Filamentary-based Resistance Switching RRAM Devices for Memory Application

This dissertation investigates the resistive switching devices based on nickel oxide. Such a device is an example of metal oxide based RRAM (or ReRAM), which is a type of memory whose logical value depends on its resistance state. There have been a few types of such devices proposed in the literature whose physical properties depend on different phenomena. The need for this research comes from industry's quest to find better computer memory. The term 'better' is based on a few figures of merit which are described and compared in detail in this dissertation. The switching mechanisms are attributed to various physical phenomena which depend on the type of materials used, fabrication method, and are modeled accordingly. Generally, RRAMs are classified as unipolar, bipolar and complementary resistance switching (CRS) types, which is based on the voltage polarity for which the transitions from one state to the other occur.;As part of the dissertation research, different samples were fabricated in the department cleanroom according to carefully prepared process flow. Various processing steps and modifications were done which enabled different properties of the device. These samples were thoroughly measured and characterized, yielding different figures of merit and parameters allowing better understanding of switching phenomena. These steps have shown that the resistance switching is filamentary-based and the process can be fine-tuned to fabricate devices that depict complementary resistance switching (CRS) properties. Such CRS characteristics are especially interesting for memory arrays, because they prevent so called 'sneak-path' currents that are detrimental to crossbar arrays of RRAMs with regular unipolar or bipolar resistance switching.;The findings of the device characterization enabled the creation and enhancement of the model for the complementary resistive switching RRAM including temperature dependence which is implemented in Verilog-A and could be used in circuit simulators for design of RRAM memory circuits.;This Verilog-A model was implemented in the design of memory arrays together with peripheral circuits for bit line and word line encoding and decoding as well as sensing circuitry. This proved that the model (and ultimately the technology under investigation) is viable and can be implemented in a design of real memory products.;Overall, the results of this research showed that filamentary-based RRAMs with NiO used as switching oxide have a potential to become a reliable technology of choice, if described pertaining issues will be solved.