Study On The Preparation Of HfO₂Nano-films By Sol-Gel Method

HfO2is one of the representative dielectric materials with high k property, and it has favorable compatibility with CMOS integrated circuit. Recently, researchers reported that HfO2thin film could have excellent ferroelectric property under special fabrication technology. Therefore, this new type of ferroelectric thin film is promising to replace traditional ferroelectric material and break through the barriers for the application of Ferroelectric RAM.This thesis explored two different Sol-Gel processes to fabricate HfO2thin film and Y doped HfO2thin film. In order to product HfO2thin film with ferroelectric property, there are some key matters that should be paid attention to. At first, it should ensure the thickness of the film is thinner than20nm. Then the doping element should be carefully chosen and the experiment should be feasible. During the experiment, it used ellipsometer and XRR to measure the thickness of the films. And the surface topography and surface roughness of the films were measured by AFM. Then XPS detected the content of different elements at the surface of the film and it also reflected the situations of the surface bonds. At last, it applied Multiferroic100V Test System to measure the electrical properties of the films.The result reflected that the surface Sol-Gel process can fabricate the ultrathin HfO2films successfully. However, the growth of the films tended to be saturated as the increasing of the cycle number. Moreover, the surface Sol-Gel process was difficult to solve the problem to add yttrium into the films. Therefore, it fabricated HfO2thin films by aqueous precursor Sol-Gel process. According to the results of XRR, XPS and I-V, this Sol-Gel process can prepare HfO2thin film that can meet the requirement for application of FRAM.