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Impact of device size and thickness of Al2O 3 film on the Cu pillar and resistive switching characteristics for 3D cross-point memory application.

Panja R, Roy S, Jana D, Maikap S - Nanoscale Res Lett (2014)

Bottom Line: The 8-μm devices show 100% yield of Cu pillars, whereas only 74% successful is observed for the 0.4-μm devices, because smaller size devices have higher Joule heating effect and larger size devices show long read endurance of 10(5) cycles at a high read voltage of -1.5 V.On the other hand, the resistive switching memory characteristics of the 0.4-μm devices with a 2-nm-thick Al2O3 film show superior as compared to those of both the larger device sizes and thicker (10 nm) Al2O3 film, owing to higher Cu diffusion rate for the larger size and thicker Al2O3 film.This conductive bridging resistive random access memory (CBRAM) device is forming free at a current compliance (CC) of 30 μA (even at a lowest CC of 0.1 μA) and operation voltage of ±3 V at a high resistance ratio of >10(4).

View Article: PubMed Central - PubMed

Affiliation: Thin Film Nano Tech. Lab., Department of Electronic Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kwei-Shan, Tao-Yuan, 333, Taiwan, panjarajeswar@gmail.com.

ABSTRACT
Impact of the device size and thickness of Al2O3 film on the Cu pillars and resistive switching memory characteristics of the Al/Cu/Al2O3/TiN structures have been investigated for the first time. The memory device size and thickness of Al2O3 of 18 nm are observed by transmission electron microscope image. The 20-nm-thick Al2O3 films have been used for the Cu pillar formation (i.e., stronger Cu filaments) in the Al/Cu/Al2O3/TiN structures, which can be used for three-dimensional (3D) cross-point architecture as reported previously Nanoscale Res. Lett.9:366, 2014. Fifty randomly picked devices with sizes ranging from 8 × 8 to 0.4 × 0.4 μm(2) have been measured. The 8-μm devices show 100% yield of Cu pillars, whereas only 74% successful is observed for the 0.4-μm devices, because smaller size devices have higher Joule heating effect and larger size devices show long read endurance of 10(5) cycles at a high read voltage of -1.5 V. On the other hand, the resistive switching memory characteristics of the 0.4-μm devices with a 2-nm-thick Al2O3 film show superior as compared to those of both the larger device sizes and thicker (10 nm) Al2O3 film, owing to higher Cu diffusion rate for the larger size and thicker Al2O3 film. In consequence, higher device-to-device uniformity of 88% and lower average RESET current of approximately 328 μA are observed for the 0.4-μm devices with a 2-nm-thick Al2O3 film. Data retention capability of our memory device of >48 h makes it a promising one for future nanoscale nonvolatile application. This conductive bridging resistive random access memory (CBRAM) device is forming free at a current compliance (CC) of 30 μA (even at a lowest CC of 0.1 μA) and operation voltage of ±3 V at a high resistance ratio of >10(4).

No MeSH data available.


Related in: MedlinePlus

Data retention characteristics. Good data retention of >48 h is obtained for the CBRAM devices at CC of (a) 1 mA and (b) 300 μA. The thickness of the Al2O3 layer is 2 nm.
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Fig11: Data retention characteristics. Good data retention of >48 h is obtained for the CBRAM devices at CC of (a) 1 mA and (b) 300 μA. The thickness of the Al2O3 layer is 2 nm.

Mentions: Figure 11 shows data retention characteristics for the 0.4-μm devices with a 2-nm-thick Al2O3 film. It is found the stable retention characteristics of >48 h at a CC of 1 mA (Figure 11a). The LRS is increased (slightly) with retention time, however, long time retention of 48 h at a CC of 300 μA is obtained (Figure 11b), which may be the higher dissolution rate of the existing filament at lower CC. The resistance ratio for a CC of 300 μA is higher than the ratio at CC of 1 mA (100 vs. 10). At a lower CC, the small amount of the Cu atoms is responsible for the conducting filament formation. If small amount of Cu atoms from the thinner filament may be dissolved by neighbor defects into the AlOx film or dissolved by reading data, then both HRS and LRS could be increased with time. For larger diameter of the Cu filaments under higher CC, it shows stable with time because dissolution of small amount Cu from the filaments does not affect the filament resistance of LRS, or even HRS. However, further study is needed to form a stronger Cu filament with thinner diameter. By adjusting measurement parameters, this CBRAM device shows forming-free I-V characteristics under a low CC of 30 μA and a RESET current of <30 μA with a high resistance ratio of >105 at a read voltage of +0.2 V (Figure 12a). This device is operated even at a lowest CC of 0.1 μA (Figure 12b) with a large resistance ratio of >104, which is very useful for future nanoscale nonvolatile memory applications.Figure 11


Impact of device size and thickness of Al2O 3 film on the Cu pillar and resistive switching characteristics for 3D cross-point memory application.

Panja R, Roy S, Jana D, Maikap S - Nanoscale Res Lett (2014)

Data retention characteristics. Good data retention of >48 h is obtained for the CBRAM devices at CC of (a) 1 mA and (b) 300 μA. The thickness of the Al2O3 layer is 2 nm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4494016&req=5

Fig11: Data retention characteristics. Good data retention of >48 h is obtained for the CBRAM devices at CC of (a) 1 mA and (b) 300 μA. The thickness of the Al2O3 layer is 2 nm.
Mentions: Figure 11 shows data retention characteristics for the 0.4-μm devices with a 2-nm-thick Al2O3 film. It is found the stable retention characteristics of >48 h at a CC of 1 mA (Figure 11a). The LRS is increased (slightly) with retention time, however, long time retention of 48 h at a CC of 300 μA is obtained (Figure 11b), which may be the higher dissolution rate of the existing filament at lower CC. The resistance ratio for a CC of 300 μA is higher than the ratio at CC of 1 mA (100 vs. 10). At a lower CC, the small amount of the Cu atoms is responsible for the conducting filament formation. If small amount of Cu atoms from the thinner filament may be dissolved by neighbor defects into the AlOx film or dissolved by reading data, then both HRS and LRS could be increased with time. For larger diameter of the Cu filaments under higher CC, it shows stable with time because dissolution of small amount Cu from the filaments does not affect the filament resistance of LRS, or even HRS. However, further study is needed to form a stronger Cu filament with thinner diameter. By adjusting measurement parameters, this CBRAM device shows forming-free I-V characteristics under a low CC of 30 μA and a RESET current of <30 μA with a high resistance ratio of >105 at a read voltage of +0.2 V (Figure 12a). This device is operated even at a lowest CC of 0.1 μA (Figure 12b) with a large resistance ratio of >104, which is very useful for future nanoscale nonvolatile memory applications.Figure 11

Bottom Line: The 8-μm devices show 100% yield of Cu pillars, whereas only 74% successful is observed for the 0.4-μm devices, because smaller size devices have higher Joule heating effect and larger size devices show long read endurance of 10(5) cycles at a high read voltage of -1.5 V.On the other hand, the resistive switching memory characteristics of the 0.4-μm devices with a 2-nm-thick Al2O3 film show superior as compared to those of both the larger device sizes and thicker (10 nm) Al2O3 film, owing to higher Cu diffusion rate for the larger size and thicker Al2O3 film.This conductive bridging resistive random access memory (CBRAM) device is forming free at a current compliance (CC) of 30 μA (even at a lowest CC of 0.1 μA) and operation voltage of ±3 V at a high resistance ratio of >10(4).

View Article: PubMed Central - PubMed

Affiliation: Thin Film Nano Tech. Lab., Department of Electronic Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kwei-Shan, Tao-Yuan, 333, Taiwan, panjarajeswar@gmail.com.

ABSTRACT
Impact of the device size and thickness of Al2O3 film on the Cu pillars and resistive switching memory characteristics of the Al/Cu/Al2O3/TiN structures have been investigated for the first time. The memory device size and thickness of Al2O3 of 18 nm are observed by transmission electron microscope image. The 20-nm-thick Al2O3 films have been used for the Cu pillar formation (i.e., stronger Cu filaments) in the Al/Cu/Al2O3/TiN structures, which can be used for three-dimensional (3D) cross-point architecture as reported previously Nanoscale Res. Lett.9:366, 2014. Fifty randomly picked devices with sizes ranging from 8 × 8 to 0.4 × 0.4 μm(2) have been measured. The 8-μm devices show 100% yield of Cu pillars, whereas only 74% successful is observed for the 0.4-μm devices, because smaller size devices have higher Joule heating effect and larger size devices show long read endurance of 10(5) cycles at a high read voltage of -1.5 V. On the other hand, the resistive switching memory characteristics of the 0.4-μm devices with a 2-nm-thick Al2O3 film show superior as compared to those of both the larger device sizes and thicker (10 nm) Al2O3 film, owing to higher Cu diffusion rate for the larger size and thicker Al2O3 film. In consequence, higher device-to-device uniformity of 88% and lower average RESET current of approximately 328 μA are observed for the 0.4-μm devices with a 2-nm-thick Al2O3 film. Data retention capability of our memory device of >48 h makes it a promising one for future nanoscale nonvolatile application. This conductive bridging resistive random access memory (CBRAM) device is forming free at a current compliance (CC) of 30 μA (even at a lowest CC of 0.1 μA) and operation voltage of ±3 V at a high resistance ratio of >10(4).

No MeSH data available.


Related in: MedlinePlus