60th Gaseous Electronics Conference
Volume 52, Number 9
Tuesday–Friday, October 2–5, 2007;
Arlington, Virginia
Session VF1: Materials Processing in Low Pressure Plasmas II: Etching, deposition, new materials
8:00 AM–10:00 AM,
Friday, October 5, 2007
Doubletree Crystal City
Room: Crystal Ballroom A
Chair: Evgeniya Lock, Naval Research Laboratory
Abstract ID: BAPS.2007.GEC.VF1.1
Abstract: VF1.00001 : Reaction of Fluorocarbon Species with Si and SiO$_{2}$ Surfaces*
8:00 AM–8:30 AM
Preview Abstract
Abstract
Author:
Hirotaka Toyoda
(Nagoya University)
Highly-selective high-aspect-ratio etching of SiO$_{2}$/Si is an
indispensable key issue in the ULSI manufacturing processes. Furthermore,
recent etching technology utilizes high density plasmas and requires complex
fluorocarbon molecules such as C$_{4}$F$_{6}$ or C$_{5}$F$_{8}$ to achieve
high etching speed and high etching selectivity. To improve etching
performance, precise control of fluorocarbon plasmas based on deep
understanding of radical reactions on SiO$_{2}$ and Si surfaces is required.
Well-defined beam experiments in ultra-high vacuum are powerful for basic
study of surface reactions. This paper shows elementary surface processes of
fluorocarbon etching process, especially focused on the unique chemical
reactivity of C$_{5}$F$_{8}$ molecule under co-incidence of Ar ion. The
device was specially designed so as to enable \textit{in situ} measurements of etching yield
and etched surfaces. Namely, Ar$^{+}$ beam at energies from 50 to 400 eV and
various kinds of fluorocarbon neutral species (C$_{5}$F$_{8}$,
C$_{4}$F$_{8}$, CF$_{2})$ are co-incident on a clean SiO$_{2}$ surface at a
controlled flux. Etching yield of beam-incident surface is measured by
profilometer while \textit{in-vacuuo} X-ray photoelectron spectroscopy (XPS) analysis reveals
a time evolution of atomic composition of surface layer during the etching.
In the case of C$_{4}$F$_{8}$/Ar$^{+}$, surface atomic composition after
SiO$_{2}$ etching was almost similar to that of pure Ar$^{+}$ sputtering
except for a small amount of F component. In the case of
C$_{5}$F$_{8}$/Ar$^{+}$, however, formation of fluorocarbon layer after
SiO$_{2}$ removal was observed as in the case of CF$_{2}$/Ar$^{+}$. The
SiO$_{2}$ etching yield monotonically increased with the Ar$^{+}$ incident
energy above 400 eV, and the etching yield of 2.4 was obtained at an
Ar$^{+}$ incident energy of 900 eV with C$_{5}$F$_{8}$ co-incidence, which
was about 3 and 1.5 times larger compared with pure Ar$^{+}$ sputtering and
CF$_{2}$/Ar$^{+}$ co-incidence, respectively. These results suggest that
fluorocarbon molecules themselves are important species in fluorocarbon
etching plasma.
*The author would like to thank Prof. H. Sugai and Dr. N. Takada for their supporting this work.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.GEC.VF1.1