Ferroelectric Properties of Lead-Free (Bi,La)₄Ti₃O₁₂ Thin Film Deposited on MTP Cell Structure for High Density FeRAM Device

Abstract:

Ferroelectric properties of Pb-free (Bi,La)4Ti3O12 (BLT) films were optimized on a newly developed MTP cell structure. BLT films were coated on Pt/IrOx/Ir bottom electrode using sol-gel solutions. The composition of the optimized BLT film was about Bi3.25La0.75Ti3.0O12, which was analyzed by ICP-MS method. The switchable polarization obtained in a 100nm-thick BLT film was about 20 uC/cm2 at the 3 V applied voltage, and the optimized BLT film showed little fatigue loss about 10% up to 1×1011 cycles. The imprint properties of the BLT film were also characterized at 25 °C and 90 °C operating temperature after 125 °C data storage. Regardless of operating temperature, switchable polarization of BLT had a sufficiently large margin for device operation up to 10 years.

• Periodical: Materials Science Forum (Volumes 486-487)
• Pages: 285-288
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.486-487.285
• Online since: June 2005
• Authors: K.W. Cho, N.K. Kim, S.H. Oh, E.S. Choi, H.J. Sun, S.J. Yeom, K.N. Lee, Seoung Soo Lee, Suk Kyoung Hong, S.K. Choi, Tae Whan Hong, Il Ho Kim, J.I. Lee, Soon Chul Ur, Young Geun Lee, Sung Lim Ryu, Soon Young Kweon
• Keywords: (Bi,La)₄Ti₃O₁₂, FeRAM, Ferroelectric Property, Lead-Free, MTP Cell Structure

References

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[4] B. Yang, et al., Jpn. J. Appl. Phys., vol. 42, pp.1327-1330, 2003. 100 102 104 106 108 1010 1012 -1. 2 -0. 9 -0. 6 -0. 3 0. 0 0. 3 0. 6 0. 9 1. 2 100nm 70nm 50nm Fatigue Cycles Normalized dP; P*-P^ (uC/cm.

[2] ) Fig. 5. Fatigue properties of NB-BLT thin films at various thicknesses.

[10] [0] [10] [1] [10] [2] 103.

[10] [4] [10] [5] [0] [5] [10] [15] [20] [25] [30] [35] 70nm RTB-BLT Polarization (uC/cm.

[2] ) Time (Hr) 1E-3 0. 01 0. 1 1 10 Time (year) (1): 25℃℃℃℃.

[10] [0] [10] [1] [10] [2] [10] [3] [10] [4] [10] [5] [0] [5] [10] [15] [20] [25] [30] [35] 70nm RTB-BLT Polarization (uC/cm.

[2] ) Time (Hr) 1E-3 0. 01 0. 1 1 10 Time (year) (2): 90℃℃℃℃ Thick: 70 nm Thick: 70 nm (a) 25℃ (b) 90℃.

[10] [0] [10] [1] [10] [2] [10] [3] [10] [4] [10] [5] [0] [5] [10] [15] [20] [25] [30] [35] 70nm RTB-BLT Polarization (uC/cm.

[2] ) Time (Hr) 1E-3 0. 01 0. 1 1 10 Time (year) (1): 25℃℃℃℃.

[10] [0] [10] [1] [10] [2] [10] [3] [10] [4] [10] [5] [0] [5] [10] [15] [20] [25] [30] [35] 70nm RTB-BLT Polarization (uC/cm.

[2] ) Time (Hr) 1E-3 0. 01 0. 1 1 10 Time (year) (2): 90℃℃℃℃ Thick: 70 nm Thick: 70 nm (a) 25℃ (b) 90℃ Fig. 6. Imprint properties of 70 nm NB-BLT thin film measured at 25 o C (a) and at 90 o C (b), respectively.