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Investigation of LRS dependence on the retention of HRS in CBRAM.

Xu X, Lv H, Liu H, Luo Q, Gong T, Wang M, Wang G, Zhang M, Li Y, Liu Q, Long S, Liu M - Nanoscale Res Lett (2015)

Bottom Line: The HRS degradation was found strongly dependent on the LRS: the lower the resistance of the LRS (R LRS) is, the worse HRS retention will be.The degradation of HRS is due to the filling or widening of the neck point by the diffusion of copper species from the residual filament.As the residual filament is stronger in case of the lower R LRS, the active area around the neck point for copper species diffusion is larger, resulting in higher diffusion probability and faster degradation of HRS during the temperature-accelerated retention measurement.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Nano-Fabrication and Novel Devices Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, #3 Beitucheng West Road, Chaoyang District Beijing, 100029 China.

ABSTRACT
The insufficient retention prevents the resistive random access memory from intended application, such as code storage, FPGA, encryption, and others. The retention characteristics of high resistance state (HRS) switching from different low resistance state (LRS) were investigated in a 1-kb array with one transistor and one resistor configuration. The HRS degradation was found strongly dependent on the LRS: the lower the resistance of the LRS (R LRS) is, the worse HRS retention will be. According to the quantum point contact model, the HRS corresponds to a tiny tunnel gap or neck bridge with atomic size in the filament. The degradation of HRS is due to the filling or widening of the neck point by the diffusion of copper species from the residual filament. As the residual filament is stronger in case of the lower R LRS, the active area around the neck point for copper species diffusion is larger, resulting in higher diffusion probability and faster degradation of HRS during the temperature-accelerated retention measurement.

No MeSH data available.


The typical I-V characteristics of the 1T1R structure during FORMING and SET/RESET operations. The memory cells show the bipolar resistive switching.
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Fig2: The typical I-V characteristics of the 1T1R structure during FORMING and SET/RESET operations. The memory cells show the bipolar resistive switching.

Mentions: During the FORMING/SET operation, the wordline (WL) was forced by a positive bias to open the access transistor and provide compliance current. Positive sweeping voltage was applied on the sourceline (SL) to switch the memory cells from HRS to LRS with bitline (BL) kept on ground and vice versa for the RESET operation. Typical current–voltage (I-V) switching characteristics (FORMING, SET, and RESET) in DC modes are illustrated in Figure 2. The FORMING voltage was about 1.2 V, the SET and RESET voltages were about +0.6 and −0.75 V, respectively. Figure 3a shows the global statistical distribution of RLRS and RHRS. RLRS is distributed in a range of 300 Ω to 1,000 Ω, whereas RHRS concentrates around 10 kΩ approximately. To elucidate the influence of LRS on HRS retention properties, the RLRS was divided into four groups (marked as ‘G-n’ below) as follows: G-1: 300 Ω to 400 Ω, G-2: 400Ω to 500 Ω, G-3: 500 Ω to 600 Ω, G-4: >600 Ω. The distributions of four groups screened LRS (solid-symbol lines) and corresponding HRS (open-symbol lines) were plotted in Figure 3b. It should be noted that although the LRS were different, the consequent HRS distributions were nearly the same. The reason for this result will be discussed later.Figure 2


Investigation of LRS dependence on the retention of HRS in CBRAM.

Xu X, Lv H, Liu H, Luo Q, Gong T, Wang M, Wang G, Zhang M, Li Y, Liu Q, Long S, Liu M - Nanoscale Res Lett (2015)

The typical I-V characteristics of the 1T1R structure during FORMING and SET/RESET operations. The memory cells show the bipolar resistive switching.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4385049&req=5

Fig2: The typical I-V characteristics of the 1T1R structure during FORMING and SET/RESET operations. The memory cells show the bipolar resistive switching.
Mentions: During the FORMING/SET operation, the wordline (WL) was forced by a positive bias to open the access transistor and provide compliance current. Positive sweeping voltage was applied on the sourceline (SL) to switch the memory cells from HRS to LRS with bitline (BL) kept on ground and vice versa for the RESET operation. Typical current–voltage (I-V) switching characteristics (FORMING, SET, and RESET) in DC modes are illustrated in Figure 2. The FORMING voltage was about 1.2 V, the SET and RESET voltages were about +0.6 and −0.75 V, respectively. Figure 3a shows the global statistical distribution of RLRS and RHRS. RLRS is distributed in a range of 300 Ω to 1,000 Ω, whereas RHRS concentrates around 10 kΩ approximately. To elucidate the influence of LRS on HRS retention properties, the RLRS was divided into four groups (marked as ‘G-n’ below) as follows: G-1: 300 Ω to 400 Ω, G-2: 400Ω to 500 Ω, G-3: 500 Ω to 600 Ω, G-4: >600 Ω. The distributions of four groups screened LRS (solid-symbol lines) and corresponding HRS (open-symbol lines) were plotted in Figure 3b. It should be noted that although the LRS were different, the consequent HRS distributions were nearly the same. The reason for this result will be discussed later.Figure 2

Bottom Line: The HRS degradation was found strongly dependent on the LRS: the lower the resistance of the LRS (R LRS) is, the worse HRS retention will be.The degradation of HRS is due to the filling or widening of the neck point by the diffusion of copper species from the residual filament.As the residual filament is stronger in case of the lower R LRS, the active area around the neck point for copper species diffusion is larger, resulting in higher diffusion probability and faster degradation of HRS during the temperature-accelerated retention measurement.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Nano-Fabrication and Novel Devices Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, #3 Beitucheng West Road, Chaoyang District Beijing, 100029 China.

ABSTRACT
The insufficient retention prevents the resistive random access memory from intended application, such as code storage, FPGA, encryption, and others. The retention characteristics of high resistance state (HRS) switching from different low resistance state (LRS) were investigated in a 1-kb array with one transistor and one resistor configuration. The HRS degradation was found strongly dependent on the LRS: the lower the resistance of the LRS (R LRS) is, the worse HRS retention will be. According to the quantum point contact model, the HRS corresponds to a tiny tunnel gap or neck bridge with atomic size in the filament. The degradation of HRS is due to the filling or widening of the neck point by the diffusion of copper species from the residual filament. As the residual filament is stronger in case of the lower R LRS, the active area around the neck point for copper species diffusion is larger, resulting in higher diffusion probability and faster degradation of HRS during the temperature-accelerated retention measurement.

No MeSH data available.