skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Influence of redeposition on the plasma etching dynamics

Abstract

This work reports on measurements of the degree of redeposition of sputtered species during the etching of platinum (Pt), barium-strontium-titanate (BST), strontium-bismuth-tantalate (SBT), and photoresist (PR) in a high-density argon plasma. While PR exhibits a redeposition-free behavior, the degree of redeposition of Pt, BST, and SBT species increases from 10% to 95% as the argon pressure increases from 0.5 to 10 mTorr. These results are in good agreement with the predictions of a simple model accounting for the backscattering of sputtered species following their interaction with the gas phase. Based on these results and using other experimental data reported in the literature, it is further demonstrated that, depending on the plasma etching conditions, redeposition effects can induce misinterpretation of the etch rate data.

Authors:
; ; ; ;  [1];  [2];  [2];  [3]
  1. Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611 (United States)
  2. (Canada)
  3. (United States)
Publication Date:
OSTI Identifier:
20982815
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 101; Journal Issue: 8; Other Information: DOI: 10.1063/1.2719015; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ARGON; BACKSCATTERING; BARIUM COMPOUNDS; BISMUTH COMPOUNDS; ETCHING; PLASMA; PLATINUM; SPUTTERING; STRONTIUM TITANATES; TANTALATES

Citation Formats

Stafford, L., Margot, J., Delprat, S., Chaker, M., Pearton, S. J., Departement de Physique, Universite de Montreal, Montreal, Quebec H3C 3J7, INRS, Energie, Materiaux et Telecommunications, Vasrennes, Quebec J3X 1S2, and Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 116400. Influence of redeposition on the plasma etching dynamics. United States: N. p., 2007. Web. doi:10.1063/1.2719015.
Stafford, L., Margot, J., Delprat, S., Chaker, M., Pearton, S. J., Departement de Physique, Universite de Montreal, Montreal, Quebec H3C 3J7, INRS, Energie, Materiaux et Telecommunications, Vasrennes, Quebec J3X 1S2, & Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 116400. Influence of redeposition on the plasma etching dynamics. United States. doi:10.1063/1.2719015.
Stafford, L., Margot, J., Delprat, S., Chaker, M., Pearton, S. J., Departement de Physique, Universite de Montreal, Montreal, Quebec H3C 3J7, INRS, Energie, Materiaux et Telecommunications, Vasrennes, Quebec J3X 1S2, and Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 116400. Sun . "Influence of redeposition on the plasma etching dynamics". United States. doi:10.1063/1.2719015.
@article{osti_20982815,
title = {Influence of redeposition on the plasma etching dynamics},
author = {Stafford, L. and Margot, J. and Delprat, S. and Chaker, M. and Pearton, S. J. and Departement de Physique, Universite de Montreal, Montreal, Quebec H3C 3J7 and INRS, Energie, Materiaux et Telecommunications, Vasrennes, Quebec J3X 1S2 and Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 116400},
abstractNote = {This work reports on measurements of the degree of redeposition of sputtered species during the etching of platinum (Pt), barium-strontium-titanate (BST), strontium-bismuth-tantalate (SBT), and photoresist (PR) in a high-density argon plasma. While PR exhibits a redeposition-free behavior, the degree of redeposition of Pt, BST, and SBT species increases from 10% to 95% as the argon pressure increases from 0.5 to 10 mTorr. These results are in good agreement with the predictions of a simple model accounting for the backscattering of sputtered species following their interaction with the gas phase. Based on these results and using other experimental data reported in the literature, it is further demonstrated that, depending on the plasma etching conditions, redeposition effects can induce misinterpretation of the etch rate data.},
doi = {10.1063/1.2719015},
journal = {Journal of Applied Physics},
number = 8,
volume = 101,
place = {United States},
year = {Sun Apr 15 00:00:00 EDT 2007},
month = {Sun Apr 15 00:00:00 EDT 2007}
}
  • The etching characteristics of indium zinc oxide (IZO) films were investigated using a high-density plasma in Ar, Ar/Cl{sub 2}, and Ar/CH{sub 4}/H{sub 2} chemistries. The IZO layers were deposited by means of rf magnetron sputtering, in which the target composition and growth temperature were varied to selectively tune the film properties. X-ray diffraction, elastic recoil detection, and Rutherford backscattering spectroscopy were used to determine the crystallization quality, atomic density, and composition of the as-deposited IZO films. As the In/(In+Zn) composition ratio in the IZO layer increases, the etch yield in Ar and Ar/Cl{sub 2} plasmas remains fairly constant, indicating thatmore » the etching dynamic is essentially independent of the film properties. In sharp contrast, a strong increase of the IZO etch yield with the In/(In+Zn) fraction is observed in Ar/CH{sub 4}/H{sub 2} plasma due to the preferential desorption of the group-III etch products. By comparing these experimental data to the predictions of a simple rate model accounting for preferential desorption effects, it is concluded that the balance between etching and polymer deposition in the Ar/CH{sub 4}/H{sub 2} plasma plays an important role in the evolution of the IZO etch rate with the In concentration fraction.« less
  • Previously, Adalsteinsson and Sethian have applied the level set formulation to the problem of surface advancement in two and three-dimensional topography simulation of deposition, etching, and lithography processes in integrated circuit fabrication. The level set formulation is based on solving a Hamilton-Jacobi type equation for a propagating level set function, using techniques borrowed from hyperbolic conservation laws. Topological changes, corner, and cusp development, and accurate determination of geometric properties such as curvature and normal direction are naturally obtained in this setting. Part I presented the basic equations and algorithms for two dimensional simulations, including the effects of isotropic and uni-directionalmore » deposition and etching, visibility, reflection, and material dependent etch/deposition rates. Part II focused on the extension to three dimensions. This paper completes the series, and add the effects of redeposition, reemission, and surface diffusion. This requires the solution of the transport equations for arbitrary geometries, and leads to simulations that contain multiple simultaneous competing effects of visibility, directional and source flux functions, complex sputter yield flux functions, wide ranges of sticking coefficients for the reemission and redeposition functions, multilayered fronts and thin film layers. 50 refs., 20 figs., 2 tabs.« less
  • The redeposition of sputtered Au,Ag, and Cu onto glass surfaces, which are in the same plane as bombarded metal foils, has been established by ion scattering spectrometry. Sites near the sputtering center were analyzed with sensitivities of 0.0008–0.001 monolayers after neon bombardmant of the foils for up to two hours. From the data, the redeposition coverage is estimated to be from 0.009 4 to 0.04 2 monolayers after two hours of Ne bombardment at 1500 eV. Finally, the electric field of the incident ion beam, acting on low-energy sputtered ions, is a likely cause of the redeposited material.
  • Comparative studies on ion beam etching (IBE) and reactive ion beam etching (RIBE) of HfO{sub 2} film have been carried out using photoresist as the masking layer. The etching rates of HfO{sub 2} film and photoresist mask in pure Ar and Ar/CHF{sub 3} mixture plasmas were measured as a function of ion energy, plasma composition, and ion beam incident angle. It has been found that the RIBE with Ar/CHF{sub 3} plasma is capable of lowering the threshold energy of ion beam and increasing sputtering yield, compared to the IBE with pure Ar. The redeposition of photoresist sidewall is a majormore » issue, due to the formation of nonvolatile etching products during sputtering of HfO{sub 2} film in both IBE and RIBE. However, the sidewall redeposition can be easily removed in HCl solutions with assistance of ultrasonic wave for RIBE with Ar/CHF{sub 3} plasma. Alternatively, the sidewall redeposition can be eliminated by controlling the slope of photoresist sidewall or combined with ion incident angle.« less
  • The influence of redeposition on the space and time evolution of feature profiles during platinum etching in high-density argon plasmas is examined using simulations. The simulator takes into account redeposition resulting from either direct sticking of the sputtered species on the materials walls (line-of-sight redeposition) or from sputtered species returning from plasma (indirect redeposition). Overall, the simulator successfully reproduces experimental profiles sputter etched in platinum, in particular V-shaped profiles reported in literature. From comparison between experimental and simulated profiles at very low pressure, Pt/resist sticking probability was estimated to be 0.1 and the angular spread of the sputtered atom distributionmore » was predicted to be about {+-}50 deg. . It was further found that indirect redeposition becomes crucial at higher pressure for explaining the amount of redeposited matter.« less