Diagnostics of a wafer interface of a pulsed two-frequency capacitively coupled plasma for oxide etching by emission selected computerized tomography

Abstract

We have carried out emission selected computerized tomography time and space measurements of the absolute net production rate of Ar(2p 1 ) in a pulsed capacitively coupled plasma for SiO 2 etching pulsively sustained at 100 MHz and continuously biased at 500 kHz between electrodes in CF 4 /Ar and pure Ar at 25 mTorr. Double-layer formation by excessive negatively charged particles in the interface close to the wafer is experimentally estimated only at the wafer's anodic phases during the off-period of the plasma source as seen by the probed net excitation rate. The successive space and time configuration of the net excitation rate will support a sufficient capability to inject energetic negative ions to the biased wafer having microstructures and to neutralize the inner wall to be etched.

Ion behavior in capacitively-coupled dual-frequency discharges

“…The control of plasma properties in these applications is of primary importance. During the last couple of years it has been recognized that the plasma maintenance and ion properties may be controlled independently from each other using plasma sources excited by two different radio frequencies [3,4,5].…”

“…The flux and energy distribution of the ions interacting with the electrode (target) surfaces is of primary importance. Understanding the details of ion properties is the motivation of the present study, in which we investigate discharges in Ar, CF 4 and their mixtures, the latter being used in the etching of silicon and silicon-dioxide. One should bear in mind that recently Turner and Chabert [12] have given a deeper understanding of the interaction between the two plasma sources and their effect on the mechanism of electron heating.…”

On formation of thin SiO2/a-Si:H interface when biased oxidized semiconductor surface interacts with plasma or liquid solution

“…Additional interesting results in the research of production and properties of negative ions in Ar/CF 4 can be found (for example, in [10][11][12]). …”

Non-Neutral/Quasi-Neutral Plasma Edge Definition for Discharge Models: A Numerical Example for Dual Frequency Hydrogen Capacitively Coupled Plasmas

“…[4][5][6] In the recent years, the characterization of multi-frequency rf discharges has retained the attention of many authors. Optical emission spectroscopy and diagnostic measurements [7][8][9][10][11][12] have been performed in capacitive and inductive configurations. The complications introduced by multiple rf sources were focused by several numerical models.…”