Effect Of High-k Interfacial Layer On Ferroelectric Performance Of HfO₂-based MFIS Gate Structure

HfO₂-based FeFET（Ferroelectric Field Effect Transistor）has the advantages of low power consumption,fast running speed,good compatibility with the CMOS（Complementary Metal Oxide Semiconductor）process,good miniaturization,and has good application potential,but HfO₂-based Fe FET has a small switching window and poor fatigue resistance.The ferroelectric gate is the core part of Fe FET to realize the storage function.Using the high-k interface layer to improve the interface quality between the ferroelectric gate layers is an effective method to control the storage performance of the ferroelectric gate and Fe FET.In addition,the gate-first and gate-last process are the two mainstream technical routes for the preparation of FeFET ferroelectric gates.The research on PMA（Post Metallization Annealing）/PDA（Post Deposition Annealing）ferroelectric gates can provide theoretical and experimental support for the preparation of Fe FET ferroelectric memory compatible with the gate-first and gate-last process.MFIS（metal/ferroelectric layer/interface layer/semi-conductor）ferroelectric gates with different interface layers were prepared in this paper.The influence of different high-k interface layers on the electrical properties of PMA（post metallization annealing）/PDA（post-deposition annealing）-HfO₂-based MFIS ferroelectric gate was systematically studied.The main contents are as follows:（1）By optimizing the ferroelectric gate preparation process compatible with the gate-first process,MFIS ferroelectric gates with three different high-k interface layers,HfO₂,Zr O₂ and Al₂O₃ are prepared on the p⁺-Si substrate.The effect of the interfacial layer on the crystallization of Hf_0.5Zr_0.5O₂（HZO）ferroelectric thin films and the electrical properties of ferroelectric gates are also studied.The characterization results of the samples show that the HfO₂ and Zr O₂ high-k interfacial layers have obvious interface-induced crystallization effects on the HZO ferroelectric layer,which increases the ferroelectric phase content of the HZO thin film,thereby improving the remanent polarization and fatigue properties.Electrical tests show that HfO₂,Zr O₂,and Al₂O₃high-k interfacial layers can improve the fatigue resistance of MFIS ferroelectric gate and reduce leakage current.（2）By optimizing the preparation process of PDA-HfO₂-based ferroelectric gate,the influence mechanism of the high-k interface layer in the HfO₂-based MFIS ferroelectric gate compatible with the gate-last process on the microstructure and electrical properties of the ferroelectric layer is studied.The results show that the three high-k interface layers of HfO₂,Zr O₂,and Al₂O₃ can significantly improve the electrical properties of the MFIS ferroelectric gate,and the fatigue resistance is improved by6.14%,14.58%,and 11.38%,respectively.In addition,the influence of the thickness of the high-k interface layer on the MFIS ferroelectric gate is studied,and the results show that the optimal thickness of the high-k interface layer is about 3 nm.