Progress and outlook for STT-MRAM

New product applications have an increasing demand for a non-volatile memory (NVM) exhibiting higher speeds, extended endurance and lower power consumption as existing solutions are not fully capable to deliver on all of these attributes. Of the group of new NVMs, Phase-change RAM (PRAM), Resistive RAM (RRAM) and Spin-Transfer Torque based MRAM (STT-MRAM) [1-8], STT-MRAM has the most attractive combination of fast read and write speed (<;30 ns) and high endurance (>;10¹⁵) along with non-volatility. We will review the recent progress on STT-MRAM at both the MTJ device and CMOS integrated chip levels. In the technical area, the key focus is switching current (or voltage) reduction at short pulse width (<;10 ns) while maintaining high magnetic bit thermal stability. Results from novel MTJs achieving low switching current while maintaining high thermal stability will be presented. First generation STT-MRAM products are being targeted using in-plane based MTJs, and future products below 45 nm will likely require perpendicular MTJ (pMTJ) designs. The later is the key focus of recent research in this area. We will review the current state of pMTJ development, along with micromagnetic modeling results for key understanding of STT switching dynamics and latest experimental data of pMTJs. Finally, we discuss the market positioning of the STT-MRAM. While it is currently being targeted for stand-alone commodity memory (replacing DRAM) [4], and embedded memory (replacing embedded Flash, SRAM and DRAM) [6], new market applications such as storage-class solid state drives and embedded solutions in advanced System-on-Chip (SoC) are also being explored. We will compare key value adds from STT-MRAM in these emerging market segments.