Magnetic Tunnel Junction Layer Structure for Stable TMR and Exchange Field

An amorphous buffer layer is introduced as an intermediary between the pinned layer and the auxiliary layer. This buffer layer prevents direct crystalline collision and diffusion between the pinned layer and subsequent layers, thereby maintaining high tunneling magnetoresistance and exchange field without requiring complete redesign of the overall structure

The patent employs a composite layer structure combining amorphous buffer layer (CoFeBX), crystalline auxiliary layer (W, Mo, or Ta), and polarization enhancement layers with varying boron concentrations. This composite structure leverages the advantages of different material phases and compositions to simultaneously achieve high TMR and exchange field while preventing detrimental diffusion and crystalline collisions

The amorphous buffer layer serves as a protective intermediary that can be inserted between closely spaced layers without significantly increasing the overall device volume. It prevents diffusion and crystalline collisions between adjacent layers even when they are placed close together for scaling, thereby maintaining exchange field stability in compact device configurations

The buffer layer is strategically positioned only where diffusion and crystalline collisions are most problematic (between the pinned layer and auxiliary layer), rather than uniformly throughout the entire structure. This localized approach prevents exchange field degradation while minimizing the impact on device volume and maintaining scalability