Ion-Beam-Etched Profile Control of MTJ Cells for Improving the Switching Characteristics of High-Density MRAM

• Published in: IEEE transactions on magnetics Vol. 42; no. 10; pp. 2745 - 2747
• Main Authors: Takahashi, S., Kai, T., Shimomura, N., Ueda, T., Amano, M., Yoshikawa, M., Kitagawa, E., Asao, Y., Ikegawa, S., Kishi, T., Yoda, H., Nagahara, K., Mukai, T., Hada, H.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: New York, NY IEEE 01.10.2006; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Arrays; Cross-disciplinary physics: materials science; rheology; Equations; Etching; Exact sciences and technology; Fluctuation; Fluctuations; Identity-based encryption; Ion beam etching (IBE); Ion beams; Magnetic materials; magnetic random access memory (MRAM); magnetic tunnel junction (MTJ); Magnetic tunneling; Magnetism; Magnetoresistive random access memory; Materials science; Mathematical analysis; Micromagnetics; Other topics in materials science; Physics; Random access memory; Simulation; Switching; Testing; Tunnel junctions; magnetic random access memory (MRAM); Proceedings; Random-access storage; Ion beam etching (IBE); Ion beam; Ion bombardment etching; Density; magnetic tunnel junction (MTJ); Switching; Magnetic properties; Tunnels
• ISSN: 0018-9464; 1941-0069
• DOI: 10.1109/TMAG.2006.878862

The effect of the reduction of the sidewall redeposition layer of magnetic materials is investigated for submicron-patterned magnetic random access memory (MRAM) cells. The sidewall redeposition layer is made at the first etch step of a magnetic tunnel junction (MTJ) with ion beam etching (IBE) in the case that the sidewall angle of a hard mask is steep. By controlling the etched profile at the time of the first IBE step, formation of the redeposition layer is prevented. Functional test results of 1-Kb MRAM arrays show that the sidewall redeposition layer enlarges fluctuation of switching current, and reduces the write operation region. The effect of the sidewall redeposition on the switching characteristics of MRAM arrays is explained qualitatively by micromagnetic simulation solving the Landau-Lifshitz-Gilbert (LLG) equation