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Pure Appl. Chem. Vol.
74, No. 3, pp. 381-395 (2002)
Pure and Applied
Vol. 74, Issue 3
Study for plasma etching of dielectric film in semiconductor device
manufacturing. Review of ASET research project*
Plasma Technology Laboratory, Association of Super-advanced
Electronics Technologies (ASET), 292 Yoshida, Yokohama 244-0817, Japan
Abstract: Conventional developments were conducted in a very
empirical way, such as a trial and error with many speculations using
qualitative data. This approach requires more and more resources and
time for the development of future devices with a design rule below
100 nm in the system on a chip (SOC) era. It is necessary to establish
a systematic methodology for process development and qualification.
ASET Plasma Laboratory had been found to research a basis for the systematic
development of the plasma etching technology. Fluorocarbon (CF) plasma
for the etching of high-aspect-ratio contact holes in SiO2 was investigated
intensively in the 5-year program that finished in March 2001. They
introduced 5 plasma sources that can etch 0.1-mm contact holes on a
200-mm wafer in production, and state-of-the-art diagnostics tools for
the plasma and etched surface. The SiO2 etch mechanism was revealed
from the etch species generation to the reaction in a deep hole. The
number of electron collisions to fluorocarbon gas molecule is proposed
as an important parameter to control the gas dissociation and etch species
flux to the surface. An etch reaction model was also proposed using
the estimated-surface-reaction probability that is a function of ion
energy and CF polymer thickness that reduces the net ion energy to the
reaction layer. The CF polymer thickness was determined by a balance
equation of generation term (radical fluxes) and loss terms (etching
by ions, radicals, and out-flux oxygen from SiO2). A program was developed
and successfully predicts the etch rates of Si-containing materials,
including organic dielectrics. Requirements for the next-generation
plasma etch tools are also discussed.
* Lecture presented at the 15th International Symposium
on Plasma Chemistry, Orléans, France, 9-13 July 2001. Other presentations
are presented in this issue, pp. 317492.
** Corresponding author.
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