Single-nanometer CoFeB/MgO magnetic tunnel junctions with high-retention and high-speed capabilities
Junta Igarashi, Butsurin Jinnai, K. Watanabe, T. Shinoda, Takuya Funatsu, H. Sato, Shunsuke Fukami, Hideo Ohno
Abstract
Abstract Making magnetic tunnel junctions (MTJs) smaller while meeting performance requirements is critical for future electronics with spin-transfer torque magnetoresistive random access memory (STT-MRAM). However, it is challenging in the conventional MTJs using a thin CoFeB free layer capped with an MgO layer because of increasing difficulties in satisfying the required data retention and switching speed at smaller scales. Here we report single-nanometer MTJs using a free layer consisting of CoFeB/MgO multilayers, where the number of CoFeB/MgO interfaces and/or the CoFeB thicknesses are engineered to tailor device performance to applications requiring high-data retention or high-speed capability. We fabricate ultra-small MTJs down to 2.0 nm and show high data retention (over 10 years) and high-speed switching at 10 ns or below in sub-5-nm MTJs. The stack design proposed here proves that ultra-small CoFeB/MgO MTJs hold the potential for high-performance and high-density STT-MRAM.