Abstract: Hafnium oxide based thin film has excellent ferroelectric properties even with ultra-thin thickness, which favors high-density integration of ferroelectric storage. La-doped hafnium oxide based films exhibit excellent cycling endurance, but their remnant polarization(2 Pr ≤ 35 μC/cm~2) needs further improvements. In this study, the La-doped Hf_0.5Zr_0.5O₂(HZLO) thin films were deposited by atomic layer deposition(ALD) and then annealed at 500 ℃, 550 ℃ and 600 ℃ by rapid thermal annealing(RTA) to investigate the influence of La doping and annealing temperature on the ferroelectric properties of the TiN/HZLO/TiN/W structure. La doping facilitates the transformation of the Hf_0.5Zr_0.5O₂ thin films from a tetragonal phase into an orthorhombic phase with an improvement in remnant polarization(49.8 μC/cm~2). In addition, La doping reduces the device coercive field(~1.25 MV/cm) and improves the symmetry of coercive field under the positive bias and the negative one. As the annealing temperature increases to 550 ℃, the proportion of orthorhombic phase of the HZLO thin films increases to ~77%, resulting in a much larger remanent polarization(49.8 μC/cm~2). While if the annealing temperature is up to 600 ℃, the orthorhombic phase, the tetragonal phase and the cubic phase of the HZLO thin films transform to the monoclinic phase with a degraded remnant polarization.