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The dynamics of the charged particles in a dual frequency capacitively coupled dielectric etch reactor.

Abstract : Dual frequency capacitively coupled plasmas are used for the etching of dielectric materials as part of the microelectronics fabrication process. The use of two frequencies is intended to allow for the independent control of the ion flux and the ion energy. Fluorocarbon gases play a key role in producing the precursor species that eventually etch the nano-scale patterns. These fluorocarbon-containing plasmas are complex in nature, forming many types of neutral radicals, positively charged ions and negatively charged ions. We have studied a customized industrial etch reactor, running in Ar/O2/C4F8 and Ar/O2/CF4 gas mixtures at pressures in the region of 50 mTorr (6.6 Pa) and driven by 2 and 27 MHz RF power. The measurement of negative ion densities and their effect on the plasma's electrical properties are the main focus of this thesis. Several diagnostic techniques have been implemented to characterise the densities and fluxes of the various charged species. An RF biased ion flux probe, installed in the upper electrode, is used to measure the ion flux. The electron density in the centre of the plasma was measured using a microwave resonator probe, known as a hairpin probe. Cavity ring-down spectroscopy (CRDS) is applied to the measurement of the negative fluorine ion density by the absorption in its broadband photodetachment continuum. The negative ion fraction was deduced from the probe measurements by comparing the ratio of the ion flux to the electron density to the theoretical ratios obtained by an electronegative plasma fluid model. It was found that the temperature of the negative ions must be very high (about 1 eV) if the experimental and theoretical results are to agree
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Contributor : Garrett Curley <>
Submitted on : Monday, September 14, 2009 - 6:08:50 PM
Last modification on : Friday, October 16, 2020 - 3:21:14 AM
Long-term archiving on: : Tuesday, June 15, 2010 - 9:54:41 PM

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  • HAL Id : tel-00416652, version 1

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Garrett Curley. The dynamics of the charged particles in a dual frequency capacitively coupled dielectric etch reactor.. Fluid Dynamics [physics.flu-dyn]. Ecole Polytechnique X, 2008. English. ⟨tel-00416652⟩

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