Forming-free nitrogen-doped aluminum oxide resistive random access memory grown by atomic layer deposition technique [electronic resource]

As flash memory devices begin to scale into the sub-20nm lithographical regime, scaling is becoming a challenge because of high electric field requirements for a high programming or erase voltage and rigid leakage requirements for long term storage. In addition, the flash memory design has been based on a two-dimensional approach and density of integration is reaching its limits. To tackle these issues, many candidates for next generation non-volatile memory such as phase change random access memory (PCRAM), STT-magnetic random access memory (STT-RAM), ferroelectric random access memory (FeRAM), and resistive random access memory (RRAM) have been introduced and studied. Among these devices concepts We have demonstrated nitrogen-doped aluminum oxide RRAM grown by an atomic layer deposition technique and have monolithically integrated such RRAM cells on top of selection transistors to achieve accurate control of the voltage and current waveforms for programming. We have studied the control of the on-and off-behavior of the RRAM cell by gathering the statistics on the turn-on and turn-off voltage, current and resistance as a function of the bias voltages and the limiting current on the selection MOSFET, and thereby evaluated the feasibility of multi-level programming, reliability, endurance and retention of nitrogen-doped aluminum oxide RRAM. Through this study, novel multi-bit programming strategies were investigated through accurate control of the programming waveform. The data collected RRAM is a prime candidate because of its unique characteristics. In order for RRAM technology to be adopted for manufacturing, the technology must meet the following requirements. First, the direct integration of metal oxide RRAM on MOSFET should be feasible and RRAM cells must be compatible with the standard CMOS process. Second, it must not require a high forming voltage and it should be programmed with an applied current below sub-uA at high data rates for many switching cycles. Finally, RRAM cells must be feasible for storing multiple bits. We demonstrated nitrogen-doped aluminum oxide RRAM that meets the requirements and the RRAM cell was deposited by a physical vapor deposition technique. However, it has been found that more uniform films can be deposited by an atomic layer deposition technique, and we believe that more uniform films are responsible for uniform switching characteristics. That is the motivation of this dissertation. We have demonstrated nitrogen-doped aluminum oxide RRAM grown by an atomic layer deposition technique and have monolithically integrated such RRAM cells on top of selection transistors to achieve accurate control of the voltage and current waveforms for programming. We have studied the control of the on-and off-behavior of the RRAM cell by gathering the statistics on the turn-on and turn-off voltage, current and resistance as a function of the bias voltages and the limiting current on the selection MOSFET, and thereby evaluated the feasibility of multi-level programming, reliability, endurance and retention of nitrogen-doped aluminum oxide RRAM. Through this study, novel multi-bit programming strategies were investigated through accurate control of the programming waveform. The data collected through this extensive study will provide important information on the viability of metal-oxide films for future generation stand-alone and embedded non-volatile memory applications. The demonstration of multi-level programming will greatly extend the scalability of RRAM. The evaluation methodology we develop can be extended to other resistance-change films.

Keywords: Electrical Engineering.
Advisor: Wong S. Simon primary advisor. Thesis advisor
Nishi Yoshio
Wong Hon-Sum Philip