Etch characteristics of CoFeB thin films and magnetic tunnel junction stacks in a H2O/CH3OH plasma

Su Min Hwang; Adrian Garay; Il Hoon Lee; Chee Won Chung

Korean Journal of Chemical Engineering, Vol.31, No.12, 2274-2279, December, 2014

DOI10.1007/s11814-014-0254-5 Export Citation

Etch characteristics of CoFeB thin films and magnetic tunnel junction stacks in a H2O/CH3OH plasma

Su Min Hwang, Adrian Garay, Il Hoon Lee, and Chee Won Chung^†

Department of Chemistry and Chemical Engineering, Center for Design and Applications of Molecular Catalysts, Inha University, 100 Inha-ro, Nam-gu, Incheon 402-751, Korea

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Inductively coupled plasma reactive ion etching of CoFeB thin films and magnetic tunnel junction (MTJ) stacks with nanometer-sized patterns was performed using H2O/CH3OH gas mixture. As the CH3OH concentration in H2O/CH3OH increased, the etch rate of both the CoFeB films and MTJ stacks increased, but the etch selectivity decreased while the etch profiles of CoFeB films and MTJ stacks improved. Field emission transmission electron microscopy observation clearly revealed that the MTJ stacks etched at 75% CH3OH in H2O/CH3OH gas mixture showed a good etch profile without any redeposition and a high degree of anisotropy. These results indicate that there were some chemical reactions between CHX in H2O/CH3OH plasma and the films that comprise the MTJ stacks, such as CoFeB magnetic films. It was confirmed that H2O/CH3OH gas mixture could be a good etch gas in attaining a high etch rate and high degree of anisotropy in the etch profile.

Keywords:CoFeB;Magnetic Tunnel Junction Stack;Inductively Coupled Plasma Reactive Ion Etching;H2O/CH3OH

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[2] Wolf SA, Lu J, Stan MR, Chen E, Treger DM, Proc. IEEE, 98, 2155 (2010)

[3] Miyazaki T, Kumagai S, Yaoi T, J. Appl. Phys., 81, 3753 (1997)

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[6] Sousa RC, Freitas PP, IEEE Trans. Magn., 37, 1973 (2001)

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