Role of Oxygen in Poly-Si Etching by Cl2/O2 Plasmas
- 1 December 1995
- journal article
- Published by IOP Publishing in Japanese Journal of Applied Physics
- Vol. 34 (12S)
- https://doi.org/10.1143/jjap.34.6815
Abstract
The increase in poly-Si etch rate at low O2 concentration (1-5%) in Cl2/O2 plasmas was investigated using optical emission spectroscopy (OES) and X-ray photoelectron spectroscopy (XPS). The OES spectrum indicates that the Cl (837.5 nm) intensities increase at low O2 concentration during the poly-Si etching but the dissociation of Cl2 is not promoted by the addition of O2 to Cl2. SiCl (287 nm) intensities decrease in the range of O2 concentration where poly-Si etch rate increases. The result of XPS shows that by increasing O2 concentration from 0% to 3%, the amount of Cl and O adsorbed onto poly-Si surface decreases and increases, respectively. In Cl2/O2 plasmas, a cause of the poly-Si etch rate increase may be that oxygen atoms adsorb more easily on the poly-Si surface than chlorine atoms, and this weakens the Si-Si back bonds.Keywords
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