Impact of stress and doping effects on the polarization behavior and electrical characteristics of hafnium–zirconium oxides

Temperature-Dependent Polarization Switching and Endurance Cycling Properties of HfAlO Ferroelectric Thin Film

“…According to our previous work, [11][12][13][14] the Al doping engineering not only can reduce the shallow traps of oxygen vacancies of the HfAlO film or near TaN/HfAlO interface, but also be helpful to suppress the gate-injection electron current at negative bias region due to the formation of Al 2 O 3 with a larger bandgap (∼8.8 eV). [10][11][12][13][14] At 25 °C, the HfAlO MFM capacitor show a low leakage current of ∼2.4 × 10 −10 A at the applied voltage of −3.5 V. At 75 °C, there still remains a low leakage current of ∼3.7 × 10 −10 A at the applied voltage of −3.5 V. As applied voltage is up to −4V, the leakage current starts to degrade obviously with the increase of operation temperature. The lower the gate-injection electron leakage current is ascribed to a larger bandgap (∼8.8 eV) of doped Al 2 O 3 film at negative bias region.…”

“…The HfO 2 and Al 2 O 3 dielectrics were deposited by tetrakis (dimethyla-mido) hafnium (TDMAHf), trimethylaluminum (TMA) and water. From our previous analysis result [10][11][12][13][14] of positive-up-negative-down (PUND) double peak measurement and X-ray diffraction (GI-XRD) spectrums, the optimized Al doping concentration of 6.5% exhibits the largest z E-mail: james_hao2402@hotmail.com (S. H. Lin); hhhsu@mail.ntut.edu.tw (H. H. Hsu)…”

“…The discovery of memory applications and low-power CMOS devices using HfO 2 -based ferroelectric materials have been widely investigated [1][2][3][4][5][6][7][8][9][10][11][12][13][14] due to the merit of scalability, high-k metal gate integrity, fast read/write speed, and good CMOS process compatibility. Pure hafnium oxide (HfO 2 ) is known as high-k dielectric and typically exhibits the paraelectric monoclinic structure.…”

“…According to our previous work, we have demonstrated the excellent ferroelectric performance in HfZrO and HfAlO films by the extensive studies of doping concentration, thickness, annealing temperature, metal workfunction, and the metal mechanical stress effect to enhance the crystallization of ferroelectric orthorhombic phase. [10][11][12][13][14] In particular, HfZrO films have been found to be very promising as the ferroelectric layer in the integration application of ferroelectric circuits in the back-end of the line because of the advantages of a suitable the ferroelectric memory window (2Pr) for a memory application and the lower thermal budget process (<450 °C) of HfZrO films induced ferroelectricity. However, with device scaling, HZrO films had higher leakage current issue due to the high diffusion coefficient of the Zr atom and poor interface thermal stability.…”