Browsing by Author "Lin, Chen-Hsi"

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3D resistive RAM cell design for high-density storage class memory-a review
(2016-06)
Hudec, Boris
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Hsu, Chung-Wei
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Wang, I-Ting
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Lai, Wei-Li
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Chang, Che-Chia
In this article, we comprehensively review recent progress in the ReRAM cell technology for 3D integration focusing on a material/device level. First we briefly mention pioneering work on high-density crossbar ReRAM arrays which paved the way to 3D integration. We discuss the two main proposed 3D integration schemes-3D horizontally stacked ReRAM vs 3D Vertical ReRAM and their respective advantages and disadvantages. We follow with the detailed memory cell design on important work in both areas, utilizing either filamentary or interface-limited switching mechanisms. We also discuss our own contributions on HfO2-based filamentary 3D Vertical ReRAM as well as TaOx/TiO2 bilayer-based self-rectifying 3D Vertical ReRAM. Finally, we summarize the present status and provide an outlook for the nearterm future.
3D Vertical TaOx/TiO2 RRAM with over 10(3) Self-Rectifying Ratio and Sub-mu A Operating Current
(2013-01-01)
Hsu, Chung-Wei
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Wan, Chia-Chen
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Wang, I-Ting
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Chen, Mei-Chin
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Lo, Chun-Li
The 3D double-layer vertical RRAM with ultralow sub-mu A operating current and high self-rectifying ratio over 10(3) has been demonstrated for the first time. This Ta/TaOx/TiO2/Ti interfacial switching device overcomes the intrinsic trade-off between operating current and variability in filamentary RRAMs and shows promising potential for high-density data storage.
A study on low-power, nanosecond operation and multilevel bipolar resistance switching in Ti/ZrO2/Pt nonvolatile memory with 1T1R architecture
(2012-06-01)
Wu, Ming-Chi
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Jang, Wen-Yueh
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Lin, Chen-Hsi
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Tseng, Tseung-Yuen
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電子工程學系及電子研究所
Low-power, bipolar resistive switching (RS) characteristics in the Ti/ZrO2/Pt nonvolatile memory with one transistor and one resistor (1T1R) architecture were reported. Multilevel storage behavior was observed by modulating the amplitude of the MOSFET gate voltage, in which the transistor functions as a current limiter. Furthermore, multilevel storage was also executed by controlling the reset voltage, leading the resistive random access memory (RRAM) to the multiple metastable low resistance state (LRS). The experimental results on the measured electrical properties of the various sized devices confirm that the RS mechanism of the Ti/ZrO2/Pt structure obeys the conducting filaments model. In application, the devices exhibit high-speed switching performances (250 ns) with suitable high/low resistance state ratio (HRS/LRS > 10). The LRS of the devices with 10 year retention ability at 80 degrees C, based on the Arrhenius equation, is also demonstrated in the thermal accelerating test. Furthermore, the ramping gate voltage method with fixed drain voltage is used to switch the 1T1R memory cells for upgrading the memory performances. Our experimental results suggest that the ZrO2-based RRAM is a prospective alternative for nonvolatile multilevel memory device applications.
Effects of Vanadium Doping on Resistive Switching Characteristics and Mechanisms of SrZrO(3)-Based Memory Films
(2010-08-01)
Lin, Meng-Han
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Wu, Ming-Chi
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Lin, Chen-Hsi
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Tseng, Tseung-Yuen
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電子工程學系及電子研究所
The effects of vanadium doping on resistive switching (RS) characteristics and mechanisms of RF-sputtered SrZrO(3) (SZO)-based thin films are investigated in this paper. The physical and electrical properties of SZO-based thin films are modulated by vanadium doping due to the Zr(4+) ion replaced by V(5+), further affecting the RS parameters of SZO-based thin films. The conduction mechanisms of SZO-based thin films are dominated by ohmic conduction (hoping conduction) and Frenkel-Poole emission for the low resistance state (LRS) and the high resistance state (HRS), respectively. The turn-on process might be attributed to the formation of conducting filaments consisting of oxygen vacancies with the effective barrier height (phi(B,eff)) in the range of 0.10-0.13 eV, whereas the turn-off process might result from thermally assisted oxidation of oxygen vacancies by the Joule heating effect. Furthermore, the introduction of the high valence cation (V(5+)) in a Zr(4+) site of SZO crystalline structure can suppress the formation of oxygen vacancies due to the charge neutrality restriction. Such suppression leads to the changes in the forming voltage, turn-on voltage, HRS resistance, dielectric constant, and phi(B,eff) with vanadium doping concentration up to 0.2 mol%, which is within the solid solubility limit based on our measured lattice constants and Vegard's law.
Effects of Vanadium Doping on Resistive Switching Characteristics and Mechanisms of SrZrO3-Based Memory Films
(2010-08-01)
Lin, Meng-Han
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Wu, Ming-Chi
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Lin, Chen-Hsi
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Tseng, Tseung-Yuen
;
電子工程學系及電子研究所
The effects of vanadium doping on resistive switching (RS) characteristics and mechanisms of RF-sputtered SrZrO3 (SZO)-based thin films are investigated in this paper. The physical and electrical properties of SZO-based thin films are modulated by vanadium doping due to the Zr4+ ion replaced by V5+, further affecting the RS parameters of SZO-based thin films. The conduction mechanisms of SZO-based thin films are dominated by ohmic conduction (hoping conduction) and Frenkel-Poole emission for the low resistance state (LRS) and the high resistance state (HRS), respectively. The turn-on process might be attributed to the formation of conducting filaments consisting of oxygen vacancies with the effective barrier height (phi(B,eff)) in the range of 0.10-0.13 eV, whereas the turn-off process might result from thermally assisted oxidation of oxygen vacancies by the Joule heating effect. Furthermore, the introduction of the high valence cation (V5+) in a Zr4+ site of SZO crystalline structure can suppress the formation of oxygen vacancies due to the charge neutrality restriction. Such suppression leads to the changes in the forming voltage, turn-on voltage, HRS resistance, dielectric constant, and phi(B,eff) with vanadium doping concentration up to 0.2 mol%, which is within the solid solubility limit based on our measured lattice constants and Vegard's law.
Enhanced Properties in Conductive-Bridge Resistive Switching Memory With Oxide-Nitride Bilayer Structure
(2016-10)
Tsai, Tsung-Ling
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Jiang, Fa-Shen
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Ho, Chia-Hua
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Lin, Chen-Hsi
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Tseng, Tseung-Yuen
In this letter, we propose a new method to improve resistive switching properties in ZrO2-based conductive-bridge resistive memory devices by introducing a thin AlN layer with high thermal conductivity between the ZrO2 layer and TiN bottom electrode. Compared with the Cu/TiW/ZrO2/TiN single-layer device, the Cu/TiW/ZrO2/AlN/TiN bilayer device exhibits lower operation voltages, higher endurance performance, and higher resistive switching uniformity. These substantial improvements in the resistive switching properties are attributed to the formation and rupture of conductive filament that can be effectively controlled in the device after inserting the AlN layer.
Flexible One Diode-One Resistor Crossbar Resistive-Switching Memory
(2012-04-01)
Huang, Jiun-Jia
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Hou, Tuo-Hung
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Hsu, Chung-Wei
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Tseng, Yi-Ming
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Chang, Wen-Hsiung
We report the first demonstration of a flexible one diode-one resistor (1D1R) resistive-switching (RS) memory cell capable of high-density crossbar array implementation at an extremely low cost. A Ti/TiO2/Pt diode with a large rectifying ratio and a stable Ni/HfO2/Pt unipolar RS memory element have been fabricated on a polyimide substrate using only room-temperature processes. No significant degradation of the rectifying ratio of the TiO2 diode and the cycling variations, retention, and read disturb immunity of the HfO2 memory was observed in the bending state. The series 1D1R cell shows highly reproducible unipolar RS because of the low reset current of the HfO2 memory, which greatly mitigates the adverse effect of diode series resistance. Furthermore, the 1D1R cell can effectively suppress read interference and realize a crossbar array as large as 512 kbit. (C) 2012 The Japan Society of Applied Physics
High Device Yield of Resistive Switching Characteristics in Oxygen-Annealed SrZrO(3) Memory Devices
(2011-04-01)
Lin, Meng-Han
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Wu, Ming-Chi
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Huang, Yi-Han
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Lin, Chen-Hsi
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Tseng, Tseung-Yuen
This paper reports the effects of rapid thermal annealing (RTA) on resistive switching (RS) characteristics and mechanisms of SrZrO(3) (SZO)-based memory devices. SZO thin films were deposited on LaNiO(3) (LNO) (100)/Pt/Ti/SiO(2)/Si using radio-frequency magnetron sputtering and were followed by an RTA process in N(2), Ar, and O(2) ambients, respectively, at various temperatures for improving RS performance. Experimental results indicate that an SZO device annealed in O(2) at 600 degrees C (O(2)-600) exhibits stable RS properties and has a high device yield (similar to 90%), a reliable retention characteristic (up to 1 x 10(6) s at 100 degrees C), and steady nondestructive readout properties (over 1.4 x 10(4) s at 100 degrees C). However, by increasing RTA temperature to more than 700 degrees C, random formation of LNO (110) precipitates on the bottom surface of SZO grains might shorten the effective thickness of the SZO thin films. Furthermore, a strong electric field possibly occurs at the region between Al top electrodes and low-resistivity LNO precipitates. It is speculated that an RS phenomenon, which occurs within SZO grains instead of on grain boundaries, easily leads to RS failure, further resulting in severe degradation of device yield in the O(2)-700 and O(2)-800 devices. When compared with other devices, O(2)-600 SZO memory devices exhibit highly reliable RS characteristics.
High Device Yield of Resistive Switching Characteristics in Oxygen-Annealed SrZrO3 Memory Devices
(2011-04-01)
Lin, Meng-Han
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Wu, Ming-Chi
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Huang, Yi-Han
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Lin, Chen-Hsi
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Tseng, Tseung-Yuen
This paper reports the effects of rapid thermal annealing (RTA) on resistive switching (RS) characteristics and mechanisms of SrZrO3 (SZO)-based memory devices. SZO thin films were deposited on LaNiO3 (LNO) (100)/Pt/Ti/SiO2/Si using radio-frequency magnetron sputtering and were followed by an RTA process in N-2, Ar, and O-2 ambients, respectively, at various temperatures for improving RS performance. Experimental results indicate that an SZO device annealed in O-2 at 600 degrees C (O-2-600) exhibits stable RS properties and has a high device yield (similar to 90%), a reliable retention characteristic (up to 1 x 10(6) s at 100 degrees C), and steady nondestructive readout properties (over 1.4 x 10(4) s at 100 degrees C). However, by increasing RTA temperature to more than 700 degrees C, random formation of LNO (110) precipitates on the bottom surface of SZO grains might shorten the effective thickness of the SZO thin films. Furthermore, a strong electric field possibly occurs at the region between Al top electrodes and low-resistivity LNO precipitates. It is speculated that an RS phenomenon, which occurs within SZO grains instead of on grain boundaries, easily leads to RS failure, further resulting in severe degradation of device yield in the O-2-700 and O-2-800 devices. When compared with other devices, O-2-600 SZO memory devices exhibit highly reliable RS characteristics.
High-speed and localized resistive switching characteristics of double-layer SrZrO(3) memory devices
(2010-07-28)
Lin, Meng-Han
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Wu, Ming-Chi
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Huang, Chun-Yang
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Lin, Chen-Hsi
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Tseng, Tseung-Yuen
The fabrication of SrZrO(3) (SZO) memory devices with oxygen-rich (OR) and oxygen-deficient (OD) double layers, their resistive switching (RS) characteristics and mechanisms are investigated in this study. Due to the difference in oxygen content between the OR and OD layers formed by an oxygen flow control (OFC) process during SZO deposition, the RS region is effectively reduced and localized within the OR layer, which leads to a low operation voltage and stable RS behaviours. Furthermore, the OFC SZO device exhibits high-speed switching (10 ns) over 400 times and long retention (>10(6) s), showing promising potential for next-generation nonvolatile memory applications.
High-speed and localized resistive switching characteristics of double-layer SrZrO3 memory devices
(2010-07-28)
Lin, Meng-Han
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Wu, Ming-Chi
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Huang, Chun-Yang
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Lin, Chen-Hsi
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Tseng, Tseung-Yuen
The fabrication of SrZrO3 (SZO) memory devices with oxygen-rich (OR) and oxygen-deficient (OD) double layers, their resistive switching (RS) characteristics and mechanisms are investigated in this study. Due to the difference in oxygen content between the OR and OD layers formed by an oxygen flow control (OFC) process during SZO deposition, the RS region is effectively reduced and localized within the OR layer, which leads to a low operation voltage and stable RS behaviours. Furthermore, the OFC SZO device exhibits high-speed switching (10 ns) over 400 times and long retention (>10(6) s), showing promising potential for next-generation nonvolatile memory applications.
Highly Stable SrZrO3 Bipolar Resistive Switching Memory by Ti Modulation Layer
(2010)
Wu, Ming-Chi
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Lin, Meng-Han
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Yeh, Yu-Ting
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Lin, Chen-Hsi
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Tseng, Tseung-Yuen
In this study, we investigated the resistive switching characteristics of the SrZrO3 (SZO)-based resistance random access memory (RRAM). After the sequential thin-films Pt/Ti/SZO/LaNiO3 deposition, the post annealing (PA) treatment under various conditions was carried out to form the interfacial layer (TiOx) between Ti and SZO. It can be proved that the Ti modulation layer act as an oxygen getter can modify the resistive switching property of RRAM. With the suitable thickness of Ti layer and the proper annealing temperature, the SZO-based RRAM device could have a lower operation voltage, a lower compliance current a long retention behavior, and stable resistance ratio over 10(4) s under 0.3 V reading voltage.
Improved Resistive Switching Characteristics by Al2O3 Layers Inclusion in HfO2-Based RRAM Devices
(2013)
Huang, Chun-Yang
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Jieng, Jheng-Hong
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Jang, Wen-Yueh
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Lin, Chen-Hsi
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Tseng, Tseung-Yuen
A series of complex HfO2/Al2O3 layer by layer resistive random access memory(RRAM) structure grown by atomic layer deposition are investigated. The modulation of forming voltage can be achieved by controlling the number of Al2O3 layers in HfO2 devices. In addition, the crystallization temperature of HfO2 based RRAM devices can also be improved by insetting Al2O3 layers in HfO2 film. Compared with pure HfO2 device, a significant improvement in resistive switching properties such as forming voltage variation and the distribution of HRS/LRS during resistance switching is demonstrated in the HfO2/Al2O3 layer by layer devices. Moreover, good endurance characteristic and highly reliable multibit operation are also achieved in this device structure. (c) 2013 The Electrochemical Society. All rights reserved.
Improvement of resistive switching characteristics in SrZrO3 thin films with embedded Cr layer
(2008-10-01)
Lin, Chih-Yang
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Lin, Meng-Han
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Wu, Ming-Chi
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Lin, Chen-Hsi
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Tseng, Tseung-Yuen
The stabilization of the resistive switching properties is necessary to realize the memory application of the SrZrO3 (SZO)-based resistive switching devices. During continuous resistive switching cycle, broad variations of the resistive switching parameters of the SZO-based memory devices can be improved by a thin embedded Cr layer. The Cr metal layer is proposed to diffuse into and dope the SZO thin film to produce the space charge region, further reducing the effective resistive switching region. Hence, the good stabilization of the resistive switching properties can be obtained in the SZO films with embedded Cr layer.
Investigation of thermal stability and reliability of HfO2 based resistive random access memory devices with cross-bar structure
(2015-05-14)
Chand, Umesh
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Huang, Kuan-Chang
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Huang, Chun-Yang
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Ho, Chia-Hua
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Lin, Chen-Hsi
The effect of the annealing treatment of a HfO2 resistive switching layer and the memory performance of a HfO2-based resistive random access memory (cross-bar structure) device were investigated. Oxygen is released from HfO2 resistive switching layers during vacuum annealing, leading to unstable resistive switching properties. This oxygen release problem can be suppressed by inserting an Al2O3 thin film, which has a lower Gibbs free energy, between the HfO2 layer and top electrode to form a Ti/Al2O3/HfO2/TiN structure. This device structure exhibited good reliability after high temperature vacuum annealing and post metal annealing (PMA) treatments. Moreover, the endurance and retention properties of the device were also improved after the PMA treatment. (c) 2015 AIP Publishing LLC.
Low-Power and Highly Reliable Multilevel Operation in ZrO(2) 1T1R RRAM
(2011-08-01)
Wu, Ming-Chi
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Lin, Yi-Wei
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Jang, Wen-Yueh
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Lin, Chen-Hsi
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Tseng, Tseung-Yuen
The Ti/ZrO(2)/Pt resistive memory devices with one transistor and one resistor (1T1R) architecture are successfully fabricated in this letter. The tested devices show low operation current (20 mu A), low switching voltage (set/reset, 0.8/-1 V), and reliable data retention for low-resistance state (LRS) with a 20-mu A set current at 80 degrees C (over ten years) via an excellent current limiter, namely, a metal-oxide-semiconductor field-effect transistor (MOSFET). In addition, multilevel storage characteristics are also demonstrated by modulating the amplitude of the MOSFET gate voltage. The various LRS levels obtained are possibly attributed to the formation of different numbers and sizes of conducting filaments consisting of oxygen vacancies caused by an external electric field. Moreover, reproducible resistive switching characteristics up to 2000 switching cycles are achieved in the same device. Our 1T1R ZrO(2)-based resistive switching access memory with low-power and highly reliable multilevel operation has high potential for practical applications.
Low-Power and Highly Reliable Multilevel Operation in ZrO2 1T1R RRAM
(2011-08-01)
Wu, Ming-Chi
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Lin, Yi-Wei
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Jang, Wen-Yueh
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Lin, Chen-Hsi
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Tseng, Tseung-Yuen
The Ti/ZrO2/Pt resistive memory devices with one transistor and one resistor (1T1R) architecture are successfully fabricated in this letter. The tested devices show low operation current (20 mu A), low switching voltage (set/reset, 0.8/-1 V), and reliable data retention for low-resistance state (LRS) with a 20-mu A set current at 80 degrees C (over ten years) via an excellent current limiter, namely, a metal-oxide-semiconductor field-effect transistor (MOSFET). In addition, multilevel storage characteristics are also demonstrated by modulating the amplitude of the MOSFET gate voltage. The various LRS levels obtained are possibly attributed to the formation of different numbers and sizes of conducting filaments consisting of oxygen vacancies caused by an external electric field. Moreover, reproducible resistive switching characteristics up to 2000 switching cycles are achieved in the same device. Our 1T1R ZrO2-based resistive switching access memory with low-power and highly reliable multilevel operation has high potential for practical applications.
Resistive switching mechanisms of V-doped SrZrO3 memory films
(2006-09-01)
Lin, Chun-Chieh
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Tu, Bing-Chung
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Lin, Chao-Cheng
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Lin, Chen-Hsi
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Tseng, Tseung-Yuen
The resistive switching behaviors of sputtered V-doped SrZrO3 (V:SZO) memory films were investigated in this letter. The current states of the memory films were switched between high current state (H-state) and low current state (L-state). The resistance ratio of the two current states was over 1000 at a read voltage. The switching mechanism from L- to H-state corresponds to the formation of current paths. However, this mechanism from H- to L-state is thought to be due to the fact that the defects present in the V:SZO film randomly trap electrons, and hence, the current paths are ruptured. The conduction mechanism of the H-state is dominated by ohmic conduction, whereas the L-state conduction is dominated by Frenkel-Poole emission. The polarity direction of the resistive switching is an intrinsic property of the SrZrO3 oxides. The V:SZO films with high uniformity and good stability are expected to be used in nonvolatile memory.
Resistive switching properties of sol-gel derived Mo-doped SrZrO3 thin films
(2007-12-15)
Lin, Chih-Yang
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Lin, Chun-Chieh
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Huang, Chun-Hsing
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Lin, Chen-Hsi
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Tseng, Tseung-Yuen
Hysteretic I-V characteristics of the SrZrO3 (SZO) thin films with various Mo-doping concentrations were investigated in the study. The 0.2 mol% Mo-doping SZO-based memory device showed excellent resistive switching characteristics, and the resistive switching can be operated over 300 times during successive operation. Both high and low conductive states were stable over 10(4) s. Multi-bit behavior was investigated by dc voltage sweeping with different spans of voltage scan for OFF-process and by various OFF-pulse voltages as well. The endurance test can be over 1000 times with no data loss found. The experimental results showed high potential for nonvolatile memory application. (c) 2007 Published by Elsevier B.V.
Resistive switching properties of SrZrO(3)-based memory films
(2007-04-01)
Lin, Chun-Chieh
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Lin, Chao-Cheng
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Tu, Bing-Chung
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Yu, Jung-Sheng
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Lin, Chen-Hsi
The resistive switching properties of the sputter-deposited SrZrO(3) (SZO) memory films were investigated in this study. The resistive switching behaviors of the SZO film can be improved by doping with vanadium oxide. The conduction mechanisms of the high and low current states of the 0.3% V-doped SZO (V:SZO) film are ohmic conduction and Frenkel-Poole emission, respectively, which implies the bulk effect of the memory film. The resistive ratio of two current states of the 0.3% V:SZO film remains 1000 times after applying 100 voltage sweeping cycles. Furthermore, the 0.3% V:SZO film shows stable resistive switching properties when measurement is performed at 100 degrees C. The band modulation of the SZO/LNO interface is proposed to explain the forming process of the SZO films. The 0.3% V:SZO memory film has excellent properties, such as high stability, good endurance, and long retention time, which make it a good candidate for next-generation nonvolatile memory application.