 ) with electron density (plasma power) was investigated with Laser Induced Fluorescence (LIF) in Ar ICP discharge. The laser at wavelength 696.5 nm was used to excite 1s 5 metastable state to 2p 2 state and measured the fluorescence of 772.4 nm emitted during the decay of 2p 2 state to 1s 3 state. Two distinctive transition behaviors were observed in low and high electron density ranges respectively. The one, an abrupt decrease of metastable density, observed in low electron density range can be explained by the effect of the evolution of electron energy distribution functions during E-H mode transition of ICP discharge 1 . The other one observed in high electron density range is also understood by the effect of changes of population and depopulation mechanisms of Ar metastable density 2 . It is suggested that Ar metastable atom density can exhibit various behaviors with electron density due to its intrinsic characteristic — electric dipole radiation forbidden.
Summary form only given, as follows. The absolute, spatially resolved electron densities in inductively coupled plasmas have been measured by using two different plasma diagnostic tools, a plasma absorption probe and double Langmuir probe. The plasma absorption probe is able to measure the absolute, spatially resolved electron density even when the probe is soiled with processing plasmas. The technique is based on the resonant absorption of surface waves excited in a cavity at the probe head. The plasma absorption probe consists of a small antenna connected with a coaxial cable. The antenna is enclosed in a tube inserted in a plasma. The plasma source is a planar inductively coupled plasma. Over a wide parameter range (gas type, input power and gas pressure), the results by the two techniques are compared and analyzed.
High-entropy ceramics exhibit novel intrinsic properties. Hence, they have been explored for a wide range of applications ranging from thermal insulation and energy storage to advanced optical components. Recently, the semiconductor industry has faced a demand for higher-performance chips, necessitating higher aspect ratios in wafer fabrication and further miniaturization of linewidths. Therefore, there is a need to develop novel materials exhibiting high plasma etching resistance and minimized contaminant generation. The plasma-etching resistance displayed by high-entropy ceramics can an innovative solution to this emerging challenge. In this study, we successfully fabricated single-phase high-entropy sesquioxide ceramics with high optical transparency, dense microstructure, and minimal residual pores. A structural analysis of the fabricated samples revealed a single-phase structure with excellent phase homogeneity. An evaluation of the plasma-etching resistance of high-entropy ceramics for the first time revealed a low etching rate of 8 nm/h compared to conventional plasma-resistant materials. These comprehensive characterizations of high-entropy ceramics indicate that they are promising candidates for significantly improving the production yield of semiconductors and for a wide range of potential applications, such as next-generation active optical ceramics.
In the current and next-generation Si-based semiconductor manufacturing processes, amorphous carbon layer (ACL) hard masks are garnering considerable attention for high-aspect-ratio (HAR) etching due to their outstanding physical properties. However, a current limitation is the lack of research on the etching characteristics of ACL hard masks under plasma etching conditions. Given the significant impact of hard mask etching on device quality and performance, a deeper understanding of the etching characteristics of ACL is necessary. This study aims to investigate the role of oxygen in the etching characteristics of an ACL hard mask in a complex gas mixture plasma etching process. Our results show that a small change of oxygen concentration (3.5-6.5%) can significantly alter the etch rate and profile of the ACL hard mask. Through our comprehensive plasma diagnostics and wafer-processing results, we have also proven a detailed mechanism for the role of the oxygen gas. This research provides a solution for achieving an outstanding etch profile in ACL hard masks with sub-micron scale and emphasizes the importance of controlling the oxygen concentration to optimize the plasma conditions for the desired etching characteristics.
We investigated reaction characteristics in a CH4∕N2 plasma for deposition of amorphous CNx thin films (a-CNx) by evaluating the change in electron density using the wave cutoff method, and the behavior of ions and radicals with an optical emission spectroscopy (OES). An inductively coupled plasma source that was 30cm away from the substrate stage was used for the discharge. The change in electron density in the substrate region and OES spectra in the plasma-source region were evaluated to investigate both the reaction mechanism and the remote effect while varying process conditions such as rf power, pressure, and gas-mixing ratio. We found that the electron density in the remote CH4∕N2 plasma was closely related to recombination reactions of major ions such as N2+, CH4+, CH3+, and H2+ during diffusion from the plasma source to the substrate. The electron density and optical emission of major ions and radicals in the CH4∕N2 plasma increase at higher rf power. The ratio [N]∕([N]+[C]) in a-CNx films, as measured by auger electron spectroscopy, also increases with rf power since more excited N and C species are generated. For increasing pressure, the change in electron density and emission spectra showed different behavior, which arose from recombination of ions that generated more CH4, Nx (x=1,2), and CN radicals. The majority of positive ions generated from N2 species are greatly affected by the remote effect, while the majority of positive ions generated from CH4 species are not significantly influenced, since each species has different losses dependent on the pressure. A higher N2 gas fraction in the gas mixture generated more CN radicals, which resulted not only in more N incorporated into a-CNx films but also to a reduction of H passivation that retards formation of hybrid bonding between C and N in the films. These results suggest that efficient H abstraction is required to achieve more NC triple bonding in CH4∕N2 plasma deposition.
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