Influence of HfAlO composition on resistance ratio of RRAM with Ti electrode

Four HfAlO based resistive random access memory (RRAM) devices with different HfO2 percentage (0%, 10%, 90% and 100%) were fabricated using atomic layer deposition (ALD). Three types of electroforming processes were observed with 1mA current compliance (CC), including initial high resistance state (HRS), initial medium resistance state (MRS) and initial low resistance state (LRS). The modulation of resistance ratio (HRS/LRS) was achieved by controlling the ALD deposition cycle ratio of HfO ₂ :Al ₂ O ₃ . The resistance ratio was improved by intermixing HfO ₂ and Al ₂ O ₃ under 5mA compliance condition. This can be partially attributed to fact that intermixing HfO ₂ and Al ₂ O ₃ stabilized the oxide matrix and suppressed crystallization.