AVS 47th International Symposium
    Plasma Science and Technology Monday Sessions
       Session PS-MoM

Paper PS-MoM4
Early-stage Modification of SiO@sub 2@ Surface in Fluorocarbon Plasma for Selective Etching Over Si

Monday, October 2, 2000, 9:20 am, Room 311

Session: Plasma-Surface Interactions I
Presenter: K. Ishikawa, Association of Super-Advanced Electronics Technologies (ASET), Japan
Authors: K. Ishikawa, Association of Super-Advanced Electronics Technologies (ASET), Japan
M. Sekine, Association of Super-Advanced Electronics Technologies (ASET), Japan
Correspondent: Click to Email
To understand the surface reaction mechanism that governs SiO@sub 2@ etch performance, we studied the surface evolution, starting at the very beginning of the etching process. We also studied the way in which fluorocarbon (CF) polymer reaches a steady-state at a specific thickness. For this purpose, we prepared a modified GEC reference cell and optical apparatus for in-situ time-resolved infrared attenuated total reflection (IR-ATR) spectroscopy with a germanium (Ge) substrate. The SiO@sub 2@ film was formed by plasma oxidation of Si sputtered on a Ge substrate. We made the SiO@sub 2@ film about 10 nm thick because, according to Fresnel's formula, the CF peak height is linearly proportional to CF film thickness when the underlying SiO@sub 2@ is less than a few hundred nm thick. While the SiO@sub 2@ film was being etched in Ar-diluted C@sub 4@F@sub 8@ plasma, we took spectra every two seconds. A peak, located at 1230 cm@super -1@, due to C-F stretching absorption and a trough, at about 1100 cm@super -1@, due to Si-O stretching absorption, were observed. Observations proved difficult due to an overlap between the two components. By decomposing the spectra, we obtained the separated intensities of the CF and SiO@sub 2@ films. The time-dependence observations were fitted to a model, which enabled us identify the factors that enhance and inhibit CF film growth during SiO@sub 2@ etching. @FootnoteText@ This work was supported by NEDO.