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Title: Space and phase resolved ion energy and angular distributions in single- and dual-frequency capacitively coupled plasmas

The control of ion energy and angular distributions (IEADs) is critically important for anisotropic etching or deposition in microelectronic fabrication processes. With single frequency capacitively coupled plasmas (CCPs), the narrowing in angle and spread in energy of ions as they cross the sheath are definable functions of frequency, sheath width, and mean free path. With increases in wafer size, single frequency CCPs are finding difficulty in meeting the requirement of simultaneously controlling plasma densities, ion fluxes, and ion energies. Dual-frequency CCPs are being investigated to provide this flexible control. The high frequency (HF) is intended to control the plasma density and ion fluxes, while the ion energies are intended to be controlled by the low frequency (LF). However, recent research has shown that the LF can also influence the magnitude of ion fluxes and that IEADs are determined by both frequencies. Hence, separate control of fluxes and IEADs is complex. In this paper, results from a two-dimensional computational investigation of Ar/O{sub 2} plasma properties in an industrial reactor are discussed. The IEADs are tracked as a function of height above the substrate and phase within the rf cycles from the bulk plasma to the presheath and through the sheath withmore » the goal of providing insights to this complexity. Comparison is made to laser-induced fluorescence experiments. The authors found that the ratios of HF/LF voltage and driving frequency are critical parameters in determining the shape of the IEADs, both during the transit of the ion through the sheath and when ions are incident onto the substrate. To the degree that contributions from the HF can modify plasma density, sheath potential, and sheath thickness, this may provide additional control for the IEADs.« less
Authors:
;  [1] ; ; ;  [2]
  1. Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Ave., Ann Arbor, Michigan 48109-2122 (United States)
  2. Department of Physics, University of California, Los Angeles, California 90095 (United States)
Publication Date:
OSTI Identifier:
22224109
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films; Journal Volume: 31; Journal Issue: 6; Other Information: (c) 2013 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANGULAR DISTRIBUTION; ARGON COMPOUNDS; CONTROL; DEPOSITION; ETCHING; FABRICATION; FLUORESCENCE; FREQUENCY DEPENDENCE; HIGH-FREQUENCY DISCHARGES; INTEGRATED CIRCUITS; IONS; LIGHT TRANSMISSION; MEAN FREE PATH; PLASMA DENSITY; PLASMA DIAGNOSTICS; PLASMA SHEATH; SUBSTRATES