Effect of Resistive Switching-Layer Oxygen-Concentration on Nonvolatile Memory Characteristics for Carbon-Oxide Based Reram

Abstract

Resistive random access memories (ReRAM) are highly promising as one of next-generation memories due to high current density, high speed, simple structure, and low power consumption [1]. Recently, amorphous carbon oxide based ReRAM has been researched due to its strong advantages over typical ReRAM chacacteristics such as large memory margin (Ion/Ioff > 100), high switching speed (20~50ns) and CMOS compatible process. In this work, we present the electrical features of amorphous carbon oxide, working as a resistive switching layer [2], where tunsten (W) / amorphous carbon oxide / platinum (Pt) configuration with the pattern size of ranging 34 to 1,921 nm. The thickness of carbon oxide, O2 flow rate of RF magnetron sputter, and N2-annealing temperature were varied with the device cell size to optimize the device performance. The device of amorphous carbon oxide based ReRAM demonstrated typical electrical characteristics, i.e., the set voltage of 1.8 V, the reset voltage of –2.0 V, high resistance state current of 4.6×10-11 A at 0.1 V, and low resistance state current of 7.5×10-9 A at 0.1 V. Moreover, stable endurance and retention were observed at 10 nm-thick amorphous carbon oxide after N2-annealing at 400 oC, which were the endurance of 1.0×106 cycles with a margin (Ion/Ioff ) of 3.5×101 and retention of 105 sec with a margin of 6.2×101. In particular, we present the mechanism and memory characteristics on operating behavior of the amorphous carbon-oxide based ReRAM via investigating the effect of amorphous carbon-oxide thickness, O2 flow rate of RF magnetron sputter, and N2-annealing temperature on the electrical characteristics by using auger electron spectroscopy(AES), energy-dispersive X-ray spectroscopy (EDS), cross sectional transmission electron microscopy (TEM) and X-ray diffraction (XRD). * This material is based upon work supported by the Ministry of Trade, Industry & Energy(MOTIE, Korea) under Industrial Technology Innovation Program (10068055). [1] Daniele Ielmini, Semicond. Sci. Technol. 31 (2016) 063002 [2] Claudia A. Santini et al, NAT COMMUN, 6:8600 (2015) Figure 1