Field‐Induced Ferroelectric Hf1‐xZrxO2 Thin Films for High‐k Dynamic Random Access Memory

The field‐induced ferroelectric Hf1–xZrxO2 (FFE–HZO) thin film is investigated for use as the capacitive layer in the future dynamic random access memory (DRAM). Although the dielectric permittivity of FFE–HZO is as high as ≈80, a high electric field (4 MV cm−1) is needed to activate the FFE mechanism and the accompanying high dielectric permittivity value. The Zr content is adjusted, or field cycling is performed, to obtain a high dielectric permittivity at a low electric‐field region for feasible DRAM operation. As a result, a dielectric permittivity value of 60–80 is achieved in the low field region (0–2 MV cm−1), which coincided with an equivalent oxide thickness of 0.47 nm with a stable leakage current at 0.8 V. The involvement of hysteresis in the polarization‐electric field curve of the film, however, caused significant energy loss (40–60%). Hysteresis engineering using various dopants, and improving the deposition process, annealing process, or passive interfacial layer, should be the next step. The Zr content of field‐induced ferroelectric Hf1–xZrxO2 films is adjusted to obtain a high dielectric permittivity (k) for dynamic random access memory (DRAM) application. As a result, k values of 60–80 is achieved in the DRAM operating field region, which coincided with an equivalent oxide thickness of 0.47 nm with a stable leakage current at 0.8 V.