Process integration and logic applications of SiOx based resistive memory
Zhou, Fei, 1984-
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Flash memory has been the fastest growing non-volatile memory technology, and it has been widely used in many portable electronic products. Due to its charge based memory mechanism, there are more and more challenges scaling down the flash memory device. Researchers have been looking for new memory materials and novel structures for non-volatile memory devices to replace the conventional floating gate flash. Resistive switching memory stands out from other leading contenders such as phase change memory, magnetic random access memory, and spintronic random access memory. Resistive switching memory has the advantages of non-charge based memory mechanism, simple two-terminal device structure, and fast switching speed. Therefore, it demonstrates great potential for replacing NAND flash and even DRAM to become the next-generation non-volatile memory. A comprehensive investigation on amorphous silicon oxide (SiOx) based resistive memory, starting from fabrication and material analysis, to performance optimization, then to advanced characterization, and finally ending with novel logic circuit applications, have been presented in this dissertation. New device structure and encapsulation process are developed to enable SiOx based resistive memory to operate in air ambient. External resistance effect and substrate optimization have been made to achieve good switching window, low endurance variation. Current sweep technique was used to study the Set process, which simplified multiple resistance level operation of SiOx based resistive memory. Characterization of resistive switching behavior at elevated temperature showed that SiOx resistive material has great potential for high temperature memory applications. Random Telegraph Noise and Energetic Dispersive Spectroscopy provided insights into the physical model of the resistive switching phenomenon. Finally, bidirectional implication scheme using SiOx based resistive memory was proposed and tested, which forms the corner stone of memristor based logic operations. Taking one step further, one bit full adder logic function was theoretically realized on a logic circuit consisting of 4 × 4 crossbar structure resistive memory 1D-1R array and select transistors, the findings show pros and cons of memory enabled logic circuit. In summary, this work presents the optimization and application researches on SiOx based resistive switching memory.