Integration of STT-MRAMs for Embedded Cache Memories

Abstract

We report the current status of our development of spin-transfer torque magnetic RAMs (STT-MRAMs) and their integration with the back-end-of-line (BEOL) process to replace conventional embedded SRAM cache memories. Our MRAM technology features a top-pinned, perpendicular magnetic tunnel junction (MTJ) and a highly reliable MTJ for a cache memory. We could obtain a higher density cache memory than that with conventional SRAMs with our STT-MRAMs, and leakage free characteristics, as well as unlimited write and read cycling times and 10-year time-dependent dielectric breakdown (TDDB) characteristics. They were integrated into Cu interconnects with 300 mm facilities. We also discuss variations in MTJ pattern sizes that are very important for memory applications from the viewpoint of high density embedded cache memories.