Papers by Author: Suk Kyoung Hong

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Authors: J.H. Choi, H.S. Yoo, K.W. Cho, N.K. Kim, S.H. Oh, E.S. Choi, S.J. Yeom, H.J. Sun, S.S. Lee, K.N. Lee, Suk Kyoung Hong, Tae Whan Hong, Il Ho Kim, Sung Lim Ryu, Soon Young Kweon
Abstract: A 16Mb 1-transistor /1-capacitor (1T1C) FeRAM device was fabricated with lead-free Bi3.25La0.75Ti3.0O12 (BLT) capacitors. The key integration processes contain a scalable MTP (Merged Top-electrode and Plate-line) cell structure and reliable BLT ferroelectric capacitors. Ferroelectric properties of BLT films were optimized on the 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. The switchable polarization obtained in a 100nm-thick BLT film was about 20 µC/cm2 at the 3 V applied voltage, and the optimized BLT film showed a few fatigue losses 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. The average cell signal sensing margin between data "1" and data "0" was measured to be about 900 mV, which is a sufficiently large margin for device operation.
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Authors: Myoung Sub Kim, Jin Hyung Jun, Jin Ho Oh, Hyeong Joon Kim, Jae Sung Roh, Suk Kyoung Hong, Doo Jin Choi
Abstract: Ge2Sb2Te5 (GST) has been widely studied for PRAM as reversible phase change material. GST is expected to reduce RESET (crystalline → amorphous) operation power, which is one of important issues for PRAM technology. In order to investigate the effect of nitrogen doping on electrical switching characteristics, we fabricated two kinds of PRAM cells with nitrogen-doped (N-doped) and un-doped GST, which were different bottom electrode contact size (0.80~1.00 ). N-doped GST PRAM cells have higher dynamic resistance with small sized bottom electrode contact and lower RESET voltage (about 1.2 V, 50 ns) than un-doped GST PRAM cells (about 1.6 V, 50 ns). The resistance switching ratio (RRESET to RSET) was about 100. The results of this study indicate that nitrogen doping into GST film and smaller size of bottom electrode contact reduce RESET power for PRAM operation.
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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
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.
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Authors: B.I. Seo, No Jin Park, Sung Jin Kim, B. Yang, Y.H. Oh, Suk Kyoung Hong
Abstract: Issues of ferroelectric high-density memories (>64Mb) indispensable for upcoming ubiquitous era have been on the cell integration less than 0.1um2 and reliabilities. Thus nanoscale control of microstructures of ferroelectric films with large switching polarization has been one of the issues to obtain the uniform electrical properties for realization of high-density memories. In this study the grain orientations and distributions of BT-based films by spin-on coatings were examined by an electron backscatter diffraction (EBSD) technique. Ferroelectric domain characteristics by a piezoresponse force microscope (PFM) were also performed to study the dependence of reliabilities on the grain orientations and distributions.
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Authors: B. Yang, No Jin Park, Sung Jin Kim, Suk Kyoung Hong
Abstract: Issues of ferroelectric high-density memories (>64Mb) indispensable for upcoming ubiquitous era have been on the cell integration less than 0.1um2 and reliabilities. Thus nanoscale control of microstructures of ferroelectric films with large switching polarization has been one of the issues to obtain the uniform electrical properties for realization of high-density memories. In this study the grain orientations and distributions of BT-based films by spin-on coatings were examined by EBSD (electron backscatter diffraction) technique. Ferroelectric domain characteristics by PFM (piezo-response force microscope) were also performed to study the dependence of reliabilities on the grain orientations and distributions. It is believed that understandings of the nucleation and growth mechanisms of the a- or b-axis oriented films during the thermal processes such as RTA and furnace annealing affecting on grain orientation and uniformity could be possible based on this experimental results.
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