[14p-A303-1~14] 【CS.4】 6.1 強誘電体薄膜、13.3 絶縁膜技術、13.5 デバイス／配線／集積化技術のコードシェア

▼ [14p-A303-11] Consideration of Charge Injection Effect on the Degradation of Ferroelectric HfO₂ during
Bipolar Voltage Cycling

〇(DC)Siri Nittayakasetwat¹、Koji Kita¹ (1.Univ. of Tokyo)

キーワード：ferroelectric HfO2, charge injection, phase transformation

The degradation of the switchable polarization (P_sw) of ferroelectric (FE) HfO₂ during bipolar voltage cycling creates a major issue to the operation stability in FE-related devise. Despite the well know fabrication process of FE-HfO₂, the degradation mechanism is still remaining unclarified. To push forward this technology into production, we investigate the possible factors contributing to the degradation of FE-HfO₂ during dipolar voltage cycling. We characterized the degradation of FE-properties using bipolar voltage cycling and constant DC-bias stress. After the voltage cycling, we found that the dielectric constant of HfO₂ (ε_HfO2) constantly decreased with the decrease in P_sw. To evaluate the dominant factors that determine the degradation mechanism, DC-bias stress was performed before measuring the P-V characteristic. We found that the ε_HfO2 measured both during the voltage cycling and DC-bias stress monotonically decrease in the same trend along with the reduction in P_sw. Therefore, we speculate that charge injection is one of the crucial factors that determine the degradation of FE-HfO₂ during bipolar voltage cycling. This finding will be valuable to the design of high performance and reliability in any FE-related devices in the future.