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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.


HRS resistance traces as a function of baking time at 150°C for 1T1R Cu/HfO2/Pt devices.
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Fig4: HRS resistance traces as a function of baking time at 150°C for 1T1R Cu/HfO2/Pt devices.

Mentions: The programmed HRS cells were then baked in a vacuum oven at 150°C. The resistance of each cell was periodically checked by a self-made array testing system after cooling down to room temperature. The criterion for judging whether the HRS failed or not was defined by RHRS ≤ 5kΩ. Figure 4 shows the dependence of the HRS on the baking time. As the baking time increases, the resistance of the HRS decreases gradually. Figure 5a-d shows the cumulative probabilities of HRS for G-1, G-2, G-3, and G-4, after baking for 0, 10, 50, and 100 h, respectively. Similar evolution trends (shift towards the left) of HRS were found in the four groups as the baking time increased. For the sake of presenting the difference of HRS retention in the four groups clearly, the cumulative probabilities of HRS after a 100-h baking were plotted in one coordinate, as shown in Figure 6. It can be clearly found that the degradation of the HRS programmed from the lowest LRS is worse than that from higher LRS, obeying a relation of G-1 < G-2 < G-3 < G-4. That is to say, the RHRS retention is highly dependent on LRS. This result is further supported by summarizing the failure percentage of the HRS at different baking times in the insert of Figure 6.Figure 4


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)

HRS resistance traces as a function of baking time at 150°C for 1T1R Cu/HfO2/Pt devices.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Fig4: HRS resistance traces as a function of baking time at 150°C for 1T1R Cu/HfO2/Pt devices.
Mentions: The programmed HRS cells were then baked in a vacuum oven at 150°C. The resistance of each cell was periodically checked by a self-made array testing system after cooling down to room temperature. The criterion for judging whether the HRS failed or not was defined by RHRS ≤ 5kΩ. Figure 4 shows the dependence of the HRS on the baking time. As the baking time increases, the resistance of the HRS decreases gradually. Figure 5a-d shows the cumulative probabilities of HRS for G-1, G-2, G-3, and G-4, after baking for 0, 10, 50, and 100 h, respectively. Similar evolution trends (shift towards the left) of HRS were found in the four groups as the baking time increased. For the sake of presenting the difference of HRS retention in the four groups clearly, the cumulative probabilities of HRS after a 100-h baking were plotted in one coordinate, as shown in Figure 6. It can be clearly found that the degradation of the HRS programmed from the lowest LRS is worse than that from higher LRS, obeying a relation of G-1 < G-2 < G-3 < G-4. That is to say, the RHRS retention is highly dependent on LRS. This result is further supported by summarizing the failure percentage of the HRS at different baking times in the insert of Figure 6.Figure 4

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.