A Novel Magnetic Tunneling Junction Shaped Cell with Large Write Operation Margin for High-Density Magnetoresistive Random Access Memory

Abstract

Magnetoresistive random access memory (MRAM) is one of several candidates for low-power and high-density system-on-chip (SoC) memory. In this paper, we propose a novel magnetic tunneling junction (MTJ) shape, called the “sandglass” (or “hourglass”), that has both an excellent asteroid curve for preventing write disturbance and a minimum memory of 8F2, where F is the feature size. A unique magnetic switching mechanism that works under decreasing magnetic switching field was compared with that of conventional MTJs simulated using the Landau–Lifshitz–Gilbert (LLG) simulator. We fabricated both a sandglass MTJ of 260×420 nm2 and a conventional elliptic MTJ of 200×400 nm2. The excellent asteroid curve of the sandglass MTJ is confirmed which exhibits both a larger write operation margin and a 50% lower switching field than those of the conventional elliptic MTJ. The sandglass MTJ cell is a promising candidate for realizing high-density MRAM.