Wet and dry etching of thin metallic multilayer structures is necessary for the development of sensitive magnetic field sensors and memory devices based on spin–valve giant magnetoresistance elements. While it is well established that Cu, Co, and Fe are soluble in HNO3 and H3PO4 at room temperature, little effort has been made to investigate selective wet and dry etch chemistries. For example, we find Ag is not etched in H2SO4, HCl, or H3PO4 under conditions where etch rates for the other metals are in the range of 2000–60 000 Å/min. Electron cyclotron resonance (ECR) SF6/Ar plasmas provide etch selectivities of ⩾5:1 for Ag over Cu, Co, and Fe, while lower selectivities are obtained with CH4/H2/Ar. Cl2-based plasma chemistries leave significant metal–chlorine surface residues, which can be removed in situ by low ion energy H2 or Ar plasma treatments that eliminate corrosion problems. Cu etch rates in excess of 3000 Å/min at 25 °C can be obtained in ECR Cl2/Ar discharges because the high ion flux prevents formation of a CuClX-rich selvedge layer, which normally only is volatile for etch temperatures ⩾220 °C in conventional reactive ion etch systems. Photoresist masks suffer severe reticulation under ECR conditions, at least for microwave powers >400 W, and SiO2 or SiNX thin films offer much better etch resistance.
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May 1997
The 43rd national symposium of the American Vacuum Society
14-18 Oct 1996
Philadelphia, Pennsylvania (USA)
Research Article|
May 01 1997
Patterning of Cu, Co, Fe, and Ag for magnetic nanostructures
K. B. Jung;
K. B. Jung
Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611
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J. W. Lee;
J. W. Lee
Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611
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Y. D. Park;
Y. D. Park
Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611
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J. A. Caballero;
J. A. Caballero
Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611
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J. R. Childress;
J. R. Childress
Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611
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S. J. Pearton;
S. J. Pearton
Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611
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F. Ren
F. Ren
Bell Laboratories, Lucent Technologies, Murray Hill, New Jersey 07974
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J. Vac. Sci. Technol. A 15, 1780–1784 (1997)
Article history
Received:
September 16 1996
Accepted:
November 11 1996
Citation
K. B. Jung, J. W. Lee, Y. D. Park, J. A. Caballero, J. R. Childress, S. J. Pearton, F. Ren; Patterning of Cu, Co, Fe, and Ag for magnetic nanostructures. J. Vac. Sci. Technol. A 1 May 1997; 15 (3): 1780–1784. https://doi.org/10.1116/1.580869
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