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RIE Plasma and ETCH Mechanisms

Published online by Cambridge University Press:  28 February 2011

John H. Keller*
Affiliation:
IBM, GTD Division, East Fishkill, Hopewell Jct., NY.12533
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Abstract

Three independent models are presented: One for determining the plasma density and target sheath voltage, one for silicon etching using CF4plus O2, and one for RIE etching of silicon dioxide.

In most dry etching techniques the target and plasma voltages play a large role.In this paper, the dc and rf mechanisms which determine the plasma density, and thus the target voltage, are presented.The mechanisms used are: 1) secondary electron ionization in the sheath, 2) secondary electron ionization in the plasma, 3) ionization by tertiary electrons, 4) I2R heating of the plasma electrons, and 5) sheath heating of plasma electrons.An equivalent circuit for an rf discharge is presented, and the relationship between the plasma voltage and target sheath voltage are discussed.

The mechanisms used to model silicon etching include chemical etching, ion enhanced etching and diffusion of reactive species.Laser induced fluorescence data from G.S.Selwyn will be discussed.These data show spatial resolution of a reactive species in an RIE plasma and show the diffusion effects.

The ion-enhanced etching effect for SiO2, shows a much stronger voltage dependence than that for Si, which is almost independent of voltage.Data from G.Fortuno show that the voltage dependence for SiO2 is similar to that of sputtering.The mechanisms used to model SiO2 etching include the work by G.Fortuno (1985) and that by B.N.Chapman and V.J.Minkiewicz (1978).

Type
Articles
Copyright
Copyright © Materials Research Society 1986

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