Stabilization of Morphotropic Phase Boundary in Hafnia via Microwave Low‐Temperature Crystallization Process for Next‐Generation Dynamic Random Access Memory Technology

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The morphotropic phase boundary (MPB), which arises from the combination of antiferroelectric and ferroelectric phases, demonstrates the highest dielectric constant (κ) compared to other phases. This emphasizes its potential as a leading contender for dielectric films in future dynamic random access memory (DRAM) capacitors. MPB‐based high‐κ materials using hafnia have shown a trade‐off between equivalent oxide thickness (EOT) and leakage current density (Jleak) when the crystallization temperature increases with scaling the thickness. Herein, a microwave annealing (MWA) method that can achieve low‐temperature crystallization below 350 °C is employed. The purpose of this method is to mitigate the trade‐off relationships and achieve the strict criteria of current DRAM capacitors. These criteria include low EOT (less than 4 Å) and Jleak (less than 10−7 A cm−2 at 0.8 V) characteristics. The MWA is capable of relatively low‐temperature annealing by supplying energy to the films through both thermal energy and dipole vibration energy. As a result, a record‐low EOT of 3.76 Å and a low leakage current characteristic of 4.2 × 10−8 A cm−2 at 0.8 V are achieved concurrently. It is confident that the research can be important in addressing the challenges associated with reducing the size of next‐generation DRAM capacitors.