Tips for single-nanometer magnetic tunnel junction know-how

Researchers at Tohoku College have developed pointers for a single-nanometer magnetic tunnel junction (MTJ), permitting for efficiency tailoring to satisfy the necessities of various functions, starting from AI/IoT to cars and area applied sciences.

The breakthrough will result in high-performance spintronic non-volatile reminiscence, appropriate with state-of-the-art semiconductor applied sciences. The small print have been revealed within the journal npj Spintronics on January 4, 2024.

The important thing attribute of non-volatile reminiscence is its capability to retain knowledge within the absence of an exterior energy supply. Consequently, in depth growth efforts have been directed in the direction of non-volatile reminiscence due to its capability to scale back energy consumption in semiconductor built-in circuits (ICs). Efficiency necessities for non-volatile reminiscence differ in accordance with particular functions. For example, AI/IoT functions demand high-speed efficiency, whereas automotive and area applied sciences prioritize excessive retention capabilities.

Spin-transfer torque magnetoresistive random entry reminiscence (STT-MRAM), a kind of non-volatile reminiscence know-how that shops knowledge by using the intrinsic angular momentum of electrons, often known as spin, possesses the potential to deal with a number of the limitations related to current reminiscence applied sciences.

The fundamental constructing block of STT-MRAM is the magnetic tunnel junction (MTJ): two ferromagnetic layers separated by a skinny insulating barrier. Scientists have lengthy tried to satisfy the problem of creating MTJs smaller whereas assembly efficiency necessities, however many issues stay.

STT-MRAM, using MTJs with dimensions within the vary of a number of tens of nanometers, has been efficiently developed for automotive semiconductors utilizing 1X nm know-how nodes. Waiting for future nodes, nonetheless, there’s a have to scale down MTJs to single-digit nanometers, or X nm, whereas guaranteeing the potential to tailor efficiency in accordance with particular functions.

To do that, the analysis group designed a method to engineer single-nanometer MTJs with a CoFeB/MgO stack construction, a de facto commonplace materials system. Various the person CoFeB layer thickness and the variety of [CoFeB/MgO] stacks allowed them to regulate the form and interfacial anisotropies independently—one thing essential for reaching high-retention and high-speed capabilities, respectively.

Consequently, the MTJ efficiency might be tailor-made for functions starting from retention-critical to speed-critical. On the dimension of single nanometers, shape-anisotropy enhanced MTJs demonstrated excessive retention (> 10 years) at 150°C, whereas interfacial-anisotropy enhanced MTJs achieved quick pace switching (10 ns or shorter) under 1 V.

“For the reason that proposed construction might be tailored to current amenities in main semiconductor factories, we consider that our research gives a major contribution to the longer term scaling of STT-MRAM,” stated Junta Igarashi, one of many lead authors of the research.

Principal Investigator Shunsuke Fukami added that “Semiconductor industries usually are usually aware of long-lasting scaling. In that sense, I feel this work ought to ship a powerful message to them that they will depend on the way forward for STT-MRAM to assist usher in a low-carbon society.”