Effects of Oxygen Precursor on Resistive Switching Properties of CMOS Compatible HfO2-Based RRAM

Abstract

In this work, we investigate the resistive switching behaviors of HfO2-based resistive random-access memory (RRAM) in two different oxidants (H2O and O-3) in an atomic layer deposition system. Firstly, the surface characteristics of the Ni/HfO2/Si stack are conducted by atomic force microscopy (AFM). A similar thickness is confirmed by scanning electron microscope (SEM) imaging. The surface roughness of the HfO2 film by O-3 (O-3 sample) is smoother than in the sample by H2O (H2O sample). Next, we conduct electrical characteristics by current-voltage (I-V) and capacitor-voltage (C-V) curves in an initial process. The forming voltage of the H2O sample is smaller than that of the O-3 sample because the H2O sample incorporates a lot of H+ in the film. Additionally, the smaller capacitor value of the H2O sample is obtained due to the higher interface trap in H2O sample. Finally, we compare the resistive switching behaviors of both samples by DC sweep. The H2O sample has more increased endurance, with a smaller on/off ratio than the O-3 sample. Both have good non-volatile properties, which is verified by the retention test.