Structure and Dielectric Properties of HfO_2 Thin Films

HfO2 dielectric thin films were deposited on Si(100) substrate by pulsed laser deposition(PLD) method.The structure of films was characterized by X-ray diffraction(XRD) and extended X-ray absorption fine structure spectroscope(EXAFS).The phonons modes and dielectric properties were investigated by far infrared spectroscope.These results show that the thin films deposited at room temperature and 400℃ are amorphous and monoclinic phase,respectively.The crystallization quality of the film is improved after annealing at 1000℃.The HfO2 thin film has shorter Hf-O bonding length and higher disorder than those of HfO2 powder.Some far infrared phonon modes disappear due to the higher disorder and worse crystalline quality of thin film,which causes the dielectric constant of thin film smaller than that of powder sample.However,main infrared phonon modes are preserved and the crystallized thin film still has enough value of dielectric constant.