Hf_(0.5)Zr_(0.5)O_(2)(HZO)ferroelectric thin films have gained significant attention for the development of next-generation ferroelectric memories by complementary-metal-oxide semiconductor(CMOS)back-end-of-line(BEOL)...Hf_(0.5)Zr_(0.5)O_(2)(HZO)ferroelectric thin films have gained significant attention for the development of next-generation ferroelectric memories by complementary-metal-oxide semiconductor(CMOS)back-end-of-line(BEOL)processing,due to their relatively low crystallization temperature.However,it remains challenging to achieve excellent ferroelectric properties with post deposition annealing(PDA)process at a BEOL compatible temperature.Along these lines,in this work,it is demonstrated that the ferroelec-tricity of 15 nm thick HZO thin film prepared by PDA process at 400℃can be improved to varying degrees,via depositing 2 nm thick dielectric layers of Al_(2)O_(3),HfO_(2),or ZrO_(2)at either the bottom or the top of the film.Notably,the HZO thin film with the top-Al_(2)O_(3)layer exhibits remarkable ferroelectric prop-erties,which are independent of the thickness of HZO.The 6 nm thick HZO thin film shows a total remanent polarization(2Pr)of 31 mC/cm^(2)under an operating voltage of 2.5 V.These results represent a significant advancement in the fabrication of high-performance,BEOL compatible ferroelectric mem-ories,as compared to previously reported state-of-the-art works.展开更多
Multilevel ferroelectric field-effect transistors(FeFETs)integrated with HfO_(2)-based ferroelectric thin films demonstrate tremendous potential in high-speed massive data storage and neuromorphic computing applicatio...Multilevel ferroelectric field-effect transistors(FeFETs)integrated with HfO_(2)-based ferroelectric thin films demonstrate tremendous potential in high-speed massive data storage and neuromorphic computing applications.However,few works have focused on the stability of the multiple memory states in the HfO_(2)-based FeFETs.Here we firstly report the write/read disturb effects on the multiple memory states in the Hf_(0.5)Zr_(0.5)O_(2)(HZO)-based FeFETs.The multiple memory states in HZO-based FeFETs do not show obvious degradation with the write and read disturb cycles.Moreover,the retention characteristics of the intermediate memory states in HZO-based FeFETs with unsaturated ferroelectric polarizations are better than that of the memory state with saturated ferroelectric polarization.Through the deep analysis of the operation principle of in HZO-based FeFETs,we speculate that the better retention properties of intermediate memory states are determined by the less ferroelectric polarization degradation and the weaker ferroelectric polarization shielding.The experimental and theoretical evidences confirm that the long-term stability of the intermediate memory states in HZO-based FeFETs are as robust as that of the saturated memory state,laying a solid foundation for their practical applications.展开更多
基金supported by grants from the National Natural Science Foundation of China(Grant Nos.52122205,52102147,52072324,11932016)the China Postdoctoral Science Foundation(2022M712674).
文摘Hf_(0.5)Zr_(0.5)O_(2)(HZO)ferroelectric thin films have gained significant attention for the development of next-generation ferroelectric memories by complementary-metal-oxide semiconductor(CMOS)back-end-of-line(BEOL)processing,due to their relatively low crystallization temperature.However,it remains challenging to achieve excellent ferroelectric properties with post deposition annealing(PDA)process at a BEOL compatible temperature.Along these lines,in this work,it is demonstrated that the ferroelec-tricity of 15 nm thick HZO thin film prepared by PDA process at 400℃can be improved to varying degrees,via depositing 2 nm thick dielectric layers of Al_(2)O_(3),HfO_(2),or ZrO_(2)at either the bottom or the top of the film.Notably,the HZO thin film with the top-Al_(2)O_(3)layer exhibits remarkable ferroelectric prop-erties,which are independent of the thickness of HZO.The 6 nm thick HZO thin film shows a total remanent polarization(2Pr)of 31 mC/cm^(2)under an operating voltage of 2.5 V.These results represent a significant advancement in the fabrication of high-performance,BEOL compatible ferroelectric mem-ories,as compared to previously reported state-of-the-art works.
基金This work was partly supported by the National Natural Science Foundation of China(Grant Nos.52122205,51902274,52072324,and 11932016)the Science and Technology Innovation Program of Hunan Province(Grant No.2020RC2077)the Natural Science Foundation of Hunan Province(Grant No.2019JJ50617).
文摘Multilevel ferroelectric field-effect transistors(FeFETs)integrated with HfO_(2)-based ferroelectric thin films demonstrate tremendous potential in high-speed massive data storage and neuromorphic computing applications.However,few works have focused on the stability of the multiple memory states in the HfO_(2)-based FeFETs.Here we firstly report the write/read disturb effects on the multiple memory states in the Hf_(0.5)Zr_(0.5)O_(2)(HZO)-based FeFETs.The multiple memory states in HZO-based FeFETs do not show obvious degradation with the write and read disturb cycles.Moreover,the retention characteristics of the intermediate memory states in HZO-based FeFETs with unsaturated ferroelectric polarizations are better than that of the memory state with saturated ferroelectric polarization.Through the deep analysis of the operation principle of in HZO-based FeFETs,we speculate that the better retention properties of intermediate memory states are determined by the less ferroelectric polarization degradation and the weaker ferroelectric polarization shielding.The experimental and theoretical evidences confirm that the long-term stability of the intermediate memory states in HZO-based FeFETs are as robust as that of the saturated memory state,laying a solid foundation for their practical applications.
