In this study, the Gaussian mixture model (GMM) was modified and implemented to determine the real-time endpoint of SiO 2 plasma etching using optical emission spectrum analysis. Optical emission spectroscopy (OES) signals were collected from the SiO 2 plasma etching processes, and the modified GMM was applied to SiO 2 etching with relative areas of 8.0, 4.0, and 1.0 %. Consequently, the sensitivity of OES signals was improved by ~5.5 times, and the sensitivity factor of the modified GMM was increased by approximately two times, compared with those of the modified K-means cluster analysis (another clustering technique). In addition, 60 peaks related to the reactants were selected out of 6144 signals to improve the sensitivity of the modified GMM with full-spectrum wavelengths. The modified GMM analysis using the 60 reactant-related peaks exhibited a higher sensitivity (~1.4 times) than that with 6144 full-spectrum OES signals. Thus, the modified GMM can be a suitable and effective clustering technique for etching endpoint detection.
Abstract Vertical graphene (VG) nanosheets are directly grown below 500 °C on glass substrates by a one-step copper-assisted plasma-enhanced chemical vapour deposition (PECVD) process. A piece of copper foil is located around a glass substrate as a catalyst in the process. The effect of the copper catalyst on the vertical graphene is evaluated in terms of film morphology, growth rate, carbon density in the plasma and film resistance. The growth rate of the vertical graphene is enhanced by a factor of 5.6 with the copper catalyst with denser vertical graphene. The analysis of optical emission spectra suggests that the carbon radical density is increased with the copper catalyst. Highly conductive VG films having 800 Ω/□ are grown on glass substrates with Cu catalyst at a relatively low temperature.
Journal Article Does Corporate Governance Predict Firms' Market Values? Evidence from Korea Get access Bernard S. Black, Bernard S. Black University of Texas, Law School and McCombs School of Business *Hayden W. Head Regents Chair for Faculty Excellence and Professor of Law, University of Texas School of Law, and Professor of Finance, McCombs School of Business, University of Texas, Austin, Texas 78705. Tel: (+1) 512-471-4632, Email: bblack@stanford.edu. Search for other works by this author on: Oxford Academic Google Scholar Hasung Jang, Hasung Jang Korea University Business School Search for other works by this author on: Oxford Academic Google Scholar Woochan Kim Woochan Kim KDI School of Public Policy and Management Search for other works by this author on: Oxford Academic Google Scholar The Journal of Law, Economics, and Organization, Volume 22, Issue 2, October 2006, Pages 366–413, https://doi.org/10.1093/jleo/ewj018 Published: 04 January 2006
Dual radio frequency (RF) powers are widely used with commercial plasma etchers for various nanoscale patterns. However, it is challenging to understand the relationship among the dual RF powers and the etching processes. In this work, the effect of the dual RF bias powers on SiO 2 sputter etching was investigated in inductively coupled plasma (ICP). The relationship was studied among 2[Formula: see text]MHz and 27.12[Formula: see text]MHz RF bias powers, a 13.56[Formula: see text]MHz ICP source power, the ion bombardment energy, the ion density and the etching rate. The results show that the ion density of Ar plasma can be controlled in the region of 10 9 –10[Formula: see text] ions/cm 3 , and DC self-bias can be controlled by controlling the ratio of dual RF bias powers while the ion density is maintained with the operation of source power. This work reveals that the dual RF bias powers expand the process window of the ion density and the ion bombardment energy independently in the ICP plasma source. The sputter etching rate is also modeled using the ion-enhanced etching model, and the model shows good agreement with the etching rate data.
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