Fabrication Of Oriented MgO Thin Films And Patterning

YBCO high temperature superconducting materials have attracted much attention because of their excellent properties.However,the properties of YBCO thin films have been greatly affected because of the lattice mismatch and mutual diffusion between YBCO thin film and substrate.Therefore,the preparation of high quality YBCO buffer layer and dielectric layer is of great significance.The lattice constants of MgO thin films are similar to YBCO,with good thermal stability and strong insulation,which make MgO thin films play an important role in the preparation and application of YBCO thin films.For example,MgO can be used as a buffer layer of YBCO thin films to provide texture substrates in the field of strong electricity.In the field of weak electricity,MgO can be used as an insulating layer of YBCO multilayer structure or a barrier layer of Josephson junction.Therefore,it is significant to prepare MgO thin films with good orientation and microfabrication property.The main contents and conclusions of this experiment are as follows:(1)The preparation process of MgO sol was studied with magnesium acetate as raw material,methanol as solvent,acrylic acid and diethanolamine as additives.The MgO gel film was prepared on the Si substrate by impregnation and pulling method.The heat treatment process was explored.It was found that the crystalline MgO film could be obtained after pretreatment at 300℃ for 10min and treatment at 600℃ for 60min.(2)The effects of substrate and heat treatment on the orientation of the films were studied.The results showed that(100)oriented MgO films with good in-plane and out-of-plane texture could be obtained by preparing MgO films on LaAlO3 substrates after pretreatment at 300℃ for 10 min and final treatment at 850℃ for 60 min.(3)In order to prepare MgO thin films,photoreceptor MgO sol was prepared with benzoyl acetone(BzAcH)and acetylacetone(AcAc)as chelating agents,respectively.The sensitization mechanism of two kinds of sol and gel films was analyzed by UV and IR spectra.The results showed that the UV absorption peaks of Mg/BzAc and Mg/AcAc gel films appeared,and their intensity decreased with the extension of light duration,and photosensitivity was formed.It is shown that by comparing the absorption peak intensity and the change amplitude with the extension of light duration,it is found that the photosensitivity of the Mg/BzAc gel film is superior to that of the Mg/AcAc gel film,and is more suitable for the preparation of MgO fine graphics.(4)The photosensitive MgO sol was prepared by using BzAcH as chelating agent.After that,the MgO film was processed by ultraviolet mask method.The Mg/BzAc gel film was dried at 70℃ for 10min and exposed to 60min.The mixed solvent of methanol and isopropanol was used for washing,in which the volume ratio of methanol and isopropanol was 3:5,and the fine graphics of MgO gel film could be obtained.Furthermore,the fine patterns of MgO thin films with good quality were obtained after heat treatment at 850℃ for 60min.On this basis,high-density MgO thin film gratings with periods of 1 and 2 microns were fabricated by laser interferometry.