Abstract
The purpose of this thesis is to develop a reliable HfO2 based resistive memory for the next generation nonvolatile memory application. In order to find the process factor to determine the resistance switch, the effect of electrode metal and anneal process on the HfO2 based metal-insulator-metal capacitor are studied. The result suggests the free energy of oxidation reaction for an electrode metal not only affect the interaction between oxide and electrode, but also is critical to the operation mode of memory device. The electrode metal of less negative free energy of oxidation reaction tends to result in the unipolar resistive memory, whereas that with more negative free energy of oxidation reaction can result in the bipolar resistive memory with the help of anneal process. In this thesis, the uipolar HfO2 based resistive memory is realized with Ru electrode, while the bipolar HfO2 based resistive memory is realized with AlCu, Ti, Ta, TaN electrode. In the study of unipolar device, the Ru device, like others in literature, suffers the serious issue of operation instability, which suggests the difficulty for real application, and a plausible mechanism is proposed to explain the fluctuated SET voltage. In the study of bipolar device, these devices show better operation stability than unipolar device. Moreover, an aggressive improvement of memory performance was found in the device with Ti electrode as it is scaled down to submicron region. As the result, a highly reliable HfO2 based resistive memory is demonstrated with Ti electrode. Excellent memory performances, including low power, high speed, acceptable reliability and capability of multi-levels operation of this device promised it application in the next generation nonvolatile memory.