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Statistical characteristics of reset switching in Cu/HfO2/Pt resistive switching memory.

Zhang M, Long S, Wang G, Liu R, Xu X, Li Y, Xu D, Liu Q, Lv H, Miranda E, Suñé J, Liu M - Nanoscale Res Lett (2014)

Bottom Line: The reset voltage increases and the current decreases with the on-state resistance, respectively, according to the scatter plots of the experimental data.The scale factor of the reset voltage increases with on-state resistance while that of the reset current decreases with it.Our work has provided an inspiration on effectively reducing the variation of the switching parameters of RRAM devices.

View Article: PubMed Central - PubMed

Affiliation: Lab of Nanofabrication and Novel Device Integration, Institute of Microelectronics, Chinese Academy of Sciences, Beijing, 100029, China, zhangmeiyun@ime.ac.cn.

ABSTRACT
A major challenge of resistive switching memory (resistive random access memory (RRAM)) for future application is how to reduce the fluctuation of the resistive switching parameters. In this letter, with a statistical methodology, we have systematically analyzed the reset statistics of the conductive bridge random access memory (CBRAM) with a Cu/HfO2/Pt structure which displays bipolar switching property. The experimental observations show that the distributions of the reset voltage (V reset) and reset current (I reset) are greatly influenced by the initial on-state resistance (R on) which is closely related to the size of the conductive filament (CF) before the reset process. The reset voltage increases and the current decreases with the on-state resistance, respectively, according to the scatter plots of the experimental data. Using resistance screening method, the statistical data of the reset voltage and current are decomposed into several ranges and the distributions of them in each range are analyzed by the Weibull model. Both the Weibull slopes of the reset voltage and current are demonstrated to be independent of the on-state resistance which indicates that no CF dissolution occurs before the reset point. The scale factor of the reset voltage increases with on-state resistance while that of the reset current decreases with it. These behaviors are fully in consistency with the thermal dissolution model, which gives an insight on the physical mechanism of the reset switching. Our work has provided an inspiration on effectively reducing the variation of the switching parameters of RRAM devices.

No MeSH data available.


Related in: MedlinePlus

Characteristics of the RRAM device and the transistor. (a) The schematic of 1T1R structure. (b) Typical I-V curves of the Cu/HfO2/Pt device in set and reset cycles. The reset points have been notated by Vreset and Ireset. (c) The transfer curve of the N+ transistor. The intrinsic parameters of the transistor (including WunCox/2 L and VT) are abstracted from the slope and the intercept of the fitting line, so the soure-drain resistance is obtained from calculation.
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Fig1: Characteristics of the RRAM device and the transistor. (a) The schematic of 1T1R structure. (b) Typical I-V curves of the Cu/HfO2/Pt device in set and reset cycles. The reset points have been notated by Vreset and Ireset. (c) The transfer curve of the N+ transistor. The intrinsic parameters of the transistor (including WunCox/2 L and VT) are abstracted from the slope and the intercept of the fitting line, so the soure-drain resistance is obtained from calculation.

Mentions: Figure 1a shows the fabricated 1T1R (one transistor and one RRAM cell) structure with which the RS statistics of the Cu/HfO2/Pt RRAM device are investigated. N+ type transistor was made up by standard 0.13 μm CMOS process of SMIC. Cu plug connected to the drain of the transistor was flattened by the chemical mechanical polished (CMP) and is used as the bottom electrode (BE) of our RRAM cell. A HfO2 RS layer was deposited by ion beam sputtering with a thickness of 6 nm on the Cu plug. Pt top electrode (TE) was then prepared by e-beam evaporation and patterned by lift-off process. The transistor in the 1T1R structure is used as the current compliance in the forming and set operation for RRAM cell to prevent the hard dielectric breakdown of the HfO2 layer and the overshoot of the current [24]. The electrical characteristics of the device were measured by Agilent B1500A Semiconductor Device Parameter Analyzer (Agilent Technologies, Inc., Santa Clara, CA, USA). The I-V curves in the 4,000 continuous set/reset cycles for the RRAM cell are tested under the DC voltage sweep mode. During the measurement, the voltage sweeping was applied on the source terminal in the set operation and on the drain terminal during the reset process, with the value of the voltage ramped from 0 to 2 V. The gate bias voltage of the transistor was set up as 2.5 V for the set operation to maintain a source-drain current of 1 mA to acquire an excellent current compliance and to avoid the RRAM cell being damaged by the current overshoot. In the reset operation, the gate bias was 3.3 V to guarantee that the CF is completely ruptured.Figure 1


Statistical characteristics of reset switching in Cu/HfO2/Pt resistive switching memory.

Zhang M, Long S, Wang G, Liu R, Xu X, Li Y, Xu D, Liu Q, Lv H, Miranda E, Suñé J, Liu M - Nanoscale Res Lett (2014)

Characteristics of the RRAM device and the transistor. (a) The schematic of 1T1R structure. (b) Typical I-V curves of the Cu/HfO2/Pt device in set and reset cycles. The reset points have been notated by Vreset and Ireset. (c) The transfer curve of the N+ transistor. The intrinsic parameters of the transistor (including WunCox/2 L and VT) are abstracted from the slope and the intercept of the fitting line, so the soure-drain resistance is obtained from calculation.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493841&req=5

Fig1: Characteristics of the RRAM device and the transistor. (a) The schematic of 1T1R structure. (b) Typical I-V curves of the Cu/HfO2/Pt device in set and reset cycles. The reset points have been notated by Vreset and Ireset. (c) The transfer curve of the N+ transistor. The intrinsic parameters of the transistor (including WunCox/2 L and VT) are abstracted from the slope and the intercept of the fitting line, so the soure-drain resistance is obtained from calculation.
Mentions: Figure 1a shows the fabricated 1T1R (one transistor and one RRAM cell) structure with which the RS statistics of the Cu/HfO2/Pt RRAM device are investigated. N+ type transistor was made up by standard 0.13 μm CMOS process of SMIC. Cu plug connected to the drain of the transistor was flattened by the chemical mechanical polished (CMP) and is used as the bottom electrode (BE) of our RRAM cell. A HfO2 RS layer was deposited by ion beam sputtering with a thickness of 6 nm on the Cu plug. Pt top electrode (TE) was then prepared by e-beam evaporation and patterned by lift-off process. The transistor in the 1T1R structure is used as the current compliance in the forming and set operation for RRAM cell to prevent the hard dielectric breakdown of the HfO2 layer and the overshoot of the current [24]. The electrical characteristics of the device were measured by Agilent B1500A Semiconductor Device Parameter Analyzer (Agilent Technologies, Inc., Santa Clara, CA, USA). The I-V curves in the 4,000 continuous set/reset cycles for the RRAM cell are tested under the DC voltage sweep mode. During the measurement, the voltage sweeping was applied on the source terminal in the set operation and on the drain terminal during the reset process, with the value of the voltage ramped from 0 to 2 V. The gate bias voltage of the transistor was set up as 2.5 V for the set operation to maintain a source-drain current of 1 mA to acquire an excellent current compliance and to avoid the RRAM cell being damaged by the current overshoot. In the reset operation, the gate bias was 3.3 V to guarantee that the CF is completely ruptured.Figure 1

Bottom Line: The reset voltage increases and the current decreases with the on-state resistance, respectively, according to the scatter plots of the experimental data.The scale factor of the reset voltage increases with on-state resistance while that of the reset current decreases with it.Our work has provided an inspiration on effectively reducing the variation of the switching parameters of RRAM devices.

View Article: PubMed Central - PubMed

Affiliation: Lab of Nanofabrication and Novel Device Integration, Institute of Microelectronics, Chinese Academy of Sciences, Beijing, 100029, China, zhangmeiyun@ime.ac.cn.

ABSTRACT
A major challenge of resistive switching memory (resistive random access memory (RRAM)) for future application is how to reduce the fluctuation of the resistive switching parameters. In this letter, with a statistical methodology, we have systematically analyzed the reset statistics of the conductive bridge random access memory (CBRAM) with a Cu/HfO2/Pt structure which displays bipolar switching property. The experimental observations show that the distributions of the reset voltage (V reset) and reset current (I reset) are greatly influenced by the initial on-state resistance (R on) which is closely related to the size of the conductive filament (CF) before the reset process. The reset voltage increases and the current decreases with the on-state resistance, respectively, according to the scatter plots of the experimental data. Using resistance screening method, the statistical data of the reset voltage and current are decomposed into several ranges and the distributions of them in each range are analyzed by the Weibull model. Both the Weibull slopes of the reset voltage and current are demonstrated to be independent of the on-state resistance which indicates that no CF dissolution occurs before the reset point. The scale factor of the reset voltage increases with on-state resistance while that of the reset current decreases with it. These behaviors are fully in consistency with the thermal dissolution model, which gives an insight on the physical mechanism of the reset switching. Our work has provided an inspiration on effectively reducing the variation of the switching parameters of RRAM devices.

No MeSH data available.


Related in: MedlinePlus