Spatially selective crystallization of ferroelectric Hf0.5Zr0.5O2 films induced by sub-nanosecond laser annealing

In this work we study the sub-nanosecond laser-induced crystallization of 10 nm-thick atomic layer deposited amorphous Hf0.5Zr0.5O2 (HZO) films in an air atmosphere. We used an infrared laser with 1064 nm wavelength and 800 ps pulses to anneal TiN/HZO/TiN capacitors by scanning an 80 mu m-diameter spot along their top surface in a controlled way. The laser annealing process was optimised in terms of fluence to achieve the complete crystallization of HZO into a non-monoclinic polymorph, as demonstrated by X-ray diffraction and transmission electron microscopy. Piezoresponse force microscopy and polarization-field loops confirm that the optimal asannealed HZO films are piezoelectric and ferroelectric from the first cycle on. Spatial selectivity was accomplished by scanning the laser on selected areas of the samples. Micro-diffraction experiments show that the transition between the crystallized and the amorphous region is abrupt within a distance of several hundred mu m.