Abstract
The period of time in which this thesis is undertaken falls within an era of overlap where Flash memory technology is reaching the physical limits of device scaling and new types of memory which include phase-change random access memory (PRAM), resistive random access memory (RRAM), and spin-transfer torque magnetic random access memory (STT-MRAM), to replace conventional Flash memories are being explored. Endurance is amongst the key reliability challenges for all these emerging memory technologies and the use of the correct statistical model to define the statistics of breakdown (BD) in ultra-thin dielectrics (which are an integral part of non-volatile memories (NVM)) is vital for the reliability qualification of a meticulous chip design. Although the breakdown of ultra-thin dielectric has been widely investigated for SiO2 and HfO2 in CMOS devices, the model and mechanism governing BD and degradation physics in these materials cannot be applied directly to magnesium oxide (MgO), in view of the stark differences in operating voltage and current density of MgO based STT-MRAM as compared to HfO2 / SiO2 based MOSFETs, FinFETs and RRAM devices. There is a lack of good understanding of the nature of the errant STT-MRAM devices that can arise during or after the write operation. In this thesis, we address all these shortcomings by the use of cyclic pulsed endurance measurements and apply the technique to state-of-the-art STT-MRAM devices, a promising alternative to substitute NAND Flash memory. In the first part of the thesis, we address the polarity and pulse width dependence of BD trends in MgO for different stress polarities through a dedicated set of experiments supported by theoretical investigations. 4 In the second part of the thesis, the time dependent dielectric breakdown (TDDB) in M